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Evaluations of Mite
Control in Apples, Urbana, Illinois,
2000 |
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Rick Weinzierl,
Mark Hurt, and John T. Shaw
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Summary |
A post-bloom application of Savey (hexythiazox)
miticide was evaluated during the 2000
crop season in apples. Savey, applied
once in mid July, reduced densities
of European red mite 85% to 97% in comparison
with the untreated control; its direct
impact on the predaceous mite Neoseiulus
fallacis seems to have been minimal.
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Plot Information and Methods
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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 date: A single
application was made on July 18, 2000.
Weather Information
See Appendix A, Tables
A.1, 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. |
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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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Table 10.1. |
European red mites (ERM) in Savey-treated
and untreated apples, Urbana, Illinois,
2000. |
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ERM / leaf
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Treatment
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14 July (3
days pre-treatment)1
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24 July (6
days post-treatment)1
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01 Aug (14
days post-treatment)1
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Savey 3 oz / A |
19.0 |
a |
1.0 |
b |
0.2 |
b |
Savey 3 oz / A |
14.1 |
a |
1.4 |
b |
0.1 |
b |
Untreated control |
17.7 |
a |
7.0 |
a |
3.1 |
a |
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1Means
in a column followed by the same letter
are not significantly different (P=0.05).
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