Conventional and innovative methods for fairy ring management in turfgrass.

Transcription

1 Conventional and innovative methods for fairy ring management in turfgrass. Science and Golf IV Proceedings of the World Scientific Congress of Golf Edited y Eric Thain Routledge, London World Scientific Congress of Golf St. Andrews, Scotland July 22-26, 2002 M.A. Fidanza, Pennsylvania State University, Reading, PA, USA. P.F. Colaugh, Texas A & M University, Dallas, TX, USA. H.B. Couch, Virginia Polytechnic and State University, Blacksurg, VA, USA. S.D. Davis, Aventis Environmental Science, Gulf Breeze, FL, USA. D.L. Sanford, Pennsylvania State University, Reading, PA, USA.

2 ABSTRACT Fairy ring is a persistent and troulesome disease of turfgrasses throughout the world. Many asidiomycete or mushroom fungi are responsile for this destructive disease on lawns, park and recreation areas, and golf course turf. Recent widespread epidemics on many golf courses throughout the United States have led investigators to evaluate possile fairy ring management strategies. Field studies were conducted at five locations in the United States during and 1999 to evaluate conventional and innovative fairy ring control methods on golf course turf. Conventional approaches tested at three locations included curative applications of nitrogen fertilizer, and curative treatments of fungicides applied in conjunction with soil s. These methods were effective at suppressing or masking disease symptoms. At a fourth location, an innovative approach tested was curative applications of fungicides applied through high-pressure injection. This method was successful at reducing diseases symptoms and rapidly enhancing turfgrass recovery. At a fifth location, another novel approach evaluated applications of a fungicide plus soil on golf course putting greens prior to the appearance of fairy ring development. No fairy ring symptoms were oserved in those plots treated with the preventive program, while severe turf injury was oserved in untreated plots. Information from these five field studies could contriute to the development of a fairy ring management program for golf courses. KEYWORDS fairy ring, turfgrass disease, asidiomycete, fungicide, fertilizer, nitrogen,soil INTRODUCTION Fairy ring is the name commonly given to circles of mushrooms or rapidly growing, lush green circular ands of grass oserved in estalished turfgrass areas (Couch, 1995; Smith et al., 1989; Vargas, 1994; Watschke et al., 1995). Fairy ring disease occurs worldwide in all cultivated turfgrasses, and is often oserved on golf course putting greens, fairways, tees, and roughs as well as general lawn areas. Turfgrass injury symptoms and damage due to fairy ring are oserved at any time during the year, ut often occur during periods of hot, dry, and drought-like weather. In many regions in the USA, fairy ring symptoms are oserved during the hot, dry summer months and sometimes into the fall. During dry periods, mushrooms can appear in a lawn within a day after a heavy rain. Fairy ring is attriuted to more than 60 species of soil inhaiting, asidiomycete or mushroom fungi (Couch, 1995; Smiley et al., 1992). Shantz and Piemeisel (1917) first placed fairy ring disease into three categories according to their effects on turfgrass. Type I fairy rings are those that kill or seriously damage turfgrass. Type II fairy rings are those that stimulate plant growth as evident y circular ands of dark green turfgrass. Type III fairy rings are those that do not stimulate turfgrass growth and cause no damage, ut produce mushrooms in circles or arcs. Couch (1995) further classified fairy ring disease into two distinct groups: edaphic and lectophilic. Edaphic fairy rings are produced y fungi that primarily colonize the soil, and lectophilic fairy rings are produced y fungi that primarily colonize the thatch and leaf litter. Fungi that cause edaphic fairy rings can extend mycelium growth to a depth of two to three feet in the soil profile, and lectophilic fairy rings are more likely to develop on putting greens and other closely mowed, high maintenance turfgrass (Couch, 1995). Current strategies for fairy ring control in turfgrass involve suppression, antagonism, and eradication (Blenis et al., 1997; Couch, 1995; Dernoeden, 2000; Nadeau et al., 1993; Watschke et al., 1995). Suppression methods include cultural practices such as core cultivation and aeration, irrigation to thoroughly water the soil profile, and fungicide and soil applications. With the antagonism method, turfgrass sod is removed, the soil is tilled and mixed in several directions on the premise that fairy ring fungi will eliminate each other when they come into direct contact, and the area is seeded or replaced with new turfgrass sod. Eradication involves soil fumigation or soil removal from the affected fairy ring area and in most cases is impractical and cost prohiitive. The ojective of this research was to evaluate oth current and new or innovative suppression methods for fairy ring control in golf course turf. Field-ased research on fairy ring is difficult to duplicate at the same location over a two-year period (Blenis et al., 1997; Nadeau et al., 1993). Fairy ring occurrence is unpredictale, and their appearance at one specific site on a golf course one year does not guarantee

3 their reappearance the following year (Couch, 1995; Watschke et al., 1995). This research involved singleyear field trials conducted over five locations throughout the United States during and The treatment structure was different for each field trial, however, and was designed to duplicate fairy ring control methods eing considered y golf course superintendents. The overall goal of this work was to developed field research-ased recommendations for fairy ring management for golf course turf. MATERIALS AND METHODS Ohio location. This field study was conducted on a fairway at Echo Hills Golf Course, Dayton, Ohio, USA. The fairway consisted of unknown cultivars of Kentucky luegrass (Poa pratensis L.) and mowed regularly at 19 mm with a reel mower. Turfgrass clippings were not removed after each mowing. At this site, fairy ring disease symptoms (type II symptoms of circles of stimulated, dark green grass) from lectophilic fungi (identified as Lycoperdon sp.) were first oserved during April Curative treatments included three rates of nitrogen from urea (46N-0P-0K) fertilizer applied at 49, 98, and 147 kg N ha -1, and an untreated check. Plot size measured 1.5 y 1.5 m, and treatments were arranged among three replications in a randomized complete lock design. The study was arranged so that a portion of each plot contained type II fairy ring symptoms. Nitrogen was applied as a liquid and delivered y a CO 2 powered ackpack sprayer from three 8002 flat fan nozzles calirated to deliver 814 L water ha -1 at 275 kpa. All treatments were applied on 26 Apr and 1 Jun Fairy ring control was determined from turfgrass response through visual quality ratings on a 1 to 9 scale, where 9 = est quality (uniform turfgrass color and density, no visual disease symptoms) and 6 = minimum acceptale quality. Turfgrass quality was assessed weekly from 26 Apr through 22 Jun North Carolina location. This field study was conducted on ermudagrass (Cynodon dactylon L. cv. Tifway 419 ) at the Aventis CropScience Research Center, Pikeville, North Carolina, USA. The ermudagrass was maintained as a golf course fairway and mowed regularly with a reel mower at 15.8 mm. Turfgrass clippings were not removed after each mowing. At this site, fairy ring symptoms were expressed as dark, stimulated circles of ermudagrass from unidentified edaphic fungi, and these type II symptoms were first oserved during June Curative treatments included 9.65 kg a.i. ha -1 flutolanil fungicide (ProStar 70WP, Aventis Environmental Science, Montvale, New Jersey, USA) alone, 19.0 L product ha -1 of a commercially availale soil (Primer, Aquatrols Corporation, Cherry Hill, New Jersey, USA) alone, a flutolanil plus soil tank-mixed at the rates listed, and an untreated check. Plot size measured 1.5 y 3 m and treatments were arranged across three replications in a randomized complete lock design so that each plot contained type II fairy ring symptoms. Treatments were applied y a CO 2 powered ackpack sprayer from one 8008 even flat fan nozzle calirated to deliver 814 L water ha -1 at 275 kpa. All treatments were applied only once on 20 Jun The original intent was to evaluate treatments ased on the reduction of disease symptoms, however, fairy ring control was actually ased on the visual appearance of asidiocarps on 15 Jul Virginia location. This field study was located at Fincastle Country Clu, Bluefield, Virginia, USA. The study was conducted on a USGA-specification sand-ased creeping entgrass (Agrostis palustris L. cv. Southshore ) putting green mowed daily with a reel mower at 3.96 mm mowing height. Turfgrass clippings were removed after

4 each mowing. At this site, type II fairy ring symptoms (darkened rings and semi-circles of creeping entgrass) from unidentified lectophilic fungi were first oserved in early June The study area was sujected to six curative treatments as follows: (1) granular formulation of a proprietary soil at kg product ha -1 ; (2) liquid formulation of the same at 25.3 L product ha -1 ; (3) 9.65 kg a.i. ha -1 flutolanil fungicide alone; (4) flutolanil plus the granular at the rates listed; (5) flutolanil plus the liquid at the rates listed; and (6) an untreated check. Plot size measured 0.6 y 1.2 m and treatments were arranged across three replications in a randomized complete lock design so that each plot contained fairy ring symptoms. Treatments were applied y a CO 2 powered ackpack sprayer from one 8002 even flat fan nozzle calirated to deliver 814 L water ha -1 at 275 kpa. All treatments were applied only once on 9 Jun Fairy ring control was ased on a reduction in disease symptoms during weekly intervals from 9 Jun through 15 Jul Fairy ring control was determined from visual oservations on a 0 to 100 % scale, where 100 % = complete control or no fairy ring symptoms, and 0 % = no control or no reduction in symptoms. Texas location. This field study was located at the Texas A & M University Research and Education Center, Dallas, Texas, USA. The study was conducted on a USGA-specification sand-ased creeping entgrass (Agrostis palustris L. cv. Crenshaw ) putting green mowed daily with a reel mower at 6.3 mm mowing height. Turfgrass clippings were removed after each mowing. At this site, type I and II fairy ring symptoms (i.e., rings of stimulated and weakened, drought-stressed appearing creeping entgrass) from unidentified lectophilic fungi were first oserved during June The study area was sujected to four curative treatments as follows: (1) high pressure injection (HPI) of 9.65 kg a.i. ha -1 flutolanil fungicide plus 19.0 L product ha -1 Primer soil ; (2) HPI of kg a.i. ha -1 azoxystroin fungicide (Heritage 50WG, Novartis Crop Protection, Greensoro, North Carolina, USA) alone; (3) HPI of water only; and (4) core cultivation only with a 76.2 mm deep solid-tine aerifier. Plot size measured 1.5 y 6.0 m and treatments were arranged in six replications in a randomized complete lock design. The entire putting green exhiited severe fairy ring/drought stress symptoms and therefore each plot contained those symptoms. The HPI treatments were delivered from an Enviroject (Cushman Enviroject Model 160, Textron Industries, Augusta, GA, USA) through a high pressure injector calirated to deliver 59.8 L water ha -1. All treatments were applied on 1 and 22 Jul The flutolanil plus soil treatment was included ecause it was the only fungicide laeled for fairy ring control at the time of this field trial. Azoxystroin fungicide plus soil, or soil alone was not included in this study due to space limitations at the test site. Within one week of the first application, all treated plots had clearly demonstrated excellent recovery of the putting green turf compared to untreated plots. Therefore, in order to accurately descrie the treatment effects on fairy ring symptoms, plots were visually rated for increase or reoccurrence in fairy ring symptoms on a 0 (no symptoms) to 100% (symptoms visile in entire plot area) scale from 1 Jul through 5 Aug Florida location. This field study was conducted on Tifway 419 ermudagrass putting greens at Sun N Lake Golf Clu, Sering, Florida, USA. In May 1995, nine putting greens were reuilt ut y late winter 1996 severe type I fairy ring symptoms were oserved on each new putting green. During early May 1996, nine additional putting greens were reuilt using the same modified USGA specification plan. A 0.30 m deep core was excavated from the existing nine putting greens and replaced with an 85:15 mix of sand and peat. Soil from the original construction, found elow and outside the cored area, was a native soil of high sand content. The new sand-ased putting greens were sprigged with ermudagrass in May 1996 and then overseeded with perennial ryegrass (Lolium perenne L. cv. Gator ) in Novemer Preventive fairy ring treatments were applied four times at six week intervals on 19 Sep, 30 Oct, and 11 Dec 1996, and 22 Jan The nine reuilt putting greens were split, with one-half of each green receiving 4.58 kg a.i. ha -1 flutolanil fungicide plus 19.0 L Primer soil, and the other half receiving

5 no treatment. Therefore, the two treatments of (1) fungicide plus soil and (2) untreated check were replicated nine times. Treatments were applied from a Cushman Turfmaster Sprayer (Textron Industries, Augusta, GA, USA) with a 4.5 m oom, nine 8006 flat fan nozzles, and calirated to deliver 1150 L water ha -1 at 200 kpa. Each putting green was irrigated to receive 1.27 mm water immediately after application. Lectophilic fairy ring symptoms from Lycoperdon sp. were visually evaluated on 13 March 1997 since darkened circles appeared on those putting greens during the second week of March Data Analysis. Data from each individual field study were sujected to analysis of variance conducted on Statistical Analysis Software (SAS Institute, 1987). For each field study, treatment means were separated y Fisher s protected least significance difference test at P < Data could not e comined across all five locations since the treatments tested were unique to each location. Therefore, data were analyzed separately for each of the five locations. RESULTS AND DISCUSSION Ohio location. Although turfgrass quality evaluations were determined on a weekly asis from 26 Apr to 22 Jun 1999, only results from 22 Jun 1999 are descried since that was final rating date (figure 1). By 22 June 1999 or 21 days after the second fertilizer application, turfgrass quality in those plots that received 98 or 147 kg N ha -1 improved to the point where no type II fairy ring symptoms were visually evident. In this field study, > 98 kg N ha -1 was needed to mask rings of stimulated turfgrass attriuted to the lectophilic fairy ring at this location. Below the surface, the fairy ring mycelium grows in a roughly circular pattern through the soil, reaking down organic matter and releasing nitrogen in the form of ammonia (Couch, 1995; Shantz and Piemeisel, 1917; Smith et al., 1989; Vargas, 1994; Watschke et al., 1995). Soil microorganisms process the ammonia into nitrates which are availale to turfgrass roots. The visile rings of lush, green grass are the result of this nitrogen release and turfgrass root uptake in the soil. In this field study, the nitrogen fertilizer treatments enhanced turfgrass quality, color, and growth to match the appearance of the type II fairy ring-stimulated areas, thus giving the visual appearance of a uniformly fertilized turf area. North Carolina location. Fairy ring control was determined on 15 Jul 1999 or 25 days after treatments were applied (figure 2). On this date, asidiocarps from an unidentified species and dark, stimulated circles of ermudagrass were oserved throughout the test area. The area received approximately 30 mm rainfall the previous day which contriuted to the rapid appearance of those asidiocarps (Couch, 1995). In this field study, the effects of the curative treatments on fairy ring-causing fungi were determined from the visual appearance of asidiocarps. The asidiocarps were considered large in size and averaged 76 mm in diameter. An average of eight asidiocarps were counted in the untreated plots, while none were oserved in those plots treated with the flutolanil or flutolanil plus soil. An average of one asidiocarp was oserved in those plots treated with the soil alone. Therefore, the use of flutolanil or flutolanil plus soil had a positive effect at inhiiting the mushroom-forming activity of the fairy ring fungi at this site. Type II symptoms expressed y the turfgrass, however, were not reduced or eliminated. Turfgrass quality or masking of disease symptoms may have een improved if a fertilizer or iron was applied to this site (Watschke et al., 1995). Also, all asidiocarps present were easily removed y mowing.

6 Virginia location. Fairy ring control was the most dramatic on 15 Jul 1999 or 36 days after treatments were applied (figure 3). Fairy ring control was ased on the visual reduction in type II disease symptoms on 15 Jul A significant reduction in the visual appearance of dark, stimulated rings of turfgrass were oserved in those plots that received a fungicide-ased treatment. Plots that received flutolanil or flutolanil plus soil resulted in > 80% fairy ring control. No fairy ring control was oserved in the untreated check plots or those plots treated with soil alone. The experimental soil, either the granular or liquid formulation, did not contriute to any significant amount of fairy ring control in this field study. Texas location. Overall est fairy ring control ased on creeping entgrass recovery (i.e., < 5% reoccurrence in type I and II fairy ring symptoms from 1 Jul through 5 Aug 1999) was oserved in those plots treated with HPI flutolanil plus soil or HPI azoxystroin (figure 4). Turfgrass recovery and regrowth effects were first oserved five days (i.e., 6 Jul 1999) after treatments were applied. The visual appearance in plots treated with HPI flutolanil plus soil or HPI azoxystroin was easily oserved due to the rapid turfgrass recovery and apparent resumptive growth within those treated areas. Turfgrass treated with HPI flutolanil plus soil exhiited the most pronounced and consistent recovery throughout the duration of this field study. By mid-july, a limited ut unacceptale amount of turfgrass recovery was oserved in plots sujected to core cultivation or HPI water. By early August, type I fairy ring symptoms increased dramatically in those plots that were cultivated or received HPI water. Therefore, the field study was discontinued after 5 Aug 1999 due to the potential loss of putting green turf in those plots from the prolonged hot and dry weather conditions normally associated with the month of August at this location. On 6 Aug 1999, the entire putting green was treated with HPI flutolanil plus soil. By 13 Aug 1999, acceptale turfgrass recovery was oserved throughout most of the putting green area and only a few small areas were slower to recover. Florida location. Although preliminary results from this field study were previously reported (Hickman et al., 1998), the data presented here represents new information. By early March 1997, type I necrotic injury symptoms attriuted to lectophilic fairy ring egan to appear only on the untreated-half of each putting green (figure 5). The appearance of fairy ring symptoms corresponded to the typical dry, drought-like conditions common in Florida at that time of year. An average of 23 rings were oserved on the untreated-half of each putting green. The majority of rings ranged from <0.30 to 0.60 m in diameter, with some as large as 1.0 m diameter. No necrotic rings or disease symptoms were oserved in the treated-half of each putting green. The overall turfgrass quality in the untreated-half was considered unacceptale y the golf course superintendent due to the appearance of drought-stress circles of turf which contriuted to an uneven and disruptive putting surface. Turfgrass quality and color, however, was considered acceptale in the treatedhalf of each putting green. On 20 Mar 1997, the untreated-half of each putting green was treated with flutolanil plus soil as a curative or rescue approach at the application rate previously descried. By 3 Apr 1997, damaged turf areas in the untreated-half of each putting green egan to recover enough where turfgrass quality was considered acceptale. By 1 May 1997, no turf injury was visile in those previously untreated-halves, and the ermudagrass had recovered and moved into the formerly damaged areas. 9 a ass Quality 6

7 Figure 1. Ohio location: Kentucky luegrass quality assessment on 22 Jul Visual quality ratings were ased on a 1 to 9 scale, where 9 = est and 6 = minimum acceptale turfgrass quality, color, and uniformity. Treatment means followed y the same letter are not significantly different according to Fisher s protected least significant difference test at P < a Basidiocarps 5 0 untreated flutolanil soil flutolanil + soil Figure 2. North Carolina location: numer of fairy ring asidiocarps oserved on 15 Jul Treatment means followed y the same letter are not significantly different according to Fisher s protected least significant difference test at P < 0.05.

8 % Fairy Ring Control c untreated c granular soil c liquid soil flutolanil + granular soil flutolanil + liquid soil a flutolanil Figure 3. Virginia location: percent fairy ring control oserved on 15 Jul Treatment means followed y the same letter are not significantly different according to Fisher s protected least significant difference test at P < % Increase in Fairy Ring Symptoms a HPI water HPI flutolanil + soil d c HPI azoxystroin core cultivation Figure 4. Texas location: percent increase in type II fairy ring symptoms from 1 Jul to 5 Aug Treatment means followed y the same letter are not significantly different according to Fisher s protected least significant difference test at P < 0.05.

9 50 Total Numer of Type I Fairy Rings Per Putting Green untreated flutolanil + soil Figure 5. Florida location: total numer of type I fairy rings oserved per putting green on 13 Mar Mean numer of rings for untreated half of all nine greens = 23. Mean numer of rings for treated half of all nine greens = 0. Treatment means were significantly different according to Fisher s protected least significant difference test at P < CONCLUSION Since a unique and different set of treatments were evaluated in each of the five field study locations, the results could not e comined across locations for further data analysis. Therefore, treatment results were evaluated for each individual field study. At the Ohio location, type II fairy ring symptoms were essentially hidden or masked from the dose of nitrogen fertilizer. This approach is very practical and economical, since fertilization is a normal component of golf course turf maintenance. The challenge is to supplement enough nitrogen-ased fertilizer or iron that will enale the surrounding turf to match the color and growth of the fairy ring-affected grass. At the Virginia location, the use of a fungicide or fungicide plus soil helped to reduced or disrupt the appearance of dark green circles of turfgrass. Although fungicide and fungicide plus soil treatments also were evaluated at the North Carolina location, there were no visile reductions of green stimulated rings of grass. At this location, however, no asidicarps appeared in the fungicidetreated plots. The success of a fungicide or fungicide plus soil program for a curative reduction in fairy ring symptoms may depend on the fungal species, whether the fungi is lectophilic or edaphic, the time of year, and the level of turfgrass maintenance. The use of high-pressure injection to deliver fairy ring control measures has the potential for not only inhiiting fairy ring-causing fungi ut also enhancing turfgrass recovery as oserved at the Texas location. High-pressure injection of fungicides and s into the soil profile may e a viale option for controlling those hard-to-reach edaphic or soil-inhaiting fairy ring fungi. Additional research is needed to evaluate the enefits and challenges of delivering effective turfgrass disease control agents via HPI. A preventive approach to controlling fairy ring similar to the one evaluated at the Florida location is proaly the most challenging since fairy ring is difficult to predict. However, fairy ring symptoms have een oserved to occur within one year on newly reuilt or renovated sand-ased putting greens (Dernoeden, 2000). Future research on fairy ring management should consider an integrated program of fungicides, soil s, and cultural practices on actual golf course test-sites. Also, more information is needed regarding the iology, ecology, and pathogenicity of fungi that cause fairy ring in turf. The overall goal should e to develop strategies for maintaining healthy turfgrass while suppressing fungi that cause fairy ring.

10 REFERENCES Blenis, P.V., L.B. Nadeau, N.R. Knowles, and G. Logue Evaluation of fungicides and s for control of fairy rings caused y Marasmius oreades (Bolt. ex. Fr.) Fr. HortScience 32: Couch, H.B Diseases of turfgrasses. Kreiger Pulishing, Malaar, Florida. Dernoeden, P.H Creeping entgrass management: summer stresses, weeds, and selected maladies. Ann Aror Press, Chelsea, MI. Hickman, R., M. Elliott, M.A. Fidanza, M. Hopkins, and D.R. Spak A preventative approach to fairy ring disease management on putting greens. Agronomy Astract Nadeau, L.B., P.V. Blenis, and N.R. Knowles Potential of an organosilicone to improve soil wettaility and ameliorate fairy ring symptoms caused y Marasmius oreades. Canadian Journal of Plant Science. 73: SAS Institute SAS/STAT Guide for personal computers. Version 6. SAS Institute, Cary, NC. Shantz, H.L. and R.L. Piemeisel Fungus fairy rings in Eastern Colorado and their effects on vegetation. Journal of Agricultural Research. 11: Smiley, R.W., P.H, Dernoeden, and B.B. Clarke Compendium of turfgrass diseases. APS Press, Minneapolis, MN. Smith, J.D., N. Jackson, and A.R. Woolhouse Fungal diseases of amenity turf grasses. E. & F.N. Spon, New York, NY. Vargas, J.M Managing turfgrass diseases. CRC Press, Boca Raton, FL. Watschke, T.L., P.H. Dernoeden, and D.J. Shetlar Managing turfgrass pests. CRC Press, Boca Raton, FL.