Can lignin degrading organisms reduce Verticillium wilt in pumpkin cropping systems?
CSANR Project 180
Raised beds in pumpkin cropping systems are mulched with polyethylene (PE), but result in waste. PE mulch can remain in the soil and is costly to remove. PE mulch also poses environmental and human health concerns when disposal is by burial in landfills or by burning. Biodegradable mulch films (BDMs) that are soil incorporated and biodegraded by microorganisms present a desirable alternative. One common problem in mulched vegetable crops is wilt caused by Verticillium dahliae, which colonizes crop vascular tissues and forms microsclerotia. Microsclerotia are composed of melanin and can survive in the soil without a host for long periods of time. Enzymes produced by lignin-degrading soil microorganisms, such as Streptomyces viridisporus, break-down melanin as well as certain plastic films. Observations indicate that incorporating BDMs may reduce microsclerotia survival. This study will determine if: (1) microsclerotia survivorship decreases when S. viridisporus is present, and (2) pumpkin followed by a high-lignin, non-host crop like corn, coupled with BDM incorporation, reduces wilt severity and microsclerotia survival more than either tactic alone. Obj. 1 will be done in conetainers, amended with BDMs, infested with S. viridisporus and/or V. dahliae, and maintained in a growth chamber; for Obj. 2, rotation crops will be grown in microplots with soils amended with S. viridisporus, and/ or V. dahliae and selected BDMs. The results of this study will address a gap in current sustainable agriculture research by investigating how the BDMs combined with high lignolytic rotation crops affects V. dahliae microsclerotia by creating an environment supportive of lignin-degrading organisms.