Abstract: Session 2 - Putting Biological Control to Work

Biological Control: Past, Present, and Future

Mike Hoffmann, an entomologist in New York, reviewed basic information about biological control agents used against insects: predators, parasitoids, and pathogens. He also reviewed the methods of using biological control: conservation of naturally occurring natural enemies, classical biological control, and augmentation of natural enemy populations. He discussed manipulation of habitat to increase natural enemy populations by planting sources of food (pollen and nectar) or shelter.

Crop Diversification and Encouraging Biological Control

What Growers Can Do to Enhance Biological Control of Insects

Sharad Phatak, a horticulturalist from Georgia, reviewed his research project investigating the effects of cover crops and conservation tillage on insect management. One goal is to provide year-round food and habitat for beneficials to ensure their presence within or near economic crops (such as peanuts or cotton). Another is to use cover crops effectively to improve soil quality. In order to maximize the benefits from the cover crops, this project has emphasized no-till or minimum-till systems, including relay cropping and strip tillage. Herbicides and conventional fertilizers are used, but no insecticides, fungicides, or nematicides. However, some of the studies have found insect damage reduced to 1% and no foliar disease.

Insect Habitat on a Diversified Farm

Cass Peterson, an organic farmer from Pennsylvania, described what she does to provide habitat for beneficial insects. She allows native wildflower stands to remain near her fields, intersperses flower crops and flowering herbs (particularly plants in the Apiaceae, such as dill, fennel, and cilantro) throughout the vegetable fields, and grows alfalfa as a nursery crop adjacent to the vegetable fields. Beneficial insects move from the alfalfa to vegetable fields at the first cutting. She uses insect and mite natural enemies in her greenhouse for biological control. She rarely uses even the botanical pesticides allowed in organic production.

Although she is generally pleased with the level of insect management, she identified tarnished plant bug and stink bugs as difficult to control.

Pests and Peacework

Elizabeth Henderson, an organic farmer from New York, also described what she has done in the past and what she plans to do at her new location, Peacework Organic Farm to provide beneficial insect habitat. She has a highly diversified farm, and practices crop rotation, cover cropping, and growing buckwheat as a green manure.

She planted flowering shrubs in the treelines to increase biodiversity. On her previous farm she seeded clover and grass in the laneways, and on the new farm she will leave existing clover and grass sod between permanent beds for growing vegetables. She has found that pest insect species are present, but usually are controlled by predators. Botanical insecticides are only used occasionally to control flea beetles on brassica seedlings.

Bio-Strip Intercropping at Ruckytucks Farm

Steve Gilman, another organic farmer from New York, also has a system of sod strips between vegetable beds. Dutch white clover was sown in the sod strips, but there are also a diversity of perennial grasses, herbs, and wildflowers. He uses a "mow-and-blow" system to cut the strips and use the cuttings as mulch. He believes that these strips have many uses in addition to insect management. He no longer needs to use any pest controls, including botanical pesticides and Bacillus thuringiensis, for the last five years.

Biodiversity in Farm Vegetable Production: Sustainable Agriculture Practices

Michael Keilty, a farmer from Connecticut, has found that biodiversity has allowed him to eliminate all need for chemical fertilizers and pesticides. The farm includes livestock (beef cattle, sheep, chickens, and turkeys), Christmas trees, and medicinal herbs, as well as vegetables. Winter squash and fall potatoes are grown in a 5-7 year rotation with forage crops and cattle grazing. Other vegetables are grown in permanent beds using the French intensive method. Poultry are allowed to forage for insects in the vegetable areas for a limited amount of time each day.

The feed for the animals is grown on the farm and the manure is used on the farm.

Discussion: Session 2

The speakers responded to questions about growing and maintaining sod strips or patches on their farms. There was also a discussion of the benefits and difficulties of integrating livestock into the farm system.