Minimizing Corn and Soybean Stand Establishment Diseases in 2011

Rhizoctonia and Fusarium

Rhizoctonia solani and several Fusarium species may also cause seedling blights on corn and soybean. Rhizoctonia solani can survive under a wide range of soil moistures and soil temperatures but may decline when soils are flooded or soil temperatures are unusually high. Fusarium root rots may be most severe when the soil is saturated and soil temperatures are around 57° F. Crusting, hard pan layers, herbicide injury, deep planting, poor seed quality, insect damage, mechanical injuries, poor fertility or other factors which delay germination and emergence favor the development of these early season diseases. Planting under good seedbed conditions and using an appropriate fungicide seed treatment (products containing active ingredients other than metalaxyl or mefenoxam such as captan, fludioxonil, azoxystrobin, carboxin, PCNB, thiram, trifloxystrobin, etc. are effective against Rhizoctonia and Fusarium spp.) are also important management options.

The bottom line is that 2011 may be a season to take precautions to minimize stand establishment problems caused by diseases in both corn and soybean. Planting high-quality seed with a high germination rate is always recommended but may be especially important this season. Corn seed comes with fungicide seed treatments already applied. Be sure that the fungicides on the seed purchased are active ingredients and rates that will be effective against the early-season diseases described above.

Seed treatment fungicides are not as standard on soybean seed but are becoming more common. If the soybean seed purchased is not treated, it may be wise to consider appropriate fungicide seed treatments applied prior to seed delivery or to use on-farm treatments. The 2011 Missouri Pest Management Guide University of Missouri Extension Publication M171 contains tables of fungicides labeled for use as seed treatments on corn and on soybean.

Monitoring soil temperatures and soil moisture conditions as planting approaches will also be important. Ideally, corn and beans would be planted under the best possible seedbed conditions. Mother Nature doesn’t always allow that luxury but following field conditions and weather forecasts may lead to planting under the best possible conditions for 2011. Finally, avoiding any other stresses which delay germination or emergence may reduce the incidence and severity of the early-season diseases. Proper planting depth, avoiding conditions that would lead to crusting or herbicide injury, proper fertility and preventing insect damage can reduce the damage from early season diseases.