Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/26/2015
Publication Date: 2/27/2015
Citation: Samac, D.A. 2015. Strategies for managing foliar and root rot diseases of alfalfa [abstract]. In Proceedings of Idaho Hay and Forage Conference, February 26-27, 2015, Burley, Idaho. p. 29-34.
Technical Abstract: Diseases can be a major source of yield loss and stand decline in alfalfa. Surveys were conducted to determine the distribution of pathogens for which there is limited resistance in commercial varieties and tests were done with new crop chemicals to determine their effectiveness in controlling several alfalfa diseases. The brown root rot pathogen was identified in alfalfa samples from sites in Wisconsin, Minnesota, South Dakota, Idaho, and Wyoming, but not in alfalfa samples from fields in Iowa, Illinois, Ontario or Manitoba. Alfalfa varieties were identified that persist under high brown root rot disease pressure. Surveys for races of the pathogen causing Aphanomyces root rot found that race 2 is the most common race in soils for commercial production fields in New York and Minnesota. Race 2 is most common in Illinois and Wisconsin. Field tests evaluating Headline fungicide on alfalfa found that foliar diseases were significantly reduced by the fungicide, but the effect on yield was inconsistent. Natural zeolite, a mineral seed treatment suitable for organic production, was effective in controlling Aphanomyces root rot, Phytophthora root rot, and Pythium seed rot. The fungicide Stamina when used as a seed treatment was effective against Aphanomyces root rot but had inconsistent control of Pythium seed rot.