DEMONSTRATION: SPRAYING HOLLIES FOR
CONTROL AND PREVENTION OF FLORIDA WAX SCALE
Bastiaan M. Drees, Professor and Extension Entomologist


Florida wax scales have become a major landscape pest problem in the eastern
half of Texas and throughout the southeastern United States. Insecticidal management
involves monitoring holly shrubs for infestation. Once light infestations are detected,
insecticidal treatments may be needed to prevent further infestation. Control of scale on
heavily-infested plants using insecticides is difficult. Severe pruning can improve
coverage by both soil-applied systemic and foliar spray treatments and eliminate
unsightly scale-infested and honey dew covered foliage that will not be eliminated by
insecticide treatments. Foliar spray treatments are best applied soon after eggs hatch into
crawler stages that infest new plant growth. When crawlers settle and begin secreting
wax, they become visible and treatment should be initiated. One foliar spray treatment
with both contact and systemic insecticidal activity contains acephate. This
demonstration was conducted to assess the impact of a single foliar treatment using a
leaf-marking method for evaluation.


Figures 1, 2 and 3. Early instar wax scale on holly, leaves marked with scale numbers
prior to treatment.











Materials and Methods


Florida wax scale infested holly shrubs were selected for treatment, May 22, 2004.
On two shrubs designated to receive treatment, the number of early instar larvae were
counted on 14 and 18 leaves, respectively. The numbers of scales were marked onto each
leaf using a Sharpie® Permanent Marker pen. Another shrub was designated as the
untreated control and received no treatment, 39 leaves were examined and scale
numbers marked on each leaf. On June 2, 11 days following application, the number of
scales remaining on marked leaves were counted to determine the difference in their
numbers following treatment.

The treatment was applied before noon, May 22, 2004, using acephate (Orthene®
Turf, Tree and Ornamental Spray, 75% wettable powder) applied using 1/8 tsp./2 pints
water with about 1/8 teaspoon Palmolive dishsoap added as a surfactant.

Results and Discussion

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Foliar spray, using acephate (Orthene® Turf, Tree and Ornamental Spray, 75%
wettable powder) plus surfactant significantly reduced the number of early instar wax
scales per leaf (Table 1). Although scales did not disappear immediately, and no rain
events were experienced between pre- and post- treatment assessments, numbers were
reduced by 83% by the treatment. On untreated plants, scale numbers also declined by
53%, possibly due to sprinkler irrigation or other mortality factors affecting young,
developing scales. However, mean or average scale numbers on the post-treatment
evaluation were significantly different. Directions suggest making a second application
14 days after initial treatment to compensate of a longer period of crawler hatch.

Table 1. Mean number (+ Standard Deviation) of early instar wax scale nymphs per leaf
on holly shrubs following treatment with acephate 75% WP (Orthene® Turf, Tree and
Ornamental Spray), Brazos Co., Texas.

Untreated
Treated
Pre-treatment (May 22, 2004)
2.53 + 1.59 S. D. (n = 39)
3.00 + 1.44 S. D. (n = 32)
Post-treatment (June 2)
1.18* + 1.47 (n = 39)
0.50* + 1.16 (n = 32)
Percent change
53%
83%

* Post-Treatment means significantly different using Students t-test (t = -2.127; P =
0.037; d. f. = 69).

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