Today, Mitchell County Ag Agent Andy Shirley discovered wheat rust in Mitchell County.Wheat leaf rust is caused by the fungus Puccinia triticina. Wheat rust has the greatest effect on yield of any disease because of its ability to develop quickly in the right environment. Rust pathogens must be re-introduced each year; they do not overwinter. The detection is by scouting. We have both leaf rust and stripe rust. Leaf rust has reddish postures on the leaves that you can rub off on your finger. Stripe rust postures coalesce to form stripes between the veins of the leaf blade.
Rust postules – Photo by Andy Shirley
We will have to treat with fungicides to manage rust disease. The most important thing is to protect our flag leaves. However, wheat is only in the jointing phase now. It is best to wait as close to flag leaf to spray – if rust is not in the field. At this time, we need to be scouting our fields for rust. If rust is found, then a spray is needed – regardless of crop maturity.
A good option is to mix our chemistries for a curative and protective effect and help manage for resistance. We have triazole and strobilurin fungicides available. UGA Extension Pathologist Dr. Alfredo Martinez says, “When leaf rust has become established in a field, triazole fungicides tend to be most effective. Strobilurins have a more preventive activity and tend to be weaker if rust is already in the field. Remember that protection of the flag leaf is of essential importance for yield preservation.” A complete list of wheat fungicides, rates and specific remarks and precautions can be found on page 60 of the 2014-15 Wheat Production Guide. More information on ID and control can be found at Identification and Control of Leaf Rust in Wheat in Georgia.
Rust spores – Photo by Andy Shirley
Thomas County Ag 