Field Crop Disease Observations -- June 5, 2006
By Laura Sweets

Barley yellow dwarf symptoms on young plants.

Wheat
There hasn’t been much change in the wheat disease situation over the last week. Barley yellow dwarf has been the most widespread and serious disease problem throughout the state this season. Foliage diseases such as Septoria leaf blotch, leaf rust and stripe rust have not been widespread or severe. In most cases they have come in late enough in the season that impact on yield should be minimal. Loose smut has been severe in some fields. This disease is best controlled through the use of disease-free seed or systemic fungicide seed treatments. Scab has been developing in some fields but does not appear to be a major problem statewide.

Corn
Unfavorable weather conditions are probably the main cause of corn problems thus far this season. Yellowing and stunting of plants has been reported from several areas of the state. In some cases these plants have poor root systems, especially very shallow root systems that run out almost parallel to the soil surface. Dry soils, compaction and other such factors could be causing this poor root system development. Some of these plants are also showing crown discoloration and/or crown decay. Very low levels of Stewart’s bacterial wilt and anthracnose have been reported.

Soybeans
Thus far, there have been few calls or questions on soybeans. Early season soybean diseases are usually evident during June so be on the lookout for symptoms of Pythium seed decay, Phytophthora seedling blight, Rhizoctonia root rot and Fusarium root rot. Septoria brown spot can develop early in the season but we have seen very little of this foliage disease yet this year.

Laura Sweets
Ag. Ext.-Plant Sciences
573-884-7307