a dramatic effect on pollen germination. 



In summary, the application of captan dur- 

 ing bloom may create problems with pollen 

 germination, and therefore inhibit pollination. 

 Dodine also may be a problem, but appears to be 

 less toxic than captan. These results may ex- 

 plain why some orchards have had problems 

 with fruit set in recent years, when captan and 

 dodine have been used much more heavily than 

 in years when the EBDC fungicides were avail- 

 able, especially around bloom. The Sis and 

 Benlate or Topsin-M appear to be less toxic to 

 pollen. The safest route to take may be to avoid 

 applying any fungicide during good pollination 

 weather. If a fungicide must be used, then one 

 of the less toxic fungicides should be applied. 

 Finally, this area needs to be studied further, 

 more carefully relating fungicide application 



and fruit set. While the results from England 

 are highly suggestive, they are not well repli- 

 cated or conclusive. 



References 



Church, R. M., B. K Cooke, and R. R. Williams. 

 1983. Testing the toxicity of fungicides to 

 apple pollen. J. Hort. Sci. 58:161-163. 



Church, R. M., and R. R. Williams. 1977. The 

 toxicity to apple pollen of several fungicides as 

 demonstrated by in vivo and in vitro tech- 

 niques. J. Hort. Sci. 52:429-436. 



Watters, B. S. and S. R. Sturgeon. 1990. The 

 toxicity of some foliar nutrients and fungicides 

 to apple pollen cv. Golden Delicious. Tests of 

 agrochemicals and cultivars 11. Ann. Applied 

 Biol. 116(supplement):70-71. 



Fruit Notes, Fall, 1991 



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