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Angie Peltier

Angie Peltier
Former Extension Educator, Commercial Agriculture

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Hill and Furrow

Current topics about crop production in Western Illinois, including field crops research at the NWIARDC in Monmouth.
Figure. Stripe rust of wheat. Note the orange to yellow spores of the fungus erupting through the leaf tissue in long stripes  (Photo: Carl Bradley).
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Time to scout your wheat

The Feekes wheat growth staging scale was developed to focus on important milestones in wheat development, particularly those that are important growth stages for scouting for insects, disease and weeds. See the blog article, Growth staging wheat, for more discussion about the Feekes scale. Scouting should typically begin at Feekes 8, when the flag leaf is first visible. The flag leaf is important to protect from fungal diseases because this leaf provides the most photosynthate (75%) to filling grain.

I have not observed disease at the NWIARDC and the dry weather conditions that we had up until this last weekend are not conducive to foliar diseases. However there are a couple of diseases to be on the look-out for yet this season.

Stripe Rust

Dr. Carl Bradley, U of I Plant Pathologist, has written about stripe rust moving into several of the southern Illinois counties (

Rusts are considered obligate parasites, meaning that they need a living host in order to survive. This is why rusts in southern states and southern Illinois can help us in central and northern Illinois anticipate its arrival. Wind and rain systems from further south will bring spores to our area. Temperatures below 70 °F and wet leaves favor disease development.

Stripe rust is caused by the fungus Puccinia striiformis. Symptoms of stripe rust begin as chlorotic stripes on the leaf. As lesions develop, the fungus produces spores that can cause secondary infections. These spores, which are yellow to orange in color, develop under the leaf epidermis and swell the leaf tissue into a pustule (blister) which breaks open to reveal the spores (Figure).

Some fungicides are registered to control stripe rust, but the most effective time to apply fungicides is between last leaf emergence and complete head emergence. Applications that occur later are not likely to provide adequate protection. If cool weather continues throughout heading, be sure to continue to scout your wheat for stripe rust.

Fusarium head blight

Fusarium graminearum, a fungus, causes a disease called Scab or Fusarium head blight. Partially resistant varieties and crop rotation can reduce the risk of disease, however corn can be a host. The fungus survives in crop residue and warm, wet and humid weather favors infection.

The Fusarium Head Blight Risk Assessment Tool uses weather data to estimate the risk of disease at flowering. Fusarium head blight risk is currently low throughout the entire state of Illinois and the wheat-growing region of the country (Figure). Knowing the growth stage of your wheat crop is important so that you can use the tool to know your risk during the most susceptible growth stages: flowering to early grain development.

The North Central Regional Committee on Management of Small Grain Diseases developed a listing of efficacy of foliar fungicides for wheat. Be sure to pay close attention to harvest intervals.

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