With wheat in the boot stage and approaching heading (Feekes 10) in many parts of Kansas, producers are considering the use of fungicides to manage foliar diseases and protect the yield potential of their crop. Susceptible varieties are at highest risk for yield loss when environmental conditions are favorable for disease development. K-State research has found that a single application can result in a 4-13% yield increase in susceptible varieties relative to wheat that remained untreated.
The publication Foliar Fungicide Efficacy for Wheat Disease Management has been updated and can be found at: http://www.bookstore.ksre.ksu.edu/pubs/EP130.pdf. The recommendations in this publication reflect several years of head-to-head comparisons of products in Kansas and many other wheat producing states.
Considerations for managing foliar diseases
Timely disease scouting is the first step in assessing the need for foliar fungicide applications. Important foliar diseases for Kansas wheat producers this year include stripe rust, leaf rust, tan spot, and leaf blotch. Producers should scout for symptoms of foliar diseases in the upper canopy, and particularly near the flag leaves of primary tillers. Damage to the flag leaf is most associated with reduced yield. If symptoms are present when scouting, a foliar fungicide application may be considered. There are many fungicides available in Kansas that provide very good to excellent control of foliar diseases and producers should consult the updated Foliar Fungicide Efficacy for Wheat Disease Management publication for details.
Managing Fusairum head blight (wheat scab)
It is important to remember that strobilurin fungicides (picoxystrobin, pyraclostrobin, azoxystrobin, etc.) should not be applied after heading (Feekes 10) if there is risk for Fusarium head blight. Strobilurins can cause increased mycotoxin levels in infected plants. Luckily, there are several products that are very good for Fusarium head blight control, including Caramba, Miravis Ace, and Prosaro. For maximum control, a single application may be applied at flowering (Feekes 10.51). The window for fungicide applications closes within a few days of the flowering period and very early stages of grain development. Most products labeled for head scab have a 30-day pre-harvest interval.
It is important to carefully consult fungicide label recommendations prior to product application.
Kelsey Andersen Onofre, Extension Plant Pathology
Erick DeWolf, Extension Plant Pathology