USE OF CULTURAL AND MICROBIOLOGICAL TREATMENTS TO OVERCOME THE REPLANT PROBLEM IN ASPARAGUS

Three treatments, formononetin (an isoflavone that promotes vesicular-arbuscular mycorrhizae (VAM) colonization) and two strains of nonpathogenic Fusarium oxysporum (NPFO) were combined with and without NaCl to determine their effects on suppressing Fusarium crown rot on asparagus (Asparagus officinalis) grown in old asparagus field soils. In the greenhouse and field, there were no interactions between the treatments and NaCl on root lesions, root growth or yield. There was an adverse effect on VAM colonization following the applications of NaCl and formononetin. All three treatments and NaCl reduced root lesions, but only NPFO strain CS-20 increased root growth. In old replanted fields, the treatment effects varied with site. Compared to untreated plots, the 3-year accumulated yield in Hamden, Connecticut was higher when the NPFO strain CWB 318 was used. In Windsor, Connecticut, yield was higher than controls when NaCl was applied. These treatments have potential for managing the asparagus replant problem.