10 



Table 2. Effects of Promalin and Sevin on thinning, fruit size, 

 L/D ratio, and seed number of 'Richared Delicious' apples. 



Treatment ' 

 (ppm) 



Blossom 

 c lust er s 

 per cm 

 limb circ 



Fruit 



per 100 Fruit 

 per cm blossom Wt . L/D Seeds/ 

 limb circ. clusters (g) ratio fruit 



1. Check 12.6a- 



2 . Proma 1 in 2 5 + 



Glyodin 12.0a 



3. Promalin 25 + 



Glyod in + 



Sevin 12.4a 



4. Sevin 12.8a 



8.1a 

 3. 7b 



3.6b 

 6.6a 



70a 

 31b 



31b 



52a 



170ab .93b 5.0a 



185a 1.03a 4,8a 



146c 1.03a 2.5b 



156bc .94b 2.7b 



F.B. May 10, 1979. Promalin 25 ppm + 1 pt/lOO gal. of Glyodin applied 

 as a dilute spray on May 10, 1979. Sevin 1/2 Ib/lOO gal. applied 

 as 



dilute spray June 1, 1979 



Numbers in a column followed by 

 different at odds of 19 to 1. 



different letter are significantly 



However, the degree of thinning was not increased by the application 

 of Sevin about 20 days after bloom. Sevin alone did not cause thin- 

 ning. It is apparent that Sevin was taken into the trees because it 

 reduced seed number of the fruit, even though it caused no thinning. 

 The Promalin-Sevin combination appears to have reduced fruit size be- 

 low that of Promalin alone (Table 2), perhaps due to the reduction 

 of seed number. 



In another experiment, Promalin concentrations of 25 to 100 ppm 

 were applied at full bloom as dilute sprays to another group of 

 Delicious apple trees. Sevin was applied as a dilute spray 20 days 

 after full bloom on half the trees in each treatment. Promalin alone 

 at 25 ppm caused no thinning (Table 3). Promalin at this cone entra t ion- 

 plus-Glyodin tended to increase the thinning response but the differ- 

 ence was not significant. Promalin alone at both 50 and 100 ppm 

 caused excessive thinning. The application of Sevin on half of the 

 Promalin-treated trees caused no additional thinning, 

 that the thinning response to Sevin in 1979 was not j 

 that previously received an application of Promalin. 



drop was light and Sevin did reduce seed number. Therefore, under 

 different conditions thinning might have occurred. 



Thus, it appears 

 ;reater on trees 

 However , June 



