Insect I.D.: Dec. 2000, Battling Pests, Cultural Control

QUARANTINE. Japanese beetle quarantines are currently operated by the USDA-APHIS-PPQP and states involved with shipping materials out of infested areas into uninfested areas. Though this has not stopped the slow progression of Japanese beetles westward, it seems to have slowed the process. Nursery plant and sod producers shipping plant material with soil out of Japanese beetle infested areas must obtain an inspection and certification. Often airports and rail yards are under quarantine and transporters must treat their containers before shipping.

The European chafer is a serious pest of nursery stock. Using planting stock certified free of this and other root pests helps further reduce their spread. Other than allowing the soil to dry out during the time eggs are developing, no other cultural controls have much influence on this turf pest.

THATCH MANAGEMENT. Thatch is a mixed blessing. On the one hand, it is a major obstacle to delivering control materials to target insects like grubs. On the other hand, thatch significantly reduces the potential for ground water contamination by pesticides and serves as a reservoir for insecticides applied to control pests such as chinch bugs, billbugs and mole crickets that live in it.

Black turfgrass ataenius and Aphodius larval infestations usually occur in thatchy turf. Management practices that help reduce thatch and compaction may help in reducing the chance of infestation. Occasionally, when thick thatch exists and normal management practices are no longer effective, a complete dethatching or renovation (removal) may be necessary.

HABITAT MODIFICATION. Eggs and young grubs are very susceptible to desiccation in dry soils. Therefore, omitting irrigation during the time eggs and first instar larvae are developing is detrimental to the insects. While this tactic is generally impractical for golf courses, it may have some application in other turfgrass situations. If natural rainfall occurs, this approach is nullified.

Trees or shrubs highly attractive to adult Japanese beetles near turf should not be planted, especially along golf course fairways and surrounding athletic fields. Trees and shrubs most attractive to adults include: grape, linden, Japanese and Norway maple, birch, pin oak, horse chestnut, Rose-of-Sharon, sycamore, ornamental apple, plum and cherry, rose, mountain ash, willows, elms, and Virginia creeper. Trees and shrubs rarely attacked include: red and silver maple, tuliptree, magnolias, red mulberry, forsythia, ashes, privet, lilac, spruces, hydranges, and taxus (yew).

Masked chafer adults are attracted to lights at night and grub damage is often common under or near street, athletic field, or other bright lights. Replacement with sodium vapor or yellow lights will reduce attractiveness.

TRAPS. Various traps have been developed to capture certain grub adults and mole crickets. Adult beetle traps use pheromones or chemical lures to attract beetles while mole cricket traps use sounds that mimic the call of males to attract females.

The commonly available Japanese beetle trap uses a beetle aggregation (floral) pheromone plus a sex lure to attract both sexes of beetles. Experimental tests with this trap indicate that the trap may attract beetles from ½ mile away, but can not collect all that are attracted to the area. When this trap is placed in the vicinity of susceptible ornamental plants, more damage can occur from feeding by attracted adults than if no trap is used. Japanese beetle traps are not recommended for control of grubs.

Mole cricket traps consist of a four to six foot plastic wading pool with water over which is suspended an electric caller or tape recorder that produces the trill call of either the tawny or southern mole cricket. Mainly females are attracted, but males will also respond. The crickets fall into the water in the wading pool and drown within a day or tow. The trap is more useful for monitoring mole cricket flights than as a control measure.

RESISTANT/TOLERANT TURF. Turfgrass varieties with extensive root systems often have some tolerance to soil-inhabiting insects. Tall fescues can commonly tolerate annual grub populations in excess of 15 per square foot, while bluegrass-ryegrass blends may be damaged by eight to ten grubs per square foot. Among southern grasses, Cavalier® zoysiagrass is reported to have resistance to the tawny mole cricket.

Endophyte enhanced perennial ryegrasses and fescues have been shown to be quite resistant to leaf and stem attacking insects. However, the toxins produced by the endophyte, a fungal symbiont that lives between the cells of the leaf and leaf sheath, are not translocated to the root systems. Except for bluegrass billbug, soil-inhabiting insects such as grubs are apparently not affected by endophytic grasses.

Adults and young larvae of billbugs feed in and on the stems of grasses and therefore ingest endophyte toxins. There is ample evidence to show that endophyte enhanced perennial ryegrasses and fescues can significantly reduce populations of bluegrass billbugs. Overseeding or replacing the turf with blends of Kentucky bluegrass and endophyte enhanced grasses is an effective cultural approach for control of billbug. Generally, a turf stand with 30-40 percent endophytic plants is sufficient to control billbug damage.