Successful Nursery IPM Trials in Manatee County
For almost two years, Manatee County nursery growers have been undergoing pilot studies in integrated pest management. Extension agent/horticulturist Geri Cashion, working in tandem with IFAS researchers and nursery cooperators, has been conducting on-site nursery trials using least toxic pest-management techniques -- and her experiments have met with success.
Assisted by funding from the Tampa Bay National Estuary Program and the National Foliage Foundation, Cashion and a trained field scout have implemented successful programs using biological, cultural, mechanical, and chemical controls. Initial projects involved the use of the predatory mite Phytoseiulus persimilis to control the two-spotted spider mite on container-grown areca palms and crotons. The success of these early trials in reducing or eliminating miticide use yielded an additional benefit --improved plant quality. Often, the stressful effect of frequent chemical applications on plants is overlooked. "With these nursery trials, we find repeatedly that plant quality is highest in the IPM plots," observes Cashion.
It has been possible to finish a crop of 7-gallon Chamaedorea palms over a six-month period without using any miticides at all. Only two applications of insecticidal soap were used. This reduced the population of two-spotted spider mites to a number that could be controlled with augmentative releases of predatory mites. Two crops of areca palms in 1-gallon containers were similarly produced without miticides. Fungicides were applied on the palms for control of leafspot diseases; only fungicides least harmful to the beneficials present were used. Chewing insects were controlled with an application of Diazinon, which was applied seven days before predatory mites were released.
"In enclosed areas such as shadehouses with winter poly coverings, we used lacewing larvae and ladybugs to control aphids on ixora. This approach, when closely monitored, was combined with spray applications of insecticidal soap or neem product on an as-needed basis." Cashion further reported that, over a four-month period, the aphid numbers on test blocks were generally lower than those on chemically sprayed plants.
Cashion is currently conducting other nursery trials. She is experimenting with using several species of predatory mites alone and with using combinations of predatory mite species that permit control under adverse conditions of temperature and environment. Using parasitic wasps to control aphids on greenhouse foliage crops is also being tested. A combination of several least toxic techniques are being tested to control thrips and broad mites.
As the chemical options for nursery growers become fewer, growers are more willing to try techniques and materials that were ignored in the past; however, the new approaches require careful monitoring and can be more labor intensive than previous practices. Most growers require close assistance when practicing IPM, especially at the beginning of implementation. (Geri, explain why here, in a sentence or two.) This stage is a critical period for the success of integrated approaches.
Cashion is positive about her success with IPM, but warns, "As part of an IPM program, biological control is not a silver bullet. It is merely another tool to be laboratory tested, studied, and trialed on site in small nursery test blocks with only the most reliable cooperators. Only then can it be evaluated as a practical part of an overall pest control program."