A PRACTICAL RESEARCH DIGEST FOR TURF MANAGERS

Volume 8, Issue 9 • September 1999

ENTOMOLOGY IN THIS ISSUE

• Scarab Grubs, Sampling Scarab Grubs and Identification . . 1

Sampling and Identification How to Sample

When to Sample By Jennifer A. Grant, Turf grass Entomologist, Cornell University Grub Species ID t this time of year, turfgrass managers are concerned about infestations of Scarab • Turfgrass Pests Remain grubs in the soil. These insects are present throughout the United States, but their a Constant Challenge 8 Adamage tends to be the most ubiquitous and severe in the eastern and central states. Scarabs which are considered pests of turf include the Japanese beetle [Popillia japonica Another Mild Winter Newman), oriental beetle (Anomala orientalis }, green June beetle (Cotinis nitida), Asiatic Hot Spots garden beetle (Maladera castenea), May and June beetles [Phyllophaga spp), black turf- New Control Options

• Soil Amendments Reduce Nitrate Leaching 11

• Conversion of Golf Courses and Parks to Alternate Water Sources 12

Life Cycle of an Annual Scarab Grub: May - Grubs emerge from hibernation in soil beneath the frost line and tunnel up to warmer soil where they feed on grass roots for 3 to 4 weeks. June - Grubs build a cell where they pupate and emerge from the soil several weeks later as adults. July - Adult beetles fly to foliage and cluster together feeding and mating. Females lay eggs in the soil during their 4 to 6 week life span. Aug - Eggs hatch in 9 to 30 days, generally by mid-August. The young grubs begin feeding on roots near the surface. Control grubs now before their size and appetites are fully developed. Sept - Grubs grow larger atul feed more heavily. Visible damage common. Oct - Turf damage more evident, as large grubs have been feeding for months. Nov - As the weather gets Visit us at colder, grubs burrow deep into the soil for winter hibernation. www. landscapegroup. com TURFGRASS TRENDS

Executive Editor Sue Gibson 440-891-2729; 440-891-2675 (fax) sgibson@advanstar. com grass ataenius (Ataenius spretulus), masked Sampling chafers (Cyclocephala borealis and C. luri- Managing Editor Bruce F. Shank, BioCOM da), and the European chafer (Rhizotrogus Turfgrass grown on golf course fairways, 805-274-0321 majalis). White grubs are the immature front yards or institutional grounds is likely Senior Science Editor stages of these beetles, and they live in soil to be inhabited by grubs. However, the Dr. Karl Danneberger and feed on turfgrass roots, resulting in presence of grubs does not necessarily indi- Consulting Editor wilting, reduced strength and eventual cate a problem. In fact, research has shown Chris Sann plant death and loss of turf cover. that grubs are only found at damaging pop- Group Editor The most common scarab pests have an ulations levels 20 percent of the time on Vern Henry annual life cycle, producing one generation both golf course and residential turf in New Production Manager York State. The time spent sampling is min- Karen Lenzen per year. Adult beetles emerge from the soil 218-723-9129; 218-723-9576 (fax) in late spring or early summer and proceed imal compared to the environmental and klenzen@advanstar. com to feed, mate and lay eggs. financial savings of reduced pesticide use on Circulation Manager Some beetles, such as the Japanese bee- golf courses, residential properties, parks, Frank Christopherson schools and sod farms. 218-723-9271 tle, are voracious feeders and attack the foliage of grapes, roses, linden trees and sev- Sampling is necessary to determine the Croup Publisher John D. Payne eral hundred other plants. Other beetles, species of grubs infesting turfgrass plant- 440-891-2786; 440-891-2675 (fax) such as the European chafer, are not known ings, their locations, densities and develop- jpayne@advanstar. com to feed as adults. Regardless of feeding activ- mental stages. This information enables Corporate & Editorial Office ity, mating beetles can be a nuisance as they managers to make more educated pest 7500 Old Oak Blvd. Cleveland, OH 44130-3369 "roll" down golf course fairways and playing management and cultural decisions for fields, or swarm around trees in recreational individual turfgrass situations. A "Grub New Subscriptions 1-888-527-7008 areas. Checklist" should be kept to track grub and After mating, females search for suitable beetle activity and plan management Abstracts: 800-466-8443 Reprint: 440-891-2744 turf sites where they dig into the soil and lay strategies. Permission: 440-891-2742 their eggs. Eggs of most annual grub species Single copy or back issues: Subscription/Customer Service hatch in late July or early August, and begin 1-888-527-7008; (fax) 218-723-9437 feeding on turfgrass roots. How to Sample Website address: www. landscapegroup. com Newly hatched larvae in the first instar Since grubs are feeding in the root zone, (stage) are tiny (4-10 mm long) and begin you have to dig down to their level. The feeding on minute root hairs, but soon easiest method is to remove soil cores with progress to eating larger roots as they a standard golf cup cutter (11-cm diam.). grow. Examine the core for grubs and place the ADVANSTAR checked soil back into the hole it from COMMUNICATIONS Grubs molt twice to become large (up to 23 mm long) third instar grubs, usually by which it was removed. Afterwards, firmly Chairman and Chief Executive Officer the end of the growing season. replace the sod cap. If drought stress is Robert L. Krakoff The timing of each stage varies by grub avoided, damage from the sampling Vice Chairman species, climatic region and seasonal weath- should be undetectable. Inspections take a James M. Alte er, and must be verified by monitoring and couple of minutes per core, depending on VP-Finance, CFO & Secretary sampling. soil conditions and the quantity of grubs David J. Montgomery Knowledge of the local scarab species encountered. Executive Vice President, and their life cycles, as well as options for A cup cutter is the most efficient way to Business Development Skip Farber grub management, are important founda- sample and is worth purchasing for com-

Executive Vice Presidents tions of a pest management plan. Each tur- mercial turf operations. Otherwise, cut William J. Cooke fgrass site must be monitored for the pres- three sides of a square-foot turf area with a Alexander S. DeBarr ence and abundance of grubs, and the shovel. Peel back the sod and look for grubs Vice President & General species identified in order to optimize on the soil surface and at the bottom of the Counsel Eric I. Lisman management decisions. sod mat. A bulb planter can also be used for small sites. Treasurer and Controller The following sections detail how to Adele D. Hartwick sample, identify grubs and problem areas Regardless of the tool used, record the and make treatment decisions. number of grubs found on a data sheet or Sampling is faster and more precise urith helpful tools such as a cup cutter, a surface on which to count grubs and a checklist. map and note the predominate stage in open, sunny areas, near flowerbeds and in (instar) and species of the grubs. front yards, where grubs are more prevalent. Institutional Properties, Parks, and Cemeteries • Sample only in high priority, Pattern visible areas. Take as many samples as Checking soil samples in a grid pattern time allows, a minimum of 20 per acre. across any turf area will help delineate grub Sod Farms • Examine a minimum of 20 infestations. Prioritize areas with histories cores per acre on sod scheduled for of grub damage and where beetle activity harvest in the current season and a has been observed. Sample the turf area, minimum of 10 cores per acre in all other based on the amount of time available. Spe- areas. Alternatively, sod strips and the soil cific recommendations for different turf underneath can be inspected behind a sites follow. sod-cutting machine. Monitor popula- Golf Courses - On fairways, a pattern of tions in newly cut sod whenever possible. four cup-cut cores taken across the fairway at 20-30 meter intervals is suggested. Sam- ples can be skewed towards the roughs, When to Sample where grub populations are often higher. Knowledge of the species inhabiting the Irrigation heads serve as convenient land- area will indicate when local monitoring marks for sampling lines. After data is col- should begin. Most annual grubs lay their lected, map the grub population on a eggs in July, and inspections can begin in course map. Plan on 36 labor hours to late July through mid-August, depending check an 18-hole course; a four-person on regional and local weather patterns. team can check an entire course in one day. Observations of heavy adult activity also Residential Properties • A minimum serve as indicators that grub sampling can sample of 20 cores (distributed throughout begin two to three weeks later. the area) is suggested for any home lawn. Sampling should be targeted for when More samples are recommended on lawns grubs are small (1st and 2nd instar) before trger than a half acre. Concentrate efforts they cause significant damage. This win- dow of opportunity is approximately two weeks after a treatment, and count and to four weeks after egg hatch. Sampling map live grubs to evaluate the effectiveness indicator areas several weeks before grubs of the control practice. Spot monitoring is are expected will monitor the insect's sufficient to judge whether a control mea- development and sure was successful. This practice is termed Examine soil suggest when to a "post-treatment efficacy evaluation", and begin comprehen- provides information on the value of grub in infested areas sive sampling at each management strategies. turfgrass site. Indica- two to four weeks after a tor areas should be treatment, and count and monitored even if a Grub Species map live grubs to evaluate prophylactic treat- Identification ment, such as Imida- Correct identification of grub species is the effectiveness of cloprid (Merit) has essential for determining damage potential applie Ma ps and developing appropriate short and long- the control practice. f' , term management strategies. Some grubs r or these early instar are small (e.g. black turfgrass ataenius) and grub populations are large populations are required to damage used to make immediate treatment deci- turf. Others, such as European and masked sions before damage is visible. chafer grubs, may be encountered when Sampling after a control practice has small, but will grow into large, voracious been implemented is also important. eaters. The timing of developmental stages Examine soil in infested areas two to four

Black tuifgrass Aphodius spp. Green June beetle ataenius

Northern-southern Asiatic garden beetle European chafer masked chafer

May or June beetle Japanese beetle Oriental beetle

Raster locations and patterns of common scarab grubs. Growth stages of a European chafer. Illustrations courtesy New York State Agricultural Extension Service. and adult eating habits are also species Management Decisions dependent. In addition, different grubs are and Strategies affected differently by various biological and chemical control agents. The potential for turf damage can be Grubs have soft, C-shaped bodies with evaluated by comparing sampling results three pairs of legs and a brown head cap- with damage threshold values (see Table 1 sule. Note that other soil-inhabiting on page 6). Tolerance to grub injury varies insects such as billbugs and annual blue- greatly by turfgrass species, site characteris- grass weevils may look similar, but lack tics and stress factors. legs. Generally speaking, The only way to reliably The only way to reliably differentiate healthy turf with scarab grub species is by examining the pat- strong roots, adequate differentiate scarab grub tern of rastral hairs and the shape of the anal soil moisture and low species is by examining the slit in the last abdominal segment of the stress will tolerate insect. These features are located on the grub infestations pattern of rastral hairs insect's raster. above the threshold and the shape of the anal slit Hold the grub gently between thumb level. Conversely, and forefinger, and examine the end of the stressed turf will be in the last abdominal grub with a hand lens. The anal slit is either susceptible to dam- segment of the insect. crescent or "Y" shaped, and a set of stiff age at, or even below, hairs located directly below the slit form a threshold levels. distinct pattern. Therefore, thresholds serve only as guide- The combination of anal slit shape and lines for management decisions. rastral hair pattern is species-specific, as Assess damage potential by looking at a shown in the accompanying drawing. Turf map of grub populations, not by averaging managers can easily learn to identify com- counts over a wide area. Intervention may mon grubs. However, local Cornell Cooper- be warranted if three or more adjacent sam- ative Extension offices and turfgrass consul- ples reach or exceed the threshold level; tants also provide this service. whereas isolated spots of grub activity TABLE 1. COMMON GRUB THRESHOLDS

Common Grub Thresholds Grub Type per ft2 per 4-inch cup-cut

Ataenius 30-50 3-5 Asiatic garden beetle 18-20 2 Masked Chafers 8-20 1-2 Japanese Beetle 8-10 any European Chafer 5-7 any Oriental Beetle 5-7 any Green June Beetle 5 any May and June Beetles 3-4 any

rarely cause visible damage. Adherence to sites indicate favored and susceptible areas thresholds can be conservative in high pri- for grub infestation. Managers can also cus- ority areas and liberal on low maintenance tomize threshold levels for their own turf- turf. grass by comparing grub counts and resul- High population areas, delineated by tant damage in indicator areas. In addition, sampling, can be targeted for spot treat- post-treatment efficacy evaluations are ments rather than treating an entire turf essential for evaluating the cost effective- area. The maps shown illustrate typical ness of previous and future management treatment decisions based on sampling strategies. In short, you can't afford not to results. sample. Grubs are most vulnerable to stress in the early instars, typically found in August. Jennifer Grant is an entomologist with the As they grow, grub susceptibility decreases New York State Agricultural Extension Ser- as their appetites increase. Therefore, the vice at Cornell University in Ithaca. optimal time for most Grubs are most vulnerable biological and chemi- cal control practices is to stress in the early instars, directly after sam- typically found in August. pling. If intervention 7 .7 .7. t is necessary, consider Grub susceptibility decreases the grub species and as they grow; and developmental stage, j . thatch, and soil type their appetites increase. when selecting the most appropriate management practice or product. Success- ful treatment at this time will prevent sig- nificant damage from occurring. Irrigation and overseeding in the fall can also mini- mize visible damage from low to moderate infestations of grubs in healthy turf. Sampling data is useful beyond making immediate management decisions. Records compiled over several seasons at individual GRUB CHECKLIST

Occur History Damage History of locally? on- site? threshold (ft2) high populations?

ANNUAL GRUBS

Japanese beetles

Oriental beetles

Masked chafers

European chafers

Asaiatic gearden beetles

Green June beetles

THREE-YEAR GRUBS

May and June Beetles

Adult Activity Species Date Where "Feeeding, mating, around lights or in traps"

Management Options

Preventive

Biological

Chemical TUrfgrass Pests Remain a Constant Challenge

By R. L. Brandenburg, Turf grass Entomologist, N. G State University

ach year seems to offer its own set of Control is most effective if applied challenges for turfgrass managers. against smaller worms. Treating late in the EUnusual weather patterns, pest out- day also helps. If one can avoid irrigation as breaks, and product performance can cre- well as mowing the turf for at least 24 hours ate their own concerns each year. Most of following treatment, better control will be these situations are difficult to predict, so obtained. In some years, multiple applica- it generally leaves the turfgrass manager tions of treatments are necessary. with little advance notice about pest problems. The most appropriate remedy often changes with each situation. The Another mild winter past two years have presented significant Much of the South has experienced challenges from both a pest and a regula- three consecutive mild winters. This winter tory perspective. was perhaps the mildest of all in many areas, particularly in the Southeast. The only really cold weather experienced was 1998: Fall armyworm year from around Christmas to New Year's Day. For example, in 1998, many areas of the Other than that brief period, many areas Southeast suffered through a record year experienced temperatures 4 to 6 degrees for fall armyworms. Fortunately, these above normal, which is a rather significant severe outbreaks only occur on an infre- shift over a several month period. quent basis, but when they happen, it is a Whenever we have unusual winters, major concern. Unfortunately, such out- either warmer or colder than normal, indi- breaks could occur viduals in the insect pest control business In 1998, many areas again any year, so get inundated with calls concerning what being prepared is the impact the unusual weather will have on of the Southeast suffered best defense. the summer's insect problems. through a record year One obvious chal- While warm weather can favor the sur- lenge is that of early vival and development of some insect pests, for fall armyworms detection. Small it might also favor natural enemies of these worms are hard to insects. The ecology of most insects is fairly see, and by the time the worms are large, complex and affected by a number of fac- they are harder to control and have already tors. caused a lot of damage. Early detection is possible by using a soapy water fluid (2 tbs. liquid dishwashing detergent in 2 gallons of Hot Spots water). During 1999, we have seen plenty of fire While small armyworms feed day and ants in the northern extremes of their night, larger ones hide during the day. Even range, probably due to the mild winters. so, both sizes are hard to see without the Most turfgrass managers saw fewer help of a soapy flush. The presence of birds Japanese beetles this year due to extreme searching for food in the turf is often the drought and heat of the summer. first indication that an insect problem is Problems associated with southern developing. chinch bugs on St. Augustinegrass were greatly enhanced due to these same weath- timely implementation of management er patterns. strategies. This is made possible through an We experienced an abundance of two- efficient program of scouting and monitor- lined spittlebugs in many areas, possibly ing pest populations, including weeds, due to the increasing use of centipedegrass insects and diseases on a regular basis. Time in home lawns, which the nymphs prefer spent on such monitoring generally pays big and hollies in the landscape, which the dividends. adults like. This has been an increasing problem in many high growth areas of the Southeast. New Control Options Mole cricket egg hatch occurred early in Research is continually producing new the Carolinas this year despite the dry tools to aid in the battle against insect pests weather, and we are starting to see them in turf. Recently, there has been a bit of spread more into bahiagrass similar to the emphasis on "natural" situation observed in Florida for many or biological controls Previously when we treated years. and new classes of for one pest, we generally chemistry. In 1998, we saw products such cleaned up most of the other Growing Concerns as Mach 2 and Delta- problems we had. As the population growth in the Sun gard registered and Belt continues, we see increasing problems marketed for a wide Now it is possible when you with pests in turfgrass. It only makes sense range of turfgrass treat with one of the newer, that, as the number of lawns, commercial pests. properties, athletic fields, park, golf courses, Mach 2 entered more environmentally and other turf areas increase, the pests will primarily into the friendly products, you will take advantage of what we offer them. white grub market as In recent years, we have observed a "reduced risk" insec- not obtain control of other increases in the incidence of green June ticide, similar to the pests present, and their pop- beetles, two-lined spittlebugs, fire ants and manner Merit was short-tailed crickets. In addition, we are see- introduced. ulations may increase. ing more of the Oriental beetle white grub Deltagard joined in the South. Historically, this has been a the list of broad spectrum pyrethroid insec- pest in the northeastern United States. ticides, characterized by low use rates, such Is it simply a result of increasing popula- as Talstar, Scimitar, Tempo, Astro and tions and urban sprawl in the southeastern Mavrik. United States and other areas? Is it the In recent years, the registration of other result of higher expectations and simply products with different chemistries, such as noticing more problems in turf? Or is it the Chipco Choice for mole crickets, Con- result of the loss of the old broad-spectrum, serves C, and Merit has broadened the long-residual-activity compounds that range of materials available for use on turf- killed every bug and lasted forever? grass. New products for 1999 included Dis- As mentioned earlier, certain weather tance Fire Ant Bait from Valent, which conditions do encourage specific pest prob- works as an insect growth regulator and lems on a short-term basis (e.g. chinch continues this trend of new chemistries bugs), but the debate over global warming against our major pests. makes one wonder if those who predict the One point that is true for many of the doom of warmer temperatures are seeing newer products, such as Chipco Choice, the initial phases of their predictions come Merit, and Mach 2, is that the spectrum of true. insects they control is narrower than some During 1999, and any other year, the key of the older products we used. It used to be to cost-effective pest management was that when we treated for one pest, we gen- erally cleaned up most of the other prob- organophosphates (such as Dursban and lems we might have had. Now, it is possible Mocap) and the carbamates (such as Sevin that when you treat with one of the newer, and Turcam). Under this new law, some more environmentally friendly products, uses of some products on turf could be lost. you will not obtain control of other pests In an effort to help compensate for any present and their populations can increase. pesticide losses from a commodity, the EPA Such "secondary pest" problems might is taking several steps. One of these is to explain some of the increases in pests we facilitate the registration of "reduced risk" have seen. pesticides and biological pesticides. In The constant search for new materials is 1998, almost half of the new pesticides reg- critical to our future. Some of the older istered by the EPA were biological or nat- compounds, such as chlorpyrifos (eg. Durs- ural type products. ban), could have an uncertain future under The EPA is also funding research to the Food Quality Protection Act, and new develop new alternatives to many of the replacement compounds might be neces- older pesticides that may eventually be lost. sary. Some of the older compounds used on This funding will encourage the devel- golf courses for grub control, such as diazi- opment of new approaches to pest control, non, have been lost. The label for Oftanol while FQPA itself indirectly encourages for turf was voluntarily withdrawn by Bayer companies to pursue new pesticide chem- Corp. Mach 2 and Merit help fill the void istry. In the long run, this will undoubtedly left by the loss of these "old standards." create a rather significant shift in the types Research on the development of biolog- of materials we are using as pest manage- ical materials continues with products such ment tools. as entomogenous nematodes, fungal and Of course, this legislation and its impact bacterial pathogens and natural com- on the availability of certain pesticides fur- pounds. While we have seen increasing suc- ther adds to the uncertainty of each year. cess with many of these products, they are The question of which pests will occur is yet to provide consistency of control seen difficult to answer, and the uncertain future with many of the conventional pesticides. of many of our broad spectrum products However, that gap is narrowing. that would cure whatever ails us make The greatest success stories are from planning even more difficult. The newer, turfgrass managers who were persistent and narrow spectrum pesticides make it diffi- have found a particular technique to get the cult to keep a small inventory of one or two most out of these products. products to cover all potential problems. From the pests to the pesticides, it's a con- tinually evolving picture that requires a lot FQPA Will Shift of effort to keep abreast of the latest infor- Pest Control Approaches mation. This scenario further emphasizes The Environmental Protection Agency the need we all have for continued educa- continues to move forward in the imple- tion in the area of pest management. mentation of the FQPA. This legislation will affect the availability of some pesticides for Rick L. Brandenburg is professor of ento- use on turfgrass. mology in the College of Agricultural and Generally, the groups of pesticides that Life Sciences at North Carolina State are the initial targets are the older University in Raleigh. He can be reached chemistries like the organophosphates and at (919) 515-2703. carbamates. This means as a general rule, the newer products are not currently affect- ed by this law. The first group of pesticides going through this process are the