Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/22/1998
Publication Date: N/A
Technical Abstract: A disorder of unknown etiology has been described in soybean in Wisconsin. Symptoms associated with affected plants include stunting, blue stems and petioles, bud proliferation, dull seed coat, and stems that remain green after leaves and pods have matured. We have initiated studies to investigate these symptoms in soybean plants that can not be explained by common biotic or abiotic factors. Initial diagnosis of plants by 4',6-diamidino-2-phenyl-indole*2HC1 (DAPI) and Dienes' stains suggests that phytoplasmas (plant pathogenic Mollicutes) or other prokaryotes may be associated with this soybean disorder. Phytoplasmas belonging to the clover proliferation group (R16SrVI) and the aster yellows group, subgroup B (16SrI-B) were identified by RFLP analysis of PCR-amplified 16SrDNA sequences using nested PCR with phytoplasma-specific primers. We are surveying the distribution of phytoplasmas in Wisconsin and characterizing variation among soybean varieties in field studies usin visual symptoms and PCR. We are also investigating the role of insects in the epidemiology of the disease using two insecticides, lambdacyhalothrin (Warrior 1EC) and diflubenzuron (Dimilin 25W).