Conserving beneficial lawn predators with wise pesticides use (5-18-09)

While scouting a newly sprigged sod field for potential disease and insect damage I noticed a young caterpillar crawling along the soil between two sprigs of grass. As the caterpillar got close to one of the grass sprigs, a small spider darted out and ambushed the caterpillar. Another incident was noted with a red paper wasp hovered over the turf and darted down to pick up another small caterpillar. Healthy lawns are inhabited by a multitude of beneficial insects like the spider, wasp and other small invertebrates, that feed on plant debris, fungi, and other insects. Almost all turfgrass pests have one or more natural enemies that can be important in suppressing their populations.

Natural predation is a legitimate explanation why pest outbreaks are more uncommon in low-maintenance turf than in many higher maintained lawns. There are documented cases of outbreaks of southern chinch bugs on heavily insecticide treated lawns, but not on neighboring untreated lawns where predators were abundant.

Many conventional insecticides are just as toxic to beneficial insects as to the targeted pests, therefore when we apply insecticides to our lawns we are most likely destroying the natural enemies as well. I do not advocate we do away with insecticides, but to be prudent in their use and apply them only when and where they are needed. Good turf management, including pests scouting and understanding pest threshold levels will help provide wiser more effective use of pesticides.

Published May 18, 2009

Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. wwells@ext.msstate.edu