Sustainable Pecan Production
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Sustainable Pecan Production

Sustainable Pecan Production

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    Sustainable Pecan Production Sustainable Pecan Production Document Transcript

    • SUSTAINABLE PECAN 800-346-9140 PRODUCTION Appropriate Technology Transfer for Rural Areas HORTICULTURE PRODUCTION GUIDE www.attra.ncat.org ATTRA is the national sustainable agriculture information center funded by the USDA’s Rural Business -- Cooperative Service.Abstract: In Sustainable Pecan Production we briefly introduce essential knowledge on the basics of pecan culture such asgeography, native versus plantation systems, and economics. This is followed by notes on pecan farming techniques that emphasizesustainable and organic production methods: non-chemical weed control; orchard floor vegetation management using legumes;pecan nutrition with emphasis on organic fertilizer options; and recommendations for organic and least-toxic control of pecaninsects and diseases. A selection of pecan literature and web resources available from the Extension Service and horticulturalindustry are provided as further sources of information.By Steve Diver and Guy AmesNCAT Agriculture SpecialistsRevised November 2000The pecan, Carya illinoinensis, is the mostimportant commercial nut crop in the easternUnited States. Pecan culture, like most treecropping systems, is inherently more sustainablerelative to other forms of agriculture. Cultivationof the soil, which increases the risk of erosion, israrely necessary in a bearing orchard. In a fewsections of the U.S., pesticide use is minimal orunnecessary. Where insects and diseases areprevalent, some of the most complete andsophisticated IPM (Integrated Pest Management)programs have evolved to meet the challenge. suggest the excellent resources already compiled by the Cooperative Extension Service. See thePecans also provide us with the oldest and Pecan Resources section at the end of thislargest example of agroforestry in North package for a listing of pecan literature and webAmerica—the grazing of livestock in native resources.pecan groves. (See the box on page 4 for moreinformation.) Pecan CultureFor general information on pecan production There are two pecan cultivation systems in the(planting, pruning, cultivar recommendations, U.S. and Mexico: native pecan groves andirrigation, harvest, and orchard management) we varietal pecan orchards. Varietal pecans—which are planted as orchards but can also be Table of Contents topworked onto native trees—are also known as "papershells." Management of pecan groves andPecan Culture: orchards differ to a degree with respect to The Native Pecan Grove ................................. 1 The Papershell Pecan Orchard ......................... 5 cultural inputs, pest management, and economicInsect and Mite Pests .................................... 12 returns.Diseases........................................................ 16References .................................................... 17 The Native Pecan GrovePecan Resources .......................................... 19Appendix........................................................ 22 The pecan is native to alluvial soils of the lower Mississippi River and its tributaries, as well as IS A PROJECT OF THE NATIONAL CENTER FOR APPROPRIATE TECHNOLOGY
    • other river bottoms throughout its range. The Recent innovations in pecan culture that relate topecan extends southward into Central Mexico, sustainable agriculture include:and ranges northward through Texas, Louisiana,Mississippi, Arkansas, Oklahoma, Kansas, and • legume management to supply nitrogenMissouri. It extends as far north as southern • cover crop management to provide beneficial insect habitatNebraska, Iowa, Illinois, and Indiana, to the • monitoring of key insect pests with pheromone andTexas panhandle in the west, and western weevil trapsKentucky and Tennessee to the east. • release of biological control agents in orchards • cultural practices to improve economic returnsPecan trees grow in bottomlands along with • adopting organic farming practices in pecanother hardwoods; often these bottoms are productionclassified as climax pecan forests where pecan • new pesticides and insect growth regulators withtrees comprise more than 50% of the native forest low impact on the environment, also known as "least-toxic" or "soft" pesticidesbiomass. Sustainable agriculture is a goal rather than aBill Reid, pecan specialist at Kansas State specific set of farming practices. A sustainable farmingUniversity, summarized the five steps involved system strives to be productive and economicallyin converting a bottomland forest into a viable, yet at the same time preserving environmentalproductive native pecan grove (1): quality and making efficient use of nonrenewable resources. Though biological practices and products are favored over chemical inputs, pesticides and First, all species of trees other than pecan are fertilizers may be used within an IPM framework. removed. A permanent ground cover is then established under the trees to facilitate harvest and Organic farming is growing in the United States and to prevent soil erosion. After the initial forest soon there will be a National Organics Program thinning process, most native pecan areas are too regulated by the USDA. Certified organic production crowded for optimum nut production. Old, weak, completely excludes synthetic fertilizers and pesticides or diseased trees are removed to allow adequate for three years prior to harvest of the first crop. space for younger, more productive trees. Nut production in the native grove is further stimulated by the annual application of nitrogen and Thanksgiving and Christmas holiday sales fertilizer. And finally, an insect management are other marketing strategies that put more program is initiated to prevent serious yield losses from nut feeding insects. money into the growers pocket.Selective thinning of pecan trees should result in Yields from well-managed native pecan grovesa density of 30 square feet of cross-sectional trunk average about 600 lbs. per acre, although yieldsarea per acre. This is equivalent to 30 trees per over 1,000 lbs. per acre are not uncommon inacre if all the trunks are, for example, 13½ inches well-managed groves. Wholesale returns to thein diameter measured at 4.5 ft above the ground. grower have averaged around $.60 per pound inA larger tree of 23½ inches would result in a final recent years, although $.80 to $.90 per poundspacing of 10 trees per acre (2). have been obtained some years. Natives sold at the retail level bring around $1.00 per pound.Nuts from native pecans are small, but possessgood flavor due to a high oil content. Wholesale On average, the net return from native pecansnuts are shelled and sold as halves, or chopped sold wholesale is $100 per acre. An economicand used in food preparation and baking. Retail unit of native pecans—which is the acreagesales, when feasible, can make an important needed to finance pecan equipment and provideeconomic contribution to the farm. Native pecan an annual income—is somewhere betweengrowers will often plant a block of papershells, or 80–300 acres. Thats a wide range, but it willtopwork native trees to a good cultivar. Thus, a ultimately depend on what percentage of farmmix of pecan sizes can be offered to entice income will come from pecans; family needs;customers to purchase retail. Special packaging equipment needs; condition of the grove; // SUSTAINABLE PECAN PRODUCTION Page 2
    • wholesale versus retail markets; and red clover-white clover mixture supplied up togeographical location. 118 lbs. N/acre. White clover or red clover alone were less effective in supplying N than whenOverall, the potential to get into native pecan grown together. Over the course of the study,production is not great. The best situation would leaf nitrogen concentrations were typicallybe that of a landowner with existing bottomland maintained above the minimum sufficiency levelhardwoods supporting native pecan trees. (2.25%) by either crimson clover plus hairy vetch,Advice on clearing and establishing a grove is or red clover plus white clover (4–6).available from Extension Specialists and privateconsultants. Otherwise, few farmers — new or In practice, Oklahoma growers favor the whiteexperienced — possess sufficient capital to clover-red clover mix— even though the nitrogenpurchase 300 acres of rich bottomland stocked contribution isn’t as great — since it lasts five orwith native pecan trees. Such land frequently more years before the clover stand needssells in excess of $2,000 an acre. replanting, whereas the crimson clover-hairy vetch ground cover requires more frequent re-An alternative is to lease pecan land, manage the establishment.grove, and harvest the crop. The proceeds aresplit with the landowner on shares of 60/40 to Zinc, an important element in pecan nutrition, is90/10, with the larger percentage going to the commonly applied in 2–4 foliar applications permanager. Percentages vary depending on the growing season to alleviate leaf symptoms of zincinput provided by the owner and manager. deficiency. The standard thresholdApparently, this is a common practice in the recommendation in the two major native pecannative pecan industry. The biggest expense in a states, Oklahoma and Texas, has been 60 ppmlease operation is the equipment required to and 80 ppm as determined by leaf analysis.manage a grove. Many leased groves are in fact Recent research by Darrell Sparks at themanaged by pecan farmers who take on extra University of Georgia shows that most nativeacreage in order to make payments on their pecan groves can forego this input. Instead, hepecan equipment. suggests that zinc levels required for maximum vegetative growth and nut yields coincide withLow-input strategies are essential in the the threshold value for visible leaf symptoms ofmanagement of native pecan groves because nut zinc. In other words, trees without visible leafyields, unlike those in pecan orchards, are deficiency symptoms do not require zincinherently low. The only way growers can make sprays (3).the operation economically feasible is to cut inputcosts (1, 3). Native pecan groves are often managed both for nuts and for grazing of livestock. In fact, pecanOne low-input strategy is to use legumes as an grove grazing is a well-known form ofalternative source of nitrogen (N) fertilization. agroforestry. However, livestock should beThe nitrogen production potential of legumes removed at least two months prior to harvest tovaries between species, location, and growing avoid potential bacterial contamination fromseason but can range from 75 to 250 lbs. N/acre. feces.In a three-year study funded by the U.S.D.A. While grazing cattle (or sheep) in pecan grovesSustainable Agriculture Research and Education can generate additional income from the land asProgram (SARE), researchers at Oklahoma State well as enhance nutrient cycling, there are certainUniversity evaluated legumes for their ability to grazing restrictions following pesticidesupply nitrogen and provide habitat to beneficial application that growers need to be aware of. Seeinsects. Recommended Intervals Between Last Application, Harvest, and Other Restrictions inA crimson clover-hairy vetch ground cover Pecans in the accompanying box for grazingsupplied the equivalent of 90–142 lbs. N/acre. A restrictions in relation to choice of pesticide. // SUSTAINABLE PECAN PRODUCTION Page 3
    • AgroforestryAgroforestry is the deliberate growing of trees on the Livestock grazing most often involves cattle, thoughsame unit of land as crops or livestock. The idea behind intergrazing with sheep has increased in popularity.agroforestry is to derive both economic and ecological Regardless, grazing restrictions sometimes exist — eitherbenefits, two key goals of sustainable agriculture. temporarily or permanently —following application of common pecan pesticides.Pecan silvopasture (livestock grazing) andalleycropping (alternating rows of annual crops and As an example, see the grazing restrictions associatedtrees) systems are among the oldest examples of with pesticides in the table below. Thus, one of theagroforestry in temperate climates. factors pushing pecan pest management towards "soft spray" and biological control programs is the desire toAlleycropping, also known as intercropping, can be done generate dual incomes from grazed orchards.with a wide range of vegetable, flower, field, and foragecrops during the pre-bearing stage of pecans to help Low impact spray programs rely on pesticides withoffset establishment costs. Nut trees are particularly well- short term environmental persistence and low toxicity tosuited to alleycropping because of the wide spacing beneficial insects and wildlife.between tree rows.In the South, raising square bales of bermudagrass hay in Resources on Agroforestry:the alleyways for the first 10 years is said to pay for thecost of orchard establishment. The caveat is that Agroforestry Overview, an ATTRA publication by Alicebermudagrass is a heavy feeder and haying requires Beetz, is available in-print as well as on-line.supplemental fertilization and close attention to vegetation http://www.attra.org/attra-pub/agroforestry.htmlmanagement to avoid competition with young trees.Recommended Intervals Between Last Application, Harvest, and Other Restrictions in Pecans‡Chemical Interval Between Last Application and Harvest and Other RestrictionsAbound Do not apply within 45 days of harvest.Asana, Ammo 21 days. Do not feed or graze livestock on treated orchard floors.Benlate, Topsin M Do not apply after shuck split. 15 day waiting period before harvest.Confirm 14 days to harvest. Do not graze livestock in treated areas or feed cover crops grown in the treated area to livestock.Dimethoate Do not apply within 21 days of harvest. Do not graze livestock in treated areas.Dipel, Javelin No grazing restrictions. 0-day waiting period.Di-Syston Do not harvest nuts within 80 days of treatment.Enable Do not apply after shuck split or within 28 days of harvest. Do not graze.Fury Do not apply within 21 days of harvest. Do not graze livestock on cover crops in treated areas.Guthion Do not apply after shuck split. Allow 21 days before grazing livestock.Imidan Do not apply within 14 days of harvest. Do not graze livestock on cover crops in treated areas.Lorsban Do not make more than 5 applications per season and do not graze livestock in treated orchard. Do not apply within 28 days of harvest.Malathion, Sevin No grazing restrictions. Sevin has a 14-day waiting period before harvest.Orbit Do not apply after shuck split. Do not graze or feed cover crops in treated areas.Provado Do not graze in treated areas. 0 days waiting between application and harvest.Super-Tin 80W, Cyprex Do not apply after shucks have started to open, and do not graze treated areas.Thiodan Do not graze cattle in treated groves and do not apply after shuck split.Ziram Do not apply within 55 days of harvest.‡From: Extension Agents Handbook of Insect, Plant Disease, and Weed Control. Cooperative Extension Service, Oklahoma State University. January 2000. // SUSTAINABLE PECAN PRODUCTION Page 4
    • Management of a native pecan grove is an art as name," a cultivar must be propagated asexually,much as a science. The best way to learn about i.e., by budding or grafting rather thannative pecans is to attend pecan field days, short propagation by seed).courses, and annual growers meetings. A shortlist of considerations associated with native There are hundreds of pecan cultivars, but only apecan grove management includes: few dozen make up the commercial industry. Papershell cultivars are classified according to• Clearing the site size, percent kernel fill, and northern or southern• Selecting trees for nut production versus trees range of adaptation. An economic unit for a for firewood & timber pecan orchard—which is the acreage needed to• Orchard floor management finance pecan equipment and provide an annual• Legume establishment income—is somewhere between 30-60 acres,• Plant nutrition depending on the economic model one uses.• Livestock grazing Prime bottomland farms in soybeans, corn,• Grazing restrictions due to pesticides wheat, and alfalfa are usually good sites for pecan orchards, provided the soil drains well.• Low-cost approach to inputs• Harvest preparation Yields from pecan orchards range from 800–1,200• Cleaning, grading, and marketing nuts lbs. per acre on average, though yields as high as 2,500 lbs. are not uncommon. Pecans are Grazing, Legumes, and Bloating of Cattle notorious for alternate bearing, with heavy harvests usually followed by one or two "off"Bloating can result when cows graze on fresh, years. Wholesale returns of $.80–.90 per poundnitrogen-rich legumes on an empty rumen. What are common. Retail prices range from $1.50–2.25happens is that the legumes are so easily digested by per pound, but prime quality nuts can also bringrumen bacteria that massive quantities of gas are over $2.50. On average, net wholesale returnsreleased, thus causing bloating to occur which canrequire the emergency aid of a veterinarian. Alfalfa, from a papershell orchard are $300–400 per acre.red clover, and white clover are most notable asproblem legumes species, while crimson clover and One aspect of pecan culture that may be an eye-hairy vetch are less worrisome. opener to the prospective orchardist is the equipment associated with pecan productionGrazing on a grass-legume mix rather than a 100%legume stand is a standard grazing practice to avoid and harvesting. A 1988 report listed an estimatebloating problems. Feeding hay, or grazing on grass, of $45,000 new or $21,000 used for the minimumbefore turning the animals onto the legume stand is a pecan orchard equipment—a 50–60 horsepowertypical precaution. In general, legumes are an tractor, a 500 gal. PTO (power-take-off) sprayer,excellent forage and bloating does not occur very often a 3-pt. hitch shaker, a pull-type harvester, and a(and only sporadically in the herd), especially when pecan cleaner (7). Additional expenses toanimals are acclimated to high levels of legumes intheir diet. Finally, bloat blocks may be set out as a consider include a rotary mower, an orchardpreventative nutritional supplement. Also see: rake, a harvest sweeper, harvest bins, drying equipment, a shed for farm equipment andTips to Avoid Bloat pecan nut cleaning and storage operations, anhttp://www.dairyherd.com/nutr73.htm irrigation system, and tools. One horticulturist stated that "most folks grow into their equipment needs."The Papershell Pecan Orchard The papershell pecan industry has evolved as anThe establishment of a pecan orchard by planting important horticultural enterprise in non-nativetrees in rows is how most new growers enter the states like Georgia, Alabama, South Carolina,pecan industry. Trees can be purchased with the North Carolina, and Florida in the Southeast, andcultivar already budded to the top, or planted as in New Mexico, Arizona, and California in thea seedling and grafted in the field. (To be "true to West. // SUSTAINABLE PECAN PRODUCTION Page 5
    • Pecan orchard systems in the Southeast and West containerized nursery stock, and non-buddeddiffer from each other primarily in the need for seedling rootstocks versus pre-buddedirrigation (in the West) and in the severity of rootstocks.pests and diseases (in the Southeast). Much ofthe disease and pest pressure in the Southeast is There is considerable variation in cold hardinesssimply non-existent in the West. among rootstocks. Most commercial-scale pecan nurseries are in the South, and rootstocks areLikewise, the establishment of pecan orchards is most likely to be seedlings from southern trees,an important horticultural industry throughout which may or may not have the cold hardiness tothe trees native range in states like Texas, withstand more northerly conditions.Oklahoma, Louisiana, and Mississippi.Management of these orchards closely resembles Growers in more northerly regions should checkthat of plantations in the Southeast due primarily with their Extension Service for advice regardingto similar pest and disease problems. rootstocks, or ask for assurance from the nursery that the understock has the necessary cold Spacing, Trees per Acre, Planting hardiness. See the accompanying box on Northern Pecan Varieties for ExtensionThe spacing of pecan trees depends on specialists who can address this topic.geographical location. In their native and easternranges, pecan trees are commonly spaced on a One method of pecan seedling production that is40 ft x 40 ft grid pattern, which is the equivalent appealing from the sustainable angle is on-farmof 27 trees per acre. After about 16–22 years, trees production of pecan seedlings using the "milk-are thinned by half on a diagonal, thus leaving 14 carton" nursery production method developed attrees per acre. At about 25–35 years old, the third Oklahoma State University. These "superand final thinning will leave a spacing of 80 ft x seedlings" are raised in square, bottomless80 ft with 7 trees per acre. containers (quart-size milk cartons fitted inside plastic milk crates) filled with a standard nurseryFor a long time the pecan industry was based on mix.a 35 ft x 35 ft tree spacing. However, recenteconomic analysis showed an initial 40 ft x 40 ft When the seedling germinates, the tap rootplanting pattern is more profitable because the grows out the bottom of the containerwider spacing allows the temporary trees more whereupon the root tip is exposed to the air andtime to produce nuts before they are removed (8). dies back. Repeated air root pruning stimulates vigorous lateral branching and results in aEstablishing a Pecan Orchard, OSU Extension fibrous root system. From a container nurseryFacts F-6247, provides illustrations and details for production viewpoint, air root pruning ispecan orchard layout and thinning operations, particularly appealing for strong tap-rootedlocated on the web at: trees such as pecans. Containerized trees arehttp://www.okstate.edu/OSU_Ag/agedcm4h/ easy to transplant and with the addedpearl/hort/frtnuts/f6247.htm advantage of a vigorous, fibrous root system due to air root pruning they establish well inIn the western range, where sunlight is more the field.intense, trees are planted at 30 ft x 30 ft, which isthe equivalent of 48 trees per acre. Ultra-high This method was first described in Growing Treedensity western pecan orchards, spaced at 15 ft x Seedlings in Containers (9), an out-of-print OSU30 ft, are typically managed by mechanical agricultural experiment station bulletin writtenhedging. by Dr. Carl Whitcomb. Root-control nursery pots are now commonly available in the commercialPecan nursery stock is available from reputable nursery industry. ATTRAs Sustainable Small-pecan nurseries. There are several options to Scale Nursery Production publication provideschoose from, including bare root versus additional resources on this topic. // SUSTAINABLE PECAN PRODUCTION Page 6
    • NORTHERN PECAN VARIETIES competition for moisture and nutrients as well as allelopathy (13). Recent research suggests that aPecan varieties can be classified into Eastern, Western 10-foot square area under newly planted treesor Northern types based largely upon climate and should be vegetation free (14).geographical location. Eastern varieties are adapted tothe humid southeastern states from Louisiana to Though sustainable agriculture has a goal ofFlorida and have some scab tolerance or resistance.Since scab is not a problem in the arid West, western reducing chemical inputs in general, herbicidesvarieties do not have appreciable scab tolerance or are often used within a sustainable framework asresistance. an alternative to cultivation; to manage cover crops; or to create a sod-free strip in the tree row.Northern pecan varieties are adapted to a shorter Overall, herbicides account for a small percent ofgrowing season (as few as 140–180 days) than total active pesticide ingredients used in pecaneastern or western types (between 190–220 days).When eastern or western types are grown in northern production.areas, the nut fails to properly mature. Summary of Pesticide Use in Pecans in TexasThe adaptation of pecans to the northern half of theU.S. is gaining increased interest. In addition to Type of Pesticide % of Totalregions within the northern pecan belt (northern Insecticides 75Oklahoma, Kansas, Missouri, Nebraska, Iowa, Illinois, Fungicides 23Indiana, Kentucky, and Tennessee), horticulturists Herbicides 2have made selections that are hardy to Zone 4 and areplanting pecans as far north as Ontario, Canada. Total 100Dr. William Reid (10), at Kansas State University, or Source:Dr. Bill Gustafson (11), at the University of Nebraska-Lincoln, can provide advice and recommendations to Crop Profile for Pecans in Texasprospective orchardists in the upper U.S. USDA Office of Pest Management Policy & Pesticide Impact Assessment ProgramNames of standard northern varieties include James, http://pestdata.ncsu.edu/cropprofiles/Colby, Fritz, Greenriver, Major, Peruque, Witte, Posey, Detail.CFM?FactSheets__RecordID=291Giles, Hirschi, and Starks Hardy Giant. Selectionsfrom Gustafsons collection — collected from pecantrees growing along the banks of the Mississippi and Herbicides are restricted in certified organicMissouri rivers — include Boltens S-24, C.L. McElroy, production, however, and therefore the followingCanton, Gibson, Lucas, Mullahy, and Norton (12). weed control options will focus on non-chemical alternatives. Tree Care, Irrigation, Weed Control, Mulches Mechanical cultivation by disking is an old weed control practice in pecan orchards. AThe first 3–5 years after planting are crucial to the recent study in Alabama provides insight into thesurvival and establishment of a tree. relation between disking and soil moistureSufficient soil moisture and a vegetation-free availability on pecan yields. Disking as a methodzone around the tree itself are foremost among of weed control was comparable to herbicide-the factors affecting tree survival. Supplemental treated plots when drip irrigation was used.irrigation is normally recommended, especially However, when the pecan trees were notwhere precipitation falls below 32–36" per year. irrigated, yields from disked plots were reduced by half in comparison to weed-free plots treatedPerhaps the most important factor affecting tree with herbicides (15).vigor is vegetation control underneath the treecanopy. Weeds are known to severely curtail Mulches control weeds by excluding light andpecan tree growth, and insufficient weed control forming a physical barrier to growth. Organicis the most frequent reason new orchards fail or mulches may be viewed as the ultimate soilare slow to begin production. Apparently, treatment because they can suppress weeds,interference from weeds is a combination of moderate soil temperatures, retain soil moisture, // SUSTAINABLE PECAN PRODUCTION Page 7
    • and release nutrients and feed soil organisms negate its intended purpose. Invariably, weedduring decomposition. Sheet mulching seeds land in the organic mulch on top of the weedsignificantly enhances the efficacy of organic barrier , subsequently germinating in this moistmulches. This is where a thick layer of straw, medium and sending roots down through thegrass hay, or wood chips are laid on top of small pores of the fabric.several layers of newsprint or heavy-duty kraftpaper. Still, organic mulches biodegrade over Regardless of which mulching system istime and require labor and materials to maintain. employed, constant attention to weeds emerging through the mulch or on the edges of the mulch isWood chips —which can often be obtained free critical. IPM farmers can use a post-emergentby the truckload from municipalities and tree herbicide to deal with these renegade weeds, buttrimmers — make a superb organic mulch for organic growers committed to non-herbicidaltrees. Research in Oklahoma showed that tree weed control will have to be vigilant, especiallygrowth was significantly enhanced by the during the first few years of a planting. Steam,presence of a wood chip mulch, laid 12 inches used as a portable thermal weed controldeep in a 6-ft wide square around the base of the technique for spot treatment, is one option worthtree (16). This was combined with a 13-ft wide exploring in combination with geotextileweed-free herbicide strip in the tree row. These mulches.horticulturists are saying that trees grow betterwhen a wood chip mulch and a herbicide strip are Living mulches, which are desirable cover cropsused in combination. planted in the alleyways between pecan trees, should be kept away from the trees themselves.Fungi inhabiting the cellulose-rich environment Even legume cover crops, which can be sounderneath a wood chip mulch may have an important in providing nitrogen to mature trees,important role to play in tree health, too. Dr. should be excluded from the immediate areaElaine Ingham, soil microbial ecologist at Oregon around young pecan trees or the trees can sufferState University, says it is the soil food web that from competition (14).ultimately determines nutrient availability,disease occurrence, and related production ATTRAs Overview of Organic Fruit Productionfactors. Wood chips, which are highly publication contains a review of non-chemicalcarbonaceous, foster a fungal-dominated weed control strategies relevant to tree crops.environment ideal for trees and vines. Row cropsand grasslands, by comparison, are dominated by Legumes in the Orcharda bacterial microflora (17). Legumes play an important role in sustainableGeotextile weed barriers (often called fabric pecan management because they fix nitrogen andweed barrier or landscape cloth) offer an effective enhance biological insect control. This latterlong-term weed control alternative to chemicals, aspect, the use of legumes to attract "food aphids"organic mulches, and cultivation. These and the predators that feed on them and onmaterials suppress weeds but allow water and air associated pecan canopy aphids, is covered ininfiltration. Growers can purchase pre-cut tree more detail in the Insect and Mite Pests section.squares, obtain bulk material and cut it to size(e.g., 10x 10), or run the material down the entire The nitrogen (N) contribution from legumes isrow length (e.g., 10 to 15 wide strips). Higher significant. Cover crop legumes fix 75–250 lbs.grades of fabric mulch will last as long as 10 N/acre, depending on species and environmentalyears. conditions. At least half the total N fixed by legumes is released during decomposition theTopping landscape weed barriers with a wood first year after legume dieback. In succeedingchip mulch is a common practice in the landscape years of cover cropping, an increase in soil N isindustry, primarily for aesthetic purposes, but in common. As pecan orchards need about 100–150field production it is not necessary and in fact can lbs. N/acre to maintain healthy, productive trees, // SUSTAINABLE PECAN PRODUCTION Page 8
    • legumes seem like a perfect match. The • Creeping red fescueOklahoma State University study, previously • Orchardgrasscited, demonstrated that legume N is ample for • Centipedegrassnative trees. Papershell trees, however, mayrequire supplemental N inputs because orchard • Regal white clovertrees are more productive. • Arrowleaf clover • Merion bluegrassThe choice of legume species will vary by climate • Common bermudagrassand soil type, and therefore local • Louisiana S-1 cloverrecommendations should be obtained from theExtension Service. Several desirable qualities of • Reseeding crimson cloveran orchard legume and example selections areprovided below. Though the Alabama publication states that deep-rooted, coarse, turf-producing grasses likeUse of Legumes in Pecan Orchards (18), an Kentucky fescue and bahiagrass should beOklahoma State University report, identifies the avoided, fescue is a common orchard grass inlegume characteristics that are most compatible other parts of the pecan belt, especially wherewith pecan production: grazing is conducted. First, a cool season legume is less Finally, successful legume establishment is a competitive with the trees for soil critical factor in how well a biological-nitrogen moisture than a warm season legume, program will perform. In the Oklahoma study plus the cool season legume would (4), Roundup® (glyphosate) herbicide was used stimulate an earlier increase in the to eliminate existing vegetation. Light disking beneficial insects. followed by broadcast seeding and rolling benefited stand establishment. One alternative to The legume should be tolerant to both sun and shade. Many pecan orchards are herbicides includes partial tillage and legume prone to flooding; therefore, flooding establishment into the existing vegetation, thus tolerance is desirable. Also, the legume arriving at a mixed grass-clover stand. Clean must not cause an increase in undesirable cultivation is the only practical non-herbicidal insects, such as stink bugs, while alternative if complete elimination of existing attracting beneficial insects. The legume vegetation is desired. should be capable of fixing large quantities of N. Additionally, the legume Organic Fertilization must be capable of withstanding the traffic associated with orchard maintenance and harvesting. Fertilization of pecan trees is based on a soil test and leaf analysis. A soil test is taken in the yearThe researchers in the Oklahoma study found a of establishment, and thereafter every 3 years, tocombination of self-seeding annual and perennial monitor soil pH and nutrient levels. The mostlegumes performed the best. The annual legumes accurate indicator of orchard fertility, however, isand seeding rates were Dixie crimson clover at nutrient status of the leaves. Leaf samples are10 lbs./acre and hairy vetch at 8 lbs./acre. The taken in July and sent to a lab for analysis.perennial legumes and seeding rates wereLouisiana S-1 white clover at 2 lbs./acre and Nitrogen is the element that most influencesKenland red clover at 8 lbs./acre (5–6). pecan growth, and it is the element most likely to become deficient in a pecan orchard. Normal leafPecan Production in the Southeast: A Guide for concentrations of N fall between 2.3 and 3.0Growers (19), an Alabama Cooperative Extension percent. The minimum leaf nitrogenService publication, lists the preferred orchard concentration for productive orchards iscover crops for pecans in the Southeast as: considered to be 2.2 or 2.3%. // SUSTAINABLE PECAN PRODUCTION Page 9
    • This table, from Pecan Production in the Southeast: A Guide for Growers (19), shows how leaf analysis is relatedto fertilization. General Fertilizer Guidelines Based on Leaf Analysis Percent Pounds of Nitrogen Nitrogen to in Leaves Apply Per Acre Below 2.0 150* 2.1 140* 2.2 130* 2.3 120 2.4 110 2.5 100 2.6 100 2.7 100 Above 2.7 None, unless specifically suggested *Use only on trees 30 years or olderIn addition to leaf analysis, the terminal growth positive effects, but others find no benefit. Pecanof pecan shoots can provide a visual indication of trees become so enormous and bear so much leaftree N status. Most pecan varieties fruit well mass that foliar-applied nutrients do not havewhen shoots are 4–8 inches long. Young, non- sufficient impact to make a significant change inbearing trees should make more growth. leaf analysis or nut yields. Western orchard trees, kept short by hedging, may be an exception.An interesting result of the USDA-SARE study inOklahoma was a leaf N concentration of 2.6% On the other hand, foliar feeding can play anwhen crimson clover-hairy vetch produced 166 important role in pest management (altering leaflbs. N/acre. culticle structure and confusing insects, increasing soluble solids, and manipulating theSurface application of compost to pecan trees, foliar food web) and that may be a good enoughespecially in the weed-free zone, is a common reason for growers to employ this practice. Inpractice in organic orcharding. In the early years, addition, organic materials such as seaweed andcompost alone is often sufficient to enhance tree compost teas can be viewed as biostimulants thatvigor, provided minerals are not deficient as have a non-nutritive benefit akin to how compostdetermined by a soil test. Compost not only functions in the soil beyond its N-P-K value.supplies mineral elements, but fosters soilmicrobial activity and contains beneficial by- Phosphorus (P) levels in orchard soils should beproducts. In bearing orchards compost can be maintained for the nutrition of the pecan trees asviewed as a supplement to nitrogen-fixing well as the legumes. Normal leaf concentrationslegumes. of P range between .12 and .20 percent. Rock phosphate is the chief source of P inFoliar applications of organic fertilizers and commercial-scale organic production. Bone mealbiostimulants, another common practice in is a good source of P, and may be useful as a soilorganic orcharding, may be worthwhile in a amendment at tree establishment, but it is tooyoung pecan orchard to enhance tree vigor. But expensive to apply by the acre. Application ratesin a mature pecan orchard, foliar feeding is of rock phosphate are considerably higher thanquestionable. In studies with commercial soluble single or triple superphosphate fertilizer, andfertilizers, some growers and researchers report may range from 300–1,000 lbs per acre. // SUSTAINABLE PECAN PRODUCTION Page 10
    • Potassium (K) is the second most importantelement in pecan production, after nitrogen. Organic Fertilization ResourcesPotassium deficiency can cause small, poorly-filled nuts, accelerate the tendency towards Sources for Organic Fertilizers and Amendmentsalternate bearing, and lower resistance to disease. ATTRANormal levels of leaf K range between 0.75 and http://www.attra.org/attra-pub/orgfert.html1.75 percent. Sulfate of potash-magnesia This is the ATTRA resource list on organic(Sul–Po–Mag®K–Mag®) is widely used in fertilizers that provides an extensive listing oforganic agriculture, especially in nut production. dealers and suppliers carrying bulk organicCertain brands of potassium sulfate (mined and fertilizers, listed state-by-state.untreated) can also be used in organic programs. OMRIs Brand Name Products ListZinc (Zn) is the other critical element in pecan Organic Materials Review Institute http://www.omri.org/brand_list.htmlnutrition. Normal leaf concentrations of Zn arebetween 50 and 150 ppm. A severe zinc OMRI is the Organic Materials Review Institute.deficiency, especially prevalent in highly It provides a technical review of organic cropcalcareous soils, may lead to a physiological production materials (fertilizers and pestdisorder known as pecan rosette. In calcareous controls) supplied by manufacturers. Products that receive an Allowed or Regulated statussoils with a pH over 7.0 (most of the western can state that the product is "OMRI Listed"pecan belt), zinc is tied up by calcium into an and may use the OMRI seal on packaginginsoluble form, and the application of foliar zinc and literature.is a standard practice. The Brand Name Products List on OMRIsIn Oklahoma three foliar sprays per growing Website includes crop production materials Organized alphabetically by Generic Material,season at 6 lbs of 36% zinc sulfate per acre is Supplier, and Product.common, whereas six sprays are common insouth and west Texas. Zinc sulfate is an accepted Alternative Soil Testing Laboratories Resource Listmaterial in organic certification programs. ATTRA http://www.attra.org/attra-pub/soil-lab.htmlBrent Wiseman (20), Coordinator for Organic Whereas the pecan industry is heavilyPrograms at the Texas Department of Oriented to standard commercial fertilizerAgriculture, says that zinc sulfate mixed with recommendations available from land-grantseaweed and fish emulsion and applied foliarly is university soil labs, organic farmers may finda common practice in Texas organic pecan the advice from crop advisors who specializeorchards, though constant agitation of the spray in organic fertilizer recommendations to be more helpful.tank solution is necessary to keep the solutionfrom settling. Alternative Soil Testing Laboratories also provides an extensive list of resources and webAdditional concepts and practices associated sites on alternative soil fertility concepts andwith ecological soil management and organic practices.fertilization are contained in the following Commercial Organic Nutrient RecommendationsATTRA Publications: University of Maine Soil Testing Service/Analytical Lab http://anlab.umesci.maine.edu/handout/ organ01.HTM• Overview of Organic Fruit Production• Sustainable Soil Management In these handy tables from University of Maine• Alternative Soil Amendments you can quickly see how many pounds of• Alternative Soil Testing Laboratories organic fertilizer are needed to meet desired pounds of nutrient element per acre; e.g.,• Sources of Organic Fertilizers and 670 lbs fish meal equals 60 N lbs per acre, Amendments 890 lbs fish meal equals 80 lbs N per acre, and• Farm-Scale Composting 1100 lbs fish meal equals 100 N lbs per acre.• Overview of Cover Crops and Green Manures // SUSTAINABLE PECAN PRODUCTION Page 11
    • Insect and Mite Pests Kansas, it rarely occurs in densities sufficient to cause concern.Introduction There are many natural enemies of aphids andIn the East, in addition to foliar-feeding aphids mites, including ladybeetles, lacewings, damseland mites, there are several serious direct pests of bugs, assassin bugs, spiders, and predaciousthe nut. Researchers have developed advanced mites. The planting of cover crops to provideIPM programs to minimize damage from these refuge, insect prey, honeydew, nectar, pollen, andpests, and in most cases a biological control or a water supply for these beneficial insects is howotherwise organically acceptable control is growers and researchers are beginning to solveavailable. However, two key pests throughout aphid and mite problems through biologicalmost of the eastern pecan production areas, the control (5,21,22).pecan weevil and the hickory shuckworm,present serious obstacles to organic production. USDA-SARE research conducted in OklahomaIn western production regions where pecan and (5) and Georgia (21) evaluated cool-seasonits relatives (especially the hickories) are not legumes as beneficial insect refuge. The goal wasnative, some of the worst pecan pests have been to identify which cover crops support predatorsleft behind. In such areas the most troublesome and parasites of pecan pests, and to identifypests are likely to be aphids and mites that feed when they actually migrate from the groundon the foliage and stems. covers into the trees to achieve biological control of the pecan pests.Aphids and Mites Research thus far indicates that predators likeAphids and mites are similar in that they are lady beetles and green lacewings are attracted to"indirect pests" (i.e., they feed on plant parts cover crops to feed on pea aphids, cowpeaother than the harvested nut), have multiple aphids, and blue alfalfa aphids which inhabit thegenerations through the growing season, and legumes. The number and species of beneficialsare often raised to pest status by the found in the tree tops varied, but an increase ininadvertent killing of their natural enemies by canopy numbers of predators was apparentpesticides targeted for them or other pests. where a crimson clover-hairy vetch ground coverThis last characteristic has provided a major was grown (5).impetus for researchers to investigate therefinement of ecologically-based pest Dr. Glenn Cat Taylor (23), former pecanmanagement systems to preserve the beneficial specialist (retired) at the Noble Foundation inorganisms and achieve natural biological Ardmore, Oklahoma, said the need for aphidcontrol of aphids and mites. insecticide application is regionally specific as determined by the presence of aphid species. AsTwo species of yellow aphids attack pecans: the an example, the only aphid occurring in sufficientblack-margined aphid (Monellia caryella) and the numbers in Oklahoma is the yellow aphid. Heyellow pecan aphid (Monelliopsis pecanis). The advises Oklahoma growers to go with a "softprimary damage caused by yellow aphid feeding spray" program — using pesticides with low-is the deposit of honeydew on leaves, which toxicity to beneficials and with shortsupports the growth of sooty mold and reduces environmental persistence —and foregoing aphidphotosynthesis. control because the yellow aphid causes more concern than actual damage.The black pecan aphid (Melanocallis caryaefoliae)can be more destructive than other aphids found At the other extreme, aphid problems in Georgiaon pecans. If left unchecked, its feeding can are severe enough to warrant the registration andcause premature defoliation of the orchard. It is a use of the highly toxic, systemic insecticidepest in southeastern pecan groves and in Texas. aldicarb for aphid control. Dr. Jim Dutcher (24)While it can also be found in Oklahoma and reported that a four-step, less-toxic alternative // SUSTAINABLE PECAN PRODUCTION Page 12
    • has been developed for Georgia growers. Theprogram includes: [1] a row of legumes planted Biological Controlin the aisle; [2] controlling fire ants by sprayingthe trunks with insecticides (fire ants are Adverse weather, inadequate food supply or naturalindiscriminate predators and kill beneficial enemies may hold insect and mite populations below damaging levels. It is important to recognize the impactinsects that would otherwise prey on aphids); [3] of these natural control factors and, where possible,irrigation to ameliorate the stress to trees caused encourage their action.by aphid feeding; and [4] releases of aphidpredators. Biological control is the use of living organisms (parasites, predators and diseases) to reduce pest numbers. Important natural enemies of pecan pestsIn short, while pesticides may occasionally be include lacewings, spiders, lady beetles, assassinnecessary to control mite or aphid problems, the bugs, predatory mites and many kinds of tiny waspsmanipulation of the orchard floor to provide that parasitize insect pests.habitat for beneficials and the release ofbeneficials into the grove or orchard will in many Biological control includes conserving, augmenting andcases be sufficient to control aphid problems. importing natural enemies. Conserve existing populations of natural enemies in the orchard byArnold Brothers Biological Insect Pest Control minimizing insecticide applications and by using(25) is an insectary in New Mexico specializing in insecticides least toxic to the natural enemy.aphid control for pecan orchards. Examples include B.t. (Bacillus thuringiensis)Pecan Weevil insecticides (Dipel®, Javelin®), which are toxic only to certain moth caterpillars and not to insect predators or parasites. Ground covers such as legumes canThe pecan weevil (Curculio caryae) emerges as an provide food and shelter for natural enemies.adult from the soil under or near pecan trees Unsprayed native pecans serve as reservoirs of naturalprimarily during August and September. The enemies that can move into adjacent sprayedweevils mate and begin feeding on the orchards.developing pecan nuts soon after emergence. Augmentation involves periodically buying and releasing natural enemies. Research is under way toFemales lay eggs in the nuts, the eggs hatch, and determine if such releases control pecan peststhe larvae feed on kernels inside the nutshells for effectively and practically. Natural enemies can alsoapproximately six weeks. Larvae then burrow be imported from other countries, then colonized andout through the shell, fall to the ground, and released. Once established, these natural enemiesenter the soil where they pupate and overwinter maintain themselves without further releases.as adults. If conditions are favorable over several Source:years, weevil "populations can increase untilvirtually all pecan nuts are infested" (26). Managing Insect and Mite Pests of Commercial Pecans in TexasThe pecan weevil is present throughout most of Texas Agricultural Extension Service, B-1238the South wherever pecans and hickories grow http://entowww.tamu.edu/extension/bulletins/ b-1238.htmand is considered the most important pest ofmanaged pecans in the southeastern U.S. (27). A Resources:large percentage of damaged nuts can render acrop practically unmarketable. Farmscaping to Enhance Biological Control ATTRA http://www.attra.org/attra-pub/farmscape.htmlInterestingly, the pecan weevil is mysteriouslyabsent from certain areas within states where the Suppliers of Beneficial Organisms in Northweevil is otherwise common. As an example, AmericaBrent Wiseman explained that areas around http://www.cdpr.ca.gov/docs/ipminov/Stephenville and El Paso, Texas, harbor few bensuppl.htmweevils while the central Texas region is heavily // SUSTAINABLE PECAN PRODUCTION Page 13
    • infested. Consequently, location influences the timed insecticide applications (e.g., Sevin®,degree to which pecan weevil control is necessary Imidan®, Ammo®, Asana®, Fury®).and where organic production is most feasible. Pecan Nut CasebearerThe Pecan Weevil Wanted Poster from TexasA&M shows the distribution —the presence or The casebearer (Acrobasis nuxvorella) is a majorabsence — of pecan weevil in Texas. It is located pest in Texas, Oklahoma, Missouri, Kansas,on the web at: Arkansas, and Louisiana, and occasionallyhttp://pecankernel.tamu.edu/publications/ reaches serious pest status further east. There ispwwanted.PDF patchy distribution in New Mexico, but casebearers do not occur in Arizona or California.Biological control options for pecan weevils arelimited. Fire ants prey on pecan weevils, but they The casebearer commits several types of damage.also prey on beneficials and are a nuisance to In the spring, partially grown larvae emerge fromfarm workers. Researchers have tried using soil- their overwintering site (a cocoon attached to aapplied, beneficial, parasitic nematodes as well as bud on a pecan twig) and burrow into buds andentomopathogenic fungi, but nothing reliable has stems where they will pupate. Later in the springemerged from these efforts as yet. (usually during May in most pecan growing regions) the moths emerge, lay their eggs on theSeveral methods have been developed to monitor tips of nutlets, and the resulting larvae feed onweevil emergence, thus allowing for accurate buds and the developing nutlets. These larvaespray timing. Heretofore, the two most will pupate within fruits, emerge as adults andimportant techniques have been the cone trap again lay eggs on other fruits. The cycledeveloped at Oklahoma State University (28), continues throughout the summer, but third andand the pyramid trap developed by USDA-ARS fourth generation larvae usually cannot penetrateat Byron, Georgia (29). This latter trap is shaped the hardened nut shell. The primary damagelike a pyramid, about 21 inches wide and 48 caused by the casebearer is dropping of nuts.inches tall, painted brown, and capped with ascreen funnel trap. When adult weevils emerge Monitoring is done by visual inspection of thefrom the soil, they normally fly to the dark trunk nut tips. A hand lens can be used to look at nutof a pecan tree, but by whitewashing the tree tips more closely, though the trained eye is alltrunks researchers found they could divert the that is necessary. The Texas Agricultureweevils from the trunks to the traps. Ten to 15 Extension Service and the University of Georgiatraps per 100 acres is enough to monitor weevil have both developed models based on degreeemergence. days that predict emergence and egg laying of the casebearer. Thus, monitoring of this pest canMore recently, the Circle trap (named for its be very tightly managed by combining visualinventor, Kansas pecan grower Edmund Circle) inspection with degree day reports from thehas proved to be cheaper to construct and reliable Extension Service. Both the Georgia and Texasas a monitoring tool, plus it is mounted on the models can be seen at the Oklahoma Pecantrunk and therefore out of the way of grazing Management website at:animals and mowing operations. Complete plans http://www.hortla.okstate.edu/pecan/for fabricating this trap are available inMonitoring Adult Weevil Populations in Pecan Pecan nut casebearer pheromone traps,and Fruit Trees in Oklahoma, OSU Extension developed by Dr. Marvin Harris at Texas A&MFacts F-7190, on the web at: University, are a recent innovation in pecan IPMhttp://www.okstate.edu/OSU_Ag/agedcm4h/ monitoring.pearl/insects/cropbugs/f-7190.pdf. A new low-impact pesticide effective against theThe only viable control for pecan weevil at the casebearer is Confirm®, an insect growthpresent time appears to be one or two accurately regulator. Sprays of Confirm are most effective // SUSTAINABLE PECAN PRODUCTION Page 14
    • when the majority of eggs on the nut tips are in the pecan nut casebearer, the shuckworm isthe pink or red stage. difficult to monitor. The second reason is that soft spray options like Bt are limited because theAs the casebearer itself is a lepidopteran (moth) larval stage is spent mostly inside the pecaninsect, organic growers can use the biological shuck and, therefore, short-lived pesticidescontrol Bacillus thuringiensis kurstaki (Bt). Trade sprayed on the foliage have limited efficacy.names include Javelin® and Dipel®. Combinedwith a monitoring program, control is quite The standard tool for monitoring of shuckwormeffective. Because Bt does not last long in the until recent years was a blacklight trap.environment, sprays of Bt should be timed However, such traps attracted all kinds of insectsdirectly at the larvae rather than eggs. Apply and it was a time-consuming process to separatewhen 1–2% of the nuts have been entered. and count shuckworm moths. More recently, a pheromone that attracts female shuckwormA rule-of-thumb method is to spray when the nut moths was identified at Oklahoma Statetips turn brown. This is not as accurate, so it is University. Pheromone traps for the hickoryadvisable if using this latter method to make a shuckworm are available through commercialsecond application 7–10 days later. pest management suppliers.Hickory Shuckworm Several pesticides are registered for shuckworm control, including the insect growth regulatorThe adult hickory shuckworm (Cydia caryana) is a mentioned earlier, Confirm®. Growers raisingmoth. Larvae of the shuckworm tunnel into certified organic pecans will have to rely onpecan fruits from early spring until the shells accurately timed applications of Bt, or useharden in mid to late summer, thus destroying appropriately registered botanical insecticides.the fruit and resulting in premature nut drop.Three to four generations can occur each year. PhylloxeraLater generations attack pecans after shellhardening; damage from larvae tunnelling into There are five known species of phylloxera (a.k.a.pecan shucks (hull) causes poor kernel filling and "plant lice") that attack pecan, but the pecanprevention of shuck split. phylloxera, Phylloxera devastatrix is generally considered to be the most economicallyEarly in the spring, the shuckworm feeds important. The pecan phylloxera is mostprimarily on native hickory and is often found in common in its native range through Texas,phylloxera galls on pecan trees. Thus, one of the Oklahoma, Arkansas, Louisiana, and Mississippi.most effective control strategies for hickory This aphid-like pest causes galls or knots toshuckworm is targeting of phylloxera galls in appear, primarily on leaves though it also occursspring. The soft-spray control method for on fruits and stems. Severe infestations, whenphylloxera gall is a dormant application of they do occur, can result in plant stress,horticultural oil. In northern production regions defoliation, terminal dieback, and reduction in(Kansas, Missouri) where shuckworm pressure is yield and nut quality. Phylloxera galls also servenot too high, the nut thinning process associated as a host for developing larvae of the hickorywith hickory shuckworm may actually do more shuckworm.good than harm, according to Dr. William Reid atKansas State University. The shuckworm is In native groves, removal of susceptible treesabsent in the western pecan belt and in certain during normal thinning programs can reduce ordistricts of other pecan-producing states. eliminate phylloxera problems (8).Where it does occur, the shuckworm is Some cultivars are known to be more susceptibleconsidered a major pest for two reasons. The first to pylloxera than others. Resistant cultivarsreason is that, compared to the pecan weevil and include Mohawk, Chickasaw, Cherokee, // SUSTAINABLE PECAN PRODUCTION Page 15
    • Shawnee, Sioux, Kiowa, Caddo, Cowley, Standard pecan fungicides can provide adequateShoshoni, and Sumner (30). Cape Fear, Mahan, control for scab. Some of the copper fungicidesWichita, Cheyenne, and Tejas appear only are permitted in certified organic production. Inmoderately susceptible, while Apache, Riverside, any case, early-season control is important.Stuart, Success, Schley, and Desirable are knownto be susceptible (30-31). Failure to control scab on susceptible cultivars early in the season can lead to 50–100% cropBy the time galls appear it is too late to do loss (33).anything, since the galls encase the insect andthereby protect it from insecticides. If damage is Abound®, a new-generation fungicideanticipated, a dormant oil can be applied as part synthesized from a compound first discovered inof a certified organic program though control strobilurin mushrooms, is very effective againstmay not be as effective. Regular pecan scab and registered for that use. However, due toinsecticides are typically applied at bud break to Abound’s mode of action, C. caryigenum couldone-inch shoot growth. If sprays are delayed develop resistance if Abound is over-relied upon.past this period there is a risk the pest will Therefore fungicide rotation is stronglyalready be sequestered within a gall. encouraged.Diseases In the humid Southeast, the standard recommendation for scab control may call forPecan Scab fungicide sprays every 2–3 weeks from early spring to near harvest. Fortunately, models forPecan scab, caused by the fungus Cladosporium scab prediction are being developed. One suchcaryigenum, is the most serious disease of pecans. model, developed by Sharon von Broembsen ofScab pressure is particularly bad in the Southeast Oklahoma State University, can be viewed at thewhere humidity and rainfall are high. It presents Oklahoma Pecan Management website at:few problems in West Texas, New Mexico, http://www.hortla.okstate.edu/pecan/.Arizona, and California. In northern pecangroves, where the climate is drier than in the Other Diseasesdeep South and where genetic variation keepsscab from becoming epidemic, fungicidal control There are several foliar diseases, includingis not a regular practice. powdery mildew, downy spot, zonate leaf spot, vein spot, leaf blotch, et al., which can beDr. Bruce Wood (32), horticulturist with the troublesome for pecans, but rarely outside ofUSDA Fruit Research Station located in Byron, commercial plantings in the Southeast. In mostGeorgia, explained that while scab-resistant cases, sprays for scab will also control thesecultivars exist, many of the best commercial problems.pecan cultivars are susceptible. Additionally,scab resistance has been found to diminish over Appendix:time. For instance, Stuart was rated as veryresistant to scab for over 40 years, but by 1956 Scab Resistant Pecan Cultivarswas considered susceptible (33).Nevertheless, where scab is a factor mosthorticulturists are now suggesting that scabresistance be taken into account when selectingvarieties and planning an orchard. Susceptiblecultivars simply require too many fungicidesprays to be profitable.See the table in the Appendix for a list of pecancultivars currently rated as scab resistant. // SUSTAINABLE PECAN PRODUCTION Page 16
    • References: 10) Dr. William Reid Pecan Experiment Field1) Reid, William and R.D. Eikenbary. 1991. Kansas State University Developing low input management strategies P.O. Box 247 for native pecan orchards. p. 69–76. In: Bruce Chetopa, KS 67336-0247 W. Wood and Jerry A. Payne (eds.) Pecan 316- 597-2972 Husbandry: Challenges and Opportunities. 316- 597-2758 Fax ARS-96. USDA-Agriculture Research Service, Washington, D.C. 11) Dr. Bill Gustafson Dept. of Horticulture2) Taylor, Glenn Cat. 1990. Thinning native 211 Mussehl Hall pecan trees. p. 187–190. In: Proceedings of the University of Nebraska 9th Annual Oklahoma Horticulture Industries Lincoln, NE 68583-0714 Show. Held January 5–6, Tulsa, OK. 402-472-3674 402-472-3858 Fax3) Sparkes, Darrell. 1993. Leaf levels of zinc serc004@unlvm.unl.edu required for maximum nut yields and vegetative growth in pecan. p. 104–110. In: 12) Anon. 1991. Pecans move north. American 84th Annual Report of the Northern Nut Horticulturist. September. p. 11. Growers Association. Held August 1–4, Pittsburg, Kansas. 13) Wolf, Margaret E. and Michael W. Smith. 1999. Cutleaf evening primrose and Palmer4) Rice, N.R., et al. 1993. Evaluation of low amaranth reduce growth of nonbearing pecan input pecan orchard floor management trees. HortScience. Vol. 34, No. 6. p. 1082– systems. p. 95–103. In: 84th Annual Report of 1084. the Northern Nut Growers Association. Held August 1–4, Pittsburg, Kansas. 14) Foshee, W.G, W.D. Goff, M.G. Patterson, and D.M. Ball. 1995. Orchard floor crops reduce5) Smith, Michael W., et al. 1994. Screening cool- growth of young pecan trees. HortScience. season legume cover crops for pecan orchards. Vol. 30, No. 5. p. 979–980. American Journal of Alternative Agriculture. Vol. 9, No. 3. p. 127–134. 15) Patterson, Michael G. and William D. Goff. 1994. Effects of weed control and irrigation on6) Smith, Michael W., Asrat Shiferaw, and pecan (Carya illinoinensis) growth and yield. Natasha R. Rice. 1996. Legume cover crops as Weed Technology. Vol. 8. p. 717–719. a nitrogen source for pecan. Journal of Plant Nutrition. Vol. 19, No. 7. p. 1117–1130. 16) Smith, Michael W., Becky L. Carroll, and Becky S. Cheary. 2000. Mulch improves7) Hedger, George H. 1988. Considerations pecan tree growth during orchard involved in purchasing pecan production establishment. HortScience. Vol. 35, No. 2. equipment. p. 108–111. In: Proceedings of 7th p. 192–195. Annual Oklahoma Horticultural Industries Show. Held January 28–29, Tulsa, OK. 17) Soil Foodweb, Inc. 980 NW Circle Blvd8) Dr. Mike Smith Corvallis, OR 97330 Department of Horticulture and L.A. 541-752-5066 Oklahoma State University 541-752-5142 Fax 360 Agricultural Hall Contact: Dr. Elaine Ingham Stillwater, OK 74078 sfi@soilfoodweb.com 405-744-6463 http://www.soilfoodweb.com mws@okstate.edu 18) McCraw, Dean, M.W. Smith, R. Eikenbary,9) Whitcomb, Carl E. 1981. Growing Tree and D. Arnold. 1995. Use of Legumes in Seedlings in Containers. Oklahoma Agri- Pecan Orchards. Current Report No. 6250. cultural Experiment Station Bulletin 755. Cooperative Extension Service, Oklahoma Oklahoma St. University, Stillwater, OK. 18 p. State University. 4 p. // SUSTAINABLE PECAN PRODUCTION Page 17
    • 19) Pecan Production in the Southeast: A Guide 26) Harris, Marvin. 1985. Pecan phenology and for Growers. 1989. ANR-459. Alabama pecan weevil biology and management. Cooperative Extension Service, Auburn p. 52. In: W.W. Neel (ed.) Pecan Weevil: University. 230 p. Research Perspective. Quail Ridge Press, Brandon, MS.20) Brent Wiseman, Coordinator for Organic Programs 27) Mizell, R. F., III. 1985. Risk rating: A fruitful Texas Dept. of Agriculture approach to management of the pecan weevil. P.O. Box 12847 p. 69. In: W. W. Neel (ed.) Pecan Weevil: Austin, TX 78711 Research Perspective. Quail Ridge Press, 512-463-7476 Brandon, MS.21) Bugg, R.L., M. Sarrantonio, J.D. Dutcher, and 28) Eikenbary, Raymond D. et al. 1994. S.C. Phatak. 1991. Understory cover crops in Monitoring Adult Pecan Weevil Populations, pecan orchards: Possible management OSU Fact Sheet No. 7175. Cooperative systems. American Journal of Alternative Extension Service, Oklahoma State Agriculture. Vol. 6. p. 50–62. University. 4 p.22) Tedders, W.L. 1983. Insect management in 29) Anon. 1995. Pyramidal weevil traps offer deciduous orchard ecosystems: Habitat option to cone trap. Pecan South. July. manipulation. Environmental Management. p. 22–23, 26. Vol. 7. p. 29–34. 30) Calcote, V.R. 1985. Resistance of pecan clones23) Dr. Glenn Cat Taylor (retired) to Phylloxera devastatrix Pergande and P. The Samuel Roberts Noble russellae Stoetzel. p. 63–69. In: W.W. Neel, et Foundation, Inc. al. (ed.) Aphids and Phylloxeras of Pecan. P.O. Box 2180 Georgia Agricultural Experiment Station Ardmore, OK 73402 Special Publication 38. 405-223-5810 [Scott Landgraff at The Noble Foundation can 31) Pecan Entomology in Louisiana provide current pecan recommendations] Louisiana State University http://www.agctr.lsu.edu/agcenter/research24) Dr. Jim Dutcher /pecan/MJH/ento.htm Associate Professor of Entomology Entomology Department 32) Dr. Bruce Woods Coastal Plain Experiment Station USDA Fruit and Research Station, ARS Box 748 P.O. Box 87 Tifton GA, 31793 Byron, GA 31008 913-386-3567 912-956-565625) Arnold Brothers Biological Insect Pest Control 33) Ellis, H.C. et al. 1984. Pecan Pest P.O. Box 450 Management in the Southeast. University of Fairacres, NM 88033 Georgia Cooperative Extension, Athens, GA. 505-526-6165 p. 35–37. // SUSTAINABLE PECAN PRODUCTION Page 18
    • Print Resources Books: Pecans—A Growers Perspective. 1994. By Wes Rice.Pecan Grower’s Handbooks: PecanQuest, Ponca City, OK. 198 pages. $57.50 hardback, $39.50 softcover.Pecan Production in the Southeast: A Guide forGrowers. 1989. Alabama Cooperative Extension Pecan Cultivars: Past and Present. 1985. By TommyService, Auburn University. 230 pages. 300 full-color E. Thompson and Fountain Young. Texas Pecanphotographs. $45.00 Growers Association, College Station, TX. 265 pages. $19.95 hardback, $12.95 softcover.Available from: Alabama Cooperative Extension Service The Pecan Tree. 1994. By Jane Manaster. University Publications of Texas Press, Austin, TX. 109 pages. $17.95. 6 Duncan Hall Auburn University, AL 36849-5632 Pecan Pest Management in the Southeast. 1984. By 334-844-1592 H.C. Ellis, et al. University of Georgia Cooperative Extension Service, Athens, GA. 62 pages. $28.00.Texas Pecan Growers Handbook. 1994. TexasAgriculture Extension Service, Texas A&M University. Pecan Production in the Southeast: A Guide for200 pages. $15.00. Growers. 1996. By William D. Goff, John R. McVay, and William S. Gazaway. Alabama CooperativeAvailable from: Extension System, Circular ANR 459. 222 pages. Extension Horticulture $45.00. Texas A&M University College Station, TX 77843-2134 409-845-8904 Periodicals:New Mexico Pecan Growers Handbook. 1991. Pecan South (monthly), $18.00Cooperative Extension Service, New Mexico StateUniversity. 214 pages. $35.00 The Texas Horticulturist (monthly), $12.00Available from: The Pecan Newsletter, $85.00 Dr. Esteban Herrera [Pecan marketing information delivered in weekly New Mexico State University issues through the harvesting and marketing Plant Sciences Dept. season, late September thru late January]. Box 3AE Las Cruces, NM 88003 All the periodicals listed above are available from 505-646-0111 The Olde Pecan Bookstore.Books and Periodicals on Pecans: Pecan Grower (quarterly), $8.00 Available through:Several good books and trade magazines on pecans are Georgia Pecan Growers Associationavailable from one source in Texas. Contact: 4807 Woodland Dr. Tifton, Georgia 31794 The Olde Pecan Bookstore 912-382-2187 P.O. Drawer C College Station, TX 77841 409-846-3285 409-845-1752 Fax http://www.texaspecan.com/books.htm // SUSTAINABLE PECAN PRODUCTION Page 19
    • Electronic Resources on Pecan New Mexico State University Pecan Publications Production and Pecan Pest Management http://www.cahe.nmsu.edu/pubs/_h/An Introduction to the Genus Carya The New Mexico State University website hostsNational Clonal Germplasm Repository for Pecans and about 36 different fact sheets on pecan productionHickories and pecan pest management.http://extension-horticulture.tamu.edu/ /carya/species/index.htm Also at New Mexico State University:Pecan Cultivars Index Controlling the Pecan Nut Casebearer byPecan Genetics and Improvement Research, Applying Insecticide Based on Heat UnitsAgricultural Research Service, USDA New Mexico State Universityhttp://extension-horticulture.tamu.edu/ http://weather.nmsu.edu/nmcrops/pecans/ /carya/pecans/cvintro.htm /pecan_nut_casebearer.htmlGrowing Pecans in Kansas Oklahoma Pecan ManagementKansas State University Extension Service, MF-1025 Oklahoma State Universityhttp://www.oznet.ksu.edu/library/ http://www.hortla.okstate.edu/pecan/ /hort2/SAmplers/MF1025.htm The Oklahoma Pecan Scab ModelGrowing Pecans in North Carolina http://blaze.ocs.ou.edu/~nassar/scab/North Carolina State Universityhttp://www.ces.ncsu.edu/depts/hort/ The Oklahoma Pecan Nut Casebearer Model /hil/ag81.html http://blaze.ocs.ou.edu/agwx/models/pecan/ /pnc/Pecan Cultivar Performance at the Coastal PlainExperiment Station, 1921-1994. Georgia Agricultural Oklahoma Cooperative Extension ServiceExperiment Station Research Bulletin 426. 34 p. Pecan Publicationshttp://www.ces.uga.edu/pubs/PDF/RB426.pdf http://agweb.okstate.edu/pearl/hort/fruits/ /index.htmlIPM for Alabama Fruit and Nut TreesAlabama Cooperative Extension Service The OSU website hosts about 17 different facthttp://www.aces.edu/department/ipm/ sheets on pecan production and pecan pest /treefipm.htm management.Pecan Diseases in Alabama Also at Oklahoma State University:Alabama Cooperative Extension Service, ANR 606http://www.aces.edu/department/extcomm/ F-7642 - Pecan Diseases: Prevention and Control /publications/anr/anr-606/anr-606.html http://agweb.okstate.edu/pearl/plantdisease/ /f-7642.pdfPecan Entomology in LouisianaLouisiana State University Texas A&M University Aggie Horticulturehttp://www.agctr.lsu.edu/agcenter/research/ http://aggie-horticulture.tamu.edu/ /pecan/MJH/ento.htm Texas Nut Culture 418Pecan Insects, Images & Descriptions in South Texas A&M online Horticulture CourseCarolina http://aggie-horticulture.tamu.edu/Clemson University /syllabi/418/schedule.htmhttp://entweb.clemson.edu/cuentres/cesheets/ /pecan/ Managing Insect and Mite Pests of Commercial Pecans in TexasPecan Pest Management: Insects and Diseases Texas Agricultural Extension Service, B-1238University of Missouri-Columbia, MP711 http://entowww.tamu.edu/extension/http://muextension.missouri.edu/xplor/miscpubs/ /bulletins/b-1238.html /mp0711.htm // SUSTAINABLE PECAN PRODUCTION Page 20
    • Controlling the Pecan Nut Casebearer Pecan Kernel (Texas)Texas Agricultural Extension Service, L-5134 http://pecankernel.tamu.edu/http://entowww.tamu.edu/extension/ /bulletins/l-5134.html A pecan pest management site from Texas A&M entomology. It provides a convenient link to allPecan Pest Management CD-ROM the current and back issues of Texas Pecan Pest Management Newsletter and Texas IPM for Pecan Developed at Texas A&M University, the Pecan Press articles. Here, you can also find a list of Pest Management CD-ROM features: pecan specialists working at 19 land-grant universities and research and extension centers. General Information — pecan tree overview, pecan phenology, calendar checklist, chemicals, UC Pest Management Guidelines: Pecans cover crops, diagnostic key. University of California http://www.ipm.ucdavis.edu/PMG/ IPM Information — key pests, natural enemies, /selectnewpest.pecans.html diseases, casebearer and pecan weevil management. 1998 Sample Costs to Establish a Pecan Orchard and Produce Pecans (San Joaquin Valley, Flood Irrigated) Tutorial — pecan tree, pest management graphics University of California by region, early-, mid-, and late-season pests. http://www.agecon.ucdavis.edu/outreach/crops/ /cost-studies/98pecans.pdf With 166 color photos and the ability to search by keyword. Available for $60 through The Olde Routing Pecan Scab — Protecting a Popular Nut Pecan Bookstore. USDA Agricultural Research Service http://www.ars.usda.gov/is/AR/archive/aug98/Field Guide to the Insects and Mites Associated with /scab0898.htmPecan, B-6055http://entowww.tamu.edu/extension/forsale/ Crop Profile for Pecans in North Carolina /b-6055.html USDA Office of Pest Management Policy & Pesticide Impact Assessment Program Texas A&Ms entomological field guide to http://pestdata.ncsu.edu/cropprofiles/ important pests and beneficial insects found in /Detail.CFM?FactSheets__RecordID=205 pecan orchards, with color photos and descriptions; available for $12.95 per copy Crop Profile for Pecans in Texas (includes postage and handling). Make checks or USDA Office of Pest Management Policy & Pesticide purchase orders payable to: Texas Agricultural Impact Assessment Program Extension Service Account #233206 http://pestdata.ncsu.edu/cropprofiles/Detail.CFM?F actSheets__RecordID=291 Publication and Supply Distribution Texas Agricultural Extension Service The USDA Office of Pest Management Policy & P.O. Box 1209 Pesticide Impact Assessment Program website Bryan. TX 77806-1209 provides a state-by-state assessment of pesticide use in crop production. Reports provide cropTexas Pecan Pest Management Newsletter status, key pests, and typical pesticideEntomology at Texas A&M University recommendations. Currently North Carolina andhttp://entowww.tamu.edu/extension/ Texas are the only two states that have completed /newsletters/ reports on pecans. These crop profiles are valuable because they summarize the important Published 8–10 times during the growing season pests and what pesticides are used to control them. between March and September. Back issues to Where least-toxic or cultural controls are available, 1998 are located online, as well as the current these are also included. growing season. Northern Nut Growers Association, Inc.Texas Pecan IPM Articles in The Pecan Press Articles & Books on Pecanshttp://pecankernel.tamu.edu/newsletters/ http://www.icserv.com/nnga/pecan.htm // SUSTAINABLE PECAN PRODUCTION Page 21
    • Texas Pecan Growers Association Trecehttp://www.texaspecan.com/ 1143 Madison Lane Salinas, CA 93907Darrell Sparks Pecan Page 831-758-0204University of Georgia–Horticulture 831-758-2625 Faxhttp://www.geocities.com/CollegePark/Campus/ http://www.trece.com /3370/ Supplier of pheromone traps & lures. IPM Pest Management Supplies The electronic version of Sustainable Pecan Production is located at: http://www.attra.org/attra-pub/pecan.htmlBioQuip Entomology Products17803 LaSalle Ave.Gardena, CA 90248-3602310-324-0620310-324-7931 Faxbioquip@aol.com By Steve Diver and Guy Ames Supplier of entomology books and supplies: NCAT Agriculture Specialists handlens, catch nets, blacklights, pheromones traps, etc. Revised November 2000Gemplers IPM ProductsP.O. Box 270Belleville, WI 535081-800-332-6744 (Customer Service) Special thanks to Dr. Michael Smith, Department of1-800-382-8473 (Phone orders) Horticulture at Oklahoma State University, forhttp://www.gemplers.com comments and resources he contributed to the Supplier of IPM books and manuals; IPM field authors during revision of this publication. products, & pesticide safety gear. The ATTRA Project is operated by the National Center for Appropriate Technology under a grant from the Rural Business-Cooperative Service, U.S. Department of Agriculture. These organizations do not recommend or endorse products, companies, or individuals. ATTRA is located in the Ozark Mountains at the University of Arkansas in Fayetteville at P.O. Box 3657, Fayetteville, AR 72702. ATTRA staff members prefer to receive requests for information about sustainable agriculture via the toll-free number 800-346-9140. // SUSTAINABLE PECAN PRODUCTION Page 22
    • APPENDIX: Pecan Cultivars Resistant to Pecan Scab* ________________________________________ Cultivar Average rating1 ------------------------------------------------------------ Apache 5.0 Wichita 5.0 Burkett 5.0 Western Schley 5.0 Tejas 4.0 Cherokee 4.0 Cherokee 4.0 Cheyenne 3.5 Mahan 3.3 Shawnee 3.0 Sioux 2.7 Pawnee 2.5 Shoshoni 2.5 Mohawk 2.5 Maramec 2.5 Forkert 2.3 Osage 2.2 Colby 2.0 Barton 1.7 Peruque 1.7 Kiowa 1.7 Cape Fear 1.7 Podsednick 1.7 Choctaw 1.7 Chickasaw 1.5 Curtis 1.5 Desirable 1.5 Stuart 1.5 Caddo 1.2 Moreland 1.2 Sumner 1.2 Jackson 1.0 Success 1.0 Starking Hardy Giant 1.0 Gloria Grande 1.0 Melrose 1.0 ------------------------------------------------------ 1No scab lesions = 1; Lesions on over half of nut surface area = 5 From: Thompson, Tommy E. and L.J. Grauke. 1994. Genetic Resistance to Scab Disease in Pecan. HortScience. September. p. 1078–1080. // SUSTAINABLE PECAN PRODUCTION Page 23