-6- 



Grape groiTcrs in L'lassachusetts who might v/ant to try the mulch system for 

 grovdng grapes will have to adjust their fertilizer program according to the amount 

 and kind of mulch applied and to observations of plant response. 



Because of our short growing season tho delay in ripening caused by the mulch 

 system might be very serious on Concord and other varieties ripening with or later 

 than it, 



— Yif, J, Lord 



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EFFECT OF FROST UPON THE VIABILITY OF APPLE POLLEN 



Some fruit grovrers have wondered about the effect of the recent frost upon 

 the viability of apple pollen. The amount of injury to apple pollen at a given 

 lo\T temperature depends upon the variety and the condition of the bloom at the 

 time the frost occurred. It is generally stated that considerable pollen is still 

 viable at temperatures v>rhich kill the styles and stigmas. 



In a paper published in the Proceedings of the American Society of the Hort- 

 icultural Science in 1930^ W, E. Lommel and Laurenz Green reported on the effects 

 of frost upon the viability of apple pollen. The follov/ing are some excerpts 

 from that article. The minimum temperature was not knovra but "a relatively heavy 

 freeze occurred in the orchard v/here the apple trees were in varying stages of 

 blossoming, ranging from kO per cent full bloom in the case of Rome Beauty to 90 

 per cent v;ith Delicious, Considerable damage was done to the blossoms of which a 

 considerable percentage v/ere killed. Later many frost bands developed on the fruits. 



Pollen v/as taken from blossoms and buds at various stages of development and 

 showing different amounts of pistil and stamen injuries. The pollen was thoroughly 

 dried in the laboratory and germination tests were made in a 10 per cent sugar 

 solution, 11 and 12 days after the freeze. 



Unopened buds shovring no pistil injury gave a high percentage of viable pollen 

 in all varieties except Stayman Vfinesap,, Stayman Winesap produced practically no 

 viable pollen in any case. 



Unopened buds with dead pistils yielded high percentages of viable pollen in 

 Delicious, Grimes Golden, and Jonathan, Rome Beauty in this class shovjed less 

 than UO per cent viable pollen. Unopened buds of Delicious with dead pistils and 

 brovm anthers and filaments gave a high percentage of germinating pollen, Jonathan 

 pollen from blossoms of the same class contained only an occasional grain of ger- 

 minating pollen and all of these were low in vigor, 



Delicious was the only variety that produced even a fair percentage of viable 

 pollen from opened blossoms with dead pistils, Delicious pollen was injured veiy 

 little at the temperatures experienced even when the anthers and filaments v/ere 

 killed, Stayman Winesap produced practically no viable pollen even in uninjured 



