Best Practices by Pest
Aphids, Beetles, True Bugs, Caterpillars, Grasshoppers, Spider Mites, Thrips
Aphids
- Susceptible crops include Ranunculus, Anemone, Foxglove, Mum, Sweet Pea, Lupine, Dahlia, Lilly, Rudbeckia, Hollyhock, Zinnia, Aster, and more.
- Found on the undersides of leaves and on new growth. Drawn to plants with high nitrogen, keep fertilizers in check. Make sure organic N sources are available consistently throughout the crop cycle.
- Use a strong stream of water to hose aphids off plants.
- Use organic pesticides for knock-down before releasing beneficials for heavy infestations.
- Release Aphidoletes aphidimyza in the spring before the first sign of aphid infestation and once aphids are detected. Release every two weeks 2-3 times until established at a rate of .05-.1/ft² or 100-1,000 in hot spots.
- Release Aphidius colemani (or ervi) weekly at a rate of 1-5/100 ft² until established or 5-25/100 ft² for hot spots.
- Release green lacewing eggs and larvae every two weeks from March through October. Rates for eggs are 5/ft²and larvae 1-5 larvae/ft².
Thrips
- Susceptible crops include Poppies, Campanula, Lisianthus, Godetia, Feverfew, Freesia and Gladiolus.
- Focus biocontrols on susceptible varieties and use these as indicator plants.
- Use biocontrols preventatively, especially in propagation (most cost effective). Establish good populations of predators early in the season!
- Thrips thrive in hot weather spring through fall and are found hiding in flowers, buds, and tight spaces. Exhale or blow into flowers to activate thrips or tap onto white surface to find them.
- Use insect netting to exclude thrips from tunnel houses.
- Use organic pesticides for knock-down before releasing beneficials for heavy infestations.
- Greenhouse vs. outdoor recommendations will vary.
- Release Orius, the minute pirate bug at rates of .05 to .1/ft² as needed. Two releases generally a minimum, depending on habitat. If releasing early in the season, provide habitat plants to help support Orius as they establish. Alyssum, early flowering peppers, Dianthus and other plants can host the Minute Pirate Bug, Orius.
- Apply Amblyseius cucumeris predatory mites at rates of 5-10/ft² bi-weekly throughout the season or, for extra control (including whitefly), use Amblyseius swirskii at rates of 2-5/ft².
- Release green lacewing eggs and larvae every two weeks from March through October. Rates for eggs are 5/ft²and larvae 1-5 larvae/ft².
- Drench with nematodes for Western Flower Thrips pupae in soil.
Beetles
Cucumber beetle, Corn Rootworm Beetle, Japanese Beetle, etc.
- Susceptible crops are Marigolds, Zinnias, Dahlias and Roses.
- For cucumber beetles, delay plantings, don’t plant cucurbit crops near flower fields.
- Row covers for the first 30-40 days of new crops to exclude beetles.
- Mulch crops to prevent beetles from laying eggs at the base of plants. Use straw or plastic sheet mulching. Aluminum coated plastic mulch is highly effective.
- Use pheromone lures in sticky traps to attract and capture adult beetles.
- Consider sowing Blue Hubbard squash as a trap crop for Striped and Cucumber Beetle.
- Encourage birds to the garden for natural pest control.
- Target adults with insecticide applications, rotate products for best results. Make sure spray coverage comes in contact with insects. Spray under and above leaf surfaces. See ATTRA publication for more info.
- Apply beneficial nematodes to target larvae in the soil at rates of 1 million nematodes on sponge/1,000ft²
- Release green lacewing eggs and larvae every two weeks from March through October. Rates for eggs are 5/ft²and larvae 1-5 larvae/ft² applied before full bloom.
- Release Dalotia coriaria the rove beetle to prey on eggs, larvae or pupae in the soil at rates of 100-500 every 1,000 ft².
True Bugs
Tarnished Plant Bug, Stinkbug, etc...
- Susceptible crops are Dahlias, Zinnias, Chrysanthemums-late summer and fall.
- Find more on Lygus Bugs from UC IPM
- Provide habitat to support natural enemies like parasitic wasps and naturally occurring predatory insects like damsel bugs and spiders.
- Control weeds to minimize overwintering populations, use insect netting for exclusion..
- Use pheromone lures in sticky traps to attract and capture adults.
- Release Orius, the minute pirate bug at rates of .05 to .1/ft² as needed.
- Release Podicus, the Spine Soldier Bug. Rates are 1-5/plant depending on infestation.
- Release green lacewing eggs and larvae every two weeks from March through October. Rates for eggs are 5/ft²and larvae 1-5 larvae/ft² applied before full bloom.
Caterpillars and Moths
- Susceptible crops are Brassicas, fruit trees, mums, dahlias and more.
- Active year round. Look for fluttering moths, holes in foliage and caterpillar frass.
- Use pheromone lures in sticky traps to attract and capture adults (ex. codling moth).
- Target with Bt products like Dipel for broad spectrum caterpillar control.
- Release Trichogramma wasps at rates of 2/ft² weekly, 100,000-300,000/acre
Grasshoppers
- Most plants are susceptible to grasshopper feeding; however, they tend to avoid eating cilantro, squash, peas, tomatoes and most nitrogen fixing crops.
- Till soil in the spring to destroy overwintering eggs. Control weeds.
- Consider repellent sprays made from Garlic, Hot Pepper, Vinegar and Insecticidal Soap.
- Use floating row covers to protect small garden areas and row crops. Rotate crops.
- Build a ‘beetle bank’ to attract natural enemies.
- Cold wet weather is very destructive to newly hatched grasshoppers as well as very dry winter and spring conditions.
- Apply the pathogenic fungal product Lalguard M52 to the soil as the grasshoppers are hatching.
- Apply beneficial nematodes (Lawn and Garden) blend every two weeks for 6-8 weeks starting just before grasshoppers hatch. They will infect the juveniles that are more vulnerable. Apply at rates of 1 million nematodes on sponge/1,000ft²
Whitefly
- Susceptible crops include Poinsettia, Hibiscus, Gerbera Daisy, Lantana, Verbena, Mums, Scented Geraniums and Salvia. Check Kale and Cabbage nearby.
- Start with a clean, weed-free crop at the beginning of the season. Dispose of plant debris away from crops.
- Reducing the pest load by vacuuming large infestations can really help remove adults under leaves (early morning is best when pests are quiet).
- Use yellow sticky traps to monitor pests in the crop if needed.
- Sprays of insecticidal soap can help, but contact with pests underneath the leaves is critical.
- Reflective mulches (silver color) can be effective for repelling whitefly.
- Repellent plants such as Marigolds, Basil, Chives and other aromatics can help deter whitefly.
- Know your pest! Predators are dependent on the species of Whitefly.
- Release Encarsia formosa the parasitoid at rates of .1 to 1 per ft² bi- at least 5 times until established or use Eretmocerus eremicus to target the sweet potato whitefly (Bemisia tabaci) at rates of .1 to 2 per ft² bi-weekly at least 5 times until controlled.
- Release Delphastus the predatory beetle at rates of .05 to .5/ft² bi-weekly until established. Delphastus do not survive in the absence of prey, therefore only release when whitefly are detected.
Spider Mites
- Susceptible crops include Roses, Dahlias, Scabiosa, Asters, Carnations, Cornflowers, Snapdragons, Statice, Gomphrena, Acroclinium and plants in tunnels when it gets hot and dry
- Spider mites thrive in hot weather, spring through fall. Misting or hosing foliage can help prevent sider mite infestations.
- Thoroughly clean up the crop at the end of the season. Keep area weed-free.
- Release Amblyseius fallacis preventatively at time of planting. Rates are .1-3/ft² or 10,000/acre one time.
- Release Phytoseiulus persimilis if infestations are increasing quickly under humid conditions for a quick clean-up. Rates are .5 to 2/ft².
- Release Neoseiulus californicus under hotter, dryer conditions. Read more about the nuances of these predator mites to make the best informed choice. Rates are .5 to 2/ft².
- Release Galendromus occidentalis for higher temperatures and very low humidity. Rates are .5 to 1.5/ft² bi-weekly, two to three times.
Effective Organic Pesticides
Rotate for Best Results. Check to make sure you are choosing the best natural pesticide for the particular pest, as well as environmental condition. For instance, Mycoinsecticides work well only if the humidity around the plants is over 60rH. Soaps work best on Aphids, oils work better on Mites. Always choose the pesticide with the least toxic impact on beneficial insects. Make sure that the risk of spraying truly outweighs the cost of the loss of natural predators in the crop. Consider your options before you spray.
Insecticidal Soap - M-Pede, Safer Soap
- Horticultural Oils - Pure Crop1, Suffoil-X
- Botanical Oils - Circadian Sunrise, Ecotech, Epishield
- Neem based products - Azaguard or Azatin (these are very effective mixed with mycoinsecticides).
- Mycoinsectides - Botanigard, BioCeres, Mycotrol LalGuard M52, NoFly, Velifer
- Pyrethrins – Pyganic
Effective Organic Products for Disease
- Apply Trichoderma for soil pathogens - Root Shield, ProMot Plus, Tenet
- Use Mycorrhizae when planting for increased root development, optimizing water and nutrient uptake. Available in Mycos Gold and Big Foot Mycorrhizae.
- Apply Beneficial Bacteria to outcompete and interfere with bacterial and fungal diseases. – Actinovate, Armory, Cease, Mycostop.
- Use Botanical Oils – Circadian Sunrise, Guarda, Long Shadow, Regalia
- Utilize the power of Compost Tea and Kelp
Use dips for incoming cuttings, plugs and liners. Assume that all incoming plant material has pests. Treat early to save headaches later.
Best Practices by Season
In the Spring
- Monitor pest populations with weekly scouting of plants and sticky traps to help make informed and timely pest management decisions.
- Rotate crops to prevent pests from establishing in one area.
- Treat with insecticides before feeding injury is too much and to prevent mating and egg-laying. Use LalGuard M52 OD as a drench to target larvae in the soil.
- Plant trap crops to keep pests away from valuable crops. See ATTRA publication for more on trap crops and companion planting.
In the Summer
- Continue monitoring populations with weekly scouting of plants and sticky traps to help make informed and timely pest management decisions.
- Include insectary strips and beetle banks in the garden to attract beneficial insects. Flowers and herbs like alyssum, calendula and lemon balm invite ladybugs, lacewings, ground beetles and tachinid flies, all natural predators of garden pests.
- Learn to identify native predators and don’t kill them with pesticides. Provide habitat, water, and food resources so they will stick around.
- Practice good cultural controls like sanitation, spacing, proper irrigation and fertilization practices.
In the Fall
- Cultivate soil and remove plant debris, especially roots and fruits, to reduce overwintering pests and disease organisms.
- Remove weeds in and around the garden that could provide habitat for overwintering adults.
In the Winter
- Utilize organic pesticides during the colder months when beneficial insects are not active, but pests are starting to reproduce (aphids)!
Scouting and Monitoring
Continually scout throughout the season. Create a plan and stick to a schedule. Learn to identify pests as well as beneficials, and their developmental stages. Knowing crop history will make scouting more efficient as you identify trends with specific plants. Look under leaves and open flower buds to find pests hiding inside. Look for native predators as well as these might be a sign of pest infestations. For help with ID contact us at info@soundhorticulture.com or reach out to your local extension agent.
Resources
Cut Flowers: Insects and Mites in Commercial Production of Field Grown Cut Flowers UMass Extension, 2013
Integrated Pest Management for Cut Flower Growers with Dr. Betsy Lamb of NYS IPM Feb. 2023
Sound Horticulture The Dig on Dahlias Podcast with Alison Kutz 2024, 2025
Year Round Flower Farm Pest Management by Rebecca Kutzer-Rice April 2024