Handbook of Turfgrass Insects, Second Edition

Handbook of Turfgrass Insects 2nd Edition

Photo by R. Brandenburg.

The past ten years have seen the spread of many long-time pests and the occurrence of several new ones, so proper identification and knowledge of the most current pest biology and ecology is critical. The book covers all major pests of warm- and cool-season turfgrass in the United States, with each section written by one or more experts on each pest. Numerous color photos of various insect stages and damage are included as well as illustrations of life stages in their actual size, life cycle charts, and distribution maps. There are important chapters on the principles of integrated turfgrass pest management, microbial control, use of insecticides, insecticide resistance management, and beneficial and innocuous invertebrates in turf. A glossary, index, and sources of local information are also included.

Entomological Society of America

Published by the Entomological Society of America ISBN 978-0-9776209-4-4

Edited by Rick L. Brandenburg and Callie P. Freeman

This highly-anticipated second edition of the Handbook of Turfgrass Insects, edited by Rick L. Brandenburg and Callie P. Freeman, contains the most current information covering all areas of turfgrass insect management. The handbook provides a comprehensive, yet easy-to-use guide for students, practitioners, extension staff, Master Gardeners, teachers, and others.

Handbook of

Turfgrass Insects SECOND SECOND EDITION EDITION EDITED BY

Rick L. Brandenburg Callie P. Freeman

ENTOMOLOGICAL SOCIETY OF AMERICA

Pest Information

Black cutworm mature larva showing damage (courtesy D. Shetlar).

Black cutworm male moth (courtesy D. Shetlar).

erally dull-colored moths with wing spans of 1.4–1.8 in. (35–45 mm). At rest, the wings are folded flat over the abdomen. The black cutworm adult is grayish black with a pair of distinguishable black markings known as

daggers. The bronzed cutworm adult is a mottled burgundy–brown color, and the variegated cutworm adult ranges from brown to gray.

Pest Status. Black cutworm is a perennial problem on the closecut creeping bentgrass and Poa annua turf of golf course putting greens, tees, and even fairways. Rarely is black cutworm a problem on home lawns, especially lawns of Kentucky bluegrass. Bronzed and variegated cutworms are occasional pests in lawns comprising various turfgrass species.

Injury. Most cutworm species are semisubterranean pests. They usually dig or create a burrow in the ground or thatch (or use an aeration hole) and emerge at night to clip off grass blades and shoots. This feeding damage often shows up as circular spots of dead grass or depressed spots that resemble ball marks on golf greens.

The bronzed cutworm is active in the fall and spring and can completely destroy lawns by clipping off all grass stems at ground level.

Life History. It is unclear whether black cutworm is capable of overwintering in northern states; it likely overwinters in southern states and migrates to northern states in the spring via the jet stream. Bronzed and variegated cutworms overwinter as larvae or as pupae in the northern states. In southern turf, these species remain active all year. In the northern states, black and variegated cutworms may have two to four generations per year; in the southern states, three to seven generations may occur.

The bronzed cutworm has a single generation per year regardless of location.

In general, female moths of all three cutworm species mate and feed at night in trees, shrubs, and weeds that are in bloom. Mated females seek out crops or grasses and lay eggs on leaf blades. The black cutworm female has a

Egg, first through sixth larval instars, pupa, and adult of the black cutworm (courtesy D. Shetlar).

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Pest Information

Cutworm distribution.

unique egg-laying behavior in which she strategically lays eggs singly on the terminal 25% of turfgrass leaf blades.

Most cutworm female moths can lay 300–2,000 eggs over several days. Under optimum conditions, these eggs hatch in 3–10 d, and the young larvae begin to feed on the turf leaves. Cutworms excavate holes into the thatch or ground or occupy aeration holes. These holes are rarely lined with silk, as are those of sod webworms. From this retreat, the larvae venture forth at night to feed on plant material.

In comparison, armyworms do not build a hiding place in the thatch or soil, and older armyworms feed continuously during the day and night. Most cutworms take 20–45 d to complete their larval development. The pupae may be located in the cutworm retreat or, occasionally, in the thatch or soil–thatch interface. The pupa takes ≈2 wk to mature. Developmental times may be greatly lengthened during the cooler parts of the season.

Management. Traditionally, these pests were controlled by using commercially available contact or stomach insecticides. Recent development of plant systemic insecticides, however, have given turfgrass managers an alternative strategy that makes it possible to manage cutworms preventively. Such products have exhibited >80 d of residual control; therefore, fewer applications are needed. Biological control strategies and resistant turfgrass species also can be used. Cutworm larvae can be readily sampled and monitored by using a soap-dis30

closing solution to determine population pressure. If a disclosing-solution test indicates considerable activity ­— about two to six or more larvae per square yard (0.8 m2) — an insecticide application may be needed. Irrigation, mowing, or both within 24 h after the application is not recommended.

The bacterium Bacillus thuringiensis is available commercially and may control cutworms if enough material is ingested by first to third instars. Do not wash the material off the turf foliage or mow the turf after the application.

Entomopathogenic nematodes in the genus Steinernema have effectively managed black cutworm larvae in golf course putting greens at a rate of 1.0 billion nematodes per acre (0.4 ha). Irrigation immediately after making the application is important to maximize the performance (efficacy) of the nematodes.

Selected References. 222, 223, 224, 280, 288, 289 David J. Shetlar and R. Chris Williamson

Eriophyid Mite Pests (Bermudagrass, Zoysiagrass, Buffalograss, Grain Rust and St. Augustinegrass) Bermudagrass Mite Scientific Classification. Eriophyes cynodoniensis Sayed (Acari: Eriophyidae).

Origin and Distribution. The bermudagrass mite is probably native to Australia, where bermudagrass has become a naturalized plant. The mite is now widespread, however, occurring in New Zealand, North Africa, North America, the Caribbean Islands, and Mexico. In the United States, it was first found in Phoenix, AZ, in 1959 but soon spread throughout the southern states where bermudagrass is grown (California, New Mexico, Texas, Oklahoma, Louisiana, Mississippi, Alabama, Georgia, South Carolina, and Florida).

Description. The bermudagrass mite is a whitishcream color, wormlike in shape; and it has two pairs of legs typical of eriophyid mites. Adult are ≈0.006–0.008 in.

(0.165–0.210 mm) long and are just visible with a 15–20× hand lens.

Pest Status. This mite is host specific to bermudagrass, Cynodon spp.

Injury. Infestations are easily recognized when signaled by plant injury. Infested grass first exhibits a slight yellowing of leaf tips followed by shortening of the internodes and leaves, producing a rosette or tufted growth (“witches’-

Pest Information

Bermudagrass mites under leaf sheath (courtesy NYSAES, H. Tashiro).

Eriophyd mite damage to bermudagrass fairway (courtesy J. Reinert).

Adult bermudagrass mite. Silhouette (in frame) shows actual size.

broom” effect). Severe infestations result in stand loss, and large dead areas soon become infested with weeds.

Life History. Mites are active primarily during late spring and summer. Development from egg to adult requires 5–10 d. After eggs hatch, they pass through two nymphal stages and molt to adults. All life stages live to-

Bermudagrass mite distribution.

“Witches’-broom” effect caused by shortening of internodes and leaves (courtesy J. Reinert).

gether protected under the leaf sheath, and, often, 100– 200 mites and eggs can be observed under a single leaf sheath. Mites spread on grass clippings and have been observed hitchhiking on other turf insects. Dispersal in the wind is common.

Management. Chemical controls can be effective, but no available pesticide provides a high level of control.

Repeated applications are necessary. In southern Florida, where mites are active most of the year, cumulative treatment costs can be high. Cultural manipulation of the host by using adequate irrigation and nutrition often can help the grass outgrow mite damage, as can removing clippings after mowing. Severe damage is usually linked to other stress factors, especially drought stress.

The bermudagrass cultivar ‘FloraTex’ is highly resistant to the mite. ‘Cardinal’, ‘Greg Norman1’, ‘Midlawn’, ‘Tifsport’, and ‘Tifway’ expressed no symptoms (termi31