Stripe rust is still present and very active in winter wheat, even what was treated a month ago.

I heard from Bayer CropScience of multiple reports of stripe rust in winter wheat in South Dakota. Unfortunately this rust was on on wheat that had been previously treated with a fungicide at the Feekes 4 to 5 stage of growth.

Active stripe rust pustules were found on the flag-1 leaf (below the flag leaf) on Ideal, SY-Wolf and Overland winter wheat in Aurora and Davison Counties. Fungicides move upward and outward in the tissue they are applied to, so the top leaves would not be protected by the earlier fungicides.


A few key points:

1) Flag and flag minus one leaves are tremendously important for the developing head. 

2) We have optimum conditions for stripe rust to reproduce. Optimum temps are 50 – 80 degrees with moisture and humidity present. 

3) Heading is still probably 10 days to two weeks away. Scab fungicides are excellent for control of leaf rust! HOWEVER- dead is dead! What I mean is that once you lose leaf area you cannot gain it back, even if you control the rust. You may HAVE TO SPRAY before heading. 

4) Tebuconazole has a max yearly use rate of 4 oz, so if you use a teb fungicide now, you cannot use the full rate of Prosaro later for scab. Manage your fungicides to keep the best tool available for scab.