Note to readers, attached is the complete final report for FNE94-071.
Are spiders practical bio-control agents? I compared spider and pest populations in mulched and un-mulched potatoes. There were three questions I hoped to address:
1) Does mulch create a habitat that encourages spiders (and perhaps other pest predators) to move in?
2) Do increased spider populations have any correlation with decreased pest populations or level of damage to vegetable crops?
3) Is mulching a practical alternative for market growers?
Test plots were established in fields where the crops were being grown for market. All crops were grown organically, using standards established by NOFA. We monitored pests using the same methods IPM scouts use and tracked populations of Colorado Potato Beetles and leafhoppers each week throughout the growing season. Spider populations were sampled weekly as well. At the end of the season we compared yields from mulched and unmulched plots.
Overall, there were fewer insect pests on mulched plants than unmulched plants. Mulched plots supported higher spider populations than did unmulched plots. Surprisingly, there was no discernible difference in yields between potatoes that were mulched and those that were not.