BEST PRACTICES: Stop Insects Before They Start

Preventive programs for turf are presented with the view that one pest is often the primary focus of treatments directed by the lawn care operator. This is called the primary target. But the impact of the program or treatment on secondary pests causing damage at application time should also be considered.
 
PREVENTIVE PROGRAMS FOR NORTHERN TURF. The major justification for following a preventive approach is a past history of infestation and confidence that damage from insect pests will reoccur. Such history is based on previous years’ experiences, observations, monitoring and knowledge of the seasonal spectrum of pests occurring at any specific location.
 
Consideration of a treatment’s impact on the primary target and the spectrum of secondary pests can reduce the number of applications needed to achieve the objective.
 
White Grubs. If grubs (black turfgrass Ataenius, Aphodius, Japanese beetle, masked chafer, European chafer, Asiatic garden beetle, Oriental beetle, etc.) are determined to be the primary target, and a preventive program is selected, early May is the optimal time to apply imidacloprid (Merit) or clothianidin (Arena). In addition to providing season-long control of these grubs, other secondary pests in the spectrum (billbug larvae, first generation cutworm larvae, greenbug aphids and frit fly) will also be prevented. In our opinion, ants (i.e., Lasius neoniger) will also be suppressed. Label directions regarding rate(s) to apply should be followed.
 
While an application of imidacloprid or clothianidin in June provides season-long control of grubs, it is too late to prevent the first generation of cutworm and billbug larvae. Application from July to mid-August will prevent annual grubs, including green June beetle, but is too late to control most other secondary pests.
 
In our experience, preventive control of Japanese beetle, masked chafer and black turfgrass ataenius grubs has been achieved with a single application of the new thianicotinyl, thiamethoxam (Meridian), in May, June or July. Larvae of billbugs, cutworms, sod webworms and chinch bugs existing during and for a time after application are also controlled.
 
Season-long preventive control of black turfgrass ataenius and Aphodius, Japanese beetle and masked chafer grubs can be achieved with June applications of halofenozide (MACH2). Control of European chafer and Asiatic garden beetle is limited. Infestations of billbugs, cutworm and sod webworm larvae existing at the time of application may also be controlled with treatment at this time.
 
Application of halofenozide from July thru early August also prevents infestation of the above grubs and controls existing infestations of cutworm and sod webworm. Treatments applied from mid-August to mid-September control Japanese beetle and masked chafer and may provide some degree of control of sod webworm larvae that normally overwinter.
 
Annual Bluegrass Weevil. On turf where grubs and annual bluegrass weevil are major targets, a combination of imidacloprid plus a pyrethroid insecticide or clothianidin from mid- to late-April prevents damage from first and second generation annual bluegrass weevil larvae. This treatment should also prevent larval infestations of billbug, black turfgrass ataenius, Japanese beetle, masked chafer, European chafer and first generation cutworms.
 
On turf where grubs are not major targets, a single application of the labeled pyrethroid insecticides during the third week of April should prevent damage from annual bluegrass weevil larvae. The principle of this approach is to target overwintered adults as they return to annual bluegrass to begin egg laying, but treatment must be applied before significant egg laying occurs.
 
Black Turfgrass Ataenius. In situations where BTA is the only grub of concern, another preventive option has been used successfully. The principle of control involves a labeled pyrethroid to target overwintering adults just as egg laying begins.
 
Bluegrass Billbug. The bluegrass billbug is a significant cause of damage to Kentucky bluegrass and non-endophytic perennial ryegrass. Damage can be as subtle as a chronic thinning of the stand. Symptoms are often misdiagnosed as irrigation not reaching the turf, drought or disease such as dollar spot. If uncontrolled for extended periods, the Kentucky bluegrass portion of a sward continues to diminish over time. Kentucky bluegrass varieties vary in their susceptibility to this pest.
 
An application of imidacloprid, clothianidin or thiamethoxam during the first week of May for prevention of major targets also prevents bluegrass billbug damage and controls a spectrum of other pests.
 
Other Insects/Cutworms. When cutworms (mainly the black cutworm) are the primary target of concern on turf, a preventive approach is not recommended. We discourage adding an insecticide to a treatment of which the objective is fertilization, growth regulation or disease control just in case there may be cutworms present. Instead, we recommend a curative approach and application of a control when evidence of damage first appears.
 
Sod Webworm. Sod webworm larvae commonly overwinter in turf. The overwintered larvae resume feeding in early spring (mid-April to early May) by constructing a C-shaped cover of webbed-together topdressing over its burrow. Spring damage can be prevented by treating the turf areas of concern with an insecticide from late September to mid-October to kill the larvae that would otherwise overwinter. A May application of imidacloprid for preventive control of grubs or other primary targets has not controlled overwintered sod webworms.

PREVENTIVE PROGRAMS FOR SOUTHERN TURF. Categorized by insect, these strategies can improve your preventive control strategies.
 
Mole Crickets. The most difficult time to control mole crickets is late fall and early spring when adults are flying to relocate and mate. These adults may burrow deep in the soil profile (below the target zone) during cool or dry soil conditions and, therefore, are less prone to feed, which minimizes their exposure to control materials. Little can be done to prevent this.
 
At sporadic times, usually associated with warm and rainy weather, adults move to the surface, tunnel extensively, fly in mass and mate. Research has shown that moist (not saturated) sites with dense turf or weed growth are highly attractive to spring-active adults so eggs will be concentrated there.
 
Mapping mole cricket activity can help determine treatment areas. In spring, areas where mole crickets are most actively tunneling, emerging, calling and digging back into the soil are where most of the eggs will be laid. A visual inspection of the turf should allow for easy detection of mole cricket “hot spots.”
 
Subsurface Application. In the recent past, insecticides with moderately long residual activity (isofenphos and isazofos) were applied to high risk areas at the beginning of mole cricket egg hatch (usually late May to early June). Fipronil (Chipco Choice) applied with subsurface placement equipment can provide season-long control of hatching mole cricket nymphs.
 
Surface Application. When applied at mole cricket first egg hatch, surface application of imidacloprid, clothianidin or thiamethoxam adequately prevents mole cricket nymphal damage. The actual calendar date of this event varies considerably from south to north. For example, tawny mole cricket egg laying may begin as early as late March in south Florida, mid-April in north Florida and early May in south Georgia, and egg hatch occurs about 20 days later. Generally, each major biological event in the life history of mole crickets is delayed by one week as one moves 100 miles from south to north. Coastal and island areas can vary from this rule.
 
Our opinion is that a single surface application of imidacloprid, clothianidin or thiamethoxam (at the highest label rate), made within the first three weeks of first egg hatch, should effectively prevent damage from tawny and southern mole crickets. One of these insecticides, applied within this time period, should suppress (if not control) the first new generation of cutworms, fall and true armyworms, and tropical sod webworms for 25 to 30 days after application, thereby eliminating the need for a surface insecticide treatment during this time.
 
Grubs. If grubs are the primary target, and a preventive program is selected, the first priority is to determine which species is present.
 
In many Gulf States, masked chafers and annual forms of May/June beetles are the most common grub pests. In Texas, Oklahoma and the West, the southwestern masked chafer and annual May/June beetles are the common pests. The adults of these southern grubs usually fly and lay eggs when the rainy season begins or when summer rain fronts pass through.
Flights of the southern and southwestern masked chafers are common in late July through August. The May/June beetles usually fly from May to August, depending on the species. Knowing which species is dominant and when it flies and lays eggs is essential for successful control timing.
 
May and early June applications of imidacloprid generally provide control of masked chafer and annual May/June beetle grubs except where the adults delay flight until mid- to late August (e.g., West Texas). This application should also control secondary targets such as mole crickets, cutworms, armyworms, tropical sod webworms and hunting billbugs.
 
Where green June beetle is also present, or late flying masked chafers or annual May/June beetles occur, imidacloprid, clothianidin or thiamethoxam applications should be delayed until mid-July. This treatment will provide season-long control of the grubs and suppress secondary pests such as cutworms, armyworms, tropical sod webworms and hunting billbugs. However, it is too late to provide mole cricket control.
 
May and early June applications of thiamethoxam or clothianidin should provide control of masked chafer and annual May/June beetle grubs and also control mole crickets, armyworms, cutworms, tropical sod webworms and hunting billbug.
 
June application of halofenozide has been shown to control masked chafer and annual May/June beetle grubs in July and August. Application at this time will also control secondary pests, such as cutworms, armyworms and sod webworms, that are present at the time of the application.
  
Niemczyk, Ph.D., is a professor emeritus, department of entomology, The Ohio Agricultural and Development Center, The Ohio State University, Wooster, Ohio. Shetlar, Ph.D., is an associate professor, department of entomology, The Ohio State University, Columbus, Ohio.

EDITOR’S NOTE: Arena is a registered trademark of Arysta, MACH2 is a registered trademark of Dow AgroSciences, Meridian is a registered trademark of Syngenta and Merit and Chipco Choice are registered trademarks of Bayer. This article was excerpted from Niemczyk and Shetlar’s book Destructive Turf Insects, which is available for purchase at www.lawnandlandscape.com/store.