Can Surround™ Be Applied 

 Successfully with a Back-pack 

 Sprayer to Control Plum Curculio? 



Ronald Prokopy 



Tiickaway Farm, Conway, Massachusetts 



In the preceding article, information was presented on 

 the effectiveness of kaolin clay (Surround™) in controlling 

 plum curculio (PC) when applied by a mist blower to apple 

 trees on M.26 rootstock at the Horticultural Research Cen- 

 ter. Good though not excellent control was obtained using 

 four applications 10 days apart. In the summer 1999 issue 

 of Fruit Notes, we reported results of a 1999 trial in which 

 Surround was applied twice against PC to M.26 trees using 

 a Solo™ motorized back-pack sprayer. That study occurred 

 in my small orchard of scab-resistant cultivars in Conway. 

 Again, control of PC was good though not excellent. 



Here, I report results of a 2000 trial evaluating effec- 

 tiveness of Surround applied against PC in my orchard us- 

 ing the Solo sprayer. 



Materials & Methods 



The trial was carried out using six rows of Liberty apple 

 trees, each with five trees per row. Every other row was 

 sprayed tliree times with Surround: May 16 (petal fall). May 

 25 and June 6. Surround was applied at the rec- 

 ommended rate of 50 pounds per acre. Remain- 

 ing rows were sprayed on these same dates with 

 phosmet at 3 pounds of 70 WP per acre. After 

 June 6, no insecticides were applied to any trees 

 in the orchard. Four apple trees about 200 yards 

 away did not receive any insecticide and served 

 as indicators of PC pressure in the area. At har- 

 vest, one-sixth of the fruit (approximately 70 

 fruit) on each tree were sampled for PC 

 egglaying scars. 



received a large amount of PC injury, but these trees were of 

 different (unknown) cultivars than the Liberty trees in the 

 orchard. Approximately 12 inches of rain fell between May 

 15 and June 30 (the approximate end of the PC season), 

 which might have compromised the residual effectiveness 

 of Surround to a greater extent than that of phosmet. 



Remarks & Conclusion 



I experienced little difficulty in mixing the 2000 ver- 

 sion of Surround WP in a small amount of water and intro- 

 ducing the mixture as a slurry into the 3-gallon tank of the 

 sprayer. Maintaining adequate mixing of Surround with 

 water did require me to jounce the sprayer frequently, how- 

 ever. This was not kind to my back. To attain the very 

 thorough coverage needed for Surround to be effective in 

 controlling PC on trees 10 feet tall required 0.6 gallons of 

 mixture per tree per application. Effective application of 

 phosmet required only 0.25 gallons of mixture per tree, less 

 than half as much. This resulted in more frequent filling of 



Results 



Results (Table 1) show that three sprays of 

 Surround were much less effective than three 

 sprays of phosmet in controlling PC in my or- 

 chard. Untreated trees about 200 yards away 



Table 1, Percent apples infested by plum curculio adults 

 in coininercial orchard trees receivmg three applications 

 of Surround or phosmet, Conway, MA, 2000. 



Treatment 



Number of trees Injured apples (%) 



Sunound 



Phosmet 



Untreated* 



14 

 15 

 4 



15.5 

 2.3 

 91.0 



*Data from sampled fruit of unsprayed trees of unknown 

 cultivar about 200 yards from the orchard trees. 



28 



Fruit Notes, Volume 65, 2000 



