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  • Author or Editor: Farah Heraux x
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Trichoderma virens (Gliocladium virens) (Miller et al.) von Arx is a soilborne fungus with a high degree of rhizosphere competence that produces a potent herbicidal compound, viridiol, and therefore has potential for development as a bioherbicide. We investigated the possibility of using composted chicken manure (CCM) as a medium for the production and deployment of T. virens. We chose CCM since the safe disposal of chicken manure presents significant logistic problems, and composted manures, as well as serving as an organic source of nitrogen, have been shown to support the activity of other biological control agents. Composted chicken manure supported the growth of T. virens and the rapid production of high concentrations of viridiol, but only when it was supplemented with large quantities of nutrients, including sucrose (16% w/w). Viridiol was not stable when stored in CCM, with a rapid decline in viridiol concentrations observed in T. virens-inoculated CCM cultures. Clearly, a cheaper alternative to sucrose is required as a carbon source for T. virens in CCM or similar media, and effective storage methods would need to be found for a T. virens-based bioherbicide product. Importantly, CCM did not need to be sterilized to support the growth of T. virens and its concomitant production of viridiol, suggesting that on-farm production systems may be feasible. Trichoderma virens-colonized CCM reduced the emergence and seedling growth of redroot pigweed (Amaranthus retroflexus L.) in a greenhouse experiment and dramatically reduced the emergence of a mixed community of broadleaf weeds in the field.

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More than 500 Master Gardeners in Indiana and Illinois were taught alternatives to the use of insecticides in workshops that focused on biological control of insect pests in home gardens. Gardeners also learned to conduct experiments in their backyards and were encouraged to participate in a summer research program that tested specific control methods. Workshop participants were surveyed before the workshop, and in two successive growing seasons to measure changes in their pest management practices. Overall, a significant percentage of gardeners stopped applying insecticides for up to two consecutive growing seasons after attending workshops. In addition, the adoption of biological control by participants appeared to be linked to their insecticide use and willingness to participate in the research process. A significant increase in the adoption of biological control was noted among garden researchers who did not use insecticides before the workshop or had reduced insecticide use following the workshop. No such change was noted for gardeners that did not conduct research. The relative contributions of workshop participation and hands-on research experience in pesticide reduction and biological control adoption are discussed.

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