Stripe Rust Confirmed in Wheat in Southeast Nebraska - UNL CropWatch, May 8, 2013

Stripe Rust Confirmed in Wheat in Southeast Nebraska - UNL CropWatch, May 8, 2013

Stripe rust on a wheat leaf   Stripe rust on wheat

Figure 1: Stripe rust on a leaf of a wheat plant at an early stage of development at the ARDC near Mead on May 7.

  

Figure 2: Stripe rust on a leaf of a wheat plant at an advanced stage of development.

 

May 8, 2013

Wheat field

Figure 3: Field in which stripe rust was found at the ARDC on May 7.

Stripe rust

Figure 4: Close-up of stripe rust-infected plants at the ARDC on May 7.

On May 7 stripe rust (Figures 1 and 2) was confirmed in research plots at the UNL Agricultural Research and Development Center (ARDC) near Mead. Wheat in the plots is still in the early stages of development (Figures 3 and 4), having been delayed by prolonged cold spring temperatures. When wheat is in these early stages of development, stripe rust does not form distinct stripes on the leaves (Figure 1). Stripes (Figure 2) usually develop on upper leaves after stem elongation.

Conditions Conducive to Disease Development

It is recommended that wheat fields be scouted regularly for detection of stripe rust. Weather conditions are currently favorable for rapid development and spread of this disease. If stripe rust is detected in a wheat field, consider applying a fungicide, especially if favorable weather conditions (rain and cool temperatures) are forecast and a susceptible variety was planted. A list of wheat fungicides and their efficacy ratings for stripe rust and other wheat diseases is given in Table I, a resource developed by the North Central Regional Committee on Management of Small Grain Diseases. (The blue hightlighted text indicates newly registered fungicides.)

The race of stripe rust this year has not been determined yet. Therefore, varieties that were rated as resistant last year may be at risk if there is a new race this year. Wheat at earlier stages of development is at greater risk of substantial yield loss from stripe rust than wheat at advanced stages of development.

Stephen Wegulo
Extension Plant Pathologist