Trget Spot: Potentil Impcts on Tennessee Cotton Hether M. Kelly Field Crops Plnt Pthologist UT-WTREC, Jckson, TN
Trget Spot/ Corynespor lef spot First ppers on lower leves fter cnopy closure Defolites bottom cnopy nd in severe cses middle nd upper cnopy Moisture nd het driven (Corynespor cssiicol)
Fctors tht cn increse Trget Spot risk: No- or strip-till cotton fields tht re cotton followed by cotton Frequent showers nd/or irrigtion High nitrogen fertility levels High-yielding vrieties re most effected
2014 Regionl Tril Sttes involved: Vigini*, Louisn*, Florid*, Georgi*, Albm, Mississippi, nd Tennessee 5 tretments Hedline SC @ 6 fl oz/a (pyrclostrobin) Topgurd @ 7 fl oz/a (flutrifol) Prixor @ 4 fl oz/a (pyrclostrobin + fluxpyroxd) Qudris 2.08 SC @ 6 fl oz/ A (zoxystrobin) 2 ppliction timings First week of bloom First week of bloom followed by second ppliction 2 weeks lter 2 vrieties Phytogen 499 DetlPine 1137
Dt collection Disese onset Biweekly rtings of severity or incidence nd defolition Yield Loction Plnting dte 1st fungicide ppliction Disese onset Mx defolition, % VA 5/20 7/22 9/1 50 LA 5/23 7/17 7/24 55 FL 6/4 8/6 8/25 50 GA 6/24 8/28 9/1 40
Disese differed between vrieties Disese severity ws generlly higher on PHY499 thn on DP1137, but PHY499 yielded consistently higher 100 Corynespor Finl Severity 100 Corynespor Finl Defolition Percent Severity 80 60 40 20 Percent Defolition 80 60 40 20 0 0 PHY499 DP1137
Fungicide by timing interction (GA) Cotton seed yield (lbs/a) 3000 2500 2000 1500 1000 500 0 1 Spry 2 Sprys * Control Hedline Prixor Qudris Topgurd Hedline (2 Sprys) is significntly different [p < 0.05]
Regionl Tril Conclusions Trget spot onset, severity, nd defolition vried mong loctions Defolition nd severity ws generlly higher on Phytogen 499, but it consistently yielded higher Fungicide pplictions did not impct yields t VA, LA, nd FL loctions Only the Attpulugus, GA loction disese nd fungicide ppliction hd significnt impct on yield 2 pplictions of Hedline t 6 fl oz/a
2014 TN Trils Conducted in Jckson t the WTREC Plnt My 12, 2014 Evluted Hedline t 6 fl oz/a t single nd multiple ppliction timings on Phytogen499 nd DeltPine1321 One spry t 1 st week of bloom (7/18), 3 rd week of bloom (8/1), or 5 th week of bloom (8/19) Two sprys 3 rd week of bloom nd 5 th week of bloom Disese onset occurred on August 15 Some plots rted up to 65% defolition (47% verge) Additionl tril looked t single nd double pplictions of Prixor nd single ppliction of Qudris
DeltPine 1321 B2RF 3rd + 5th wk of bloom % Trget Spot % Defolition P=0.0001 P=0.0001 c c 5th wk of bloom bc b 3rd wk of bloom b b 1st wk of bloom b b Nontreted check 0 5 10 15 20 25 30
DeltPine 1321 B2RF Turn out (%) P=0.04 3rd + 5th wk of bloom c 5th wk of bloom bc 3rd wk of bloom bc 1st wk of bloom Nontreted check bc 42.4 42.6 42.8 43 43.2 43.4
DeltPine 1321 B2RF Uniformity Index (%) P=0.032 3rd + 5th wk of bloom 5th wk of bloom b 3rd wk of bloom bc 1st wk of bloom bc Nontreted check c 84 84.5 85 85.5 86
DeltPine 1321 B2RF Lint P=0.76 3rd + 5th wk of bloom 1,846 5th wk of bloom 1,794 3rd wk of bloom 1,757 1st wk of bloom Nontreted check 1,804 1,827 1700 1750 1800 1850 1900
Phytogen 499 WRF 3rd + 5th wk of bloom % Trget Spot % Defolition P=0.0001 P=0.0001 c c 5th wk of bloom b b 3rd wk of bloom b 1st wk of bloom Nontreted check 0 10 20 30 40 50 60
Phytogen 499 WRF Lint P=0.135 3rd + 5th wk of bloom 2,178 5th wk of bloom 3rd wk of bloom 1st wk of bloom Nontreted check 2,083 2,024 2,050 1,967 1800 1900 2000 2100 2200
Additionl tril on Phytogen499 % Trget Spot % Defolition P=0.0001 P=0.0001 HEADLINE SC + HEADLINE SC b c PRIAXOR + HEADLINE bc d HEADLINE SC + PRIAXOR cd d PRIAXOR + PRIAXOR d cd QUADRIS PRIAXOR HEADLINE SC CHECK b b 0 20 40 60
Additionl tril on Phytogen499 Lint P=0.0585 HEADLINE SC + HEADLINE SC PRIAXOR + HEADLINE HEADLINE SC + PRIAXOR PRIAXOR + PRIAXOR QUADRIS PRIAXOR HEADLINE SC CHECK c b b bc b b bc 1800 1900 2000 2100 2200
Preliminry Conclusions for TN Phytogen 499 hd higher disese severity, defolition nd yield thn DeltPine 1321 Fungicide pplictions t 3 rd nd 5 th week of bloom reduced disese, defolition, nd yield loss Hedline SC t 6 fl oz/a, Prixor t 4 fl oz/a, nd Qudris t 6 fl oz/a cn provide protection from trget spot Very high disese pressure (high defolition) will significnt yield losses possibly occur Continued reserch on products nd ppliction timing will provide better informtion on best mngement options
QUESTIONS/COMMENTS Thnks for your ttention! Hether Kelly youngkelly@utk.edu 731-425-4713