STRIPE RUST
LEAF RUST
With the high humidity in the early morning hours, sporadic rains, and now the cool, rainy fronts that are moving in, rust is flaring up pretty good right now. If you have any plans of taking a crop to harvest it would be a good idea to at the very least take a walk through your fields and see what kind of rust pressure you may have. Leaf Rust generally has small circular pustules which are bright orange to a dark, brick red color. Stripe Rust has smaller, yellow pustules which are more elongated and will form a stripe along the leaf. Leaf Rust is a warmer weather disease which prefers temperatures around 68-77 degrees and generally shows up in late spring. Stripe Rust prefers cooler temperatures of 50-64 degrees and will usually appear in the early part of the spring. There can be some overlap as Leaf Rust appears as Stripe Rust fades away. The number one control strategy for rust is variety resistance. Of the approximately 40 or so varieties that I have information on, about 3/4 of them have resistance to Leaf Rust, Stripe Rust, or both. The race of rust can change from season to season however, so even though the variety that you have is resistant to rust, scouting should still take place. Resistant or moderately resistant varieties can also show moderate flecking or yellow spots or even small lesions. This damage is generally insignificant under “normal” rust levels but occasionally even resistant varieties can become overwhelmed under extremely heavy rust levels. When rust infection does takes place fungicide applications are not necessarily required immediately. The most important thing to keep in mind with rust is to protect the flag leaf. If the flag leaf becomes infected, necrotic, and dies, you will have tremendous yield loss. Fortunately the fungicides for controlling rust, whether it is Leaf Rust, Stripe Rust, of even Stem Rust are the same. There are also generics available now which have made control much cheaper. For additional information on wheat diseases visit amarillo.tamu.edu
