ISSUE 14 July 31, 2003
NDSU IPM DISEASE SURVEY RESULTS, 7/21- 7/25
NDSU IPM scouts surveyed 115 wheat and 41 barley fields last week for leaf and head diseases. Wheat and barley crops are fast maturing, with wheat in the southern half of the state in dough development or ripening stages.
In wheat, a combination of leaf rust, Septoria, and tan spot caused an average leaf disease severity of 26%, with Septoria (= Stagonospora nodorum) being dominant (see figure below). These values are averages; in the eastern half of the state, disease levels were higher than in the southwest or north-central and northwest counties. In barley, a combination of spot blotch, net blotch, Septoria, and leaf rust combined to cause an average 22% leaf disease severity in crops ranging from boot stage to mid-dough.
Average Leaf Disease Severities on Wheat and Barley ľNDSU IPM Survey, 7/25/03
IPM scouts also found 26% of the surveyed wheat fields to have some level of scab or FHB symptoms, but field severity averaged less than 1%. In barley, 10% of the surveyed fields showed scab symptoms, with an average field severity of 1%. The majority of fields showing scab symptoms were in the Red River Valley area, areas that got the more frequent and heavier rains in late June and in July.
Symptoms of barley yellow dwarf virus (BYDV) were found in 47.8% of the wheat fields surveyed in the Northeast and East Central counties, with an average of 10% of the plants in the field showing some symptoms. BYDV symptoms were not observed in the Southwest or Northcentral counties surveyed. Symptoms of bacterial blight (= bacterial stripe) were primarily reported from wheat fields and barley fields in the northeast.
Extension Plant Pathologist