You Are Here: Management Updates 2000 Archive August 2, 2000

Date: August 2, 2000
Category: Insects
Subject: Beetle Adults, Black Cutworm

The relatively cool and wet weather we have experienced this summer has continued to mask insect activity. The adults of most grub species (e.g., Japanese beetles, European chafers, oriental beetles) have emerged but the cloudy weather has curtailed adult activity to a certain degree. If the weather pattern changes markedly (in other words, if we finally see warm and dry weather!), we can expect to see adults beginning to fly more actively and females will start laying eggs.
Some ornamentals are beginning to show damage from Japanese beetle adult feeding. Carbaryl (Sevin) continues to be one of the better options for foliar sprays to protect specimen trees, but remember that the material will be washed off in rain or steady irrigation.

A precautionary note - earlier this week Gail Schumann received a turf sample from a superintendent who was certain he had the dreaded "bentgrass dead spot". The sample had the telltale dead-looking spots that look like ball marks. But when Gail looked closer, she found some suspicious "calling cards". To shorten the story, the culprit in this case turned out to be one of the cutworms, probably the BLACK CUTWORM. The caterpillar often feeds in bentgrass on putting greens or tees, and the large caterpillars usually simply stick their heads out of burrows and nibble on grass right around the burrow. The end result is an area that resembles a ball mark - it almost looks like somethiing came out with tiny hedge trimmers and cleared the area right around the hole.

The telltale sign in this case was tiny green pellets that were quite noticeable in the center of the dead spot. The pellets were caterpillar feces, evidence of the feeding the cutworms had been doing.

So if a golf course superintendent sees ball marks on the green, check out the specific signs - do you see "pruning" of blades right around the hole? do you see little green pellets in the area? do you see evidence of birds pecking in the vicinity? If so, you probably are dealing with cutworms, rather than a disease. The good news is that cutworms continue to be treatable - Dursban or a pyrethroid should work pretty well.

The usual disclaimer - While specific products have been mentioned here, there are other options that are labelled and can be effective. Mention of any particular product does not imply endorsement by the author or any member of the UMass Turf Team.

- Submitted by: Dr. Pat Vittum