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Data & ChartsThe type of pests and their numbers vary each year. Pests in a Virginia tomato greenhouse were monitored over several years with yellow sticky cards. The results for each year can be found in the menu on the left. Several conclusions can be reached. 1. Thrips are present only towards spring when large populations suddenly appear. This is likely a result of the first generation of winged adults developing outside and migrating to new hosts. Most Insect screening is not effective in keeping them out and the fine mesh sceening that is effective reduces air flow too much for the volumes needed during sunny days in late winter and spring. A good strategy would be to introduce natural enemies in anticipation of this invasion. 2. Fungus gnats were a continuing problem. The lower quantities of nematodes applied through the irrigation system were not always effective. Because these predatory nematodes do not reproduce well in pupae of fungus gnats or thrips it is advised to utilize the largest quantity of nematodes available for a reasonable price and do not expect to develop a balanced predatory/prey population over time. Repeated applications will be necessary. Not all greenhouses have the same degree of problems with fungus gnats. It is thought that water that is not sufficiently low in pH may play a role. 3. Rove beetles may be an effective new predator of pests with a life stage spent in the planting media, i.e., thrips pupae and fungus gnats. Rove beetles were recovered months after release, indicating they were reproducing. |
