Gowan Report 2007

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2007 Corn Spider Mite Miticide Trial – Montrose, CO

Bob Hammon & Melissa Franklin, Colorado State University Extension, Tri River Area, Grand Junction, CO, bob.hammon@mesacounty.us

Objective: Evaluate Onager 1E at 3 rates, ground or aerially applied, for Banks grass mite control in field corn. Treatments are listed in Table 1.

Cooperator/Plot location:Diamond F Cattle & Farm, 14231 6100 Rd, Montrose, CO 81401.


Figure 1. Aerial and ground application of treatments.

Plot layout: Treatments were applied in strips. The ground application was 80 ft wide, aerial applications were 74 ft wide. Sampling was done 50, 100, 150 & 200 paces into the center of the strips.

Ground Application: 9 July 2007; Fedler Spraying Service, Delta, CO; Hagie 2101 Sprayer with 80 ft boom equipped with drop nozzles. Application rate 20 gal/A.

Aerial Application: 11 July 2007, Olathe Spray Service, Olathe, CO. Applied at 5 gal/A with AT402B aircraft with CP03 nozzles, 0.172 orifice, 30° deflection angle and 30 PSI boom pressure. Sprays were applied half boom, with the overlap positioned in the center of the plot (Figure 1).

Sampling: Five leaves (waist level) were chosen from each plot on each sample date. Mites and eggs were brushed from the leaves onto round glass slides with a Leedom Engineering mite brushing machine.

Results: All treatments had lower mite and egg counts than the untreated control. Counts in the Onager 10 oz/A aerial treatments tended to be greater than those in the Onager 8 oz/A ground or Onager 12 oz/A aerial treatments although differences were not always significant. Mite populations were increasing in Onager 12 oz/A and Comite plots in late August.

Table 1. Mite and egg counts. Data was log (X + 1) transformed before AOV. Actual means are shown. Means within a column followed by the same letter are not significantly different (LSD P<0.05).