Small Grain Disease Update – May 27, 2011

Bob Mulrooney, Extension Plant Pathologist;

The most prevalent diseases that can still be seen in areas where the barley has not returned yet are the spot blotch form of net blotch and powdery mildew. After checking the barley varieties today near Sandtown in western Kent County I don’t believe that net blotch will be affecting yields, but powdery mildew on unsprayed ‘Thoroughbred’ will reduce yields if the flag leaf is infected. There is some scab infected barley in Kent County.

The wheat in the Kent County variety trial has tan spot moving in rapidly on some varieties. Most of the varieties are in the watery ripe stage of development and will not likely be adversely affected. Leaf rust was easily seen on a public variety ‘Rumor’. Powdery mildew in general was low in most varieties but was in the upper canopy on SS8302, Milton, Bravo, and USG3770. There is a low level of scab in the trial as well. If scab is going to appear it should be evident now or very soon depending on location. Low levels of scab (less than 1% of the heads infected and most of the infected heads were only partially infected) were present in 8 out of 45 varieties (around 18%).There is some sort of physiological spotting that could look like a disease but is probably a resistance reaction by the variety in response to a fungal infection. This spotting was evident on the following varieties at this Sandtown location: Merl, Sunburst,USG3665, USG3409, USG3251, and Grow Mark FS627.