Early Dollar Spot Disease Control for Chicago Fairways

Transcription

1 Early Dollar Spot Disease Control for Chicago Fairways Researchers: Chicago District Golf Assoc. Derek Settle, Tim Sibicky, and Nick DeVries with Dan Dinelli and Jerry Dinelli Goal: Evaluate Early timed Fungicide Applications to Delay Dollar Spot Development Location: 8 Fairway, North Shore Country Club, Glenview IL Background: Creeping bentgrass is highly susceptible to dollar spot (Sclerotinia homoeocarpa). Most Chicago golf courses are grassed from tee to green with creeping bentgrass (Agrostis stolonifera). To maintain acceptable bentgrass quality, superintendents must make multiple fungicide applications. A newer way to improve fungicide efficacy has been through manipulation of application timing. Previously, control of dollar spot focused on scheduling fungicides two ways, either preventive (calendar basis) versus curative (post infection basis). In 2000 researchers found a post infection fungicide timing could reduce fungicide input without sacrificing necessary visual quality for L 93, a dollar spot resistant bentgrass variety (Settle et al.). However, if the variety was dollar spot susceptible (e.g., Crenshaw) they found a calendar based preventive program performed best. Today, few studies have looked at mixed stands comprised of creeping bentgrass and Poa spp. and this is typical of most older golf courses and would be dollar spot susceptible. In this study we looked at a mixed fairway stand and tested preventive, curative as well as a new early dollar spot strategy. Early dollar spot applications are made 1 to 2 months prior to initial disease development. The hypothesis is that superintendents will benefit because they will see a reduction of about 1 application during the growing season. For unknown reasons, the early spring fungicide timing can provide a longer lasting residual effect than is usual for dollar spot suppression on bentgrass fairways. Objective: Test hypothesis Can we reduce initial onset of dollar spot disease (usually begins in May or June in Chicago) by applying fungicides earlier than usual? Brief Material and Methods: North Shore s number 8 fairway used a randomized complete block design with 4 replications. Individual plot size was 4 ft by 6 ft. The fairway is unknown creeping bentgrass with Poa annua and a lesser amount of Poa trivialis present. The components are about 50% bentgrass and 50% Poa spp. The fairway is maintained at a mowing height of inch and annually receives 3 lbs N 1000 ft 2. Thirteen fungicides were applied at label rates and were applied once, twice or three times. Two rotation programs were applied according to a calendar day schedule and amounted to 4 and 5 applications (Table 1). The first application was timed to coincide with sighting of first seedheads in the Chicago area (18 Apr in Joliet). At North Shore neither disease, nor seedheads existed when first applications were made. Data collected included; dollar spot number and dollar spot percent. NDVI and visual quality (1 9, 6 = acceptable) assessed impact of disease / phytotoxicity. Page 1

2 Material and Methods Table. Treatments for disease control on 8 fairway at North Shore Country Club, Glenview, IL in Number/ Sponsor Treatments and application dates Interval Rate per 1,000 sq ft 1 Untreated Tourney 50WD 3 apps oz Valent 3 S apps. 0.5 fl oz Valent 4 S apps. 0.6 fl oz Valent 5 DuPont Velista + Banner (21 Apr) then Velista + Daconil Ultrex (17 May) 2 apps. 0.5 oz fl oz 0.5 oz oz 6 DuPont Emerald (21 Apr) then Banner Maxx + Daconil 2 apps oz 1.0 fl oz oz 7 Emerald 2 apps oz 8 Banner Maxx 2 apps. 1.0 fl oz 9 Bayleton FLO (21 Apr) once 1.0 fl oz 10 Bayleton FLO (21 Apr, 9 May) 2 apps. 21 day 11 Bayer Rotation 2 5 apps. 1.5 fl oz A Bayleton FLO (21 Apr) 1.0 fl oz B Triton Flo + Chipco Signature (17 14 day 0.5 fl oz oz May) C Daconil Ultrex + Signature (6 Jun) 14 day 3.2 oz oz D Triton Flo + Signature (14 Jun) 14 day 0.5 fl oz oz E Daconil Ultrex + Signature (27 Jun) 14 day 3.2 oz oz 12 Bayer Rotation 5 4 apps. A Bayleton FLO (21 Apr) 1.0 fl oz B Interface (25 May) 21 day 4.0 fl oz C Tartan + Chipco Signature (14 Jun) 14 day 1.5 fl oz oz D Interface + Chipco Signature (27 Jun) 14 day 5.0 fl oz oz 13 Chipco GT (21 Apr, 17 May, 14 Jun) 3 apps. 14 Emerald + Daconil Ultrex once aka CDGA Bookend (2 Jun) 4.0 fl oz 0.18 oz oz Page 2

3 Resultss using 8 Figures (Weather, Disease Development, and Data of Quality, NDVI, Dollar spot, Brown patch), 5 Tables, and 12 Images 100 Chicago Summer 2011 Data = North Shore Country Club, Glenview Temperature degrees (F) Min Max 23-Sep 13-Sep 3Sep 3-Sep 24-Aug 14-Aug 4-Aug 25-Jul 15-Jul 5-Jul 25-Jun 15-Jun 5-Jun 26-May 16-May 6-May 26-Apr 16-Apr Figure 1. Temperature: Chicago s July weather extremes (100 F) caused physiological decline Rainfall for 16 Apr to 30 Sep = ~25 inches multiple flood events and wind storms Daily precipitation Inches May 6 May 26 Apr 16 Apr 5 Jul 25 Jun 15 Jun 5 Jun 26 May 24 Aug 14 Aug 4 Aug 25 Jul 15 Jul 23 Sep 13 Sep 3 Sep North Shore Country Club, Glenview Figure 2. Rainfall: Chicago s July rainfall was the greatest on record (O Hare saw 11+ inches). Page 3

4 Incidence of disease (% per plot) Fairway: Disease Development Untreated Plots, North Shore Country Club Dollar spot Jul 30 Jun 23 Jun 16 Jun 9 Jun 2 Jun 26 May 19 May 12 May 5 May 28 Apr 21 Apr Figure 3. Disease development in untreated plots on 8 fairway at North Shore Country Club, Glenview, IL. Dollar spot did not occur until the third week of May and then progressed. Visual quality (0 9, 6 = acceptable) Fairway: Disease Development Untreated Plots, North Shore Country Club Visual quality Jul 30 Jun 23 Jun 16 Jun 9 Jun 2 Jun 26 May 19 May 12 May 5 May 28 Apr 21 Apr Page 4 Figure 4. Visual quality in untreated plots on 8 fairway at North Shore Country Club, Glenview, IL. Dollar spot did not occur until the third week of May and then progressed.

5 Area Under Progress Curve (AUPC) 8 Fairway: Influencee of Fungicides on Visuall Quality North Shore Country Club, Glenview 13 weekly rating dates (21 Apr to 111 Jul) a a 85 ab abc ab bc 80 bc bc c c c c d e e 55 Figure 5. Visual Quality: Compared to untreated plots, all fungicides except Bayleton (once) improved quality. Banner Maxxx (2 apps) provided intermediate quality and best quality was associated with treatments thatt received 3 or more applications. Bars with same letter are not significantly different (P<0.05) according to Fisher s Protected LSD.. Area Under Progress Curve (AUPC) 1.48 a Fairway: Influence of Fungicides on NDVI Normalized Difference Vegetation Index 3 rating dates (24 May, 3 Jun, 14 Jun) a a a a a a a a a a a a a Figure 6. NDVI: All treatments were of similar NDVI. However, trends did exist and showed low levels associated with untreated plots as would be expected given highest levels are best. Bars with same letter are not significantly different (P<0.05)) according to Fisher s Protected LSD. Page 5

6 Area Under Disease Progress Curve (AUDPC) 8 Fairway: Influence of Fungicides on Dollar Spot data = infection centers (% per plot) 8 weekly rating dates (24 May to 11 Jul) 120 a b 60 bc 40 cd c d cd cd cd 20 d d d d d d 0 Figure 7. Dollar spot percent: Compared to untreated, all treatments effectively controlled dollar spot under high disease pressure. One application of Bayleton had greatest dollar spot levels as expected, and interestingly Banner Maxx (2 apps) was no different. Lowest levels were consistently associated with experimental S 2200, Chipco GT, Tourney and Emerald. Of those, Emerald (2 apps) received fewest applications. North Shore Country Club, Glenview, IL in Bars with same letter are not significantly different (P<0.05) according to Fisher s Protected LSD. Page 6

7 Area Under Disease Progress Curve (AUDPC) Fairway: Influence of Fungicides on Dollar Spot data = infection centers (number per plot) 8 weekly rating dates (24 May to 11 Jul) a b bc bcd cde cde cde de de e e e e e Figure 8. Dollar spot number: Compared to untreated, all treatments effectively controlled dollar spot under high disease pressure. Counting infection centers was better at separating treatment differences compared to percentage estimates. Bayleton (once) provided intermediate suppression as was expected and Banner r Maxx (2 apps) and CDGA bookend were no different. Lowest dollar spot level was associated with Chipco GT (3 apps). Nevertheless, most treatments provided statistically similar control too Chipco GT. North Shore Country Club, Glenview, IL in Bars with same letter are not significantly different (P<0.05) according to Fisher s Protected LSD. Page 7

8 Image 1. Dollar spot development began the third week of May. Tim Sibicky takes NDVI measurements used to assess plant health. North Shore CC, Glenview, IL. Settle Image 2. Nathaniel Settle rates dollar spot within each plot by counting infection centers and by estimating percent area blighted. North Shore CC, Glenview, IL. Settle Page 8

9 Image 3. Two treatments were 14 day Bayer fungicide rotations with a green pigmented product, Aliette Signature containing StressGard. North Shore CC, Glenview, IL. Settle Image 4. The early dollar spot study concluded in July and was signed for a summer field day for the Chicagoland Association of Golf Course Superintendents (CAGCS). Settle Page 9

10 Image 5. By July, untreated plots were 40% blighted by dollar spot. Settle Image 6. A summer field day concluded the dollar spot study on 8 fairway with about 20 superintendents, Univ. of Wisconsin, and Univ. of Illinois attending, Glenview, IL. Settle Page 10