Organic Cotton Production


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Organic Cotton Production

  1. 1. ORGANIC COTTON PRODUCTION CURRENT TOPIC Abstract: Cotton sold as “organic” must be grown according to the federal guidelines for organic crop production. Soil fertility practices that meet organic certification standards typically include crop rotation, cover cropping, animal manure additions, and use of naturally occurring rock powders. Weed management is accomplished by a combination of cultivation, flame weeding, and other cultural practices. A wide variety of insects attack cotton. Management options include trap cropping, strip cropping, and managing border vegetation to encourage high populations of native beneficials. Certain biopesticides using bacteria, viruses, and fungal insect pathogens are available as insect control tools. We discuss specific insect management strategies for cutworm, cotton bollworm, tobacco budworm, pink boll- worm, armyworm, loopers, thrips, fleahoppers, lygus bugs, aphids, whitefly, spider mite, and boll weevil. Seedling disease, soil disease, and foliar disease management is also discussed. Pre-harvest defoliation methods that meet organic certification are mostly limited to citric acid, flamers and frost. The publication concludes with sections on marketing organic cotton and the economics and profitability of organic cotton production.By Martin Guerena andPreston SullivanNCAT Agriculture SpecialistsJuly 2003 Table of Contents Introduction .................................. 1 Overview of Organic Production ..................................... 2 Soil Fertility ................................... 2 © Crop Rotation ............................... 3 Cover Cropping ............................. 3 Weed Management ........................ 4 Introduction Insect Management Practices......... 5 Biopesticides .................................. 9 Organic cotton has provided significant price premiums for growers willing to meet the many Specific Insect Management challenges inherent in its production without the Strategies ..................................... 10 aid of conventional pesticides and commercial Diseases of Cotton ....................... 16 fertilizers. Growing organic cotton is demand- ing, but with commitment, experience, and de- Defoliation .................................. 18 termination, it can be done. This publication Marketing Organic Cotton .......... 19 covers the major steps in organic production of Economics and Profitability......... 19 cotton. It covers soil fertility, weed control op- Summary ..................................... 19 tions, and alternative pest controls for the many insect problems that plague cotton. Finally, mar- References .................................... 20 keting of organic cotton is discussed as well. Web Resources ............................. 23ATTRA is the national sustainable agriculture information service operated by the National Centerfor Appropriate Technology, through a grant from the Rural Business-Cooperative Service, U.S.Department of Agriculture. These organizations do not recommend or endorse products,companies, or individuals. NCAT has offices in Fayetteville, Arkansas (P.O. Box 3657, Fayetteville,AR 72702), Butte, Montana, and Davis, California.
  2. 2. Organic cotton acreage declined 18% from 2000 In order to market a crop as “organic,” a growerto 2001 in the seven states where most of it is must be certified through a third party. Thisgrown (Marquardt, 2002). Most of this decline process involves several on-farm inspections andcame from one large organic cotton farmer in paying a certification fee. More on this subjectNew Mexico who lost it all to drought and with- can be found in the ATTRA publication Organicdrew from organic cotton farming altogether. A Farm Certification and The National Organics Pro-total of 11,459 acres of either certified organic or gram. Applicants for certification are encouragedtransitional organic cotton was produced in 2001. to become familiar with provisions of the FinalTexas produced the most organic cotton—8,338 Rule posted on the USDA’s National Organicacres—with Arizona and California being the Program Web site, two highest producing states. nop.World production of organic cotton amounts to Organic production begins with organically6,000 tons of fiber annually, or about 0.03% of grown seed. If certified organic seed cannot beglobal cotton production. Turkey produces the located, untreated seed may be used as long as itmost at 29%, with the U.S. being second at 27% is not derived from genetically modified plants.and India third at 17% (Ton, 2002). Demand for Most certifiers will accept proof that growersorganic cotton is highest in Europe (about 3,500 have tried unsuccessfully to buy organic mate-tons or 58% of the total) and the U.S. (about 2,000 rial from at least three different suppliers as evi-tons or 33%) (Ton, 2002). Demand in the U.S. dence of unavailability. Federal organic regula-increased at an annual rate of 22% between 1996 tions also address composting and the use of rawand 2000 (Organic Trade Association, 2001; cited manures. These may have implications for cot-by Ton, 2002). ton production when used as fertilizer.Overview of Organic Production Soil FertilityGrowing cotton organically entails using cultural Mineral nutrition of crops in organic systemspractices, natural fertilizers, and biological con- comes from proper management of soil organ-trols rather than synthetic fertilizers and pesti- isms that are responsible for releasing nutrients.cides. A systems approach to organic produc- Rather than feeding plants with fertilizer, organiction involves the integration of many practices farmers feed the soil and let the soil organisms(cover crops, strip cropping, grazing, crop rota- feed the plants. The biological activity in the soiltion, etc.) into a larger system. Through good can be likened to a digestive process wherebysoil and biodiversity management, farms can organic food sources are applied to the soil andbecome increasingly self-sufficient in fertility, then digested by soil organisms to release nutri-while pest problems are diminished, and some ents for the crop. Soil mineral levels are built uppests are even controlled outright. A diverse through the application of animal manure, com-rotation, using legumes and other cover crops, post, soluble rock powders, and deep-rootedis at the heart of good humus and biodiversity cover crops that bring up nutrients from deepmanagement in an organic cropping system. within the soil. Plant nutrition is supplementedCotton, for example, would be but one of sev- with foliar fertilization in some situations. Soileral crops an organic farmer would grow. For fertility, levels of organic matter, minerals, pH,more complete coverage of general organic crop and other measurements can be monitored withproduction, we recommend the ATTRA publi- regular soil tests. The overall cropping sequencecation Overview of Organic Crop Production. fosters a system in which a previous crop pro- vides fertility benefits to a subsequent crop—such as a legume cover crop providing nitrogen to a following corn crop. Much more detailed soil- Throughout this publication, we use ex- fertility information is available from ATTRA in amples from conventional farming that illus- these publications: Sustainable Soil Management, trate principles relevant to organic cotton Manures for Organic Crop Production, Sustainable production. Management of Soil-borne Plant Diseases, and Sources of Organic Fertilizers and Amendments.PAGE 2 //ORGANIC COTTON PRODUCTION
  3. 3. Crop Rotation serving as a catch crop when planted to reduce nutrient leaching following a main crop.Crop rotation is a traditional agricultural prac-tice involving the sequencing of different crops Fast, dense-growing cover crops are sometimeson farm fields; it is considered fundamental to used to suppress problem weeds as a “smothersuccessful organic farming. Rotations are a crop” or allelopathic cover. The mere presenceplanned approach to diversifying the whole farm of most cover crops reduces the competition fromsystem both economically and biologically, weeds. Sometimes crops are no-till planted intobringing diversity to each field over time. such covers. If the cover crop is not killed, it is referred to as a “living mulch.” Some cover cropsRotations can benefit the farm in several ways. that have been used successfully for weed sup-Planned rotations are one of the most effective pression include small grains (particularly grainmeans of breaking many insect pest and plant rye), several brassica species, hairy vetch, anddisease cycles in the soil. Likewise, many prob- forage sorghums.lem weeds are suppressed by the nature and tim-ing of different cultural practices. Rotations also For the humid Cotton Belt, crimson clover, fieldaffect the fertility of the soil in significant ways. peas, and hairy vetch are excellent winter coverThe inclusion of forage legumes, in particular, crops for nitrogen production. Also, a mixturemay serve as the primary source of nitrogen for of hairy vetch and rye works well for overall bio-subsequent crops. mass production. When flowering, these pro- vide nectar and pollen as alternate food forRotation is an important means of controlling a beneficials. Hairy vetch is noted for its densenumber of cotton pests, including nematodes. spring cover and weed suppression. Cereal ryeEven basic corn-cotton rotations have been found provides an enormous amount of biomass to theeffective in reducing some species of nematodes soil and is known to attract and shelter benefi-(Anon, 1993). A minimum of two years planted cial insects. It also suppresses germination ofto non-host species is the standard recommen- small-seeded weeds when left as a mulch coverdation. on the soil surface. Natural allelopathic chemi- cals leach from the rye residue and inhibit weedA long-term cotton study at Auburn, Alabama, germination for about 30-60 days (Daar, 1986).showed that using winter annual legumes pro- Weed suppression effectively ends once the ryeduced cotton yields equivalent to those grown residue is incorporated. Weed suppression hasusing fertilizer nitrogen. The study found an 11% made rye attractive as a cover crop/mulch in no-yield increase for a 2-year cotton-legume-corn till and ridgetill systems. Mowing or a burn-rotation compared to continuous cotton grown down herbicide is often used in conventionalwith legumes each year. Adding conventional systems to kill the rye cover crop so that no-tillnitrogen fertilizer boosted the two-year rotation plantings of field crops can be established. Ancotton lint yields in this study another 79 pounds effective organic no-till system for cotton has yetper acre. A three-year rotation of cotton-vetch, to be developed, but early indications are that itcorn-rye (fertilized with 60 pounds of conven- will be. For more information on the potentialtional N/acre), followed by soybeans, produced for organic no-till see the ATTRA publicationabout the same cotton yields as the two-year ro- Pursuing Conservation Tillage Systems for Organictation (Mitchell, 1988). Crop Production, which discusses progress in this area. It is important to mow rye at the flowering stage when the anthers are extended, and pollenCover Cropping falls from the seed heads when shaken. If mow- ing is done earlier, the rye simply grows back.Cover crops are crops grown to provide soil cover As allelopathic weed suppression subsides, a no-and erosion protection. At the same time, cover till cultivator may be used for weed control. Thiscropping may accomplish a number of other ob- is not a proven system for organic cotton pro-jectives, including providing nitrogen to the sub- duction but only presented here as food forsequent cotton crop when tilled into the soil, thought about the development of future organicimproving tilth by adding organic matter, and no-till systems. //ORGANIC COTTON PRODUCTION PAGE 3
  4. 4. In addition to producing nitrogen, cover crops crops where used. The downside of this strat-often provide excellent habitat for predatory and egy may include risks of increased damage fromparasitic insects and spiders. Some good insec- certain insect pests such as boll weevil, tobaccotary plants often used as cover crops include al- budworm, and cotton bollworm.falfa, buckwheat, sweet clover, vetch, red clover,white clover, mustards, and cowpeas. Migration Cultivationof beneficials from the cover crop to the maincrop is sometimes associated with the post-bloom Tillage and cultivation are the traditional meansperiod of the cover crop. In these instances, of weed management for organic crops. Somemowing the cover crops in alternate strips may specific tillage guidelines and techniques forfacilitate their movement, while the remaining weed management include the following:strips continue to provide refuge for other ben-eficial species. Sickle-bar mowers are less dis- • Preplant tillage. Where weeds such asruptive to beneficials than flail mowers, rotary johnsongrass are a problem, spring-tooth har-mowers, and mower conditioners with crimpers. rows and similar tools can be effective in catching and pulling the rhizomes to the soilLong-term cotton cover-crop studies have also surface, where they desiccate and die.been done in Louisiana (Millhollon and Melville, Disking, by contrast, trends to cut and dis-1991) and Arkansas (Scott, 1990). The Arkansas tribute rhizomes and may make the standstudy spanned 17 years, from 1973 to 1988. Cot- even denser.ton grown after winter cover crops of rye + hairyvetch produced an average of 234 pounds more • Blind tillage. Blind cultivation employs fin-seed cotton per acre than a control treatment of ger weeders, tine harrows, or rotary hoeswinter fallow. Cotton following pure vetch during the pre-emergent and early post-showed a 129-pound increase, while yields after emergent phase. These implements are runrye + crimson clover had a 72-pound yield im- at relatively high speeds (6 mph plus) acrossprovement. the entire field, including directly over, but in the same direction as, the rows. The large-In the long-term Louisiana study, cotton yields seeded crops like corn, soybeans or sunflowerdeclined for the first nine years when cover crops survive with minimal damage, while small-were used, but increased steadily thereafter. In seeded weeds are easily uprooted and killed.the final four years of the study, cotton yields Post-emergent blind tillage should be donewere 360 pounds-per-acre higher following in the hottest part of the day when crop plantsvetch, compared to fallow + 60 pounds of fertil- are less turgid, to avoid excessive damage.izer N per acre. Averaged over the 30-year study Rotary hoes, not harrows, should be used ifperiod, the highest cotton yields followed wheat the soil is crusted or too trashy. Seeding rates+ 60 pounds of fertilizer N, hairy vetch alone, should be increased 5-10% to compensate forcommon vetch alone, or vetch + 40 pounds of N. losses in blind cultivation (Anon., 1991; Doll,For additional information on cover crops, see 1988).the ATTRA publication Overview of Cover Cropsand Green Manures. • Inter-row cultivation. When annual weeds are the concern, cultivation is best kept asWeed Management shallow as possible to bring as few weed seeds as possible near the soil surface. WhereCotton germinates at a soil temperature of 61° F perennial, rhizomaceous weeds are a prob-at a depth of about 2 in. With planting delayed lem, the shovels set furthest from the cropuntil the soil temperature reaches 66°, the crop row may be set deeper on the first cultiva-emerges rapidly and uniformly and is more vig- tion to bring rhizomes to the surface. Tinesorous (Head and Willians, 1996), giving it a com- are more effective than sweeps or duck feetpetitive edge on weeds. The delay in operations for extracting rhizomes. Later cultivationsalso allows additional growth of winter cover should have all shovels set shallow to avoidPAGE 4 //ORGANIC COTTON PRODUCTION
  5. 5. excessive pruning of crop roots. Earliest cul- These kits do not include hoses, a tank, or a tool tivations should avoid throwing soil toward bar. It is more cost-effective to pick these items the crop row. This places new weed seed into up locally from a gas dealer or salvage opera- the crop row where it may germinate before tion. An Arkansas cotton grower uses a “water the crop canopy can shade it out. As the crop shield” to help protect the cotton plants, but still canopy develops, soil should be thrown into feels flaming should be delayed until the crop the crop row to cover emerging weeds. has developed a woody bark on the stem (Ves- tal, 1992). Adapting flame technology requiresInter-row cultivation is best timed to catch weeds careful implementation. Thermal Weed Controlas they are germinating—as soon as possible af- Systems (TWCS), Inc. of Neillsville, Wisconsin,ter rain or irrigation, once the soil has dried and Flame Engineering, Inc. (FEI), of Lacrosse,enough to avoid compaction or surface crusting. Kansas, are two flame-weeding companies that can provide technical assistance and equipmentFlame Weeding (see References). LP gas usage depends on ground speed but generally runs from 8-10 gal-Prior to the 1950s, before modern herbicides be- lons per acre, according to sources at Thermalcame available, flame weeders were used in the Weed Control. For an overview of weed man-U.S. to control weeds in cotton, sugar cane, grain agement strategies and options for agronomicsorghum, corn, and orchards. Interest in flame crops, please request the ATTRA publicationweeding has resurfaced in recent years with ris- Principles of Sustainable Weed herbicide costs. Weeds are most susceptibleto flame heat when they are young seedlings 1–2 Insect Management Practicesinches tall or in the 3–5 leaf stage. Risk of dam-aging the cotton plants diminishes as the cotton Biological and cultural insect control involvesgrows and forms a bark on the stem. Broadleaf understanding the ecology of the surroundingweeds are more susceptible to flaming than agricultural systems and the cotton field andgrasses. Grass seedlings develop a protective making adjustments to production methods thatsheath around the growing tip when they are complement the natural system to our benefit.about 1 in. tall (Drlik, 1994). Consequently, re- To realize the full benefits of a biological ap-peated flamings may be necessary on grassy proach we need to move beyond asking how toweeds for effective control. Searing the plant is kill bugs and ask the larger question: Why domuch more successful than charring. Excessive we have bugs in our cotton fields in the firstburning of the weeds often stimulates the roots place?and encourages regrowth, in addition to usingmore fuel. In a nutshell, we invite pest problems by plant- ing large expanses of a single susceptible crop.Preplant flaming has commonly been referred to When cotton is the only food available, bugs areas the stale seedbed technique. Prepared seed- going to eat cotton. When we have a more di-beds are flamed after the first flush of weeds has verse farmscape involving many types of plantssprouted. Cotton planting follows the flaming and animals, the likelihood of severe pest out-without any further disturbance to the seedbed. breaks diminishes. For more information onAssuming adequate moisture and soil tempera- farmscaping, request the ATTRA publicationture, germination should occur within two Farmscaping to Enhance Biological Control.weeks. Note that a fine-to-slightly-compactedseedbed will germinate a much larger number Many types of insects feed on cotton plants andof weeds. threaten yields. Proper identification of these pests as well as their natural enemies is the firstCosts associated with flame weeding can vary. step in successful management of pests. StateFlamers have been built for $1,200 for an eight- Extension services typically have Internet basedrow unit (Anon., 1993) and for as much as $1,520 information that can help with pest and benefi-for a 12-row unit (Houtsma, 1991). Commercial cial insect identification. Once the pest is prop-kits cost around $1900 for an eight-row from erly identified, a scouting program with regularThermal Weed Control Systems (see References). monitoring can help determine the pest pressures //ORGANIC COTTON PRODUCTION PAGE 5
  6. 6. and the densities of beneficial insects. When pest growers strategies designed to save money andpressures reach the economically-damaging reduce the need for pesticides, chemical fertiliz-threshold, control actions become necessary. If ers, and water. The BASIC program utilized thebiological controls are to be used, they must be following strategies in their 2002 program thatstarted before the pests reach critical levels. That showed a 73% reduction in pesticide use overis why monitoring is so important. the Fresno County average (Figure 1). In Figure 1, the “enrolled acreage” had the free monitor-The use of beneficial insect habitats along crop ing, habitat plantings, and insect releases pro-field borders has shown to increase the presence vided to them. “Basic growers” had imple-of beneficial insects. These habitats provide shel- mented the principles on their own fields butter, pollen and nectar sources, and refuge if the without the direct involvement of the basic pro-fields are treated with a pesticide. In the event gram staff. Regular IPM, intensive monitoring,you are releasing purchased beneficial insects, beneficials, and beneficial habitat can reducethese field-edge habitats will encourage the pesticide use whether you are organic or conven-beneficials to remain and continue their lifecycle tional. For pesticide use questions or analysisin that location, helping reduce the pest popula- questions, contact Max Stevenson at:tion. Some pests may also inhabit the field-edge maxstevenson@yahoo.comhabitats; therefore, these habitats should be moni-tored along with the crop field. For additional 1. Intensive Monitoringinformation, request ATTRA’s Biointensive Inte- Fields enrolled in the program were moni-grated Pest Management and Farmscaping to En- tored weekly. Monitoring included an over-hance Biological Control. all picture of the field and the local condi- tions, the levels of pests and beneficials,Though not completely organic, the Sustainable farmscape observations, the status of the ad-Cotton Project’s BASIC program (Biological Ag- jacent beneficial habitat, and any unusualriculture Systems in Cotton) offers California sightings or areas for concern. Farmers were Lbs/acre pe sticide activ e ingre die nt Cotton Fre sno 2002 (of 12 targe te d pe sticide s) Pesticide Active Ingredient 2.5 2532 f ields 255,373 acres 2.0 (lbs/acre) 1.5 103 f ields 8,151 acres 1.0 11 fields 0.5 625 acres 0.0 Fre sno County BASIC growe rs, all BASIC e nrolle d av e rage acre age (Fre sno acre age (Fre sno only) only) Figure 1. Pesticide reductions resulting from the BASIC program in California.PAGE 6 //ORGANIC COTTON PRODUCTION
  7. 7. given a copy of the monitoring form, and the Marcia Gibbs at, overall results were published bi-weekly in or see the Web site at a newsletter.2. Strip Cutting of Alfalfa Intercropped with Cotton Trap Cropping One of the “best management practices” pro- moted by the BASIC program has been the A trap crop is planted specifically to attract pest stri p cu ttin g of alfalfa. Th is pra ctice insects. It is then sprayed with some type of in- prevents the immigration of certain species secticide, in conventional management, or left to at harvest time and keeps one of the main detain the pests from the cotton crop, or the en- cotton pests, Lygus Hesperus, from moving out tire trap crop is tilled under to kill the pest in- of the alfalfa (its preferred host) into the ad- sects. Early-sown cotton has been used as a boll- jacent cotton. BASIC field staff and mentor weevil trap crop. Using fall-planted-cotton trap growers were also able to provide technical crops to reduce the number of over-wintering support for growers wanting to implement a boll weevils was first proposed as early as the system of strip cutting. late 1800s (Javaid and Joshi, 1995). Both early and fall cotton trap crops are effective at attract-3. Bezzerides Weed Cultivator ing boll weevil adults and can be enhanced by A Bezzerides cultivator was tried by a BA- adding pheromones such as Grandlure™ to the SIC grower during the 2002 season. The cul- trap crop. The concentrated weevils can then be tivator works in the planted row where con- killed with organically accepted insecticides, ventional cultivators can’t reach. Traditiona- which are limited to a few botanicals and lly, this is the area where chemical herbicides biologicals. Crop consultants James and Larry are used to eliminate competing weeds. The Chiles were able to reduce the cost of boll weevil trial was not considered a success, since the control by 30% using trap crops of early and late- cultivator also removes cotton plants along planted cotton. Even with the cost reduction, with the weeds, and the growers who tested they were able to maintain good yields of 1000 the equipment felt that it was not significantly to 1200 pounds per acre. They planted a trap better than their existing cultivators. crop of cotton in early April, 30 days before the normal cotton planting time, and a late-planted4. Beneficial Habitat Planting trap crop on August 10. A weevil attractant Seventy percent of the growers enrolled in pheromone was used to lure boll weevils to the the 2002 BASIC program planted beneficial cotton trap crops. The trap crops were sprayed habitat adjacent to their enrolled fields. The for weevils whenever populations were high. habitat was intended to attract and hold natu- This technique reduced the number of early rally occurring beneficials. The remaining emergent weevils infesting the main crop and thirty percent of the enrolled fields were ad- reduced the number of weevils overwintering to jacent to alfalfa fields where strip cutting was attack the next year’s crop. In a Mississippi study, practiced. Laster and Furr (1972) showed sesame (Sesamum indicum) to be more attractive than cotton to the5. Beneficial Insect Releases cotton bollworm. Robinson et al. (1972) reported Releases of beneficial insects were also uti- more predators on sorghum than on cotton in his lized during the growing season. Thousands Oklahoma strip cropping study. Lygus bug may of lacewings and predatory mites were re- also be kept out of cotton by using nearby alfalfa leased to augment the naturally occurring in- as a trap crop. Unmowed or strip-mowed alfalfa sects. When growers see a pest problem start- is preferred by that pest over cotton (Grossman, ing to develop in their fields they want fast 1988). action and so will often turn to a chemical spray. Releasing insects helped them feel like Strip Cropping something was being done, while the natu- ral enemies took over the pest control. Strip cropping takes place when harvest-width strips of two or three crops are planted in theFor additional information on the Sustainable same field. The most common strip crop grownCotton Project or the BASIC program, contact with cotton is alfalfa. Increasing the diversity of //ORGANIC COTTON PRODUCTION PAGE 7
  8. 8. crops increases stability in the field, resulting in Phatak used a crimson clover seeding rate of 15-fewer pest problems, due to natural biological pounds per acre that produced around 60 poundscontrols. Crop rotation is one means of intro- of nitrogen per acre by spring. By late spring,ducing diversity over time. Strip intercropping beneficial insects were active in the cover crop.creates biodiversity in space. At that time, 6- to 12-inch planting strips were killed with Roundup™ herbicide (not allowedStrip cropping cotton fields with alfalfa gener- in an organic system). Fifteen to 20 days laterally increases beneficial arthropod populations. the strips were lightly tilled and the cottonAmong the most notable are carabid beetles that planted. The cover crop in the row-middles wasprey on cutworms and armyworms (Grossman, left growing to maintain beneficial insect habi-1989). Alfalfa has been found to be one of the tat. Even early-season thrips, which can be abest crops for attracting and retaining beneficial problem following cover crops, were limited orinsects. Strip-cutting alfalfa (i.e., cutting only half prevented by beneficial insects in this system.of the crop in alternating strips at any one time) When the clover is past the bloom stage and lessmaintains two growth stages in the crop; conse- desirable for beneficials, they move readily ontoquently, some beneficial habitat is available at the cotton. The timing coincides with a periodall times. In some cases alfalfa is mixed with when cotton is most vulnerable to insect pests.another legume and a grass. Following cotton defoliation, the beneficials hi- bernate in adjacent non-crop areas.In a conventional cotton management study,Stern (1969) interplanted 300–500 foot cotton Phatak emphasizes that switching to a whole-strips and 20-foot wide alfalfa strips to compare farm focus while reducing off-farm inputs is notpest control needs with monoculture cotton. The simple. It requires planning, management, andintercropped field required only one insecticide several years to implement on a large scale. It isapplication, while the monoculture cotton had just as important to increase and maintain or-to be sprayed four times. The practice was aban- ganic matter, which stimulates beneficial soildoned in this specific case, however, due to modi- microorganisms.fications to irrigation systems and extra labor tocut alfalfa, which did not compensate for the re- Managing Border Vegetationduced pesticide costs. Weedy borders are particularly infamous asDr. Sharad Phatak of the University of Georgia sources of insect pests. Current recommenda-has been working with conventional cotton tions suggest mowing them prior to establish-growers in Georgia testing a strip-cropping ment of cotton. Mowing after weeds havemethod (Yancy, 1994). Phatak finds that plant- formed flower buds will tend to drive plant bugsing cotton into strip-killed crimson clover im- into the cotton field (Layton, 1996).proves soil health, cuts tillage costs, and allowshim to grow cotton without any insecticides and Grassy weed species harbor lepidopterous pestsonly 30 pounds of commercial nitrogen fertilizer generally. A specific weed, wild geranium, is anper acre. Working with Phatak, farmer Benny important spring host of tobacco budworm andJohnson reported saving at least $120/acre on his should be discouraged in border areas.16-acre clover-system test plot. There were noinsect problems in the trial acres, while beet ar- More diverse field borders with habitat plantmyworms and whiteflies were infesting nearby species support some crop pests but also sustaincotton and required 8 to 12 sprayings. This sys- beneficial insects that prey on pest populations,tem may have some applicability in an organic particularly during non-crop seasons. Manag-cotton system. In the study, cotton intercropped ing the vegetation in these areas as habitat forwith crimson clover yielded 5,564 pounds of seed beneficial insects counterbalances the threat fromcotton per acre, compared with 1,666 pounds of insect pests. The strategy entails planting or oth-seed cotton in the rest of the field (Yancy, 1994). erwise encouraging the growth of plants thatBoll counts were 30 per plant with crimson clo- provide alternative food sources (nectar, pollen,ver and 11 without it. Phatak identified up to 15 alternate prey), moisture, shelter, and perchingdifferent kinds of beneficial insects in these strip- sites preferred by beneficials. Plant species thatplanted plots. are aggressive and invasive, or are known hostsPAGE 8 //ORGANIC COTTON PRODUCTION
  9. 9. to major crop diseases or insect pests, should be and timing of applications is optimal. Spray for-avoided. Descriptions of crops, cover crops, and mulations are most effective against armywormswild plants that are known to attract certain ben- and those species feeding on exposed leaf sur-eficial insects and information on designing land- faces. B.t. sprays are very effective against to-scapes to attract beneficial organisms can be bacco budworm and moderately effective againstfound in ATTRA’s Farmscaping to Enhance Bio- cotton bollworm (Layton, 1996). Because of theirlogical Control, which is available on request. feeding habits, granular bait formulations are more effective for control of cutworms. CarefulNatural Disease Organisms as Pest Control inspection of specific product labels will assure that the product has been formulated for the pestA naturally occuring fungal disease of aphids is to be controlled.known to occur under conditions of high infes-tation. In Mississippi, this historically occurs HNPV (Heliothis nuclear polyhedrosis virus) is abetween July 10-25 (Layton, 1996). Fungal dis- commercially produced disease organism thateases commonly attack and suppress populations attacks budworms and bollworms. It has less ofof lepidopterous pests, most notably the cabbage a track record in the Southeast than B.t., but basedlooper and beet armyworm. Suppression of these on preliminary observations it appears to be apests by natural disease organisms is encouraged viable biological pesticide (Steinkraus, 1992;by developing dense crop canopies, which also Anon., 1996). When using any biopesticide, beassists in weed control. However, these are also certain the formulation is cleared for use in or-conditions that encourage plant diseases and ganic production.may not be desirable where cotton diseases arerampant. Beauveria bassiana is an insect-disease causing fungus that has been formulated and is availableEarly Crop Maturation commercially. It works on several insect larvae, including cutworms and budworms. It worksEarly maturing crops are more likely to escape best during periods of high humidity. More ondamage from late-season infestations of boll this natural control method can be found belowweevil, tobacco budworm, cotton bollworm, ar- in the Specific Insect Management Strategies sec-myworms, loopers, and other pests. The use of tion.short-season cotton is the most obvious meansof doing this. Excessive nitrogen use, late irriga- Insecticidal Soaption, and excessive stand density can result indelayed maturity and increased exposure to these Evolved from a traditional organic gardeningpests, and should be avoided (Layton, 1996). technique, insecticidal soaps control insect pests by penetrating the cuticle and causing cell mem-Biopesticides branes to collapse and leak, resulting in dehy- dration. Several commercial formulations of in-B.t. (Bacillus thuringiensis) is a naturally occurring secticidal soap have been successfully used tobacteria that produces a toxin effective in con- control aphids, spider mites, white flies, thrips,trolling many caterpillars. The toxin causes pa- leaf hoppers, plant bugs, and other pests. Soapsralysis of the worm’s digestive tract. Worms may have limited effects on chewing pests such ascontinue to live for some hours after ingestion, beetles or caterpillars. Applied as sprays, thesebut will not continue to feed. B.t. strains have biodegradable soaps work by contact only andbeen formulated into a number of commercial require excellent coverage to be fully effectiveproducts under various trade names. B.t. de- (Harmony Farm, 1996; Ellis and Bradley, 1992).grades rapidly in sunlight, requiring careful tim-ing or repeated applications. Insecticidal soaps will kill many beneficial insects and must be used with that in mind. Phytotox-B.t. must be ingested in sufficient amounts by icity has also been demonstrated, particularly onthe caterpillar to be effective. Consequently, an crops with thin cuticles (Ellis, 1992). Differentunderstanding of the feeding habits of the pests varieties of cotton will have different plant char-is necessary, so that proper formulations are used acteristics. Therefore, it is advisable to test the //ORGANIC COTTON PRODUCTION PAGE 9
  10. 10. soap solution on your plants on a small strip to If natural pesticide applications are necessary,determine whether any harm will result. Avoid choose one that is least disruptive to the naturalapplication of soap during the heat of the day, enemies. The application of a rolled oats withbecause the plant is then under extreme stress, molasses bait containing Bacillus thuringiensis orand you want the soap to remain on the plant as nighttime spraying of Bacillus thuringiensis is ef-long as possible, not evaporate rapidly. Late day fective. Again, early detection and applicationapplications will stay on the plant longer, increas- during the early developmental stages of the lar-ing the chances of contact with target pests. vae (1st and 2nd instar) make these biorationalWater hardness will affect the efficacy of soap, pesticides more effective. Pheromone traps willbecause calcium, iron, and magnesium will pre- indicate when mating flights are occurring, andcipitate the fatty acids and make the soap use- through degree-day calculations one can estimateless against the target insects. The best way to egg laying and hatching. For information on de-determine how well your water will work is the gree-day calculations contact your local Exten-soap-jar test. Let a jar full of your spray solution sion agent.sit for 20 minutes, then look for precipitates inthe soapy-water solution. Product labeling must Thyme oil serves as a toxicant, insect growthbe studied to determine suitability to crop and regulator, and antifeedant to cutwormspest in each particular state and region. (Hummelbrunner and Isman, 2001). Mock lime or Chinese rice flower bush, Aglaia odorata, in-Specific Insect Management Strategies hibits larval growth and is insecticidal to the cut- worms Peridroma saucia and Spodoptera lituraCutworms (Janprasert et al,1993). No commercial products using tyme oil, mock lime, or Chinese rice flowerCutworms wreak havoc during seedling estab- are known to us at this time. Azadirachtin, thelishment in many cotton-growing areas. Cut- active ingredient in neem, has similar effects onworm species include the variegated cutworm, various insects and is used in the form of neemPeridroma saucia; black cutworm, Agrotis ipsilon; cakes to control soil pests in India. Certis USAgranulate cutworm, Feltia subterranea; and army produces Neemix Botanical Insecticide. Its ac-cutworm, Euxoa auxiliaris. They are active at tive ingredient, Azadirachtin, is registered fornight, feeding and chewing through the stems cutworm, looper, armyworm, bollworm, white-of the seedlings. In the day they burrow under- fly, and aphid control on cotton.ground or under clods to avoid detection. Toinspect for cutworms, dig around the damaged Cotton bollworm and tobacco budwormareas during the day or come out at night with aflashlight to catch the culprits in the act. Prob- The tobacco budworm, Heliothus virescens, andlem areas are usually found near field borders cotton bollworm, Heliothus zea or Helicoverpaand in weedier areas. armigera, attack cotton in similar ways, damag- ing bolls, squares, and blooms, and feeding onCutworms have many predators and parasites plant terminal buds, causing branching that de-that can help control their numbers. Some of lays maturity. On mature damaged bolls, onethese parasites and predators can be purchased finds holes with excrement or frass surroundingor harnessed naturally through planting or con- the boll. These holes provide entry to secondaryserving habitat for them. organisms that can cause decay. Besides cotton, other bollworm hosts include alfalfa, beans, corn,Understanding the biology of beneficial organ- peanuts, sorghum, soybeans, peppers, sweetisms is imperative in order to use them effectively potatoes, tobacco, and tomatoes. Wild hosts in-as pest control agents. For example, insect para- clude toadflax, deergrass, beggarweed,sitic nematodes like Steinerema carpocapsae or in- groundcherry, geranium, and sowthistle. Insect-infecting fungi like Beauveria bassiana require feeding preference tests, 67% of females preferredadequate humidity to be effective. Other preda- common sowthistle, about 5% preferred cotton,tors include spiders, minute pirate bugs, damsel and 28% did not discriminate. Commonbugs, and lacewing larvae. Birds also prey on sowthistle was also the most preferred by newlycutworms, so do not assume that the birds in the hatched larvae among the five host plant typesfield are causing the seedling damage. presented in a multiple-choice test. (Gu andPAGE 10 //ORGANIC COTTON PRODUCTION
  11. 11. Walter, 1999). This suggests some possible man- the principal active ingredient in many neem-agement strategies using sowthistle as a trap based products, also shows promise as a growthcrop. regulator and anti-feedant against the cotton bollworm (Murugan et al., 1998).This bollworm “complex” has many natural en-emies that can be harnessed through the use of Pink bollwormbeneficial habitats or purchased from insectaries.Generalist predators such as assassin bugs, Pink bollworm, Pectinophora gossypiella—or pin-bigeyed bugs, damsel bugs, minute pirate bugs, kies, as they are commonly called—is a signifi-lacewing larvae, collops beetles, and spiders will cant cotton pest in the Southwest. They have alsofeed on the eggs of bollworm or on the larvae been found in Texas, Oklahoma, Arkansas, andthat are in early stages of development. Para- Florida. Pinkies damage cotton by feeding onsites like the wasps Trichogramma spp., Chelonus buds and flowers and on developing seeds andtexanus, and Hyposoter exiguae, and the parasitic lint in bolls. Under dry conditions, no measur-fly Archytas apicifer, parasitize eggs, larvae and able yield reduction occurs until 25 to 30% of thepupae. These groups of natural enemies are usu- bolls are infested; at this level the infested bollsally enough to keep bollworms below economi- have more than one larva. With high humidity,cally damaging thresholds. In conventional it takes only one or two larvae to destroy an en-fields where broad-spectrum insecticides are tire boll, because damaged bolls are vulnerableused, these natural enemies are so depleted that to infection by fungi that cause boll rot (Rude,continuous spraying is required to keep boll- 1984). Damaged bolls will have a pimple or wartworms and other pests in check. that develops around the hole where pinkies have entered. Unlike cotton bollworm or tobaccoCultural practices that keep bollworm numbers budworm, pinkies do not deposit frass or fecesdown include managing the cotton field to ob- at the base of the entrance hole.tain an early harvest and avoiding over-fertiliz-ing or over-watering. Tillage significantly low- Cultural practices to reduce pink bollworm num-ers bollworm populations by disrupting emer- bers consist of ceasing irrigation sooner thangence from the overwintering stage. Minimum normal, early crop harvest, shredding crop resi-tillage operations may favor bollworm popula- due after harvest, plowdown of cotton residuetions, except in the South, where minimum till- to six inches, and winter irrigation if cotton willage favors fire ant colonization (Monks and follow cotton on the same field (not a wise prac-Patterson, no date). Fire ants are effective preda- tice in organic production). Okra and kenaf aretors of many cotton pests, including bollworm. alternate hosts to pink bollworm and must also be eliminated from an area. These techniquesFor sprays of Bacillus thuringiensis (B.t.) to be ef- are used in area-wide eradication efforts. Area-fective, they need to be timed so that the boll- wide sterile release programs through the Ani-worm larva is in its early stages of development mal and Plant Health Inspection Service (APHIS)(1st or 2nd instar). Night spraying will prolong of the USDA is a biological control method alsothe exposure to the B.t., since ultraviolet rays of used in eradication efforts.the sun break it down. The use of Beauveriabassiana as a biopesticide can be effective against Pink bollworm eggs are very small, making thembollworm only when temperature and humidity susceptible to many natural enemies, includingrequirements are met. Research from China in- mites, spiders, minute pirate bugs, damsel bugs,dicates that the ideal temperature and humidity bigeyed bugs, and lacewing larvae. A numberfor high bollworm kill using Beauveria bassiana is of parasitic wasps such as Trichogramma bactrae,77oF with humidity between 70-95%. Mortality Microchelonus blackburni, Bracon platynotae, anddrastically decreased when humidity dropped Apanteles ornone attack pink bollworm. Studiesbelow 70% (Sun et al., 2001). Nuclear polyhe- have shown that the use of the insect-feedingdrosis virus, another biopesticide, is a disease- nematodes Steinernema riobravis and S. carpocapsaecausing virus for use on the bollworm complex on pink bollworm larvae in the fields achieved aand is available commercially in a product call larval mortality rate of 53 to 79% (Gouge et al.,Gemstar LC™ from Certis USA. Azadirachtin, 1997). //ORGANIC COTTON PRODUCTION PAGE 11
  12. 12. The success of insect-killing fungi like Beauveria supply houses and is also available in pill formbassiana depends on the timing of the applica- from most pharmacies. Organic growers inter-tion to correlate with hatching and early stages ested in this approach should ask their certify-of development of the pink bollworm, as well as ing agency about the appropriateness of thisoptimum humidity for the fungi to infect. treatment in a certified organic system.Other strategies to reduce pink bollworm popu- Many other crops are hosts to armyworms, aslations include the use of mating pheromone are the weeds mullen, purslane, Russian thistle,disruptors. Several products, such as Biolures®, crabgrass, johnsongrass, morning glory,Checkmate®, Frustrate®, and PB Rope®, are lambsquarters, nettleleaf goosefoot, and pig-available in the U.S. Pink bollworm mating dis- weed. These last three are preferred hosts thatruption trials recorded higher yields (1864 lbs/ can serve as indicators of the populations or beacre) than control fields with no mating disrup- managed as trap crops.tion (1450 lbs/acre) (Gouge et al., 1997). LoopersArmyworms The cabbage looper, Trichoplusia, feeds on leafBeet armyworm, Spodoptera exigua, and fall ar- areas between veins causing a net-like appear-myworm, Spodoptera frugiperda, can both feed on ance but rarely cause significant damage, becausecotton and on rare occasions cause yield reduc- natural enemies control them. If the enemies aretions. Beet armyworms can cause yield reduc- lacking in number, severe defoliation of cottontions in cotton if populations are high enough plants by loopers may cause problems with bollnear the end of the season. Armyworms hatch maturation. Defoliation before bolls mature canin clusters, with the small worms spreading reduce yields drastically.through the plant over time, feeding on leaves,squares, flowers, and bolls. They skeletonize Loopers feed on all the crucifers, crops andleaves and bracts, trailing frass and spinning weeds, and on melons, celery, cucumbers, beans,small webs as they go. The egg clusters are cov- lettuces, peas, peppers, potatoes, spinach, squash,ered with white cottony webbing, making them sweet potatoes, and tomatoes. Other hosts in-easy to spot. Outbreaks are attributed to favor- clude some flowers, like stocks and snapdrag-able weather conditions and the killing off of ons, and tobacco. Some weed hosts includenatural enemies. lambsquarters, dandelion, and curly dock.Natural enemies are assassin bugs, damsel bugs, Natural enemies are assassin bugs, bigeyed bugs,bigeyed bugs, lacewing larvae, spiders, the para- damsel bugs, minute pirate bugs, lacewing lar-sitic flies Archytas apicifer and Lespesia archippivora, vae, spiders, and numerous parasitic wasps, suchand the parasitic wasps Trichogramma ssp., as Trichogramma pretiosum, Hyposoter exiguae,Hyposoter exiguae, Chelonus insularis, and Cotesia Copidosoma truncatellum, and Microplitis brassicae.marginiventris. The parasitic fly Voria ruralis also contributes to looper control. Trichoplusia ni NPV (nuclear poly-Nuclear polyhedrosis virus is a disease-produc- hedrosis virus) sometimes is responsible for sud-ing virus that infects beet armyworm. It is avail- den looper population decline, especially afterable in the product Spod-X LC (Certis). Bacillus rainfall. Bacillus thruingiensis is effective whenthruingiensis on young worms is effective if ap- the problem is detected early.plication is thorough. Laboratory and green-house tests showed that caffeine boosted the ef- Thripsfectiveness of the B.t. against armyworms up to900 percent (Morris, 1995). Its use is most prom- Thrips damage seedlings by rasping and suck-ising against pests that are weakly susceptible to ing the surface cells of developing leaves, result-B.t. itself. Recipe: dissolve 13 oz. pure caffeine ing in twisted and distorted young leaves. Theyin water; add the solution to 100 gallons of stan- are rarely a problem and are usually kept in checkdard B.t. spray; apply as usual. (Morris, 1995). by minute pirate bugs, parasitic wasps, preda-Caffeine can be obtained from most chemical- cious mites, and other thrips. The western flowerPAGE 12 //ORGANIC COTTON PRODUCTION
  13. 13. thrip can be a beneficial insect when it feeds on black specks covering its yellowish-green body.spider mites on a full-grown plant. The bean The whitemarked fleahopper, Spanagonicusthrip, Caliothrips fasciatus, feeds on older cotton albofasciatus, is the same size and resembles theleaves and sometimes causes defoliation. Insec- predatory minute pirate bug, Orius sp. andticidal soap is the least toxic pesticide for thrips Anthocoris sp.. Fleahoppers cause damage bybut should not be applied on hot sunny days stinging the squares, which then drop from thebecause it may burn the plants. Research has plant, reducing yields. In 1999 the cotton flea-demonstrated that cotton varieties with hairy hopper was the most damaging insect in cotton,leaves are less injured by thrips than smooth-leaf responsible for nearly a third of the total reduc-varieties (Muegge et al., 2001) tion in yield caused by all insect pests in the U.S. Total U.S. insect losses represented more thanWayne Parramore of Coolidge, Georgia, strip two million bales that year. (Williams et al.,crops cotton into lupine, providing him with ni- 2000). Fleahopper infestations usually occur introgen, soil erosion control, and a beneficial in- fields near weedy and uncultivated ground orsect habitat to control thrips (Dirnberger, 1995). near weedy borders. Some of these weeds, likeWhen the lupine is 36 inches tall, a strip is tilled false ragweed, Parthenium hysterophorus, wolly14 inches across the seedbed. A Brown plow in croton or goatweed, Croton capitatus, and horse-front of the tractor with a rotovator in the back mint, Monarda punctata, release volatile com-exposes the center strip, warming it up for the pounds that have been shown to be preferred byplanting of cotton. The remaining lupine is host fleahoppers over cotton (Beerwinkle andto aphids, thrips, and their natural enemies. It Marshall, 1999). Once the weeds start to matureprevents weeds and grasses from growing up and dry out, the pests will move to the cotton.and it reduces soil erosion. The remainder of This information can help with monitoring andlupine that is tilled in later provides a second shot establishing a trap crop system. Natural enemiesof nitrogen to the cotton. The Parramores report of fleahoppers include assassin bugs, bigeyedthat strip tilled cotton-lupine required only two bugs, damsel bugs, lacewing larvae, and spiders.insecticide applications. They later determined A study done in east Texas showed that spidersthat they could have done without the second were three times better than insects as predatorsspraying in the lupine field, based on a check- of the cotton fleahopper (Sterling, 1992).plot comparison. Neighboring conventionalfields took five spray applications. Lygus or tarnished plant bug These bugs are represented by the species Lygus In Parramore’s own words: hesperus, L. elisus, L. desertinus, and L. lineolaris. The first three species are found in the South- “By having these crop strips in my field, I have west, and L. lineolaris is found in the rest of the insects evenly distributed – nonbeneficials cotton belt. They pierce stems and suck plant feeding beneficials. Now when the cotton gets juices, causing damage to flower buds (squares), big enough for the legume to die, where are young bolls, and terminal buds. Because almost the beneficials gonna be? They’re not going any plant that produces a seed head can be a ly- to be all around the edges of the field and gus host, this pest has a wide range. Cotton is slowly come across the field; they’re all over not the preferred host of lygus, but once the sur- the field already. They’re in the middle where rounding vegetation starts to dry up, they will lupine is still growing inches away from cot- move into irrigated cotton and feed on succulent ton plants. We’re looking at a savings and plant parts. Alfalfa is a preferred host to lygus increase in production of approximately and can be grown in strip intercrops with cotton $184.50 per acre.” to assist in lygus control. The classic habitat manipulation system where alfalfa is strip har- vested or where borders are left uncut demon-Fleahoppers strates that lygus can be kept away from cotton during critical square formation. The alfalfa alsoThe cotton fleahopper, Pseudatomoscelis seriatus, harbors numerous natural enemies of lygus,is a small bug measuring about 1/8 inch, with keeping their populations in check. These natu- //ORGANIC COTTON PRODUCTION PAGE 13
  14. 14. ral enemies include the tiny wasp Anaphes iole, can contribute to boll weevil control if conditionswhich parasitizes lygus eggs, and predators like are favorable and suitable habitats are available.damsel bugs, bigeyed bugs, assassin bugs, lace-wing larvae, and spiders. If lygus populations Catolaccus grandis is originally from tropicalare reaching economically damaging levels, then Mexico but has been effective in controlling bolla pesticide application is warranted. Check with weevils in augmentative releases done in USDAyour organic certifier to determine which pesti- cooperative studies. The researchers achievedcides are allowed. Botanical insecticides such as from 70 to 90% boll weevil parasitism (King etpyrethrum, sabadilla, and rotenone are options al., 1995). Releases began on July 19 at 350 fe-but may be prohibitively expensive. Insecticidal males per acre per week over a nine-week pe-soaps can reduce the lygus nymph population. riod. The objective was to suppress or eliminateKeep in mind that these treatments will also af- weevil reproduction in six organic cotton fields.fect the natural enemies and may cause second- Similar work done in Brazil resulted in Catolaccusary outbreaks of pests like aphids and mites. grandis inflicting significant mortality on third instar weevils. The use of augmentative releasesBoll weevil strategies of C. grandis has a very high potential for supple- menting and enhancing available technology forThe boll weevil, Anthonomus grandis, is consid- suppressing boll weevil populations (Ramalhoered by some as the primary deterrent to grow- et al., 2000). Catolaccus grandis is currently noting cotton organically. In weevil eradication commercially available.zones, the boll weevil may be less of a concern.Conventional controls consist of applying pesti- Other alternative methods used by organic cot-cides to target the adults when they start feed- ton growers in Texas against the boll weevil areing and laying eggs. For organic systems, using pyrethrum used with diatomaceous earth, garlicthis approach with organically accepted pesti- oil and fish emulsion as repellants, and phero-cides would be too costly and only moderately mone traps for early detection. For more infor-effective. mation on Texas organic cotton growers and the boll weevil eradication zones, check the Web site:The use of short-season cotton may be part of an strategy to control boll weevils with littleor no sprayed insecticides. The objective of short- Aphidsseason cotton is to escape significant damagecaused by the second generation of weevils, Aphid problems in conventional cotton are usu-through early fruiting and harvest. For this to ally the result of secondary pest flair ups causedoccur, the population of first generation weevils by excessive spraying for a primary pest like ly-must also be low. Crop residue management and gus or bollweevil, because the broad-spectrumfield sanitation is essential. Destruction of cot- insecticides also kill the beneficial insects.ton stalks soon after harvest has long been rec- Aphids are usually kept below economicallyognized as a useful practice for reducing the damaging levels by predators like the ladybug,number of overwintering weevils (Sterling, 1989). syrphid fly larva, lacewing larva, minute pirate bug, and the parasitic wasp Lysiphlebus testaceipes.Early harvest, sanitation, and immediate The damage caused by aphids and other ho-plowdown are strategies that keep the overwin- mopterans, like whiteflies, comes from their hon-tering populations low for the following season. eydew excretion that contaminates the lint andIn order for these strategies to be effective, they causes sticky cotton. A study conducted inmust be practiced by all cotton growers in an Georgia’s coastal plain indicates that aphids arearea. Any volunteer cotton plants that are missed initially suppressed by the insect-eating funguscan be the source of infestation for the following Neozygites fresenii, and were kept at low levelscrop season. thereafter by parasitoids and predators, most notably the small lady beetles of the Scymnus spp., preventing further outbreak (Wells, 1999).The boll weevil has two effective insect parasites,Bracon mellitor and Catolaccus grandis. Bracon The choice of cotton varieties influences the abun-mellitor occurs naturally in North America and dance of cotton aphids and their associatedPAGE 14 //ORGANIC COTTON PRODUCTION
  15. 15. biological-control agents. A study comparing tract. Check with your certifier before applyingcotton varieties found lower aphid densities on any of these products.cotton varieties exhibiting the smooth-leaf char-acteristics. Parasitism and predation may have Whiteflyreduced cotton aphid population growth earlyin the season. Disease-causing fungal infection Whiteflies are similar to aphids in that they piercewas the primary cause of an aphid population stems and suck plant sap then excrete honeydewreduction that occurred during the week after that contaminates the lint. The adult whiteflyspeak aphid abundance, and continued disease resemble tiny white moths, the nymphs are moreactivity combined with predation maintained like scale insects. They are found on the under-aphids at a low density for the remainder of the sides of cotton leaves, and when their numbersseason (Weathersbee and Hardee, 1994). are high enough, the honeydew falls to leaf sur- faces below where sooty mold forms, turning theNitrogen management is an important tool in leaf black. Whiteflies are usually kept in checkcontrolling aphid infestations, though less eas- by natural enemies, unless broad-spectrum pes-ily done without commercial fertilizers. Studies ticides are applied for a key pest. If most preda-have shown that excessive or poorly timed fer- tors and parasites are killed, then the potentialtilizer-N application will promote tender and for devastating outbreaks exists. Beneficial in-succulent plant growth that attracts aphids. In sects that prey on whiteflies are lacewing larvae,California, experiments showed that cotton lady beetles, minute pirate bugs, and bigeyedaphids reached higher densities in high nitrogen bugs. Parasites include Ecarsia formosa, Ecarsiafertilized plants (200 lbs. N/ac.) than in low ni- meritoria, Encarsia luteola, Encarsia pergandiella,trogen fertilized plants (50 lbs. N/ac.) (Cisneros Eretmocerus haldemani, and Eretmocerusand Godfrey, 2001). This increase in aphid pres- californicus. Some of these parasites are specificsure has also increased insecticide application, to the greenhouse whitefly, Trialeurodesfrom an average of 2-3 to 4-6 or more per season vaporariorum, or the sweetpotato whitefly, Bemisiain recent years in many areas (Godfrey et al., tabaci, or the bandedwing whitefly, Trialeurodes1999). abutilonea, or the silverleaf whitefly, Bemisia argentifolii. Some of these beneficials parasitizeThe concept of induced resistance in plants has more than one whitefly species. These nymphsgenerated much interest in alternative pest con- are what most predators and parasites attack.trol circles recently. Plants can be treated withsubstances that induce resistance to plant pests. If whitefly populations near threshold levels, useOne of these substances, jasmonic acid, has been insecticidal soap or “narrow range” oil (checkused on cotton to determine the effect it has on with your certifier to determine which oils arecotton aphid, two spotted spider mites, and west- allowed) to reduce primarily the nymph andern flower thrips. Preference was reduced by pupa stage of the whitefly. Botanical insecticidesmore than 60% for aphids and spider mites, and like neem can reduce adult populations and alsoby more than 90% for thrips on jasmonic-acid- act as an insect growth regulator affecting theinduced leaves compared with control leaves pupal stage. Other botanical insecticides such(Omer et al., 2001). The effective ingredient from as pyrethrum can help reduce the adult popula-jasmonic acid is an essential oil isolated from the tion. Insect-eating fungi such as Beauveriaextracts of the jasmine plant, Jasminum bassiana are slow acting and require adequategrandiflorum. The release of plant volatiles asso- humidity. An effective sprayer that has enoughciated with the application of jasmonic acid also power to cover both sides of the leaf surface isattracts natural enemies. Other plant resistance needed, and at least 100 gallons of water per acreinducers include salicylic acid (aspirin) and salts is necessary to have sufficient potassium phosphate and potassium silicate.Amino acids such as beta-aminobutryic acid and In conventional cotton, nitrogen fertilizer man-botanicals such as the extract of giant knotweed, agement is also a factor in whitefly populationReynoutria sachalinensis, can produce systemic levels and the amount of honeydew produced.resistance (Quarles, 2002). Milfana® is a com- A California study demonstrated that increasingmercial product made from giant knotweed ex- levels of nitrogen fertilizer increased densities of //ORGANIC COTTON PRODUCTION PAGE 15
  16. 16. both adult and immature whiteflies during their Diseases of Cottonpeak population growth on cotton. Higher ni-trogen treatments also resulted in higher densi- Diseases in plants occur when the pathogen isties of honeydew drops produced by the white- present, the host is susceptible, and the environ-flies (Bi et al., 2000). ment is favorable for the disease to develop. Eliminating any one of these three factors willSpider mite prevent the disease from occurring. Organisms responsible for cotton diseases include fungi,Spider mites, Tetranychus spp., are tiny arachnids bacteria, nematodes, and viruses. If these organ-(related to spiders, ticks, and scorpions) that live isms are present, then manipulation of the envi-in colonies, spinning webs and feeding under ronment and the host, to make it less susceptible,cotton leaves. Spider mites have modified mouth helps to better manage diseases on cotton in aparts that pierce the cells of the leaf to consume sustainable manner.its contents. On the leaf’s upper surface yellowspots appear when the feeding is moderate. Once Soil health and management is the key for suc-the plants are infested, the yellow spots turn red- cessful control of plant diseases. A soil with ad-dish brown. If the infestation is severe, mites equate organic matter can house uncountablecan cause defoliation and affect yields. Spider numbers of organisms such as bacteria, fungi,mite populations are usually suppressed by natu- amoebae, nematodes, protozoa, arthropods, andral enemies, unless a broad spectrum insecticide earthworms that in conjunction deter harmfulapplication occurs to disturb this balance. Insect fungi, bacteria, nematodes and arthropods frompredators of spider mites include minute pirate attacking plants. These beneficial organisms alsobugs, damsel bugs, bigeyed bugs, some midges, help in creating a healthy plant that is able tolacewing larvae, dustywings, spider mite de- resist pest attack. For more information, see thestroyers, lady beetles, sixspotted thrips, and west- ATTRA publication Sustainable Management ofern flower thrips. Other mites that prey on spi- Soil-Borne Plant Diseases.der mites are Amblyseius ssp., Galendromus spp.,Metaseiulus spp., and Phytoseiulus ssp. When The leaf surface can also host beneficial organ-scouting for mites, a hand lens is necessary to isms that compete with pathogens for space. Adistinguish the pest mites from the predatory disease spore landing on a leaf surface has to findmites. Spider mites tend to be sedentary, while a suitable niche for it to germinate, penetrate, andtheir predators are very active. infect. The more beneficial organisms on the leaf, the greater the competition for the spore to findInsecticidal soaps, “narrow range” oils, neem- a niche. Applying compost teas adds beneficialbased products such as Trilogy®, and sulfur are microorganisms to the leaf, making it more dif-acceptable miticides in organic production (check ficult for diseases to become established. Forwith certifier regarding specific products). Ap- more information on foliar disease controls, seeplication instruments must thoroughly cover the the ATTRA publications Notes on Compost Teas,leaves’ undersides, and products that are diluted Use of Baking Soda as a Fungicide, Organic Alterna-must be applied in high volumes (more than 100 tives for Late Blight Control on Potatoes, and Pow-gallons of water per acre) to achieve complete dery Mildew Control on Cucurbits.coverage. Seedling diseasesCultural controls include keeping dust downalong roads that border cotton fields. This is usu- These diseases are soil-borne fungi and are asso-ally done by reducing traffic along those roads ciated primarily with Rhizoctonia solani, Pythiumor watering down the roads. Reducing water spp., and Thielaviopsis basicola. Cool wet soils,stress on the cotton plants helps prevent mite deep seed placement, soil compaction, and coolbuild up. Pima cotton varieties are less suscep- temperatures contribute to seedling disease de-tible to mites than highland varieties (Anon. velopment. Spreading compost and using green2001). manure crops, especially grasses, can reduce thePAGE 16 //ORGANIC COTTON PRODUCTION
  17. 17. pathogen levels in the soil. Various organisms Verticillium wilt caused by Verticillium dahliae ishave been researched as potential biological widespread, attacking many other agronomic,controls, these include Burkholderia cepacia, horticultural, and ornamental crops, as well asGliocladium virens, Trichoderma hamatum, some weeds. It is persistent in the soil becauseEnterobacter cloacae, Erwinia herbicola, of survival structures called microsclerotia.rhizobacteria, and fluorescent pseudomonads as These microsclerotia are produced throughoutseed treatments. (Zaki et al., 1998; Lewis and the infected plant and when the crop is disked,Papavizas, 1991; Howell, 1991; Nelson, 1988; these seed-like structures are also incorporatedDemir et al., 1999; Laha and Verma, 1998). into the soil. Cultural controls include resistant varieties (Pima cotton is tolerant), rotation withOf these organisms, Burkholderia cepacia is avail- grass crops, management for short season pro-able commercially in a product called Deny®. duction, and avoiding excessive nitrogen and ir-Another microorganism, Bacillus subtilis, sold rigation. Soil solarization done 6-11 weeks be-under the trade name Kodiak®, is recommended fore planting was effective in one study whereas a seed inoculant for controlling damping off the pathogen was reduced to negligible levelsfungi. The following organisms have been used (Basalotte et al., 1994).as soil treatments with varying levels of success:Stilbella aciculosa, Laetisaria arvalis, Gliocladium There are many types of nematodes in soils, mostvirens, and Trichoderma longibrachiatum (Lewis are beneficial, and a few are cotton pests. Whereand Papviazas, 1993; Lewis and Papviazas, 1992; nematode infestations are heavy, sampling andSreenivasaprasad and Manibhushanrao, 1990). laboratory analysis can be used to determine the length of rotations and the non-host crops to use.Soil diseases If the problem is root-knot nematodes, rotation to resistant soybean varieties or sorghum is aThe three most important fungal soil diseases possibility. Rotation to wheat, corn, grain sor-that cause economic damage are Fusarium ghum, or resistant soybeans is possible if theoxysporum, Phymatotrichum omnivorum, and Ver- nematodes are the reniform species (Lorenz,ticillium dahliae. Nematodes are soil-dwelling, 1994; O’Brrien-Wray, 1994). Nematodes that at-microscopic, worm-like animals. Only a few spe- tack cotton are the root knot nematode,cies are damaging to cotton. They will be classi- Meloidogyne incognita, reniform nematode,fied in this publication as a soil disease. Rotylenchulus reniformis, and the Columbia lance nematode, Hoplolaimus columbus. In sustainableFusarium alone rarely causes economic problems, production systems, nematodes can be managedbut when associated with nematodes, it forms a by crop rotation, resistant varieties, and culturalcomplex in which the nematode damage weak- practices. Eventually a “living soil” will keepens the plant, making it susceptible to the fun- harmful nematodes and soilborne fungi undergus. Organic matter and its associated microor- control (Yancy, 1994). Crop rotation is a goodganisms can serve as an antagonist to this dis- strategy, but make sure to identify the type ofease. The use of Bacillus subtilis products nematode you have and rotate with a crop that(Kodiak®) as a seed inoculum is recommended. is not an alternate host for that nematode. ForThe strategies for nematode control will be dis- example, the reniform nematode also feeds oncussed further on in this publication. vetch, tobacco, soybeans, tomatoes, and okra, so these crops are not suitable for rotation with cot-Texas root rot, caused by Phymatotrichum ton for reniform nematode reduction. Checkomnivorum, is found in the alkaline soils of Texas with your seed supplier to identify varieties re-and the Southwest. It is difficult to control and sistant to the nematodes present in your field.occurs on more than 2,300 broadleaf plants Cultural practices include cover cropping with(Goldberg, 1999). This fungus is active in high plants that are antagonistic to nematodes, suchtemperatures and in low organic-matter soils, so as rapeseed or marigolds, planting cotton on soilsadding compost or incorporating green manure that are less sandy, controlling weeds, incorpo-crops will increase organic matter and microor- ration of chicken litter and other manures, andganism competition. Avoid growing cotton on solarization. For more information, see theground that is known to harbor this disease. ATTRA publication Alternative Nematode Control. //ORGANIC COTTON PRODUCTION PAGE 17
  18. 18. Boll rots dences of the disease, causing defoliation in se- vere cases. Controls include using resistant va-Boll rots are a problem in areas with high hu- rieties and avoiding prolonged leaf wetness.midity and rainfall and where bolls are startingto open or have been damaged by insects. Most Southwestern cotton rust, Puccinia cacabata, firstpathogens are secondary invaders relying on in- appears as small, yellowish spots on leaves,sect damage for access. Diplodia spp., Fusarium stems, and bolls, usually after a rain. These spotsspp., and other fungi have been associated with enlarge, developing orange-reddish to browna basal type of rot where bracts are infected first, centers. Later, large orange spots appear on thefollowed by invasion through nectaries and the lower leaves and discharge orange spores. Rustbase of the boll (Anon., 1981). Other organisms diseases require more than one host in order tothat infect cotton bolls are Alternaria macrospora, complete their life cycle. For Puccinia cacabata thePuccinia cacabata, and Xanthomonas, which are alternate host is grama grass, Bouteloua spp., andalso responsible for foliar diseases. The boll-rot its proximity to the cotton field may determineorganism of most concern is Aspergillus flavus, the severity of infestation. If there is grama grasswhich produces aflatoxins in the cottonseed. near your field, removal by burning, plowing,Aflatoxins are carcinogens to some animals and or grazing is recommended. A season of heavyto humans. It contaminates cottonseed oil and rains and high humidity with grama grass closecottonseed meal, which then cannot be used for by has the potential for problems with cotton rust.feed. If Aspergillus is a problem in your area,consider cultural practices that reduce humid- Cotton leaf crumple virus is transmitted by theity, such as lower density seeding to allow more silverleaf whitefly, Bemisia argentifolii. Controlair circulation. Avoid tall, vegetative cotton of the vector and stub cotton, which serves as angrowth—often a result of late planting, excessive overwintering site for the virus, and the use ofnitrogen fertilizer, fertile soils, and/or excessive resistant varieties are strategies for disease reduc-moisture. Rank growth often renders cotton tion. Symptoms include wrinkled leaves that areplants more attractive and susceptible to late sea- cupped downward and plants that are small orson insects, more susceptible to boll rot, and more stunted. This disease causes economic losses ifdifficult to defoliate (Bacheler, 1994). the plants are infected when young.Foliar diseases DefoliationBacterial blight caused by Xanthomonas campestrispv malvacearum is common in areas with warm, Defoliation is a significant obstacle to organicwet weather during the growing season. It production. The organic options available tocauses defoliation and reduces lint quality. Leaf defoliate cotton include flame defoliation andspots are angular, restricted by leaf veins, water- waiting for frost. Vinegar has not been clearedsoaked when fresh, and eventually turning for use as a defoliant under the NOP rules. Ceas-brown before defoliation. Boll symptoms are ing irrigation can assist in leaf drop and bollsmall, round, water-soaked spots that become maturation in low rainfall areas. Citric acid hasblack. Affected bolls may shed or fail to open been used by at least one Missouri cotton farmerand have poor-quality lint. Quick plow down of (Steve McKaskle). Citric acid is organically ap-crop residues after harvest to give ample time proved if it comes from natural sources. Other-for decomposition will assist in the control of the wise, the only alternatives are to wait for a frostdisease. Crop rotation and using resistant vari- or hand harvest.eties are also effective strategies. Research reports from the 1960s show that con-Alternaria leaf spot caused by Alternaria siderable work was devoted to developing bu-macrospora starts off as a tiny circular spot that tane-gas flame defoliators. Several models wereenlarges to half an inch. Concentric rings form developed by engineers in various parts of theas the spot enlarges, with the center sometimes cotton belt. To our knowledge no such equip-falling out to form a shothole. Spots can also be ment is available on the market today, havingfound on bolls. High humidity increases the inci- been replaced by chemical defoliation methods.PAGE 18 //ORGANIC COTTON PRODUCTION
  19. 19. Marketing Organic Cotton Economics and ProfitabilityAs previously mentioned, marketing cotton as Results from a six-year study in the San Joaquin“organic” requires certification of the field pro- Valley of California (Swezey, 2002) showed or-duction practices. Certification also must con- ganic cotton production costs running approxi-tinue throughout the manufacturing process, mately 50% higher than those of conventionalfrom the ginner, yarn spinner, and cloth maker, cotton. The researchers found no difference be-to the garment manufacturer. Each step of the tween fiber length, strength, or micronaire be-process must use only materials (dyes, bleaches, tween conventional and organic cotton. Theyetc.) that meet organic specifications. Manufac- concluded that organic cotton production wastured products that are not already on the Na- feasible in the northern San Joaquin Valley andtional Organic Program’s approved list must go that effective marketing of organic cotton mustthrough a lengthy process to gain approval. If include a price premium to offset higher produc-any unapproved product is used in the process- tion of cotton, the fiber cannot be labeled as or-ganic (Spencer, 2002). Costs that typically differ from conventional cot- ton production include fertilizer materials suchOrganic cotton farmers usually sell either to a as manure, compost, or cover crop seed and theirmill or a manufacturer. It is usually up to the associated application and establishment costs;farmer to negotiate the price with his buyer. mechanical weed control costs; organically-ac-Buyers of organic cotton are limited. Parkdale ceptable insect and disease management mate-Mills (see References) is perhaps the largest or- rials, such as compost tea and beneficial insects;ganic cotton buyer in the U.S. Located in additional hand weeding labor; and costs asso-Belmont, North Carolina, Parkdale makes yarn ciated with being certified organic.from organic cotton. They buy mostly from thesouthern states and occasionally from California. A detailed organic cotton budget is availableThey purchase organic cotton when demand from The University of California Extension Ser-from a garment maker warrants. They buy from vice. To locate this publication on the Web gofarmers, co-ops, and merchants. to: costs/95/cotton.htmSandra Marquardt of the Organic TradeAssociation’s Fiber Council (see References) says Summaryprice premiums range from around $.95 to $1.25per pound, depending on the quality and staple Prospective growers should be aware that grow-length. This premium may decline as stiff com- ing organic cotton is not quite the lucrativepetition from foreign organic cotton increases. proposition it sounds and that there may be moreThe Organic Fiber Council lists companies that money made, and less risk involved, in growingcould be approached as potential buyers of or- other crops instead. Cotton has many pests thatganic cotton, especially the mills. must be controlled without conventional pesti- cides under an organic system. Weed controlThe International Organic Cotton Directory of- options are limited to those done without syn-fers an extensive listing of people, companies, thetic herbicides. Defoliation can be a major chal-and farmers involved in the organic cotton in- lenge, with limited options to accomplish thedustry. They are dedicated to the sustainable task. Transitioning from conventional crop pro-production, processing, and consumption of or- duction to organic cotton is fraught with risk, notganic cotton worldwide. They have directories to mention that the transition process takes threelisted by product type, business type, and alpha- years before the fields can be certified as organic.betically. There are a number of U.S. merchants/ Additionally, in the absence of institutional sup-brokers and eight U.S. mills listed that could be port and infrastructure, organic growers are un-potential buyers of organic cotton. As well, there able to move organic cotton around as easily asare several farmers and farm organizations listed do conventional growers. Markets for organicthat are involved with organic cotton. See this cotton are limited, and demand plus foreign sup-Web site at: plies influence prices. Finally, most organic cot- //ORGANIC COTTON PRODUCTION PAGE 19