Seminole Crop E News

Agricultural News for Farmers and Agribusiness in SW Georgia

Rust,Rust,Rust

Posted by romeethredge on March 11, 2013

Today, I’ve seen three different types of rust on plants. I’ve seen Oat rust, Wheat leaf rust and Daylily rust. We’ve had good conditions for it, I suppose. We’ve been seeing some rust on oats but it seems to have almost exploded this week in oats being grown for seed, the growers will likely wait for flag leaf emergence, probably another week or so, to apply a fungicide.

Rust on oats.

Rust on oats.

Oat rust.

Oat rust.

The second rust I saw today was wheat leaf rust. The very observant County Agent Andrew Sawyer in Thomas County found some there on Friday and I found some today here in Seminole county at very low levels. Not at all like the levels of oat rust we are seeing.

Flag leaves are just emerging and the rust is low on the plant so growers will likely wait until all flag leaves are out and heading is about done so they get fungicide protection on the flag leaf and hopefully on the head. This all depends on disease progression.

Here’s some  information concerning Leaf Rust from Dr. Alfredo Martinez, UGA Extension Plant Pathologist.

Wheat Leaf Rust.

Reddish-brown pustules develop on leaves and sheaths. These pustules are filled with spores of the fungus. Rubbing an infected leaf will leave rusty colored areas on your fingers. Rust pustules may be very tiny, barely large enough to see with the naked eye, to 1/8 inch in length. Generally, varieties with higher levels of resistance will have smaller pustules than varieties with lower levels of resistance. Varieties with poor resistance will also have larger yellow halos around the pustules. Leaf rust has the greatest effect on yield of the wheat diseases because it develops rapidly during favorable weather.

Rusts are the most economically important group of wheat diseases. More than $5 billion is lost to cereal rusts (leaf rust, stem rust and stripe rust) worldwide each year. The capacity of rusts to develop into widespread epidemics is well documented. Rusts have complex life cycles that involve alternate hosts and several spores stages. Adding to this complexity are the numerous “physiological races” separable by patterns of pathogenicity and virulence on differential hosts. New races continually surface due to the rusts’ ability to mutate and sexually recombine.

Wheat leaf rust.

Wheat leaf rust.

Fullscreen capture 3112013 52144 PM

When I got back into the office I was left several daylily leaves that had the third example of rust I saw today, Daylily rust. It is a bad case and the homeowner will spray right away.

Daylily Rust.

Daylily Rust.

 

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