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Golf Green Health By Fungicides – Beyond Just Disease Control
Researchers: Chicago District Golf Assoc. ‐ Derek Settle, Tim Sibicky, and Nick DeVries
Goal: Evaluate plant health effects while suppressing dollar spot and brown patch Location: Sunshine Course’s 3 green in play – Lemont, Illinois Background: Creeping bentgrass is highly susceptible to dollar spot (Sclerotinia homoeocarpa) and brown patch (Rhizoctonia solani). To protect golf greens from these two plant pathogenic fungi (and a few others) superintendents must apply fungicides with frequency. If plant protectants are applied about every 14 days can secondary plant health effects occur? Fungicides specially formulated with green pigments were first thought to improve plant health beginning about the 1990s in North Carolina (e.g., Fore, also Aliette Signature mixed with either Daconil Ultrex or Chipco 26019). The approach of this study was to use fungicides formulated with green pigments/colorants (e.g., Bayer’s StressGard) and see if they provide additional plant health benefits. Fungicides in the DMI family of were included as a comparison. We know DMIs can reduce plant health by bronzing/growth regulation if applied in summer. Brief Material and Methods: Sunshine Course’s number 3 green used a randomized complete block design with 3 replications. Individual plot size was 4 ft by 6 ft. The USGA‐constructed green is creeping bentgrass seeded in 2002 to Penn G2 plus L93. It is maintained at 0.150 inch. Dollar spot existed (1‐10%) when first applications were made on 31 May. Twelve treatments were applied every 14 days and four treatments every 7 days (Table 1). Data collected included; dollar spot number, dollar spot percent, and brown patch percent. NDVI and visual quality (1‐9 scale with 6= acceptable) assessed plant health/phytotoxicity
Material and Methods Table. Treatments for disease control on 3 green at Sunshine Course, Lemont, IL in 2011. Number Treatments Interval Rate per 1,000 sq ft 1 Untreated .... .... 2 Reserve 7 day 1.6 fl oz 3 Reserve 7 day 2.5 fl oz 4 Reserve 7 day 3.5 fl oz 5 Reserve 14 day 2.5 fl oz 6 Reserve 14 day 3.5 fl oz
7 Interface rotate Reserve 14 day 2.5 fl oz
3.0 fl oz 18 Rotation 14 day see below A 31 May Triton FLO 0.5 fl oz B 13 Jun Daconil Ultrex 3.2 oz C 27 Jun Triton FLO 0.5 fl oz D 11 Jul Daconil Ultrex 3.2 oz E 25 Jul Reserve 3.6 fl oz F 8 Aug Daconil Ultrex 3.2 oz G 22 Aug USF26019T 4.0 fl oz H 5 Sep Reserve 3.6 fl oz I 19 Sep Triton FLO 0.5 fl oz 9 Interface 14 day 3.0 fl oz 10 Interface 14 day 4.0 fl oz 11 Tartan 14 day 1.5 fl oz 12 Iprodione Pro 14 day 4.0 fl oz 13 Concert 7 day 3.0 fl oz 14 Concert 14 day 5.5 fl oz 15 Tourney (CDGA check) 14 day 0.28 oz 16 Daconil Ultrex (CDGA check) 14 day 3.2 oz 17 Emerald (CDGA check) 14 day 0.13 oz
1Dates of application began 31 May and the 14 day fungicide interval exactly follows the dates used for treatment 8. The 7 day interval occurred on and between those dates.
Figure 1improvedReducedspot (Dacor causeare not strial, Sun
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Image 1. By mid‐July, brown patch was affecting untreated and Emerald plots. Many fungicide treatments were disease‐free and in good health. Sunshine Course, Lemont, IL. Settle 7‐15‐11
Image 2. By the end of July, untreated plots were damaged by both dollar spot (20%) and brown patch (60%). Disease pressure was very high. Sunshine Course, Lemont, IL. Settle 7‐27‐11
Image 3. Bruce Monke reviews plots with Tim Sibicky. Dollar spot exploded over the preceding weekend when cooler temperatures returned to Chicago (days 80s/nights 60s). Settle 8‐16‐11
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