University of Massachusetts Snow Mold Trials

Transcription

1 University of Massachusetts Snow Mold Trials K. Campbell-Nelson, J. Popko, C. Ok, and G. Jung Department of Plant, Soil and Insect Sciences University of Massachusetts-Amherst In the Fall of 2009 researchers from the University of Massachusetts, Amherst conducted trials consisting of 34 different fungicide treatments applied on three golf courses throughout New England and at the UMass Research Center to evaluate bio-control and fungicide field efficacy for control of Typhula blight (caused by Typhula ishikariensis and T. incarnata) and pink snow mold (caused by Microdochium nivale). Two of the four locations (Ekwanok Country Club in Manchester, VT and the Joseph Troll Research Center in South Deerfield, MA) did not suffer high enough disease pressure to yield results. However, the other two locations used in this trial (Glens Falls Country Club in Queensbury, NY and Berkshire Hills Country Club in Pittsfield, MA) produced an average of 85% and 27% disease coverage respectively on untreated plots under natural disease conditions. Results from these two locations will be discussed in this article as they provide some valuable discussion into pathogen specific management of snow molds, particularly in a time of global climate change when winter weather impacting disease pressure is unpredictable. Treatments (see Table 1) were applied to a typical mixed bentgrass and annual bluegrass fairway maintained at 0.5-inch mowing height in both locations. Individual plots measured 3 ft x 6 ft (18 ft 2 ), and were arranged in a randomized complete block design with three replications (Figure 1). Fungicides listed in Table 1 were applied based on labeled or suggested rates. Individual treatments were applied at a nozzle pressure of 40 psi using a CO 2 pressurized boom sprayer equipped with two XR Teejet 8004 VS nozzles. All fungicides were agitated by hand and applied in the equivalent of 2 gallons of water per 1000 ft 2. Most fungicide applications were made in the second week of November, 2009, however treatments numbered 2, 19, 30, 32 and 33 (Table 1) were split applications made in the first week and later in the second week of November, Figure 1. Research plot in Queensbury, NY. Photo taken on March 8th 2010 by Kyle Quay, assistant superintendent of Glens Falls Country Club.

2 In Queensbury, NY most snow mold damage was caused by the basidiomycete fungal pathogen Typhula incarnata while in Pittsfield, MA most disease damage was caused by the ascomycete fungal pathogen Microdochium nivale. The different disease causing agents at these two locations are due to the different weather conditions over the Fall and Winter of The Queensbury location sustained over 90 days of continual snow cover on unfrozen ground, and experienced a wet fall with temperatures ranging from F during the week before fungicide applications began. These fall conditions were optimal for germination of Typhula sclerotia and/or basidiospores while the continual snow cover was optimal for persistence of the fungal mycelia in the grass canopy. The Pittsfield location on the other hand, sustained between 60 and 90 days of snow cover on unfrozen ground and experienced a thaw in January before receiving additional snow cover which remained till early March. Pittsfield also experienced a wet Fall with temperatures ranging from F during the week prior to fungicide applications. The lack of continual snow cover was not conducive to Typhula, however Microdochium thrived, and new infections likely occurred in January during the winter thaw and again in March during the spring thaw. Changing winter conditions make it more difficult to predict winter weather and therefore proper timing, rate, and type of fungicide application. Snow cover occurring before the ground freezes also leaves grass very susceptible to infection over the winter months. Previous research (1, 2, and 3) has indicated that certain fungicide active ingredients are best suited to control specific species of snow molds. For example, propiconazole was shown to provide better control of Typhula ishikariensis, while trifloxystrobin displayed better control of Microdochium nivale. Therefore it was not surprising that in this year's trial, one experimental fungicide (DPX-LEM17-50) provided excellent control against T. incarnata, but did not control M. nivale (Figure 2). Another interesting result was seen in the breakdown of traditional products containing multiple active ingredients such as Instrata. This premixed formulation of chlorothalonil, fludioxonil, and propiconazole even at the high rate of 11 oz/1000ft 2 was unable to control gray snow mold at both locations (Figure 3). Other treatments with multiple active ingredients such as (trt #s 3, 4, 5, 6, 16, 17, 18, and 19) did not perform well under high disease pressure either. Further research is needed to investigate key causes for those failures. Overall, most treatments did not provide acceptable control (<5% disease coverage) of snow mold at the Queensbury site because disease pressure was very high. However, most treatments did provide acceptable or close to acceptable control except for treatment #s 21, 22, 24, 28, and 29 at the Berkshire Hills site because disease pressure was not as high. As winter weather becomes more difficult to predict, superintendants must turn to more and more cultural practices in controlling snow mold. It is impossible to determine the species of snow mold expected to infect the grass or the overall disease pressure at a particular location. Good recordkeeping (snow cover duration/snow mold species) of past disease outbreaks can help give some indication of the snow mold species to be expected. For example, sites with snow cover generally exceeding 90 days can expect to see gray snow mold activity and sites with cool weather and plenty of moisture with or without snow cover are more likely to see pink snow mold. Cultural practices that reduce snow mold infection include mowing turf before winter to reduce the amount of susceptible tissue for infection, not making late fall applications of nitrogen fertilizer, and providing adequate drainage to compacted or low lying areas. 2

3 A B Figure 2. Experimental product, DPX-LEM17-50 (Treatment #20-24) provided excellent control against Typhula in Queensbury (A) but did not provide control against Microdochium (showing distinct circular patches with pinkish border after snow melt) in Pittsfield (B). A Figure 3. Instrata applied at the high rate of 11 oz/1,000ft 2 did not control Typhula in Queensbury (A) nor in Pittsfield (B). B 3

4 Table 1. Percent disease coverage on plots evaluated on March 15, 2010 at the Glens Falls Country Club, in Queensbury, NY and on March 20, 2010 at the Berkshire Hills Country Club, in Pittsfield, MA. % Diseased Area a Trt # Treatment oz/1,000 ft 2 Glens Falls Berkshire Hills Timing b 1 INSTRATA BCDE 6.7 CDEF late 2 INSTRATA DEFG 2.0 F early INSTRATA 5.50 late 3 QP IPRO 2 SE DEFGHIJ 1.0 F late QP PROPICONAZOLE late QP TM/C 6.00 late 4 QP IPRO 2 SE HIJK 5.0 DEF late QP MYCLOBUTANIL 2.40 late QP TM/C 6.00 late 5 QP CHLOROTHANIL DEFGH 1.7 F late QP IPRO 2 SE 4.00 late QP PROPICONAZOLE late 6 QP CHLOROTHANIL JKL 3.4 EF late QP IPRO 2 SE 4.00 late QP MYCLOBUTANIL 2.40 late 7 INTERFACE GHIJ 2.4 EF late TRITON FLO 0.85 late 8 INTERFACE GHIJ 1.7 F late TRITON FLO 0.85 late 9 INTERFACE FGHIJ 2.0 F late TRITON FLO 0.85 late 10 COMPASS EFGHIJ 1.0 F late RESERVE 4.8 SC 4.50 late 11 COMPASS GHIJ 2.7 EF late RESERVE 4.8 SC 5.40 late 12 DACONIL ULTREX HIJKL 1.4 F late TARTAN 2.00 late 13 INSTRATA CDEF 2.7 EF late 14 INTERFACE BCD 1.0 F late TURFCIDE 400F 8.00 late 15 COMPASS EFGHI 2.0 F late RESERVE 4.8 SC 4.50 late 16 CHLOROTHALONIL HIJKL 1.4 F late INSIGNIA (LIQUID) 0.54 late a Values are percent means of the percent disease severity of three replicates. Means followed by the same letter are not significantly different according to the Least Significant Difference test (LSD = for Glens Falls and 7.56 for Berkshire Hills). b Early applications were made in the first week of November, 2009 and late applications were made in the second week of November,

5 Table 1. Continued % Diseased Area a Trt # Treatment oz/1,000 ft 2 Glens Falls Berkshire Hills Timing b 17 INSIGNIA (LIQUID) HIJKL 1.7 F late IPRODIONE PRO 4.00 late 18 CHLOROTHALONIL IJKL 4.0 DEF late HONOR 0.83 late 19 CHLOROTHALONIL IJKL 2.0 F early CURALAN 1.00 early CHLOROTHALONIL 3.20 late INSIGNIA 0.70 late 20 DPX-LEM L 7.7 CDEF late 21 DPX-LEM KL 16.0 B late 22 DPX-LEM L 24.4 A late 23 DACONIL ULTREX L 6.7 CDEF late DPX-LEM late 24 CHIPCO FLO L 9.7 BCDE late DPX-LEM late 25 INSTRATA FGHIJ 3.7 EF late RHAPSODY 3.00 late 26 INSTRATA ABC 5.0 DEF late RHAPSODY 5.00 late 27 PEGASUS DFX AB 5.0 DEF late RAVEN 4.00 late 28 KESTREL MEX ABC 13.0 BC late PEGASUS DFX 3.60 late 29 PEGASUS DFX A 11.4 BCD late T-BIRD FL 4.00 late 30 COMPASS A 2.0 F early TURFCIDE 400F 8.00 early 31 COMPASS ABC 3.0 EF late TURFCIDE 400F 8.00 late 32 COMPASS AB 1.3 EF late TURFCIDE 400F 8.00 early 33 COMPASS ABC 1.0 F early TURFCIDE 400F 8.00 late 34 UNTREATED AB 26.7 A - a Values are percent means of the percent disease severity of three replicates. Means followed by the same letter are not significantly different according to the Least Significant Difference test (LSD = for Glens Falls and 7.56 for Berkshire Hills). b Early applications were made in the first week of November, 2009 and late applications were made in the second week of November,

6 Acknowledgements We kindly acknowledge the following companies for their financial support: AgraQuest, Inc, BASF Corporation, Bayer Environmental Science, Cleary Chemical Corporation, DuPont Turf & Ornamental, Phoenix Environmental Care, Quali-Pro Professional Turf & Ornamental Products, and Syngenta. Our appreciation extends to the following superintendents for their collaboration: Mike Salinetti at Berkshire Hills Country Club, Ted Maddocks at Ekwanok Country Club, Chris Frielinghaus at Glens Falls Country Club, and Thom Griffin at Joseph Troll Turf Research Center. We also thank Jason Lanier from the UMASS Turfgrass Extension Service. References cited 1. Chang, S., Y. Jo, and G. Jung A fresh look at fungicides for snow mold control. GCSAA Golf Course Management July 2007 pages Jung, G., and S. Chang Distribution of Typhula species and varieties in Wisconsin, Utah, Michigan and Minnesota. GCSAA Golf Course Management January 2008 pages Jung, G., S. Chang, T. Chang, P. Koch, and S. Abler Minimum fungicide rates for species-specific snow mold control. GCSAA Golf Course Management November 2008 pages