Seminole Crop E News

Agricultural News for Farmers and Agribusiness in SW Georgia

Wheat Diseases Worsen

Posted by romeethredge on March 22, 2012

I’ve seen a lot of Powdery Mildew on wheat today in Seminole County and some Leaf Rust and it’s even on the flag leaf in some fields, which really concerns me.  The flag leaf is just below the grain head and is very important for producing photosynthate for grain production. In other words, we want to protect the flag leaf.  We will spray protectant fungicides on these fields very soon to protect yield.  Fortunately most of the fields are at at least 90% headed, so we will get disease protection on most of the grain heads.

Here we can see a few speckles of reddish Leaf Rust on the flag leaf.

Here is some more rust on a lower leaf.

Here is some powdery mildew on the flag leaf of this wheat plant.

Here is a Wheat Foliar Disease Update from Dr Alfredo Martinez, UGA Extension Scientist.

1. Powdery mildew. Moderate to heavy powdery mildew (Erysiphe graminis) infections have registered throughout the state. Powdery mildew tends to diminish as temperatures consistently reach above 75ºF and RH falls below 85%. However, if powdery mildew is continuing to progress up the plant and is found in upper leaves (flag leaf minus 2) you may consider a fungicide application.

For powdery mildew, fungicides options include: propiconazole (Tilt, Propimax); metconazole (Caramba); pyraclostrobin (Headline); azoxystrobin (Quadris); prothioconazole (Proline); propiconazole + trifloxystrobin (Stratego); propiconazole + azoxystrobin (Quilt, QuiltXcel), prothioconazole + tebuconazole (Prosaro); prothioconazole + trifloxystrobin (Stratego YLD); pyraclostrobin + metconazole (Twinline); tebuconazole + trifloxystrobin (Absolute).

A complete list of wheat fungicides, rates and specific remarks and precautions can be found at the 2012 Plant Management Handbook page 145 and/or at 2011-2012 Wheat Production Guide (page 58). Always read the label for fungicide applications instructions, restrictions and proper handling.

2. Leaf Rust. Very few infections of leaf rust have been observed  in commercial fields. However, while Powdery mildew tends to diminish with warmer temperatures, leaf rust (Puccinia triticina-formerly P. recondita) and/or Stagonospora (leaf-glume blotch) (formerly Septoria) infections can surface with these present weather conditions in Georgia. Field monitoring for these diseases is advised.

3. Remember that for an appropriate filling of grain, protection of the flag leaf is essential.

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