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Common Insect Pests of Leafy Greens
- 1. Mair Murray & Nick Volesky Common Pests of Leafy Greens in Utah Snuck Farm (Utah County) Vegetable IPM Winter Webinar Series 1/11/21
- 2. Nick Volesky Common Insect Pests of Leafy Greens in Utah ‘Farm Yard Fresh’ Farm (Utah County)
- 3. • Leafy greens are popular and easy to grow on Utah farms. • Leafy greens are mostly cool-season vegetables that grow best in the spring and fall. Categorization of Leafy Greens Asters Endive, Escarole, Radicchio Beet Greens Brassicas Arugula, Collards, Kale, Mustards Lettuce Bibb, Cos, Iceberg, Leaf Spinach Swiss Chard Overview First Frost Farm (Cache County)
- 4. Aphids Cabbage Aphid (Brevicoryne brassicae) Green Peach Aphid (Myzus persicae) Melon Aphid (Aphis gossypii) Potato Aphid (Macrosiphum euphorbiae) Black Bean Aphid (Aphis fabae) Mustard (Turnip) Aphid (Lipaphis erysimi) Currant-Lettuce Aphid (Nasonovia ribisnigri) Poplar-Lettuce Gall Aphid (Pemphigus bursarius)
- 5. Aphids Aphid Colony on Lettuce Head Aphid Feeding Distortion Aphid Piercing-Sucking Mouthpart
- 6. Active Ingredients Product Names pyrethrins Evergreen, Pygan, Tersus pyrethrins + azadirachtin Azera acetamiprid Assail Burkholderia spp. Venerate Chromobacterium subtsugae Grandevo insecticidal soap M-pede horticultural oil many brands azadirachtin Aza-Direct, AzaGuard, Azatin, Mold Aphid Management Lady Beetle Lacewing Lady Beetle Larva Lacewing Larva Parasitoid Wasp Syrphid Fly Larva Row Covers Insecticide Application to Control Aphids
- 7. Armyworms + Cutwoms Bertha Armyworm (Mamestra configurata) Beet Armyworm (Spodoptera exigua) Western Yellowstriped Armyworm (Spodoptera praeefica) Variegated Cutworm (Peridroma saucia) Black Cutworm (Agrotis ipsilon) Armyworm Eggs Cutworm Eggs Armyworm Pupa Cutworm Pupa
- 8. Active Ingredients Product Names pyrethrins Evergreen, Pyganic, Tersus Tersus spinosad Conserve, Entrust, Success Success Burkholderia spp. Venerate Chromobacterium subtsugae Grandevo azadirachtin Aza-Direct, AzaGuard, Azatin, Mold spinetoram Radiant indoxacarb Avaunt tebufenozide Confirm Armyworms + Cutworms Management Protective Collar Tilling Soil in the Fall Hand RemovalRow Covers Pheromone Traps
- 10. Active Ingredients Product Names iron phosphate Sluggo, Escar-Go metaldehyde Deadline Slug + Snail Management Diatomaceous Earth Copper Barrier Slugs Eating Lettuce Bait Trap Bait Trap
- 11. enlarged femeral hind legs chewing mouth part Flea Beetles Flea Beetle Damage to Kale Western Black Flea Beetle Larva Flea Beetle Pupa Crucifer flea beetle (Phyllotreta cruciferae) Western black flea beetle (Phyllotreta pusilla) Threespotted flea beetle (Disonycha triangularis)
- 12. Flea Beetle Management Flea beetle damage to mustard greens Flea beetle damage to arugula Monitor by using a tray or white sheet of paper Yellow sticky trap Row covers Companion Planting Trap Cropping
- 13. Active Ingredients Product Names azadirachtin Azatrol, Ecozin, Molt spinosad Success, Entrust pyrethrin Pyganic Acetamiprid Assail lamba-cyhalothrin Bonide Beetle Killer permethrin BioAdvanced Complete Insect Killer, Bonide Eight cyfluthrin BioAdvanced Vegetable & Garden Insect Spray Flea Beetle Management Parasitoid Wasp (Microctonus vittatae) Big-eyed Bugs (Geocoris spp.) Lacewing Larvae (Chrysopa spp.) Damsel Bugs (Nabis spp.)
- 14. Leafminers American serpentine leafminer [Liriomyza trifolii (Burgess)] Pea leafminer [Liriomyza huidobrensis (Blanchard)] Vegetable leafminer [Liriomyza sativae (Blanchard)] Leafminer Eggs Leafminer Pupa
- 15. Leafminers Leafminer Larva Leafminer Damage on Spinach Leafminer Damage on Beet Greens Leafminer Damage on Beet Greens
- 16. Leafminer Management Active Ingredients Product Names abamectrin Agri-Mek spinosad Success, Entrust gamma-cyhalothrin Declare lambda-cyhalothrin Warrior Diglyphus isaea Dacnusa sibirica Row Covers Cultivating Soil Near Plants Spider Eating Adult Leafminer
- 17. Cabbage Maggot Cabbage Maggot Adult (Dalia redicum) Cabbage Maggot Damage on Kale Cabbage Maggot Pupa and Larvae Cabbage Maggot Larvae Burrowing Inside Stem Cabbage Maggot Larvae on Kale Root
- 18. Cabbage Maggot Management Active Ingredients Product Names zeta-cypermethrin Garden Tech Sevin pyrethrins + oil Monterey Take Down Garden Spray permethrin Bonide Eight Vegetable, Fruit, & Flower Crop Rotation Tilling Soil Row Covers Beauveria bassiana Disk Soil Surface
- 19. USU Extension – Utah Pests • extension.usu.edu/pests • Utah Plant Pest Diagnostic Lab • Educational How-To Videos • Free Guide eBooks • Informative Fact Sheets • Recorded Webinar Presentations
- 20. Utah Pest Advisories • pestadvisories.usu.edu • Timely email alerts on insects and diseases to look out for. • Fruit Pest Advisories • Vegetables Pest Advisories • Turf Pest Advisories • Landscape Pest Advisories
- 21. Utah Vegetable Production & Pest Management Guide • extension.usu.edu/vegetableguide • FREE PDF Version • Comprehensive Website • usuextension.store.com • Printed Hard Copies ($20)
- 22. Contact Nick Volesky (Vegetable IPM Associate) nick.volesky@usu.edu (435) 797-0319 USU Extension – Utah Pests @utah_pests
- 23. Earn 1 “Pesticide Use” CEU Match the term to the description: Send an email to dmatthews@utah.gov answer the following questions? natural predators, predators, parasites, and pathogens land/water management, sanitation, habitat diversification, tolerant/resistant cultivars, soil management hand removal, mowing, traps, physical barriers organic and synthetic pesticides Biological Control Chemical Control Cultural Control Mechanical Control
Editor's Notes
- INTRODUCTION Welcome everyone! My name is Nick Volesky, and I work for our USU Extension Integrated Pest Management Program. I’ll be coordinating this Vegetable IPM Winter Webinar Series. This year's series will be geared toward Utah's commercial and small urban farmers along with home gardeners. Tonight’s webinar will specifically cover common diseases and insect pests of leafy green crops. This includes arugula, collards, kale, and mustards in the Brassica family. Various bibb, cos, iceberg, and leaf lettuces. Along with beet greens, spinach, and Swiss chards. Leafy greens are popular and easy to grow on Utah farms. They are mostly cool-season vegetables that grow best in the spring and fall. • As a reminder; you are watching a Zoom webinar. So you will not have access to the camera or microphone. However, please feel to leave comments and questions in the Zoom chat box for our presenters to respond too. • This webinar will recorded and available on our USU Extension YouTube Channel along with our USU Extension-Utah Pests website. • If you have requested a “Pesticide-Use CEU” for the UDAF Pesticide Applicator’s license, there will be questions at the end of this webinar for you to answer and submit to UDAF for a certificate. I can explain more and help with that at the end. I will now give the time over to my boss and supervisor, Mair Murray, our Extension IPM Specialist to discuss diseases of leafy greens.
- Thank You Mair For this portion of the webinar, I’ll be covering some insect pests that you may come across in your leafy green production in Utah. This is not a comprehensive list, but rather highlighting some of the more common pests our growers see.
- Leafy greens or salad greens are a very popular and simple to grow on many Utah small and urban farms. They’re can potentially be grown year-around with the right facilities and management. Typically, pest pressure occurs in the traditional outdoor growing season of spring through fall. When I discuss leafy greens, I categorize them as… those in the asteraceae family: endive escarole radicchio Those in the brassica family: arugula and other mustards collards kale Different types of lettuces such as; bibb cos Iceberg butter head and beet greens, spinach, and Swiss chards. Some insects might prefer some of these specific crops over others. But for this presentation I will discuss the insect pests and crops as a whole.
- There are over 250 species of aphids that are considered pests to agronomic and ornamental crops. Aphids are pear-shaped, soft-bodies insects that suck sap from plant tissues. They are no bigger than 5 millimeters. They have notable tailpipe-like appendages called cornicles at the rear of their bodies. Color and textures range between species. Multiple species of aphids can attack leafy green crops. Here are some examples: Cabbage Aphid: identifiable for the “white powder” on them, which is actually mealy secretion they give off Hosts: collards, kale, and arugula Green Peach Aphid: Very common in Utah, they vector a lot of viruses. Hosts: arugula, chard, endive, lettuce, and spinach Winter Woody Hosts: Trees in the Prunus genus, particularly peach, apricot, and plum Melon Aphids: Hosts: spinach Winter Woody Hosts: Rose of Sharon and Catalpa Trees Potato Aphids: Can be green or pink. Hosts: beets, horseradish, kale, mustards along with spinach, arugula, and lettuce in the fall. Winter Woody Hosts: roses Black Bean Aphids: Hosts: beets, lettuce, spinach, chard, and rhubarb Winter Woody Hosts: Euonymus spp. Viburnum spp. trees and shrubs. Mustard or Turnip Aphids: Hosts: kale, collards, and mustards Currant-Lettuce Aphid: Hosts: chicory, raddicio, and lettuce Winter Woody Hosts: gooseberries and red/black currants Poplar-Lettuce Gall Aphid: Identifiable because they do not have cornicles and have the “white powder”, similar to cabbage aphids Hosts: chicory, endive, and lettuce Winter Woody Hosts: Poplar Trees
- Most vegetable aphid species have similar life cycles, with a few exceptions: One being cabbage aphids which overwinter as eggs on the debris of their summer hosts. In Washington County, they may overwinter as adults. Other aphids overwinter as eggs on a woody hosts (tree or shrub), which I mentioned earlier going over the different species. Eggs hatch as all females in the spring. Adults reproduce asexually throughout the summer, then eventually migrate to their overwintering sites. As you may already know, aphids are a problem for leafy greens because they can contaminate plant parts, leaving them unmarketable. Aphids feed with piercing-sucking mouth parts can cause distorted leaves or spread of viruses. Aphids may also secrete a sticky substance honeydew which can attract mold growth.
- To manage aphids, you want to scout frequently. Aphid colonies build up very quick. It is important to scout your leafy greens least twice weekly (when they are young and growing rapidly. Look on the underside of leaves where aphids congregate, and look for ant activity (as that can be a sign of aphids). Once aphid feeding causes leaf curling, it is more difficult to reduce aphid numbers. Greatest damage occurs when temperatures are warm, but not hot (65° to 80°F). Management: Avoid excess fertilization. (Aphid densities tend to be higher on plants that have succulent, vigorous growth). Apply row covers. (Physical exclusion) Remove/destroy plant debris post-harvest. Remove/destroy nearby weeds that can serve as an alternate host or virus reservoir. Encourage natural enemies such as lady beetles, lacewings, syrphid (sir-fid) flies, and parasitic wasps. If you purchase these from a biocontrol company they could be very affective in an enclosed high tunnel or greenhouse structure. Outdoors, they may just scatter. Many aphid species have developed resistance to insecticides, so we recommend the use of insecticides sparingly. (Not popular for consumers) Organic insecticides include products with active ingredients like pyrethrins (pai-ree-thrunzs), azadirachtins (ah-zat-er-actins), acetamiprids (as-e-tami-prids), species of the burkholderia pathogen, and the bacterium Chromobacterium subtsugae (chrom-o-bacterium subts-u-gae). Insecticides that use insecticidal soap or horticultural oils are popular.
- Both armyworm and cutwoms are the larvae stage of moths in the Noctuidae (noc-2-a-day) family. I included images of common armyworm and cutworms in species that may attack your leafy green crops here in Utah. This is not an comprehensive list, but all the species in these groups tend to be managed similarly. Keep that in mind. Armyworms Adult moths are gray with brown with light-colored markings. Larvae vary in color from tan to green to almost black. Have different markings. Larvae feed on foliage with chewing mouth parts, causing irregular holes, shredded leaves, or sometimes complete defoliation. Armyworms are a concern from Mid-July through September. Egg -> Larva (6-9 stages) > Pupa > Adult (Overwinter as pupae in the soil.) Eggs are found on leaves of crops or weeds. Maturing larvae disperse and move toward the center of the plant, or may be seen on the soil. Cutworms - Adult moths are gray with brown and light-colored markings. Larvae range from dull gray to brown, these caterpillars curl into a ‘C’ when disturbed. Larvae have chewing mouthparts and can clip off seedlings at the soil line reducing stands. Cutworms are most active and cause the most damage during spring and early summer months. (early as January into April) If your someone who uses high tunnels or does winter production, I’d be curious of the earliest you’ve seen cutworms. Egg > Larva > Pupa > Adult (Overwinter as larvae in the soil or under plant debris).
- Management Keep your farm or garden weed-free (especially lambsquarters and wild mustards), these weeds can serve as alternate host attracting adult moths Till soil in the fall to disrupt the overwinter pupae or larvae stage Implement row covers to physically exclude moths from laying their eggs. Smaller operations protect their seedlings with cardboard collars, to prevent cutworms from clipping Pheromone traps can be used to survey and monitor populations in a large area. Best management, is physically hand remove caterpillar and throw them into soapy water. Application of synthetic or organic insecticides; Bt (Bacillus thuringiensis) (bah-cill-us thur-e-gen-sis) and spinosad are very effective on caterpillar species, especially in early instars.
- Slugs and snails are probably the worst garden pests. They are obviously not insects but are mollusks that are more closely related to shellfish, such as mussels and clams. Slugs and snails have similar characteristics except snails have an external, spiral shell. Both glide with a long, flat, muscular organ called a foot. There is mucus or slime secreted by the foot of slugs and snails that help them move. But this dries and leaves a gross white trail, indicating that the pests was there, and nobody at the farmer’s market is going to buy salad mix with slug mucus trails. These pests are active at night or on dark, cloudy days. During the day they seek relief from the sun and heat in shade under plants, rocks, wood, or compost piles. They need moisture to thrive but survive in reasonably dry conditions like Utah by hiding in protected areas. These creatures are hermaphrodites, meaning they are not male or female, but all are capable of reproducing. They can lay multiple clusters of eggs throughout the growing season. (See photo of their small pearl-like eggs).
- Damage - Slugs and snails feed on a wide variety of vegetable crops including leafy greens. - They chew irregular holes that have smooth edges in leaves. Management Remove damp and dark hiding places. Don’t over irrigate your crops. Use copper barriers. Slugs and snails can receive an electric shock when they try to crawl over copper. (see photo) (Lots of mesh and strip copper products available). Diatomaceous earth is crush up fossilized shells. It will slow slugs and snails down because the sharpness cut them. But if the DE gets wet it will become soft and ineffective. Not really practical for large production. Place traps into the ground with baits like iron-phosphate or metaldeyde (meh-tal-day-hyde). Some producers use a beer, yeast, or honey mixture for the bait. Natural predators like snakes, toads, frogs, birds, and ducks like to feed on snails and slugs.
- Flea beetles are common and very problematic in Utah. You will find them in late spring and early summer Crucifer flea beetles Wide host range: primarily cabbage, kale, and mustard greens Western black flea beetle Hosts: brassica family, beet greens, and lettuce Three-spotted flea beetle Hosts: beet greens, spinach, Swiss chard, cabbage, horseradish, and lettuce Flea beetle adults typically range from 1.7 to 4.2 mm long. They have enlarged femeral hind legs which allow them to jump (where they get the name “flea” beetle. Color depends on the species. Most flea beetle species overwinter as adults in protected places. In the spring they will mate and lay their eggs at the soil base of desired host plants. Eggs then hatch into the larval stage which lasts about a month. Ten those larvae will pupae allowing for a second generation of adults in the summer. Flea beetle adults cause damage to foliage by chewing holes or leaving “pits” as shown in the first photo.
- Monitoring It is important to monitor for flea beetles on susceptible plants, especially in the spring. Check seedlings at least two times a week until they grow out of their vulnerable stage. In mature plants, treatment may be necessary when flea beetle populations are high, or on plants that are more susceptible to feeding, such as leafy greens. Sticky traps are a monitoring tool that provide a guideline of when beetles are present and in what quantity, but are ineffective in reducing populations. Either yellow or white sticky traps can be used. They should be placed around susceptible host plants just after planting but before seedlings emerge. Management Row covers are used to cover plants to create a physical barrier against flea beetle adults. Plants that are highly attractive to flea beetles can serve as a trap crop. Trap crops lure flea beetles away from the desired (cash) crop, and can be destroyed or sprayed to decrease the flea beetle population. Plant the trap crop about 2 to 4 weeks before the cash crop so that the larger, well-maintained trap crop will be more attractive to flea beetles. Some examples of successful trap crops for flea beetles include Chinese southern giant mustard, radish, pac choi, and pacific gold mustard. Once flea beetles start to feed on the trap crop, their populations can be managed. Companion plants can confuse, repel, or block insect pests from finding host plants. Bunching green onions, dill, and marigolds are a few examples of companion crops that have been used for flea beetle management. Intercropping or planting companion plants next to host plants will enhance plant diversity and make the desired crop less apparent to the beetles. Companion plants can also be used in combination with trap crops to increase success with pest control. The companion plant repels flea beetles from host plants, while the trap crop attracts the flea beetles. This is called a “push-pull” strategy.
- Management Generalist predators such as larvae of lacewing (Chrysopa spp.), adult big-eyed bugs (Geocoris spp.) and damsel bugs (Nabis spp.) feed on adult flea beetles. Additionally, a parasitoid wasp (Microctonus vittatae) can kill some species of adult flea beetles. These beneficial insects are attracted to nectar and pollen–producing plants such as anise, chamomile, clover, dill, and marigold. Although foliar application of insecticides is the most common management tactic for flea beetles, insecticides should only be used if necessary. Since plants produce continuous new growth and the highly mobile beetles can rapidly reinvade plantings, insecticides may have to be applied more than once to cover the plant’s susceptible period. I listed some synthetic and organic insecticide options on the chart.
- “Leafminer” commonly describes the larval stage of various insects, but those that feed on vegetable crops are most commonly small yellow-and-black flies in the order Diptera. In Utah, three species of leafminer flies attack vegetable crops: American serpentine leafminer, pea leafminer, and vegetable leafminer. Adult: Small fly, less than 2 mm in length with a wing length equal to or slightly longer than the body. Flies have yellow heads and grayish to black bodies with yellow markings on their underside. Wings are dark in color and held folded, horizontal over the back when at rest. Egg: White or yellowish, oval in shape. Larva: Legless maggot that can be transparent immediately after hatching, changing to white or cream in color, and yellowing with age. Pupa: Pupa color ranges from golden or reddish to dark brown, and the length ranges from 1.5-3.5 mm Leafminers overwinter in the soil as pupae with adult flies emerging in the spring and summer. After mating, females use their ovipositor (egg-laying structure) to puncture the leaf surface to feed and lay eggs inside the leaf. Eggs hatch quickly when temperatures are warm, usually within 2 to 4 days, and the developing larvae create visible winding mines as they feed below the leaf surface
- The major damage to the plant, however, is caused by the larva as it feeds and tunnels through the leaf’s mesophyll layer, resulting in blisters, blotchy mines, or serpentine tunneling. The mine increases in size as the larva grows. Frass (feces) may be visible within mines and can contaminate leaves intended for human consumption. With heavy feeding damage, photosynthesis is reduced, and leaves may dry and drop, resulting in decreased plant quality and yield. The most serious infestations usually occur late in the season and can affect large areas of the leaf.
- Check transplants for signs of leaf mines and white stippling before planting; destroy infested plants. Place a floating row cover (lightweight plant fabric) (Fig. 8) over plants to inhibit adult flies from entering and laying eggs. Immediately after the final harvest, remove plants and deeply plow crop residues to remove food sources and inhibit pupal development. Parasitic wasps pierce the soft body of a leafminer larva to deposit an egg. When the egg hatches, the developing parasitoid gradually consumes the leafminer larva. These can be commercially purchased from bio control companies. Insecticides are challenging to use due to the larvae being somewhat protected by the foliage.
- Cabbage maggot commonly attacks crops like cabbage, collards, kale, khol-rabi, and mustards. Cabbage maggot pupae overwinter in crop debris and soil. Adults emerge in early May, and mated females lay eggs in the soil at the base of host plants. Cabbage maggot larvae feed on the roots. Tunnels provide an entry for decay, fungi, and bacteria. Damaged plants show wilting, reduced growth, and lighter green plant parts.
- After susceptible crops emerge, watch for wilting, reduced growth, and signs of chlorosis (yellowing). If cabbage maggots are suspected, pull up affected plants and check the roots and soil to confirm maggot presence. If tunnels are found in roots, but no maggots are present, then maggots have already exited roots to pupate in the soil. This timing is too late for an insecticide treatment to be effective. Management • Crop rotation. Plant susceptible hosts as far away as possible from where they were planted the previous year. Immediately after harvest, destroy or disc under crop residues. Maggots are able to survive for an extended time in crop residues. • Biological Control: Carabid beetles, rove beetles, and parasitic wasps may help suppress cabbage maggots. However, biological controls alone generally do not keep cabbage maggot populations below economically damaging levels, especially once a population has established. In areas where cabbage maggot causes economic injury, treat with a band of insecticide at the base of the plant at the time of planting or transplanting.
- Complete guide to all things vegetable management in the intermountain west. Each section focusses on a certain crop family and provides information on varietal selection, transplanting, soil, fertility, planting and thinning, irrigation, harvest, and disease and insect management. All sections provide a comprehensive list of herbicides, organic pesticide, and synthetic pesticide options. Full color images of production methods, insects, and diseases are included.