EVALUATION OF INSECTICIDES ON NON-TRANSGENIC AND TRANSGENIC B.t. COTTON CULTIVARS FOR IMPACT ON TOBACCO BUDWORM, APHIDS AND SPIDER MITES

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1 EVALUATION OF INSECTICIDES ON NON-TRANSGENIC AND TRANSGENIC B.t. COTTON CULTIVARS FOR IMPACT ON TOBACCO BUDWORM, APHIDS AND SPIDER MITES Texs Agriculturl Experiment Sttion, Nueces County, 2000 Roy D. Prker nd Stephen D. Livingston Extension Entomologist nd Extension Agronomist Corpus Christi, Texs SUMMARY: Tobcco budworm lrvl numbers were very low in ll DPL 33B (trnsgenic B.t.) Cotton tretments, nd in Trcer, Stewrd (.09 lb i/cre rte) nd Denim (.01 lb i/cre rte) treted DPL 5415 (non-trnsgenic) cotton. Only the Trcer tretment nd Denim (0.1 lb i/cre) on 3 Jul mintined dmged terminls in DPL 5415 t level tht ws not significntly different from the DPL 33B counts. These results were lso reflected in dmged squres, cterpillr lef feeding nd dmged bolls. Aphid numbers were greter in the Krte tretment nd lowest in the Leverge tretment. Denim t both rtes provided excellent spider mite control. Lint production ws dversely ffected by drought which ws compounded by lte plnting. Numericlly, the DPL 33B cultivr produced more lint for ech insecticide tretment compred to the corresponding DPL 5415 tretments. OBJECTIVES: The study ws comprison between cotton vriety geneticlly expressing cterpillr B.t. toxin nd non-trnsgenic vriety. The objectives were to (1) mesure cterpillr numbers nd dmge in vrieties, (2) compre insecticides for effectiveness nd (3) determine impct on cotton production. MATERIALS/METHODS: The experiment ws conducted on the Texs Agriculturl Experiment Sttion, Meney Annex, in Nueces County. Test vrieties were plnted 17 Apr 2000 in lternting 8-row plots nd then subdivided for insecticide tretment in order tht ech folir tretment ws pplied to 4 rows of DPL 5415 (non-trnsgenic) nd 4 rows of DPL 33B (trnsgenic B.t.) cotton. Insecticide tretments were rrnged in rndomized complete block design with 4 replictions nd plots were 50 ft in length with rows spced on 38-inch centers. Cotton vrieties were plnted t 56,000 seed/cre in soil with mrginl moisture. Totl rinfll during the production seson mounted to 4.84 inches with none fter 18 Jun. Due to the lte plnting dte, cotton production ws dversely ffected by the dry conditions. Fertilizer pplied ws Zn/cre. Trefln 4HFP (1 qt/cre) ws incorported for weed control on 9 Nov Insecticides were pplied to ll 8 rows in ech plot with self-propelled Lee Compny Spider Spryer Trc on 16, 22 nd 28 Jun in totl spry volume of 5.7 gp through two 8X hollow cone nozzles 1 row t 40 psi t 4 mph. Tretment effects were ssessed by (1) exmining 20 terminls/plot on 24 Jun nd 3 Jul for heliothine eggs, lrve nd dmge, (2) exmining 20 pproximtely ½ grown squres per plot on 24 Jun nd 3 Jul for cterpillr dmge, (3) ssigning visul cterpillr lef feeding score (1 = none observed up to 5 = 20% lef loss) on 2 dtes, (4) determining the number of cterpillr dmged bolls in 20 exmined on 1- Jul, (5) estimting verge phid numbers from 5 leves on 7 nd 10 Jul, (6) ssigning mite dmge rting (1 = no dmge to 5 = severe dmge) by exmining 5 leves per plot on 3 nd 10 Jul, (7) counting spider mites on 10 leves nd estimting % lef dmge from 10 leves per plot on 6 Jul nd, (8) hrvesting 10 ft row from one of the two center rows in ech 4 row plot on 4 Aug. Seed cotton ws ginned on 10-Sw Egle lbortory mchine.

2 RESULTS/DISCUSSION: All cterpillrs exmined on 24 Jun nd 3 Jul were tobcco budworm but occsionl beet rmyworms nd loopers were observed on ech inspection dte. Heliothine eggs, lrve, dmge to terminls, nd dmged squre dt re provided in Tble 1. Egg numbers were not sttisticlly different 2 dys fter the 2 nd tretment (24 Jun) but they were reltively low nd not evenly distributed in plots 5 dys fter the 3 rd tretment (3 Jul). Cterpillr numbers were very low in DPL 33B (trnsgenic B.t.) cotton nd in Trcer, Stewrd (.09 lb i/cre) nd Denim (.01 lb i/cre) treted DPL 5415 cotton. These counts were not sttisticlly different from the DPL 33B results. Only the Trcer tretment nd Denim (.01 lb i/cre) on 3 Jul mintined dmged terminls in DPL 5415 to level not significntly different from DPL 33B counts. These results were lso reflected in dmged squres with the ddition of Stewrd t the.09 lb i/cre rte included in the lowest dmge ctegory. Cterpillr lef feeding dmge rting ws reduced compred with untreted cotton by ll tretment except for Krte nd Leverge (Tble 2). Trcer, Stewrd nd Denim treted DPL 5415 cotton sustined significntly less dmge to bolls by cterpillrs compred to the Krte, Leverge nd untreted plots. Aphid numbers were greter in the Krte tretments nd lowest in the Leverge tretment (Tble 3). Denim t both rtes provided excellent spider mite control (Tbles 3 nd 4). The Krte spider mite dmge rting ws not sttisticlly different from Denim. Boll nd lint production dt re provided in Tble 5. Numericlly, the DPL 33B cultivr produced more lint for ech insecticide tretment compred to the corresponding DPL 5415 tretments. ACKNOWLEDGMENTS: Apprecition is expressed to Zenec, Byer, DuPont, Novrtis nd Monsnto compnies for their support.

3 Tble 1. Cterpillr infesttion nd dmge in non-trnsgenic (DPL 5415) nd trnsgenic B.t. (DPL 33B) cotton cultivrs treted with vrious insecticides, Texs Agriculturl Experiment Sttion, Nueces County, TX, Number/100 terminls Rte lb eggs lrve dmge % dmged squres i/cre 6/24 7/3 6/24 7/3 6/24 7/3 6/24 7/ DPL 5415 (non-trnsgenic) Krte 1E cd b 51.3 b 3.8 b 16.3 b Leverge 2.75E b 13.8 bc 16.3 b 38.8 b b 12.5 bc Trcer 4SC b 1.3 e 0.0 d 10.0 cd 5.0 ef 1.3 bc 0.0 g Stewrd 1.25SC b 20.0 b 6.3 c 33.8 bc 45.0 bc 3.8 b 7.5 cde Stewrd 1.25SC b 6.3 de 2.5 cd 25.0 bc 22.5 d 1.3 bc 6.3 def Denim 0.16EC b 1.3 e 6.3 c 23.8 bc 38.8 c 2.5 bc 11.3 bcd Denim 0.16EC b 3.8 e 2.5 cd 22.5 bc 15.0 de 1.3 bc 2.5 efg Untreted b b DPL 33B (trnsgenic B.t.) Krte 1E b 0 e 0 d 1.3 d 7.5 ef 0 c 1.3 fg Leverge 2.75E b 0 e 0 d 0.0 d 3.8 f 0 c 1.3 fg Trcer 4SC b 0 e 0 d 1.3 d 1.3 f 0 c 0 g Stewrd 1.25SC b 0 e 0 d 1.3 d 3.8 f 0 c 0 g Stewrd 1.25SC b 0 e 0 d 0.0 d 3.8 f 0 c 0 g Denim 0.16EC b 0 e 0 d 1.3 d 6.3 ef 0 c 0 g Denim 0.16EC b 0 e 0 d 0.0 d 5.0 ef 0 c 0 g Untreted b 0 e 0 d 1.3 d 10.0 ef 0 c 0 g LSD (P = 0.05) NS P > F

4 Tble 2. Cterpillr lef feeding rting nd dmged bolls in non-trnsgenic (DPL 5415) nd trnsgenic B.t. (DPL 33B) cotton cultivrs treted with vrious insecticides, Texs Agriculturl Experiment Sttion, Nueces County, TX, b Rte lb i/cre Cterpillr lef feeding rting b 7/3 7/10 % dmged bolls (7/10) DPL 5415 (non-trnsgenic) Krte 1E b 2.50 b 6.3 b Leverge 2.75E Trcer 4SC e 1.00 c 0.0 c Stewrd 1.25SC de 1.00 c 2.3 c Stewrd 1.25SC de 1.00 c 2.3 c Denim 0.16EC e 1.00 c 2.3 c Denim 0.16EC e 1.00 c 0.0 c Untreted 2.25 bc 2.50 b 8.8 b DPL 33B (trnsgenic B.t.) Krte 1E cd 1.25 c 0 c Leverge 2.75E e 1.00 c 0 c Trcer 4SC e 1.00 c 0 c Stewrd 1.25SC e 1.00 c 0 c Stewrd 1.25SC e 1.00 c 0 c Denim 0.16EC e 1.00 c 0 c Denim 0.16EC e 1.00 c 1.3 c Untreted 1.50 de 1.00 c 0 c LSD (P = 0.05) P > F Insecticides were pplied 16, 22 nd 28 Jun in totl spry volume of 5.7 gp through 8x hollowcone nozzles t 40 psi t 4 mph. Cterpillr lef feeding rtings rnge from 1 = none observed up to 5 = 20% lef loss.

5 Tble 3. Aphid nd mite dmge in non-trnsgenic (DPL 5415) nd trnsgenic B.t. (DPL 33B) cotton cultivrs treted with vrious insecticides, Texs Agriculturl Experiment Sttion, Nueces County, TX, b c Rte lb i/cre Aphids/lef Mite d. rting b 7/3 7/10 7/3 7/ DPL 5415 (non-trnsgenic) Krte 1E c 1.3 d Leverge 2.75E g 0 b 3.3 b 2.8b Trcer 4SC fg 0 b 4.0 b 3.0 b Stewrd 1.25SC bc 0 b 3.5 b 3.0 b Stewrd 1.25SC bcd 0 b b Denim 0.16EC fg 0 b 1.0 c 1.0 d Denim 0.16EC efg 0 b 1.0 c 1.0 d Untreted 10.0 cdef 0 b 3.8 b DPL 33B (trnsgenic B.t.) Krte 1E b 0 b 1.3 c 1.5 cd Leverge 2.75E g 0 b 3.3 b 2.3 bc Trcer 4SC fg 0 b 3.8 b 3.5 Stewrd 1.25SC bc 0.3 b Stewrd 1.25SC bcde 0 b 3.8 b 2.8 b Denim 0.16EC fg 0 b 1.0 c 1.3 d Denim 0.16EC defg 0 b 1.3 c 1.0 d Untreted 7.3 defg 0 b LSD (P = 0.05) c P > F Insecticides were pplied 16, 22 nd 28 Jun in totl spry volume of 5.7 gp through 8x hollowcone nozzles t 40 psi t 4 mph. Mite dmge rtings rnge from 1 = no dmge to 5 = severe dmge. The P > F is bsed on trnsformed, [squre root (x + 1)], dt vlues; it is inpproprite to list LSD vlues bsed on trnsformed dt.

6 Tble 4. Spider mite number nd percentge lef dmge in DPL 5415 cotton treted with vrious insecticides for cterpillrs, Texs Agriculturl Experiment Sttion, Nueces County, TX, Spider mites b Rte lb i/cre No./10 leves % lef dmge c Leverge 2.75E Trcer 4SC b Denim 0.16EC c 0.22 b Denim 0.16EC c 0.88 b Untreted 38.8 b LSD (P = 0.05) b c P > F Insecticides were pplied 16, 22 nd 28 Jun in totl spry volume of 5.7 gp through 8x hollowcone nozzles t 40 psi t 5 mph. The spider mite popultion hd declined significntly by this evlution dte (6 Jul). Lef dmge is % of the lef dmged by spider mite feeding bsed on n verge of 10 leves/plot.

7 Tble 5. Cotton production in non-trnsgenic (DPL 5415) nd trnsgenic B.t. (DPL 33B) cotton cultivr treted with vrious insecticides, Texs Agriculturl Experiment Sttion, Nueces County, TX, Rte lb i/cre Bolls (1000's/cre) Green Hrvested % lint Lint lb per cre DPL 5415 (non-trnsgenic) Krte 1E b 104 ef 38.5 b 265 e Leverge 2.75E f 38.2 b 257 e Trcer 4SC c 130 b-f 38.2 b 304 de Stewrd 1.25SC b-e 148 -e 39.1 b 357 -e Stewrd 1.25SC b-f 145 b-f 38.7 b 337 b-e Denim 0.16EC c-f 161 -d 38.8 b 386 -d Denim 0.16EC b-d 116 d-f cde Untreted d 121 c-f 37.7 b 311 cde DPL 33B (trnsgenic B.t.) Krte 1E ef 162 -c 35.3 c 365 -e Leverge 2.75E c-f 174 b 35.2 c 406 -d Trcer 4SC c-f 171 b 35.0 c 361 -e Stewrd 1.25SC ef 170 b 35.6 c 440 b Stewrd 1.25SC d-f 166 -c 35.4 c 366 -e Denim 0.16EC f 175 b 35.4 c 455 Denim 0.16EC f c 417 bc Untreted 13.8 c-f 154 -d 35.7 c 359 -e LSD (P = 0.05) P > F Insecticides were pplied 16, 22 nd 28 Jun in totl spry volume of 5.7 gp through 8x hollowcone nozzles t 40 psi t 4 mph.