(F13) CORN (FIELD): Zea mays L., 'DK-6971' and 'Pioneer 3223' K. V. Tindall University of Idaho Twin Falls County rd 246 3 Ave. East Twin Falls, ID 83301 Phone: (208) 734-9590 Fax: (208) 733-9645 E-mail: email@example.com B. R. Leonard K. Emfinger P. Price Cutworms: Agrotis spp. Sugarcane beetle: Euetheola rugiceps (LeConte) Southern corn rootworm: Diabrotica undecimpunctata howardi (Barber) White grubs: Phyllophaga spp. The efficacy of two insecticide seed treatments, Gaucho Extra and Cruiser, were evaluated against soil insects in field corn at the Macon Ridge Research Station near Winnsboro, LA. Corn seed were planted into a Gigger-Gilbert silt loam soil (pH = 6.2, 1% organic matter) on 18 Mar and 15 Apr for tests one and two, respectively. Plots consisted of four rows centered on 40 inches and 35 ft in length. Treatments were replicated four times in a RCB design. All insecticides were applied as seed treatments with the exception of Lorsban which was applied at planting with a John Deere 7300 Series row crop planter and T-Banding attachments. Plots were evaluated during V1 to V4 plant growth stages for seeding injury by soil insects. Plant populations were recorded at the V6 growth stage. Grain yield was also measured with a mechanical harvester from the center two rows. Data were analyzed using ANOVA and means were separated according to DMRT (P = 0.05). In the first test, initial plant stand emergence was reduced below 15,000 plants/acre from birds feeding on seeds. However, all insecticide treatments of Gaucho Extra significantly reduced the number of insect-damaged plants compared to the non-treated control (Table 1). Plots treated with Gaucho Extra (0.96 and 1.25 mg [AI]/seed) had significantly higher plant stand counts and yields compared to that in the non-treated plots. All rates of Gaucho Extra were as effective as the standard, Lorsban, against soil insects. Plots treated with Cruiser (0.6 mg [AI]/seed) and Lorsban significantly reduced numbers of insect damaged plants compared to that in the non-treated plots (Table 2). Plant densities were higher in plots treated with Cruiser (0.4 and 0.6 mg [AI]/seed) and Lorsban than in non-treated plots. However, significant yield increases were only detected in the plots with Cruiser (0.6 mg [AI]/seed) and Lorsban. Table 1. Injured Treatment/ Rate corn seedlings Plant density Grain yield formulation mg (AI)/seed (no./70 ft) (no./acre) (bu/acre) Gaucho Extra 600FS 0.32 5.0b 10221ab 100bc Gaucho Extra 600FS 0.64 5.5b 9987ab 107abc Gaucho Extra 600FS 0.96 2.0bc 11341a 114ab Gaucho Extra 600FS 1.25 1.3c 13721a 124a Lorsban 15G 1.0 lb(AI)/acre 4.0bc 9847ab 104bc Untreated check -- 16.3a 7141b 91c P > F 0.0001 0.0395 0.0136 Means within columns followed by the same letter do not differ significantly (DMRT, P > 0.05). Cumulative injury across two weeks of sampling. Table 2. Injured Treatment/ Rate corn seedlings Plant density Grain yield formulation mg (AI)/seed (no./70 ft) (no./acre) (bu/acre) Cruiser 5FS 0.25 5.3a 22206b 119b Cruiser 5FS 0.4 2.8ab 25058a 122b Cruiser 5FS 0.6 1.8b 26087a 134a Lorsban 15G 1.0 lb(AI)/acre 1.0b 27255a 135a Untreated check -- 5.3a 20570b 112b P > F 0.0311 0.0011 0.0018 Means within columns followed by the same letter do not differ significantly (DMRT, P > 0.05). Cumulative injury across two weeks of sampling.
Arthropod Management Tests – Oxford University Press
Published: Jan 1, 2006