Diseases in Peas

The pea crop looks good and the price is right. We have the potential to have a profitable year in peas. Disease of peas can erode that profit. There are two diseases that are common in this area. Aschochyta leaf and pod spot as well as mycophaerella blight and foot rot can cause major crop losses. Understanding these diseases and how to control them is essential to having a profitable pea crop. Both Ashochyta leaf and pod spot and mycophaerella are very similar. From a practical point of view, treating the two diseases the same is the best approach. The diseases create lesions on a plant that eventually kill the tissue. If the death of the tissue occurs soon enough, the plants will not reach there maximum yield potential. The most critical area when looking at disease pressure is near the base of the plant. If this area is severely affected, nutrients and water will not translocate in the plant. Early infection will lead to pre-mature ripening and will result in yield loss. The risk of this disease goes up when there are rain showers. The plant will start to show lesions on the stem. As the lesions move up the stem, the disease pressure gets worse. The earlier the plant is infected with either disease, the more likely yield loss will result. It is important to check fields for the presence of these diseases and have a spray program in place to deal with it. As the disease moves up the stem, the potential yield loss goes up. From local experience, the timing of the fungicide should be at the stage when the disease has moved up the plant stem from 4 to 6 inches. The label of the fungicide states that the product should be sprayed at about the beginning of flowering or at the onset of the disease. Spraying the fungicide early will benefit the plants if the disease is present. Spraying too early can be counterproductive for a couple of reasons. First off, the fungicide is expensive and its use must be justified from both an economic and environmental perspective. Secondly, the fungicide only provides 10 to 14 days protection. The possibility of having to spray twice increases significantly when a field is sprayed early. Spraying does improve yield. In the field trials that we have taken yield measurements, we have only had one field that did not provide a yield response. It yielded over 70 bushels per acre, so the field did quite well. The other benefit that generally results from spraying a fungicide on the peas if the disease is present is that the peas will stand better and be easier to combine. The financial benefit to this is hard to define, but it is important at harvest time. Controlling disease in peas is essential for top yields. Rain showers increase the disease risk. Know what to look for with pea diseases so the proper control measures can be applied. If you are not sure what to do, contact your local agronomist.

 

By Dave Cubbon, P Ag