Wheat Disease Calendar

Included in this blog post find a wheat disease calendar to aid in scouting field and determining the time of the season when specific diseases may be observed. Most economically important foliar diseases occur at specific times of the year, generally immediately prior to and shortly after the emergence of the wheat head. However, in some cases, diseases such as leaf and stripe rust can be observed earlier in the season depending on whether or not the disease overwintered in fields following infection in the fall shortly after emergence. Keep in mind that all of the rust diseases observed in MS (including stem rust) need to blow into our production system on an annual basis. In addition, a disease such as Fusarium head blight (scab) occurs under extremely specific environmental conditions. Infection by the fungus that causes scab occurs if rain occurs during flowering. Scab was a major issue in the 2015 wheat growing season throughout the Mid-southern U.S.

The majority of the diseases presented in the attached calendar are foliar diseases. Keep in mind that a disease such as Barley yellow dwarf virus (BYDV) is typically observed later in season after the flag leaf has emerged. However, infection from the virus that causes BYD likely occurs much earlier than the initial observation. Sometimes, once the disease is observed it is difficult to judge when infection actually occurred depending on the specific disease. Note that some diseases can be observed in more than one growth stage (on the left column), but will ultimately depend on the environment encountered throughout the season and to a greater extent planting date. But, in some cases, previous crop will also dictate the foliar disease pressure. For example, tan spot has more regularly been observed in fields with a history of wheat whereas Septoria leaf blotch can be observed in almost any wheat field. Much like the other row crop diseases in our production system, the inoculum for rust diseases blows into MS on an annual basis from infection that occurs to our south.

Wheat disease scouting calendar (Wheat Disease Calendar 2016).