Inoculated disease screening nurseries of spring wheat and barley are grown annually at the Northwest Research and Outreach Center, Crookston. The continued objective is screening of spring wheat and barley lines for the respective University of Minnesota breeding programs in cooperation with the Plant Pathology Department. Spring wheat and barley are both screened for resistance to Fusarium Head Blight (FHB) caused by Fusarium graminearum in misted nurseries. Spring wheat is screened for resistance to leaf rust caused by Puccinia recondia f. sp. tritici and barley is screened for resistance to net blotch caused by Pyrenophora teres in non-misted nurseries. Approximately 10,000 misted rows of FHB nursery were grown at the Northwest Research and Outreach Center in 2009. Additionally, 1800 rows of wheat were screened for resistance to leaf rust at the NWROC and 560 rows of barley were screened for resistance to net blotch near Stephen, MN.

Disease nursery efforts in 2009

The misted FHB nursery is inoculated at the five leaf stage by spreading about 50 pounds per acre of corn seed which has been sterilized, infected with Fusarium graminarium and dried. A second 50 pound application is made 10 to 14 days later. The misting system simulates prolonged periods of light precipitation which are frequently associated with natural FHB epidemics. About 900 pounds of FHB infested corn seed is produced each year for use in the nurseries.

Occurrences of Fusarium Head Blight infections were infrequent in production fields during 2009. Fortunately, addition of inoculum and mist to the FHB nurseries resulted in disease levels adequate to differentiate levels of FHB resistance.

The leaf rust nursery is inoculated by spraying spores in an oil suspension on the nursery. The net blotch nursery is inoculated with infested straw which was harvested from the previous year’s nursery.

These spikes in pictures 1 and 2 should have been entirely green at the growth stage which the pictures were taken. The non green spikes are a result of FHB infection. The inclusion of check varieties throughout the nursery is essential to provide an accurate assessment of the potential for disease development. The degrees of disease development in the above checks clearly indicate that the applied inoculum and misting system were working well to provide a high level of disease potential in the nursery. Therefore, any lines exhibiting lesser disease levels most likely contain a level of disease resistance.