Subsurface Phosphorus and Potassium Fertilization with High Pressure Water Injection

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2 Subsurface Phosphorus and Potassium Fertilization with High Pressure Water Injection CM. Miller and P.E. Rieke Crop and Soil Sciences Recent studies have shown the Hydroject, a tool which utilizes high pressure water injection to cultivate the soil, to relieve soil compaction effects. This technique imparts less damage to the turfgrass plant compared to hollow tine cultivation. This feature may allow for moref requent cultivation. Current research at MichiganState-University is evaluating the use of the Hydroject as an injector of the fertilizer nutrients compared to surface (foliar) applications. Phosphorus treatments were designed to evaluate fertilization on a creeping bentgrass green growing on loamy sand soil. Annual treatments initiated in 1990 were as shown in Table 1: 1) check (no phosphorus); 2) Hydroject aerification alone; 3) surface application of 2.5 lbs P2O5 /1000 sq. ft.; 4) subsurface injection 2.5 lbs P2O5 / 1000 sq.ft.; and 5) subsurface injection 5.0 lbs P2O5 / 1000 sq.ft. Michigan State Soil Testing Laboratory recommends 3.0 lbs P2O5 / 1000 sq.ft., based on Bray -Kurtz PI soil tests of the check plots. These treatments were applied in 2 applications each in 1990 and Results of soil tests taken in November 1991 are shown in Table 1. It can be seen that phosphorus applied to the surface is found mostly in the thatch layer. Injection of phosphorus clearly places it deeper in the soil profile. The higher rate of injected phosphorus is much higher than the recommended rate of 3.0 lbs P2O5 / 1000 sq.ft., and raises the P levels deeper in the soil, as would be expected. Data is also being collected on clipping yield and analysis, root growth, and visual quality and color ratings. The deeper placement of phosphorus with the hydroject increases soil P levels deeper in the soil. Some P deficiency is developing in the check plots, even with Bray P/ soil test levels of 25 lbs./a in the 0-3" depth. We expect this amount of P to be adequate to sustain the turfgrass plants minimum requirement. Yet, removing clippings continues to mine P from the soil. Table 1. Soil phosphorus(bray Kurtz PI) levels at different depths following phosphorus fertilization with foliar spray and injected application techniques, 2 Nov Available P (lb / acre) Annual P TRT. Thatch 0-3" 3-6" 6-9" check 15 c 25 c 36 c 44c water injection 18 c 24 c 38 c 50 be surface 2.5 Ib/M 208 a 66 b 42 c 46 be inject 2.5 lb/m 38 c 64b 93 b 58 ab inject 5.0 lb/m 92 b 116 a 129 a 66 a Numbers followed by the same letter are not significantly different at the 0.05 level of probability using Fisher's PLSD test.

3 A similar study was established for potassium injection in 1990 on an annual bluegrass turf mowed at fairway height and grown on a loam soil. Treatments are similar to the phosphorus injection study, and are as shown in Table 2: 1) check (no potassium); 2) Hydroject aerification alone; 3) surface application of 3 lbs K20 / 1000 sq.ft.; 4) subsurface application of 3 lbs K20 /1000 sq.ft.; 5) surface application of 6 lbs K20 /1000 sq.ft.; and 6) subsurface application of 6 lbs K20 / 1000 sq.ft. The Michigan State Soil Testing Laboratory recommends 3.5 lbs K20 / 1000 sq.ft., based on soil tests of the check plots. These treatments were applied in 2 applications each in 1990 and Results of soil tests taken in October 1991 are shown in Table 2. As in the injection of phosphorus, the injection of potassium clearly places it deeper in the soil profile, compared to the surface application. It remains to be seen, however, whether the turf can benefit from this deeper placement of potassium. Data is also being collected on clipping yield and analysis, as well as visual quality and color ratings. Based in these studies, it can be concluded that the Hydroject can effectively inject P and K into turf soils. These studies will be continued, in addition to the initiation of a study of the injection of nitrogen, to evaluate the benefits to turf of injection of nutrients. Table 2. Available soil Potassium levels at different depths following fertilization with foliar spray and injection application techniques, sampled 23, October, Available potassium, lbs/acre Annual KTRT. 0-3 inches 3-6 inches 6-9 inches check 93 d 61 d water injection 114 d 84 d surface 3 lb/m 234 b 111c inject 3 lb/m 175 c 145 b surface 6 lb/m 304 a 158 b inject 6 lb/m 267 ab 238 a 65 c 80 be 82 be 97 ab 86 be 112 a Number followed by the same letter are not significantly different at the 0.05 level of probability using Fisher's PLSD test.

4 POTENTIAL PHOSPHORUS MOBILITY IN SAND BASED PUTTING GREENS E. D. Miltner and P. E. Rieke Department of Crop and Soil Sciences The potential for contamination of surface waters by phosphorus fertilizers is one of the areas of great concern facing the golf industry and agriculture as a whole. This topic takes on increased importance when construction of a new course in an environmentally sensitive area is proposed. Based on clay content, most soils have the capacity to adsorb a certain amount of phosphorus, limiting its downward vertical movement. Because of low clay content, the ability of a sand-based greens mix to exhibit such adsorption may be limited. Two experiments were initiated in 1991 to investigate the potential for vertical movement of fertilizer phosphorus in sand-based putting greens. Two plot areas on the HTRC putting green which have been maintained as phosphorus deficient for a number of years were used for these studies. For the first experiment, initial soil samples were taken in three inch depth increments to a total depth of 12 inches, then eight rates of fertilizer phosphorus were applied to 1.5 x 2 m plots. The first four rates of application were 0,0.5, 1.0 and 2.0 lbs. P2O5 per 1000 sq.ft. Two additional rates were based on soil test results, one according to Bray-Kurtz PI extractable P and the other based upon Olsen extractable P (two different soil extraction methods). The Bray-Kurtz method is routinely used by the MSU Soil Testing Lab. Olsen is the preferred method for soils with ph measurements in the range of 7.8 or higher. The rate of application for the first year according to both methods was 4.0 lbs. /1000 sq. ft. The six treatments described above were made with surface applied P. The final two treatments were at the rates of 1.0 and 4.0 (soil test recommendation) lbs. P2O5 per 1000 sq. ft. using a prototype of the Hydroject aerifier to inject the fertilizer to a depth of 5 inches. Soil will be sampled on an annual basis as described above to assess the phosphorus status. The fertilization treatments based on soil test recommendations will be adjusted appropriately. Treatments will be re-applied yearly and the study will continue into The second experiment is being conducted on an adjacent P-deficient area of the green constructed with Purr-Wick drainage. There are two separate regions of this plot which drain into separate collection basins. Phosphorus was applied to the two plots at the rates of 1.0 and 4.0 lbs. P2O5 per 1000 sq. ft. per year. Drainage water is collected periodically and analyzed for phosphorus content. Phosphorus deficient plot areas were chosen for these experiments so that monitoring might encompass both the phosphorus adsorption and phosphorus saturated phases. Data from soil samples collected prior to initiation of the experiments and samples collected again in July 1992 will be discussed, as well as data concerning leachate from the Purr-Wick plots.

5 Effect of Plant Growth Regulators on Green Speed M. KRICK, J.N. ROGERS 111, J. REA Crop and Soil Sciences The current study is a continuation of research initiated in The study is being conducted in order to determine the effects of plant growth regulators (PGR) on putting green ball speed and subsequent turf quality. A three year-old turf stand of Agrostis palustris (variety "Pennlinks") is being used in the study. The design is a completely randomized 3X5 factorial with three cutting heights: 1. 3/16" 2. 5/32' 3.1/8" and five PGR treatments: a).175 #ai/a flurprimidol (CUTLESS) b).25#ai/a c).175 #ai/a padobutrazol (SCOTTS TE) d).25#ai/a e)check At this time (July, 1992) three PGR applications had been administered (5/11,6/9, and 7/15). The area has received three lbs.n/1000 sq. ft. thus far along with 2 topdressings and biweekly vertical mowings. The area is cut sixtimes weekly with Toro Series 1000 walk behind mowers with each cutting height having a separate mower. One difference between the studies and the 1992 studies is the 1992 studies have began in May where as the '90-91 studies were conducted only in August and September. As shown by the accompanying bar graph, it takes approximately 14 days following PGR treatments before stimp meter readings are effected. (Thus far there has been only one significant stimp meter reading difference of the nine collection periods. The only significant PGR treatment effect on stimp meter readings (6/11) did not occur until 1 month following the first application and two days after the second application. It should also be noted, that all checks (those receiving no PGRs) of the varying cutting heights are obtaining higher quality ratings than those that are receiving either CUTLESS or SCOTTS TURF ENHANCER. PGRs can effectively increase green speed and reduce clippings yet they reduce the turf stand of a green and its overall putting smoothness. This study will hopefully provide golf course superintendents with a basis to make decisions if planning to implement PGR use into their greens management system. (As a final note: We are currently planning to study the recuperative rate of the turf stand depending on the varying PGR applications to spiking as simulated through use of golf spikes).

6 STIMP METER READINGS FOR GROWTH REGULATORS AVERAGED OVER THREE HEIGHTS STIMP METER READING (FEET) 1992 Turfgrass Research Tour 23

7 Management of Dollar Spot with Biological Controls J. F. Powell, J. M. Vargas, Jr. and M. G. Nair Botany and Plant Pathology Dollar spot is a common turf disease which is caused by the fungus Sclerotina homeocarpa. Conditions favoring the disease include warm humid days with cool nights with heavy dews as well as low nitrogen fertility. Symptoms of the disease appear as small, bleached, circular patches. Following a heavy dew active fungal growth may be seen as a white cobweb within the patches on diseased turf. Left untreated these patches may become numerous enough to cause severe turf damage. Concerns related to the use of fungicides and the development of fungicide resistance has promoted the exploration for alternative means to manage fungal turfgrass pathogens. Two bacteria strains isolated from turf samples have been shown to produce compounds inhibitory to the growth of Sclerotina homeocarpa on petri plates. These bacteria biocontrols were applied as spray treatments and as top-dressing applications in conjunction with the bio-organic carrier Compost Plus. Strains of these bacteria which do not produce the antifungal compounds were also applied in order to attribute disease management to antifungal compound production. Research into new chemicals for the management of turf pathogens has been broadened by examining antifungal compounds that are produced by organisms in nature. The antifungal compound produced by these bacteria has been isolated and was applied to deliver active ingredients at rates equal to and double that of the fungicide Bayleton. All treatments are applied to deliver 1 pound of nitrogen per month, or were fertilized with a formulation of fertilizer. Treatment applications for this study were made on a bi-weekly basis.

8 Prograss Safety on Bentgrass Varieties at Greens Height S.E. Warnke, B.E. Branham, and Tom Carlson Crop and Soil Sciences Variety Quality The National Turfgrass Evaluation Programs bentgrass variety trial, at greens height, was established in the fall of 1989 making this its second full year of rating. This trial has been established nation wide to help breeders develop a broad picture of the adaptation of a cultivar. Quality ratings this year were taken on April 21, June 7 and July 7. A score from 1-9 is given with a score of 9 meaning highest quality. Due to the cool dry weather conditions in 1992, as compared to 1991, ratings have been significantly lower this year. None of the varieties obtained an average score over 6 which could be considered acceptable performance. However, as rating dates are added this year it can be expected that the scores will increase. The variety Providence received the highest rating this year just as it did in It should be pointed out, however, that there is no statistically significant differences between the top 12 varieties which would indicate that all of these varieties may preform equally in Mid-Michigan. (Table 1) A special effort was made this year to monitor spring greenup and it was noted that 3 varieties from International seeds (Cobra, 88.CBL, and 88.CBE) all exhibited earlier greenup under this years weather conditions. PROGRASS Safety Many of the varieties present in this trial have not been released or have only been recently released. Therefore, it would be helpful to know how these varieties respond to new management practices which may be used on putting greens, such as PROGRASS application. The variety plots were each split 3 ways and subjected to a control treatment as well as PROGRASS applications of 0.50 and 0.75 lbs a.i./a on 9/24/91 and 10/16/91. Injury ratings were then taken on 10/18/91,11/08/91, and 4/19/92 to establish the extent of any injury which may have occurred. A rating scale from 1-9 was used with a score of 1 indicating death of the plot and 9 being no detectable injury. A score of 6.5 or better would indicate an acceptable level of injury. From the data it can be seen that only one creeping bentgrass variety UM84-01, with a score of 6.3, was under this 6.5 level which was after two applications of PROGRASS at the high rate. All other varieties receiving scores below 6.5 were colonial types which consistentiy perform poorly in our variety trials. (Table 2) This data would therefore indicate that PROGRASS is safe for use on these newly released varieties of creeping bentgrass.

9 Table 1. BENTGRASS VARIETY TRIAL DATA 1992 Turfgrass Research Tour Overall Variety Species Soonser Mean Hank Mean Rank M an R^nk Providence Creeping Seed Research Of Oregon Pennlinks Creeping Tee-2-Green Corp b ^ Cobra Creeping International Seeds ^ 88. CBL Creeping International Seeds B t Penncross Creeping Tee-2-Green Corp / j Putter Creeping Jacklin Seed Co b d./ j SR 1020 Creeping Seed Research a./ j 88.CBE Creeping International Seeds J d./ j Forbes Creeping Forbes Seed & Grain / J Normarc 101 Creeping Normarc, Inc b 4 Carmen Creeping Van der Have TAMU 88-1 Creeping Texas A&M Univ / d.o MSCB-8 Creeping Mississippi St. Univ d MSCB-6 Creeping Mississippi St. Univ b WPB 89-D-15 Creeping Willamette Valley P.B / UM Creeping Johnson Seeds, Ltd / Emerald Creeping International Seeds National Creeping Pickseed West Egmont A. capillaris Olsen-Fennell Seed Allure Colonial Willamette Seed Co l./ 11 Bardot Colonial Barenburg USA BR 1518 A. castellana USGA Green Section l./ id 1.4 ij Tracenta Colonial Van der Have Oregon Quality ratings 1-9 l=very poor quality 9=highest quality lsd=l.01 lsd= lsd=0.735

10 Table 2. PROGRASS SAFETY ON BENTGRASS VARIETIES Prograss Rate (lbs a.i./a) Control variety S P ecie 3 10/18 11/08 04/19 10/18 11/08 04/19 10/18 11/08 04/ Turfgrass Research Tour 27 Providence Creeping Penn1 inks Creeping Cobra Creeping CBL Creeping Penncross Creeping Putter Creeping SR 1020 Creeping CBE Creeping Forbes Creeping Normarc 101 Creeping Carmen Creeping TAMU 88-1 Creeping MSCB-8 Creeping MSCB-6 Creeping WVPB 89-D-15 Creeping UM Creeping Emerald Creeping National Creeping Egmont A. capillans J b.u A?lure co } onia l ll V 7 VI 8 * 3 'o 1:1 9 *. o 11 l: o Bardot Colonial BR 1518 A. castellana ^ Tracenta Colonial b.b a.u ' LSD (P = 0.05) CK Applied 09/24/91 10/16/91 Injury ratings 1-9 l=death 9=no injury

11 Time Domain Reflectometry and Turfgrass Irrigation C. E. Kome, M.T. Saffel, T. Nikolai, and P. E. Rieke Crop and Soil Sciences Time Domain Reflectometry (TDR) is an established method for volumetric soil moisture determination. The TDR setup consist of a set of stainless steel probes buried in the soil and crimped to cable wires that are connected to a high speed oscilloscope. The entire unit is hooked up to a computer. A signal from the oscilloscope travels through the cables and the probes and returns to the oscilloscope. A computer program automatically calculates the volumetric soil moisture content based on the the travel time and determines the irrigation needs per treatment. Traditionally, the total moisture loss from the soil and plant surfaces (evapotranspiration, (ET)) is estimated from temperature, radiation, relative humidity, wind speed and plant water requirement, among others, over a period of time. Irrigation rates and frequencies are routinely derived from weather information and soil moisture content. Evapotranspiration in an urban environment is site specific and may vary considerably from regional climatic predictions. The objectives of this study are to evaluate the effect of three irrigation treatments; maintaining at field capacity, 0.1 inch per day and water at stress only. The competition between bentgrass and annual bluegrass was evaluated on the basis of the percent encroachment of each species from pure stands. Total water use was different by plant species and irrigation treatment. The field capacity treatment received 1.45 times more water than the 0.1 inch per day treatment and 3.65 times more water than the water at stress treatment. The 0.1 inch per day treatments received 2.52 times more water than the water at stress plots. Quality ratings showed that the field capacity treatment was superior to the 0.1 inch per day treatment which was superior to the stress treatment for both turf species although the bentgrass quality was better in most cases. With respect to species composition, bentgrass was generally more competitive than Poa. A method of irrigation scheduling that is site specific, accurate, affordable, dependable and economical is most desirable in the turfgrass industry. Compared to conventional methods, the TDR method is faster, non-destructive, safer, accurate, based on known spatial volume, and can be easily automated to monitor soil moisture continuously. Time Domain Reflectometry will save time, energy, and would lead to a more efficient use of our water resources compared to traditional methods of irrigation scheduling. The efficient use of water for irrigation purposes can help maintain quality turf and reduce the potential for leaching of agricultural chemicals into groundwater.

12 Biological Control of Annual Bluegrass with Xanthomonas campestris J.M. Hubbard and D.L. Roberts Botany & Plant Pathology Xanthomonas campestris is a bacterium indigenous to the US that is currently under development as a potential bioherbicide for annual bluegrass control in turf. Annual bluegrass exists in more than one biotype. Poa annua var. annua, the predominant biotype in the South is a true annual which dies after seeding. In Michigan, however, the predominant biotype is Poa annua var. reptans which is a true perennial that is persistent and does not die after seeding. Xanthomonas control of the annual biotype has proven to be successful under field, greenhouse and growth chamber conditions but biocontrol of the perennial biotype is more problematic. Although the perennial biotype can be controlled when grown inside under controlled conditions, effective control has not been observed under field conditions field studies were initiated in early May when the turf was mowed for the first time. Xanthomonas needs grass plants to be wounded for infection to occur and therefore inoculations are made immediately after mowing. All studies were overseeded with bentgrass to provide competition for potentially weakened annual bluegrass. It is hoped that early season Xanthomonas application, combined with bent overseeding will aid in improving biocontrol. The most promising field study in terms of biocontrol of the perennial biotype is a study investigating the acceleration of Xanthomonas biocontrol with chemicals. Inoculation treatments are weekly inoculations of 10 9 cfu / ml Xanthomonas at 200 gpa and a tetracycline control. Chemical treatments are 0.1 gal/a Embark (applied 4-27), 0.1 gal/a Embark (applied monthly starting 4-27), 0.3 gal/a and 0.9 gal/a Prograss (applied 4-27), 0.3 gal/a and 0.9 gal/a Prograss (applied monthly starting 4-27), 3 lb/a Pre-M (applied twice on 4-27 & 5-27), 0.7 gal/a Acclaim (applied monthly starting 5-27) and 0.2 lb/a PP333 (applied monthly starting 5-27). 10 days after initial inoculation 0.1 lb/a Embark enhanced symptoms of Xanthomonas biocontrol. This effect was gradually lost as the Embark plots greened up until 60 days after initial inoculation inoculated and non-inoculated Embark treated plots exhibited no damage. Monthly applications of 0.9 gal/a Prograss also enhanced symptoms of Xanthomonas biocontrol as soon as 10 days after initial inoculation. By 60 days, definite thinning of the annual bluegrass in inoculated plots treated with monthly applications of 0.9 gal/a Prograss was noticeable in small patches that was comparable in appearance to biocontrol of annual bluegrass observed under non-field conditions. Annual bluegrass populations were evaluated prior to initiating inoculation and chemical application and will be evaluated at the end of the season to determine whether a population shift from annual bluegrass to bent has occurred as a result of treatments. Other 1992 field studies include:- 1. Comparison of different strains of Xanthomonas campestris for biocontrol 2. The effect of application volume and frequency of inoculation on Xanthomonas biocontrol. 3. The effect of long term weekly or biweekly inoculation on annual bluegrass populations. 4. Monitoring populations of Xanthomonas in different plant parts after inoculation of the annual and perennial biotypes of annual bluegrass.

13 Control Strategy for Annual Bluegrass Using Prograss and a Preemergence Herbicide T. M. Carlson and B. E. Branham Crop and Soil Sciences For the Michigan golf course superintendent, annual bluegrass control can be challenging and often unsuccessful. Several strategies exist for annual bluegrass control and given time may prove effective. The ultimate goal would be to control the existing annual bluegrass and prevent reinvasion by seed. Renovation as a means of annual bluegrass control is a popular strategy. In contrast preemergence herbicides used alone or in combination with postemergence products to prevent reinvasion has not been widely accepted. In 1991 a study was initiated to evaluate fall applied PROGRASS to control existing annual bluegrass and in the spring a follow up application of a preemergence herbicide to prevent reinvasion of the annual bluegrass. Plots were treated with the first application of PROGRASS on 09/24/91 at a rate of 0.75 or 1.50 lbs AI/A and received one or two additional applications at three week intervals. Plots were evaluated in the fall for control (Data not shown) and again in the spring following the addition of a preemergence herbicide. Half the plot area received a preemergence herbicide on 04/06/92 before germination of annual bluegrass had occurred. Three visual evaluations were used to rate the percent control of annual bluegrass and ground cover. All PROGRASS treatments that received a preemergence treatment gave significant control of annual bluegrass in comparison with the treatment lacking a preemergence application. The treatment that received two applications of 0.75 lbs AI/A of PROGRASS was the only exception (Table 1). In addition to the prior study we repeated the preemergence study looking at several commercially available and four experimental preemergence herbicides for annual bluegrass control. Evaluations were again done using observation circles within the plot area. Treatments applied in the fall gave us excellent control of annual bluegrass when compared to the check plots (data not shown). The evaluation taken on 10/22 showed limited preemergence activity from PROGRASS, while all other treatments gave significant control when compared to check plots. Spring treatments applied on 03/31/92 gave excellent control on the 04/23 evaluation with the low rate of BALAN being the only exception (Table 2). On the 06/01 evaluation, eight weeks after application, all herbicides were giving good control except RONSTAR, BALAN, and PROGRASS at the low rates. By the 06/22 only DIMENSION (G) at 0.38 lbs AI/A, the high rates of PRE-M and DACTHAL, and both rates of RONSTAR and BARRICADE provided significant control. In the last evaluation on 07/15 only the high rate of RONSTAR, PRE-M, and PROGRASS along with both rates of BARRICADE gave significant control.

14 Even though you may be successful in controlling annual bluegrass with a postemergence application you still have the viable seed within the soil to control. Again as we saw last year annual bluegrass continues to germinate throughout the season. As the activity of the preemergence herbicide decreases the potential for annual bluegrass germination increases. These studies show the importance of preemergence herbicides in an annual bluegrass management strategy. Additionally these studies demonstrate the need for split applications of a preemergence herbicide to achieve season long control. Table 1. PROGRASS PLUS SPRING PREEMERGENCE PRFEMFRGFNCF" YFS NO YfS N0 YES NO TREATMENT* % POA 05/06/92 % POA 05/19/92 % POA 06/22/92 Prograss Prograss Prograss Prograss Preemergence Control LSD (P = 0.05) % COVER 05/06/92 %C0VER 05/19/92 % COVER 06/22/92 Prograss Prograss Prograss Prograss Preemergence 100 loo Control LSO <P« Applied- "09/24/91 "10/16/91 "11/07/91 "04/06/92

15 Table 2. SPRING ANNUAL BLUEGRASS PREEMERGENCE TRIAL PERCENT CONTROL PERCENT CQMTRQl TREATMENT' FORMULATION, PATS»t/S MA 04/23 05/13 06/01 06/22 07/ Turfgrass Rcscarch Tour 32 1 Control Ronstor 2 G Ronstor 2G Pro M 60 WOG Pro M 60 WDG Dimension 0.25 G Dimension 0.25 G D.monsion 0.25 G Dimonsion 1 EC Dimension 1 EC Balan 2.5 G G Balan 2.6 G Barricade 65 WDG Barricade 65 WDG Lescosan 4 EC Lescosan 4 EC Dacthal 75 WP Dacthal 75 WP Prograss 1.5 EC Progress 1.5 EC Toom 2.0 G _3 LSD (P 0.05) Treated- '03/31/92

16 Field observations of Ataenius spretulus and Aphodius sp. Amy Cole and Dr. David Smitley Entomology In recent years the black turfgrass ataenius beetle, (BTA), has become a growing problem on turfgrass in southern Michigan. By sampling populations of this beetle pest, we hope to learn more about its biology and how intense golf course management effects the pest and its associated predators and pathogens. Golf courses are regularly irrigated and fertilized. Fungicides can be applied every two or three weeks beginning in the spring, and insecticides and herbicides are also applied when needed. Each of these management activities have an effect on the ecology of turfgrass. Experiments conducted on several golf courses in the Detroit area (Birmingham Country Club, Franklin Hills Country Club, Oakland Hills Country Club, and Orchard Lake Country Club) and the Hancock Turfgrass Research Center on the Michigan State campus will aid in determining what habitat and hosts are prefered by the BTA and how predator abundance is effected by insecticide and fungicide. Also, throughout the sampling season, "sick" larvae will be collected and the pathogens infecting the larvae will be identified. Answers to the questions we are asking may lead to the development of alternative control methods for BTA. Doing so could reduce the high cost of turfgrass management while deviating some of the pressure chemicals place on the turf ecosystem. Field Observations of Ataenius and Aphodius Julie Stachecki, Paul Rieke, Dave Smitley and Jeff Andresen Crop and Soil Science, Entomology, and Agricultural Climatology One of the primary goals of this Black Turfgrass Ataenius project is to begin establishing two degree day models for the Ataenius' life cycle. The degree day models will be based on air temperatures and another based on soil temperatures. During this project we hope to confirm the seasonal habits of the Black Turfgrass Ataenius (Ataenius spretulus) in Michigan. Phenological indicator plants will also be identified (tree and shrub growth activity). This insect spends a majority of its life in the soil environment. This project intends to compare the two degree day models (air and soil) to determine; 1) if there is a difference between soil and air temperature correlations, and 2) if one model is more accurate for predicting ataenius development and activity than the other. The use of soil temperatures in managing turfgrass pests has not previously been explored or applied in a structured manner. Four sites equipped with weather monitoring devices, including soil temperature probes (Envirocaster, Neogen Corp.), are monitored and sampled on a weekly basis.

17 BEETLE BACKGROUND INFORMATION The Black Turfgrass Ataenius (Ataenius spretulus) and the Aphodius spp. are turfgrass pests that have several similarities. They are both small black beetles, approximately 3-5 mm long with the only distinguishing feature being the elevated ridge or 'keels' found on the tibia of the hind leg of the Aphodius. Little information is available on the Aphodius spp. and the biology and seasonal habits of both insects are still questionable from region to region. It is believed that both of these beeties overwinter as adults, emerge from overwintering sites in the spring and immediately seek places to lay eggs, including golf course turfgrass. Eggs hatch into small white grubs which mature through three instars, pupate, and emerge as adults. The number of generations per year in Michigan is still questionable. It is likely that there are two generations for each insect. As grubs, both insect types feed on the roots of turf. Damage is usually not seen until the turf becomes water stressed. It appears that irrigated turf can withstand up to grubs per square foot before injury becomes apparent. We will be looking at the thresholds for both insects to determine if there is a difference, i.e. if one eats more voraciously than the other FIELD OBSERVATIONS The Black Turfgrass Ataenius (BTA) has been taking quite a bit of blame for golf course turf damage in recent years. Its guilt growing with each season as more superintendents observe little black beetles flying around and crawling across greens and tees on warm sunny days in the spring. In 1992, observations of Ataenius has lead to the discovery of equal or greater numbers of Aphodius, up to this point (late July 1992). The 1992 season began with several adult Ataenius observed in mid-may, 235 degree days (DD base 50 air temperature). Numbers of adult observations dropped off late May and picked up again slightly in early June, 580 DD. This rise, fall and rise can likely be attributed to the cold front that moved into our region about Memorial Day weekend and persisted for several days, keeping temperatures well below normal. Ataenius grubs were found late June, 780 DD. One unexpected swarm of adults occurred at approximately 900 DD, the last week of June. Ataenius grub counts peaked mid-july, DD, with emergence of second generation adults expected early to mid August (approximately 2600 DD). With the strungout emergence of the adult beetles, control efforts aimed at this life stage would have been very difficult to time to have achieved effective control. While efforts to find and learn about Ataenius have been taking place, Aphodius spp. information has been obtained. This is beneficial because there is a big gap in the information on this insect. The life cycles between the two insects parallel quite closely, with Aphodius being one to two weeks ahead of the Ataenius development. Based on head capsule size of grubs collected, it appears that the Aphodius in southern lower Michigan is Aphodius granarius. Only two Aphodius adult beetles were found during the spring, so emergence from overwintering sites could not be correlated to DD. Yet, while the Ataenius adult observations where at a peak, Aphodius grubs were showing up (580 DD) in great numbers. Peak Aphodius grub counts occurred three weeks following (910 DD) with grubs in the second and third instar. Second generation adults are expected to emerge early August (approximately 2100 DD). With an understanding of the biology and habits of these golf course turf pests we can be better prepared for making safe and effective pest management decisions. Thank you to the cooperating golf courses and staff; Edgewood Country Club, Forest Lake Country Club, and Tam O'Shanter Country Club. I enjoy and appreciate your help and flexibility.