What is in this article?:
- Minimizing Corn and Soybean Stand Establishment Diseases in 2011
- Rhizoctonia and Fusarium
It is difficult at this point in the year to know what conditions will be like during the upcoming planting season. However, much of Missouri was unusually wet during much of the 2010 growing season and has received substantial amounts of snow this winter. If spring conditions are wet or the spring is a cool, wet one, the potential for seed decay, seedling blights and root rot problems in both corn and soybeans could be higher than normal.
Many of the seed decay, seedling blight and root rot problems on both corn and soybean are caused by fungi present in the soil. Pythium species can cause early season diseases on both corn and soybean. Many of the Pythium species are favored by cool, wet conditions at planting. Seed decay and seedling blight tend to be more severe in low-lying areas in a field, and in soils that have been compacted or remain wet for an extended period of time. Low soil temperatures (below 50-55° F) favor seed rot and seedling blight. Disease severity is also affected by planting depth, soil type, seed quality, mechanical injury to seed, crusting, herbicide injury or other factors which delay germination and emergence of seedlings. Planting under good seedbed conditions and using an appropriate fungicide seed treatment (products containing either metalaxyl or mefenoxam as an active ingredient are particularly effective against water mold fungi such as Pythium spp.) are important management options.
Phytophthora sojae is another soil-inhabiting fungus that causes seed decay, pre-emergence or postemergence damping-off and seedling blight of soybean but not of corn. Phytophthora root rot is more severe in areas that are low or poorly drained, in compacted areas or in clay or heavy soils, but the disease can appear on plants growing in lighter soils or higher ground if the soil remains wet after planting. When soils are flooded or saturated, the fungus releases spores, which are attracted to the growing soybean root tip where infection occurs. Planting varieties with either race-specific resistance or tolerance or a combination of race-specific resistance and tolerance in fields with a history of Phytophthora is a critical management strategy. Planting under good seedbed conditions and using an appropriate fungicide seed treatment (products containing either metalaxyl or mefenoxam as an active ingredient are particularly effective against water mold fungi such as Phytophthora sojae) are also important management options.