Juang-Horng "JC" Chong, Research and Extension Entomologist
Contrary to most common beliefs, most insects that occur on turfgrass are not pests. Some, such as parasitic wasps and ground beetles, are in fact beneficial insects that feed on the pests and reduce pest population and damage. Therefore, it is important to identify insects found on turfgrass correctly. An effective integrated pest management (IPM) program takes into consideration the biology, ecology, environment impacts, and all available treatment options. An IPM system is not difficult to adopt. Unbeknown to most turfgrass professionals, they are already utilizing some of these elements in making pest management decisions.
Insecticide efficacy can be reduced by many environmental and biological factors. Water pH outside the suitable range can quickly degrade insecticides. Some insecticides may persist longer in clay than in sandy loam. Some insecticides may need irrigation after application to penetrate the soil and kill the insects that live underground. Insects may also develop resistance to one group of insecticides if the same group is applied to the same insect population repeatedly. In order to delay the development of insecticide resistance, avoid using insecticides from same mode of action or IRAC group number repeatedly. To assist in the decision to rotate insecticides, an IRAC table is included in this guide.
- Ants (nuisance & red imported fire ants)
A large number of ant mounds can interfere with the play on the greens. RIFA is also a medical concern because of their stings.
Monitoring: The small mounds made by the nuisance ants on the greens and the large mounds made by the RIFA along the periphery are the tell-tale signs.
Treatment: Most ants can be treated by one of the three methods: individual mound treatment, broadcast granules of baits or long-residual toxicants, and a combination of the two methods.
Adults feed on the leaf blades and deposit eggs in the stem. The larvae, resembles legless white grubs, first bore into the stem and then feed on the rhizomes, roots and crown as they mature.
Monitoring: Adults can often be found crawling on pavement in the spring. Larvae can be found by digging into the yellowing and thinning turf. Grasses fed by the larvae can be easily pulled out from the ground because the roots are consumed. Fine, whitish, saw dust materials often come out of the hollowed stems.
Treatment: Recent research indicates that management should target both adults and grubs. Apply insecticides in last spring (May) and fall (September) when adults are observed.
- Caterpillars (cutworm, fall armyworm, and sod webworm)
Fall armyworm begins to appear in June while cutworms and sod webworms often begin to appear in the spring.
Monitoring: Conduct soap flush (1-2 fl oz detergent per gallon water) to determine the species and size. Frequent congregations of birds and paper wasps also can indicate infestations.
Treatments are most effective against small caterpillars; therefore, it is crucial to determine size through soap flush. Treat when needed. Do not irrigate within 24 hours after application.
- Chinch bug
Southern chinch bug is the major pest of St. Augustinegrass, often create yellowing or dead patches in the hot, dry days. Thick thatch often accentuates infestations.
Monitoring: Two floatation methods can be used to monitor chinch bug population: 1) insert a large PVC pipe or cut-out coffee can deep into the turf and pour in tap water, or 2) cut a piece of sod and flood it inside a container with tap water. Chinch bugs will float to the top and can be counted.
Treatment: Established treatment threshold is 25-30 chinch bugs per sq ft. A high volume spray (minimum of 50 gal/acre) will be needed to deliver the chemicals into the thatch for control.
Although usually considered beneficial, earthworm can still interfere with play by pushing a large number of castings onto the greens. No control is recommended.
- Mole cricket
Tawny and southern mole crickets create tunnels and expose the grass roots to desiccation. Adult flight occurs in April to June. Egg hatch occurs from June through July.
Monitoring: Check for tunnels. Soap flush (1-2 fl oz lemon scented detergent per gallon water) in areas large numbers of tunnels can capture the mole crickets and determine body sizes.
Treatment: Treatment of young nymphs in June and July is more effective than treatment of adults in spring and larger nymphs in the fall. When contact insecticides are used, irrigate after application can help to push the insecticides into the soil.
- White grub
White grubs feed on the roots of turfgrass. Infested turf turns yellow and wilt. Severe infested turf feels spongy under foot and often fall apart when cut or lifted.
Monitoring: Remove sod from the ground and carefully inspect root zone for the grubs. Treat when more than 7-10 grubs are found in 1 sq ft of sod.
Treatment: Preventive treatment of young white grubs in May to June using long residual insecticides (such as neonicotinoids and diamides) is more effective than curative treatment of larger grubs in July and August (using organophosphate insecticides). Because the grubs live deep underground, the insecticides have to be irrigated in after application.
Biology and management information of the above mentioned and other pests of turfgrass are listed in the tables.