26 February 2015

Beneficial Insects manage garden pests

Julia Laughlin
Individuals making the gradual move toward organic gardening practices can look to Cuba for encouragement. The trade embargo and financial crisis led Cuba to convert to organic gardening beginning in 1989 since there was little money for fossil fuels or agricultural chemicals.

Cuba’s food crisis led to restructuring its food growing practices. Large monocultures were converted to small, local, organic farms that used lower cost organic inputs.

By 1994, 8,000 farms were being grown in Havana where front lawns, building lots, school and office gardens were converted to organic food production. By 1998 those plots grew over half a million tons of fresh, chemical-free, food for local residents.

Practices they use to keep crops healthy and productive include inter-planting food crops with plants that attract beneficial insects, growing compost worms for the worm casting fertilizer they contribute, and leaving crop compost on the soil after clearing.

According to Oklahoma State University professor emeritus, Julia Laughlin, most of the insects we do battle with here have zero impact on humans. In fact, only 15% of insects affect us at all. Of those, 12% are beneficial and only 3% can be considered pests.

Water and pollen providing plants
Laughlin said that on her organic farm, Belle Verde Gardens in Choctaw, OK, they watch for beneficial insects and encourage them by planting more of what they like, providing water sources and shelter.

Plus, she said, gardeners should learn which insects cause most of the problems (the 80/20 rule applies) and find out what natural strategies will keep them away from vulnerable plants.

Important to remember is that most insects are host specific. Grasshoppers and powdery mildew are not particular but many other bugs and diseases need certain plants or conditions in order to thrive.

Laughlin thinks the worst pests in her organic growing business are caused by the aphid/ant mutualism. Here are the steps she recommended to prevent and combat aphid problems.

Use crop rotation, plant disease resistant varieties, practice garden sanitation, cover plants with row covers and other insect barriers, vacuum insect families off of plants, stop tilling, start mulching, time the crop correctly to have strong plants, never use overhead irrigation, diversify the crops you plant, use trap cropping and companion planting, recognize and encourage beneficial insects.

For disease control, Laughlin said gardeners need to understand the disease triangle: a) host, b) pest, and, c) environment. All three are necessary for diseases to run rampant through your garden beds.

Gardeners can help themselves by being able to identify these beneficial insects: Praying mantids, ladybird beetle (adults, eggs and larvae), spined soldier bug, black and yellow garden spider, crab spider, damsel bug, assassin bug, wheel bug, big eye bug, syrphid fly and larvae, minute pirate bugs and green lacewing larvae.

Ground beetle larvae live in the soil and eat slugs, cutworms and root maggots.

The beneficial predators include: Tachinid fly, Brachonid and trichorammatid wasps.

Lady beetle larvae and adults eat aphids, scale, thrips, mealybugs and mites. Most gardeners cannot recognize the lady beetle caterpillars since they barely resemble the familiar beetles’ adult stage. Green lacewing adults eat flower nectar but when their young are in the caterpillar stage they are aphid predators.

We can also plant an insectary strip to increase the population of good bugs. Include in that planting:  Anise hyssop and zinnias to attract pollinators plus alyssum and carrot-plant family members such as Queen Anne’s lace, fennel and cilantro to attract parasitic wasps.

Other plants that attract beneficial insects: Yarrow, all clovers, vetch, sunflowers, cosmos, all milkweeds, calendula, basil, Mexican sunflower (Tithonia), asters, catnip, comfrey, coneflowers, evening primrose, mint, and ironweed.

Disease resistant plant varieties are on the OSU Fact Sheets page at http://pods.dasnr.okstate.edu.

Laughlin’s radio show, “The Garden Party” is Sat 11:00 on KTOK-1000

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RESOURCES

 

Free online book, “Pocket Guide to the Beneficial Insects of New Mexico” at http://hort.li/1EfL


“Good Garden Bugs: Everything You Need to Know about Beneficial Predatory Insects
by Mary M. Gardiner, published 2015 Quarry Books.

 

 



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