Aphanomyces Euteiches - Management

Management

The most effective management technique available to farmers is the use of disease-resistant cultivars. Resistant cultivars have been identified in alfalfa, bean, pea and red clover. Breeding for resistance has been successful in alfalfa and beans, however in beans it has been difficult to establish resistant cultivars that also meet consumer needs. The efficacy of chemical suppression is dependent on environmental factors such as temperature and soil moisture. Before widespread fungicide use, control consisted mainly of avoiding fields with high disease risk based on a field indexing procedure developed in 1958 by Sherwood and Hagedorn. Management practices should also include good soil drainage and soil testing to avoid infested fields. Crop rotation can be implemented to slow the rate of build-up of A. euteiches, however because oospores can survive for up to 10 years in the soil, rotation is not an effective means of eradicating the inoculum. Therefore, once high levels of A. euteiches have been identified in a field, growers should abstain from planting susceptible hosts in that field.

A study indicates that A. euteiches abundance is less severe when the infected plant also has significant mycorrhizal development. Excessive use of nitrogen and phosphorus fertilizers, and repeated tillage can reduce mycorrhizal development.

In alfalfa, there is evidence that another interaction can occur between A. euteiches and P. medicaginis, another important alfalfa pathogen which causes Phytophthera root rot. In this case, colonization by A. euteiches may make it more difficult for P. medicaginis to take hold.