October 16, all fruit remaining on the drop trees were 

 harvested and counted. Cumulative drop per tree was then 

 calculated. 



Results 



rating (Table 2). 

 The only effect 

 simulated rain had 

 on fruit quality pa- 

 rameters was that 

 the percent of fruit 

 in the US Extra 

 Fancy category was 

 slightly lowered 

 when trees were 

 washed one hour 

 after ReTain appli- 

 cation. As ex- 

 pected, the major 

 AVG effect was a 

 reduction in red 

 color and an in- 

 crease in fruit flesh 

 firmness. 



AVG signifi- 

 cantly retarded 

 preharvest drop 

 compared with the 

 control (Figure 2). 

 This response was 

 evident on the first 

 date dropped fruit 

 were collected, and 

 it extended through 

 the entire drop- 

 evaluation period. 

 Simulated rain did not reduce the effects of ReTain on 

 preharvest drop, since at no time during the drop pickup 

 period did any washed trees that received ReTain have more 

 dropped fruit under them (percent of total) than unwashed 

 trees that also received ReTain. 



AVG applied in 1992 significantly increased flesh 

 firmness, and reduced soluble solids, red color develop- 

 ment, and starch iodine rating (Table 1). Simulated rain 

 following application modified the AVG effect. Soluble 

 solids were restored to the levels of the control fruit and red 

 color retardation was reduced, whereas flesh firmness and 

 starch rating were not affected. AVG resulted in a greater 

 reduction in red color development at the early harvest than 

 at the later harvests (data not shown). 



All AVG treatments applied in 1992 significantly 

 and comparably retarded preharvest drop for the first 6 

 weeks after application (Figure 1). At 7 weeks after 

 application and later, the effectiveness of AVG was 

 significantly diminished on trees that were washed to 

 simulate a soaking rain. 



AVG applied in 2000 significantly increased fruit flesh 

 firmness, while reducing red color, the percent of fruit that 

 were judged to meet the US Extra Fancy grade, and starch 



Discussion 



The purpose of these experiments was to determine if 

 the performance of ReTain would be altered by subjecting 

 trees to simulated rain at intervals after application. The 

 conditions of application and the contents of the spray used 

 were quite different in the two years. The experiment done 

 in 1992 used AVG technical powder formulated for testing 

 AVG. It was applied to the drip point with a hand gun, and 

 no surfactant was used. The experiment done in 2000 

 mimicked a commercial application of AVG as the 

 commercial ReTain formulation was used, it was applied 

 according to label directions, and the application was made 

 using a commercial airblast sprayer. Further, the spray 

 contained 0.1% Silwet surfactant, a label-recommended 

 surfactant, at a recommended concentration. Clearly, there 

 were differences in response to the simulated rain in the two 

 years. In 1992, washing trees, even as much as 8 hours after 



Fruit Notes, Volume 65, 2000 



59 



