Trichoderma wrens-inoculated Composted Chicken Manure for Biological Weed Control

The fungus Trichoderma (Gliocladium) virens produces a broad spectrum of antibiotic compounds, including the phytotoxin viridiol. However, to be used as a mycoherbicide, an economical substrate must be developed that supports the growth of the fungus and production of viridiol. Composted chicken manure (CCM) is an abundant, renewable resource that could serve as a substrate for field delivery of T, virens for weed control. This research investigated the conditions necessary for the production and stabilization of viridiol, mycoherbicidal activity of viridiol, and production of viridiol on a CCM substrate. Although produced at basic pH, viridiol was more phytotoxic at acidic pH. The EC5o of viridiol for inhibition of seed germination of Setaria viridis andAmaranthus retroflexus was 312 and 764 (mo)M, respectively. The EC(50)of viridiol for the inhibition of root growth otS. viridis and A retroflexus roots was 56.3 and 1.3 (mo)M, respectively. Growth of T, virens and production of viridiol up to 170 (mo)g/g were supported on a CCM substrate supplemented with nutrients. Viridiol production was detected 10 days after incorporation into field soil. In greenhouse tests, T, virens-inoculated CCM medium mixed with field soil reduced weed emergence and weed dry weight 77 and 68%, respectively, 8 weeks after incorporation compared to controls. In conclusion, CCM supported T, virens growth and viridiol production at levels capable of controlling weed emergence and growth in greenhouse trials.