7. Cabbage / AARS / Lepidoptera Foliar Trial

Transcription

1 76 7. Cabbage / AARS / Lepidoptera Foliar Trial Field applications of Venerate XC for the control of damaging lepidopteran pests on cabbage Arlington Agricultural Research Station Arlington, Wisconsin, USA ºN, ºW Crop: Cabbage, Brassica oleracea cv. Katlin Treatments: foliar spray programs Targets: 1. Imported cabbageworm, Pieris rapae. Cabbage looper, Trichoplusia ni 3. Diamondback moth, Plutella xylostella Purpose The purpose of this experiment was to evaluate the performance of Venerate XC and two commercial standards (Exirel and Bigade) when applied as foliar sprays for the control of common lepidopteran pests (Imported cabbageworm, Pieris rapae, Cabbage looper, Trichoplusia ni, and Diamondback moth, Plutella xylostella) on cabbage (Brassica oleracea cv. Katlin ). Materials and Methods Site. This experiment was conducted at the Arlington Agricultural Research Station (AARS),.5 miles southeast of Arlington, WI on a loamy sand soil in 17 ( , ). Experimental Design. Four replicates of foliar treatments and 1 untreated control were arranged in a randomized complete block design. Cabbage, Brassica oleracea cv. Katlin transplants were planted on June 1. Plants were spaced 18 in. apart within rows. Rows were spaced 3 ft. apart. Two-row plots were 6 ft. wide by ft. long and were separated by one untreated guard row. No alleys separated replications. Treatments. Treatments consisted of the commercial standards Exirel and Brigade, the product of interest Venerate XC in two rates, and an untreated control. All treatments were applied as foliar sprays on July 13 and July 7. See Table 1 for additional details. Treatments were applied with a CO - pressurized backpack sprayer operating at 3 psi, with a 6 boom equipped with Tee Jet XR8VS flatfan nozzles spaced 18 apart, delivering. gpa while travelling at 3.5 ft./sec. All plots were maintained according to standard commercial management practices. Evaluation. Populations of each of the three target lepidopteran pests were assessed. Immature life stages of Imported Cabbage Worm, Pieris rapae (ICW), Cabbage Looper, Trichoplusia ni, and diamondback moth, Plutella xylostella (DBM), were assessed by counting the number of larvae per plant on 5 destructively sampled, randomly selected plants in each plot. Two pre-treatment counts were performed, on July 6 and 11, on 8 plots randomly selected from the entire field. Post-treatment counts

2 Carrot / HARS / Aster Leafhopper Seed Treatment Trial 77 were performed on July 17, 1, and 6 (, 8, and 13 days after first application), and on Aug, 7, and 15 (6, 11, and 19 days after second application). See Table for a calendar of spray and evaluation dates. Here we report insect counts on Aug (6 days after second application) because the highest insect counts occurred on this date and so differences in treatment performance would be most apparent (Table 3). Additionally, we report the cumulative insect count for each insect and treatment including all posttreatment count dates (Table ). Insect counts are also reported graphically as counts over time for Imported Cabbage Worm (Figure 1), Cabbage Looper (Figure ), and Diamondback Moth (Figure 3). Plant Health. Plant health and vigor was normal throughout the course of this experiment. No signs of phytotoxicity were observed. Data Analysis. All statistical analyses were performed in JMP version 13. (The SAS Institute, Cary, NC). Insect counts were log transformed prior to analysis [log( +1)]. Overall treatment effects were determined by analysis of variance, incorporating both block and treatment effects. Means

3 Carrot / HARS / Aster Leafhopper Seed Treatment Trial 78 Table 1. Treatments Trt Products Form App. Rate Adjuvant Rate 1 Exirel.83 SC fl oz/a Activator 9.5 % v/v 1.5 fl oz/a Activator 9.5 % v/v Brigade EC 1 6. fl oz/a Activator 9.5 % v/v 5 fl oz/a Activator 9.5 % v/v 3 Venerate XC 9.6 SL 1 1 qt/a NuFilm P.5 % v/v 1 qt/a NuFilm P.5 % v/v Venerate XC 9.6 SL 1 qt/a NuFilm P.5 % v/v 1 qt/a NuFilm P.5 % v/v 5 Control Application 1 delivered via foliar spray on July 13; application delivered on July 7. Table. Trial Calendar Date Day Week Events 1-Jun 1 1 Planting 6-Jul 36 6 Pre-count 11-Jul 1 6 Pre-count 13-Jul 3 7 First application 17-Jul 7 7 Insect counts 1-Jul 51 8 Insect counts 6-Jul 56 8 Insect counts 7-Jul 57 9 Second application -Aug 63 9 Insect counts 7-Aug 68 1 Insect counts 15-Aug Insect counts

4 Carrot / HARS / Aster Leafhopper Seed Treatment Trial 79 Table 3. Insect Counts, Aug (diagnostic date) Trt Product ICW Loopers DBM 1 Exirel 1. ±.9 ab.85 ±.3 ab 1.35 ±.7 a Brigade. ±.8 a.3 ±.8 a 1.35 ±.97 a 3 Venerate XC (L).9 ±.38 ab 1.5 ±.8.b 5.7 ± 1.95.b Venerate XC (H) 3.8 ± 3.5.b.5 ±.57.b 7.7 ±.3.b 5 Control. ±.6.b 3.3 ± 1.78.b 1. ± 5.8.b P<.5 P<.1 P<.1 Insect counts (larvae / plant) are presented as means ± standard deviations. Means followed by same letter are not significantly different (Tukey s HSD, Table. Insect Counts, Cumulative (excluding pre-count) Trt Product ICW Loopers DBM 1 Exirel 1.85 ±.96.b 1.5 ±.6.b.15 ±.3 a Brigade.5 ±.3 a. ±.3 a.5 ±.9 a 3 Venerate XC (L) 6.15 ±.5..c 3. ± 1.19.bc ±.73.b Venerate XC (H) 9.8 ± 5.5..c 5.3 ± 1.6..c 16. ±.99.b 5 Control 1.65 ± 1.8..c 5. ±.7..c ± 7.16.b P<.1 P<.1 P<.1 Insect counts (larvae / plant) are presented as means ± standard deviations. Means followed by same letter are not significantly different (Tukey s HSD, Figure 1. Imported Cabbageworm Counts 5 Imported Cabbageworm Counts Jul 8-Jul 15-Jul -Jul 9-Jul 5-Aug 1-Aug 19-Aug

5 Carrot / HARS / Aster Leafhopper Seed Treatment Trial 8 Figure. Cabbage Looper Counts Cabbage Looper Counts Jul 8-Jul 15-Jul -Jul 9-Jul 5-Aug 1-Aug 19-Aug Figure 3. Diamondback Moth Counts 1 Diamondback Moth Counts Jul 8-Jul 15-Jul -Jul 9-Jul 5-Aug 1-Aug 19-Aug