PEST MANAGEMENT
Masked chafer larvae . Photo by James Kalisch , UNL .
late means the chemical won ’ t be transferred throughout the plant when it needs to be . Preventive treatments must also be watered in after application in order for them to work . Core aerification before treatment followed by a uniform application of 1 / 2- to 3 / 4-inch of water greatly increases the success rate . Curative treatments , conversely , occur when damage may have already happened . These applications most often use Dylox or clothianidin and are done in August or September .
Bluegrass billbug larvae . Photo by Jonathan L . Larson , Ph . D ., University of Kentucky .
Bluegrass billbug larvae . Photo by James Kalisch , UNL
BILLBUGS Many species of billbugs – including hunting , bluegrass and Denver – cause damage to sports fields . They tend to overwinter as adults in sheltered locations in and around infested turf . Hunting billbugs may overwinter as larvae and adults . Most species become active in mid- to late spring , then mate . The females deposit eggs into cavities chewed into plant stems near the crown . Newly hatched larvae feed for two to three weeks within turf stems , then move into the
Bluegrass billbug . Photo by James Kalisch , UNL
crown and root system and continue feeding on roots and underground stems . It is at this stage when the telltale symptom of stem breakage is evident . To help diagnose damage from billbugs , grab the leaves / stems near the base and give them a sharp tug . If billbugs are responsible , they will easily break off and appear shredded , you may also note sawdust-like material . Billbug larvae look similar to white grubs in coloration , though they are smaller than grubs and are legless .
Depending on the species and overwintering styes , pupation can occur in spring or in mid-summer . In most cases , adult weevils emerge in late summer and move to overwintering sites in hedges , tall grass and tree leaf litter . The greatest injury occurs in early summer as the turf transitions from supportive to stressful conditions for root growth .
Managing billbugs can be complicated when compared with white grub control , and may necessitate more monitoring to be successful . One option is treating for adult weevils that are emerging from their overwintering spots . Reading about billbugs in local Extension factsheets or using pitfall traps can help managers to time their application of pyrethroids , carbamates or organophosphates to turf . These contact products would work by killing adults as they move through them ; avoid irrigating these early-season treatments as you don ’ t want to wash the residue off before it has a chance to kill the weevils . Luckily , billbugs can also be controlled through preventive means . The same products and timing will work to prevent these pests as white grubs , though there can be decreasing success by mid-June , making it a tighter window for management . If you find yourself needing
14 SportsField Management | March 2023 sportsfieldmanagementonline . com