Tuesday, January 18, 2011

Organic Management of Vegetable Diseases (and Pests)

The Great Plains Growers Conference held in St. Joseph MO on Jan 6-8, 2011 offered some great speakers on some fabulous topics.  For the next 5 days, you will read reviews from Rachel Deffenbaugh of Gateway Greening, Inc., St. Louis, MO who attended the Organic Track.  You will no doubt learn something from each day's post.

Organic Management of Vegetable Diseases (and Pests)
Adam Montri, Michigan State University Student Organic Farm, was the speaker for this breakout session.

When organically addressing disease and pest management, early and preventative action is key. There are four steps: identify concerns, manage environment, scout for early disease identification, and take action early. When taking action, there are four different types of approach: cultural, physical/mechanical, biological, and chemical. A cultural approach means to control a plant’s environment to make it less desirable for disease and pests (i.e. disease resistant cultivars, crop rotation, moisture management, etc.). Physical/mechanical intervention utilizes physical barriers, such as row covers, low tunnels and hoop houses. Biological approaches are based on attracting, releasing and/or applying biological agents and on managing organic soil matter. Finally, chemical approaches involve applying sprays and other chemicals to control diseases and pests. It should be noted that all certified organic operations should check with their certifier before utilizing any chemicals (although there are organically certified applications that can be used).

I will use the example of cucumber beetles, which are a vector for bacterial wilt. Some cultural approaches to controlling cucumber beetles and bacterial wilt are to select for bacterial wilt resistant plant cultivars, plow under plant residues, and to practice long distance crop rotation. Row covers and low tunnels can be used as physical barriers that keep cucumber beetles out. Additionally, growers can plant a “trap crop”; non-resistant cultivars are planted along the edge of the beds, beetles infest these plants, and the plants are tilled under when infestation levels are high (this is another physical approach). A biological treatment for cucumber beetles may include releasing parasitic nematodes that revel in infecting cucumber beetle larvae. And, lastly, Kaolin clay and/or neem contain compounds that can serve as chemical deterrents for cucumber beetles.

Because organic production depends heavily upon a healthy growing environment that mimics natural systems, there are few treatment approaches that are specific to individual diseases or pests. Rather, an organic approach aims to rectify systematic deficiencies. For example, a common biological approach to eliminating many pests is to plant flowers and herbs that attract predator species, such as lady beetles, that will prey on harmful pests, such as aphids. Those same flowers and herbs may also attract bees and birds, which serve the essential role of pollination.
(report by Rachel Deffenbaugh – Gateway Greening, Inc., St. Louis, MO)

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