Evaluations of Mite Control in Apples, Urbana, Illinois,2000
Rick Weinzierl, Mark Hurt, and John T. Shaw

Summary

Plot Information and Methods

Location

University of Illinois Pell Farm, Urbana, Illinois.

Experimental Design

Randomized, complete block, 3 replications per treatment; 3 trees per rep per treatment

Agronomic Factors

Apple cultivars: 'Red Delicious'

Application dates: A single application was made on July 18, 2000.

Weather Information

See Appendix A, Table A.1 and Table A.2.

Method of Insecticide Application

Savey miticide was applied with an FMC-320 air blast sprayer calibrated to deliver 100 gpa at 100 psi and 3.0 mph.

Evaluations

Pretreatment counts were made on July 14, and two post-treatment counts were completed on July 24 (6 days after treatment) and August 1 (14 days after treatment). Mites were counted on 30 leaves per rep per treatment on each date.

Statistical Analysis

Mite counts were transformed (log n+1) before analysis by 2-way ANOVA, with significance set at P = 0.05. Means were separated using Fisher's Protected LSD (P = 0.05). Means listed in Table 3 are means of raw data.

Results and Discussion

This European red mite infestation had reached moderately high density when first discovered, and counts dropped in the course of the evaluation in the untreated check as well as the Savey-treated trees. Nonetheless, red mite populations dropped much more rapidly and to lower densities in the Savey treatments. On July 24, 6 days after treatment, predaceous mites (Neoseiulus fallacis) numbered 9.2, 5.0, and 3.3 per 100 leaves in the untreated, Savey low-rate, and Savey high-rate treatments, respectively. On August 1, predaceous mite counts were 15, 10, and 20 per 100 leaves in the untreated, Savey low-rate, and Savey high-rate plots, respectively. These counts suggest little or no direct toxicity of the Savey applications to these predators.

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