Performance of selected phosphite fungicides on greens - GCSAA

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RESEARCHLexington. The site received nitrogentwice in the autumn and early winter.Before and during the summer test periods,nitrogen and irrigation inputs were minimalin order to provide a moderate level <strong>of</strong> stresson the turf.ControlsA bit <strong>of</strong> explanation <strong>of</strong> the treatmentdesign is in order because several treatmentsserve as experimental controls. Each testincluded plots treated with water only (treatment1 in all tables) and plots treated with aspray program expected to provide good diseasecontrol. The control spray program,applied every two weeks, was a tank-mix <strong>of</strong>Chipco Signature plus a full rate <strong>of</strong> Chipco26GT, alternating with a tank-mix <strong>of</strong> ChipcoSignature plus a full rate <strong>of</strong> Daconil Ultrex(treatment 2 in all tables).TreatmentsAll <strong>phosphite</strong> <strong>fungicides</strong> tested were usedat their full application rate in combinationwith a half-rate <strong>of</strong> Chipco 26GT alternatingwith Daconil Ultrex (referred to below as<strong>phosphite</strong> fungicide programs; treatments 4-7 inTables 1 and 2, and treatments 4-9 in Tables3 and 4). We used half-rates <strong>of</strong> Chipco 26GTand Daconil Ultrex in order to put the <strong>phosphite</strong><strong>fungicides</strong> through stringent testingconditions.Because we used the contact <strong>fungicides</strong>at half-rates, another experimental controlwas the application <strong>of</strong> half-rates <strong>of</strong> Chipco26GT alternating with Daconil Ultrex butwithout a <strong>phosphite</strong> fungicide (treatment 3 inall tables).Finally, in 2004 we added another experimentaltreatment, where we substitutedChipco Aliette for Chipco Signature to testthe effect <strong>of</strong> the green dye in ChipcoSignature (treatment 5 in Tables 3 and 4),and we added Magellan, another <strong>phosphite</strong>fungicide (treatment 9 in Tables 3 and 4).Data were collected on the intensity<strong>of</strong> dollar spot (caused by Sclerotinia homoeocarpa)and brown patch (caused byRhizoctonia solani), as well as on turf quality(excluding damage from dollar spot). In2003, we assessed turf quality <strong>of</strong> annualbluegrass (Poa annua) and creeping bentgrassseparately. Weather data from the University<strong>of</strong> Kentucky Agricultural Weather Centerwere examined. Selected data are presentedin the tables; details <strong>of</strong> methods and additionaldata are available in our publishedreports (4-8).2003 resultsAll <strong>of</strong> the <strong>phosphite</strong> fungicide programs2003 DOLLAR SPOT CONTROLNo. <strong>of</strong> dollar spot infection centers/plot †Treatment and rate/1,000 square feet* June 10 June 17 July 2 July 15 July 30Experimental controls1. Water 14.3 a 37.3 a 38.3 a 72.0 a 57.3 a2a. Chipco Signature 80WG 4 ounces + Chipco 26GT 2SC 4 fluid ounces alternated with2b. Chipco Signature 80WG 4 ounces + Daconil Ultrex 82.5WDG 3.2 ounces 2.7 b-e 0.0 f 0.0 c 0.3 cd 0.0 i3a. Chipco 26GT 2SC 2 fluid ounces alternated with3b. Daconil Ultrex 82.5WDG 1.6 ounces 2.0 cde 1.0 def 0.0 c 0.7 cd 5.7 cdePhosphite fungicide programs4a. Chipco Signature 80WG 4 ounces + Chipco 26GT 2SC 2 fluid ounces alternated with4b. Chipco Signature 80WG 4 ounces + Daconil Ultrex 82.5WDG 1.6 ounces 0.7 de 0.3 ef 0.0 c 0.0 d 1.7 ghi5a. Resyst 45.8%SL 5 fluid ounces + Chipco 26GT 2SC 2 fluid ounces alternated with5b. Resyst 45.8% 5 fluid ounces + Daconil Ultrex 82.5 WDG 1.6 ounces 3.7 a-d 1.3 def 1.0 bc 1.0 cd 7.7 b-e6a. Vital 4.2L 6 fluid ounces + Chipco 26GT 2SC 2 fluid ounces alternated with6b. Vital 4.2L 6 fluid ounces + Concorde 82.5WDG 1.6 ounces 1.3 cde 1.0 def 0.7 bc 2.0 c 10.0 be7a. Alude 5.17L 5 fluid ounces + Chipco 26GT 2SC 2 fluid ounces alternated with7b. Alude 5.17L 5 fluid ounces + Daconil Ultrex 82.5WDG 1.6 ounces 3.0 b-e 1.3 def 0.0 c 1.0 cd 9.3 bcd*Applications <strong>of</strong> the two tank-mixes were alternated at two-week intervals between May 28 and July 23.†Means within the same column followed by the same letter are not significantly different.Table 1. Dollar spot control, 2003 test.78 GCMJuly 2005
tested provided good control <strong>of</strong> dollar spot(Table 1). Surprisingly, however, we did seedifferences among <strong>phosphite</strong> spray programsin dollar spot control. On most assessmentdates, there was no significant difference indollar spot control achieved by the <strong>phosphite</strong>fungicide programs. On later assessmentdates, small but statistically significant differencesemerged, with Resyst, Vital and Alude(treatments 5-7 in Table 1) all providing lesscontrol than the Chipco Signature program(treatment 4) on July 30, 2003.All <strong>phosphite</strong> fungicide programs tested(treatments 4-7 in Table 2) providedimproved turfgrass quality when compared tothe water-treated control (Table 2) and sometimesdid not differ from one another.However, in 2003, statistically significant differenceswere evident among the <strong>phosphite</strong>fungicide programs, with Resyst, Vital andAlude (treatments 5-7 in Table 2) providingsome reduction in turf quality compared tothe Chipco Signature program (treatment 4)in several assessments. During the testperiod, there were several sustained periods <strong>of</strong>rainfall deficit.2004 resultsDollar spot pressure was less intense in2004 than in 2003. As in 2003, all <strong>phosphite</strong>fungicide programs provided good control <strong>of</strong>dollar spot, with no significant differencesamong <strong>phosphite</strong> fungicide programs onmost assessment dates (Table 3). On July 26,RESEARCH2004, a slight but significant reduction in dollarspot control was observed in the Resyst andAlude programs (treatments 6 and 8, Table 3)as compared to several other <strong>phosphite</strong> fungicideprograms.No consistent, statistically significant differencesin turf quality were observed amongthe various <strong>phosphite</strong> fungicide programstested (treatments 4-9 in Table 4). However,only the Chipco Signature and ChipcoAliette programs (treatments 4 and 5) providedturf quality statistically higher than thewater-treated control (treatment 1) in allassessments. There was no difference in turfquality between the Chipco Signature program(treatment 4) and the Chipco Alietteprogram (treatments 5). The generally mild2003 TURF QUALITY Creeping Poa Overall turfbentgrass † annua † qualityTreatment and rate/1,000 square feet* July 2 July 22 June 25 July 10 June 22 Aug 5Experimental controls1. Water ND ND ND ND 4.7 e 3.3 hi2a. Chipco Signature 80WG 4 ounces + Chipco 26GT 2SC4 fluid ounces alternated with2b. Chipco Signature 80WG 4 ounces + Daconil Ultrex 82.5WDG 3.2 ounces ND ND ND ND 7.7 a 6.3 abc3a. Chipco 26GT 2SC 2 fluid ounces alternated with3b. Daconil Ultrex 82.5WDG 1.6 ounces ND ND ND ND 6.8 abc 4.7 efgPhosphite fungicide programs4a. Chipco Signature 80WG 4 ounces + Chipco 26 GT + 2SC2 fluid ounces alternated with4b. Chipco Signature 80WG 4 ounces + Daconil Ultrex 82.5WDG 1.6 ounces 8.0 a 8.0 a 7.3 a 6.3 a 7.5 a 5.3 b-e5a. Resyst 45.8%SL 5 fluid ounces + Chipco 26GT 2SC2 fluid ounces alternated with5b. Resyst 45-8%SL 5 fluid ounces + Daconil Ultrex 82.5WDG 1.6 ounces 7.3 a 6.3 b 5.3 b 4.3 b 6.3 bc 5.0 d-g6a. Vital 4.2L 6 fluid ounces + Chipco 26GT 2SC2 fluid ounces alternated with6b. Vital 4.2L 6 fluid ounces + Daconil Ultrex 82.5WDG 1.6 ounces 7.7 a 6.0 b 5.3 b 5.0 ab 5.7 cde 4.3 fgh7a. Alude 5.17L 5 fluid ounces + Chipco 26GT 2SC2 fluid ounces alternated with7b. Alude 5.17L 5 fluid ounces + Daconil Ultrex 82.5WDG 1.6 ounces 7.3 a 6.0 b 5.3 b 3.7 b 6.0 bcd 6.7 abNote. Turf quality was scored on a 1-9 scale, where 9 = excellent turf health. Dollar spot damage was excluded from turf-quality assessments.*Applications <strong>of</strong> the two tank-mixes were alternated at two-week intervals between May 28 and July 23.†ND, no data. Means within the same column followed by the same letter are not significantly different.Table 2. Turf quality, 2003 test.July 2005GCM 79
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Performance of selected phosphite fungicides on greens - GCSAA

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