Effects of Kaolin Clay (Surround WP) On Blueberry Plants James D. Spiers, Frank B. Matta, Blair Sampson, John B. Braswell, Donna S. Marshall

Surround WP Demonstrated consistent control or suppression of almost all the major and minor apple insect pests. The Organic Materials Review Institute officially recognized Surround as “organic” in Surround actually increases net photosynthesis, and can provide secondary benefits to the trees’ overall health. Keeps the tree cool so that photosynthesis can continue longer into the afternoon on hot days, after untreated trees have already shut down because of heat stress.

Surround WP continued. Surround WP is a wettable powder which leaves a white, protective, powdery film on the surfaces of leaves, stems, and fruit. Deters insects in several ways. Tiny particles attach to insects, agitating and repelling them. Insects find the plant unrecognizable as a host.

Thrips (Frankliniella spp.) Hide within parts of flowers not easily penetrated by insecticides. Excessive feeding on floral buds, open flowers, or developing fruit can reduce yield by inducing premature fruit abortion. Color alone may attract some thrips species, but if UV reflectance is high, then anthophilous thrips are repelled from the surface of attractive colors.

Project Goals Determine effects of Surround WP on insect control (thrips) of rabbiteye blueberry plants. Determine the effects of kaolin on fruit set, development, and berry size when applied to southern highbush blueberry plants during early flower stages. Determine effects of kaolin on blueberry yield, quality, and plant growth. Determine the stage of development when kaolin clay could be the most beneficial to blueberry plants.

Study 1 - Effect of Surround WP on thrips population. Three rabbiteye blueberry cultivars (‘Delite’, ‘Tifblue’, and ‘Woodard’) were arranged in a Latin square design. Treatments consisted of sprayed and unsprayed plants. Sprayed plants were sprayed with Surround WP on 3 occasions: during bloom (March 7, 2001), post-bloom (April 20), and pre-harvest (May 17). Sticky traps were placed on the center plant in the middle of the canopy on the day of application. Traps were collected exactly 1 week following application. The number of thrips per trap was counted. Yield was collected and recorded from each plant that contained a sticky trap. Data was analyzed by ANOVA using SAS (1996).

Average number of thrips/trap during bloom stage.

Average number of thrips/trap during post-bloom stage.

Average number of thrips/trap during pre-harvest stage.

Effects of thrip control on yield

Results The number of thrips per trap was significantly reduced by the application of Surround WP. The differences in yield (kg/bush) was not significant for sprayed and unsprayed plants. Application of Surround WP did not affect pollination.

Study 2. Effects of Surround WP on bloom stage. Southern highbush blueberry plants (‘Cooper’) were arranged in a random complete block design consisting of 9 replications of 2 plants per replication. Treatments consisted of 1 application of Surround WP and no spray. Ten buds from each plant were rated according to the flower bud rating scale (1-7) with the goal of getting two of each rating 3-7 on each plant. Flower buds were rated 10 days following application and the number of flowers per bud was recorded. Fruit diameter was measured and the number of fruit per bud was recorded on 3 occasions. Data was analyzed by ANOVA using SAS (1996).

Flower Bud Development Stages

Effects of Surround WP on Fruit set and Development

Results The rate of development for the blooms sprayed with Surround WP was slower. The size of the fruit was smaller for the plants sprayed with Surround WP. The number of flowers/bud, berries present, and fruit picked was greater on the plants sprayed with Surround WP.

Study 3. Effects of time of application of Surround WP on ‘Magnolia’ blueberry plants. Four replications consisting of 3 plants per experimental block. The initial volume of the plant size was obtained prior to treatment. Treatments: pre-fruit (approx. 50% flowering), early fruit set, mid-maturity, approx. 2 weeks prior to harvest, and a control group which was not sprayed. Fruit was harvested from the middle plant in each block when ripe and yield was measured. Harvesting dates were May 14, May 23, May 31, and June 7, On each harvesting date the berries were measured for chemical analysis, compression, and turbidity (residue). Final volume of plant size was measured and growth was calculated.

Effects of application time of Surround on fruit characteristics

Average Yield for ‘Magnolia’ Blueberry Plants

Average volume (in.³) of growth for ‘Magnolia’ blueberry plants.

Results SS, TS, pH, and compression results were the same for each treatment. Residue was the same for control and pre- fruit treatments. The yield was greatest when applied before fruiting. Surround WP increased growth of ‘Magnolia’. The earlier Surround WP was applied to the plants the more growth was promoted.

Conclusion Surround WP can be used effectively to control thrips populations without affecting pollination. Surround WP can be used to enhance fruit set. Application of Surround WP before fruit set can increase yields without leaving significant residue on fruit. Application of Surround WP can promote growth of blueberry plants.