Poster: Biology & Disease Mgmt: Biological Control
Effects of Clonostachys species on charcoal rot disease caused by Macrophomina phaseolina in soybean
A. ADESEMOYE (1), H. Wei (1) (1) University of Nebraska Lincoln, U.S.A.
Charcoal rot disease caused by Macrophomina phaseolina in soybean greatly disrupt stand establishment and cause high yield losses. The pathogen was estimated to cause yield losses of over 270,000 bushels in Nebraska (NE) in 2011. Chemicals are used against many diseases but not consistently effective in the management of soilborne diseases such as charcoal rot. In 2014 and 2015, surveys were conducted in soybean fields in NE. Infected samples were collected, plated onto potato dextrose agar amended with 0.01% tetracycline (PDA-tet) and incubated in the dark for 4 days at 25°C. Morphology was examined and genomic DNA was extracted from isolates using MoBio microbial isolation kits. Two genes of interest, ITS and β-tubulin, were PCR-amplified. Amplicons were sequenced at the University of California Riverside Gencore. The pathogen M. phaseolina was identified but different species of Clonostachys (anamorph: Bionectria spp.), including isolates identical to C. rhizophaga, C. byssicola, and C. rosea were also recovered from the samples. It appeared from the field samples that Clonostachys spp. had negative impacts on the population of M. phaseolina. In repeated in vitro assay as well as in vivo co-inoculation through Rolled Towel Assays indicated suppression of M. phaseolina by Clonostachys spp. There is need for further studies to better understand the biocontrol efficacy of each Clonostachys sp. as well as the mechanisms involved.