Effects of Kaolin Clay (Surround wp) On Blueberry Plants

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 2000.

• 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, 2001.

• 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.