NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
November 22, 2000
Presence of a potentially devastating disease in southern Manitoba means North Dakota dry bean growers need to be on the watch for it next summer and be cautious about where the seed they purchase was produced, according to a North Dakota State University plant pathologist.
Anthracnose is not established in North Dakota or Minnesota, but it is present in southern Manitoba near the international border, says Art Lamey, NDSU Extension Service plant pathologist.
The most important disease management procedure is to keep the anthracnose pathogen out by avoiding seed produced in infested areas, Lamey says. Bean growers should determine where the seed they purchase was grown and not purchase seed grown in an infected state or province, including Manitoba, Michigan and Ontario. Seed developed in an infected state or province is acceptable if it was grown under furrow irrigation in a western state such as Idaho, Wyoming, eastern Washington or eastern Oregon, he says.
Genetically resistant varieties and tested "pathogen free" seed are primary controls in areas where the disease is established.
In the field, the most characteristic symptoms of anthracnose appear on the undersides of leaves, where small, angular brick red to purple-brown lesions develop. Older lesions become darker, extend to the upper leaf surface, and proceed along veins. Pod lesions are very sunken, circular, chocolate brown to black colored with a raised dark margin surrounded by a thin zone of reddish tissue. On the lesion surface, tan spores dry into dark granular masses.
Anthracnose can be blown from field to field in crop refuse and spreads within the field in splashing rain showers, as well as being carried on seed.
Moderate chemical control with multiple applications of Benlate or Topsin M is feasible but may not be economic, Lamey says.
"This warning is not to cause panic but to alert growers to make every effort to avoid accidentally introducing the disease," he says.
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Source: Art Lamey, (701) 231-7865
Editor: Gary Moran, (701) 231-7865