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Organic Field Crop Production and Marketing in North Carolina

     
Alternative Grain Crops
Soybean Disease Management

By: Jim Dunphy, Crop Science Extension Specialist, NCSU

Soybeans have very few disease problems. This makes organic disease management in soybeans relatively easy. Nematodes are the main soybean disease agent in North Carolina. However, Asian soybean rust is a possible problem for growers in the state, and if present will require much more intensive management and thought to make organic soybean production viable.

Nematodes. The best way to avoid nematode damage is to plant varieties that are resistant to the nematode (and race) present in your field. Conventional nematicides are prohibited in organic agriculture and are expensive and not very effective anyway. Crop rotation (of at least two years) will probably help reduce soybean cyst nematode populations, but is not as useful when dealing with root knot nematode because of multiple host plants. If you suspect nematode damage, you can take samples from your fields (fall is the best time) and send them to the NCDA labs (1040 Mail Service Center, Raleigh, NC 27699-1040; 919-733-2655) for nematode assays. They will identify a nematode population and species, if it is present. The Agronomic Division of NCDA&CS also has nematode management and assay information on their website.

Organic Pesticides

There are a number of pesticides approved for use in certified organic production systems—mainly non-synthetic compounds or biocontrols. Some may be used to treat soybean diseases. These include: neem (and its derivatives), hydrogen peroxide, potassium bicarbonate, pesticidal soaps and copper products. While these products do have potential for controlling pests in corn, no research has been done on them in field corn in North Carolina and, therefore, we can give no recommendations for their use in the state. The cost of organically approved pesticides may be prohibitively expensive for field crop production. Conditions for use of a pesticide must be documented in the organic system plan (NOP 2000). See the Pest Management Web Resources for more information, or check out the OMRI site.

Asian Soybean Rust. This is a soybean disease that could cause severe economic damage and has the possibility of affecting NC soybean crops. It should be considered when managing for soybean disease. To manage soybean rust potential in organic soybeans in North Carolina, careful planning must be used as well as some possible trial-and-error tactics. Early maturity groups and/or early planting may be better than late maturity groups and/or late planting because the plants may be able to avoid the rust inoculum by being out of the fields earlier than the later maturing or later planted beans. Do not, however, create such an early maturing soybean crop that yields are reduced substantially. The ATTRA website has information on possible organic treatments for Asian Soybean Rust here. For more web-based information on soybean rust, go to the USDA’s public website on Soybean Rust; or the Soybean Rust Forecast Center located at NCSU; or the USDA online soybean rust tracking site.

 

 

 
     

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