Abscission of Flowers and Fruits of the Apple 47 



Gardening take Notice, and therefore advise, that the thinning of Fruits be omitted, 



until it appears that this great Fall is over 



'Tis very easy to conceive, that if very dry Weather exhales 



away that Moisture which is necessary for those Formations [the internal parts of the 

 fruit, such as the kernels, stones, and the like], the Work will be imperfect, and con- 

 sequently the Fruits must perish. 



Several experiments to prevent the drop were attempted during Lang- 

 ley's time. The most successful method found was "to preserve them 

 [the trees] from the very hot Sun, from ten in the Morning until two or 

 three in the Afternoon" by means of a sail cloth. Langley, having tried 

 this method, recommends it to " the Practice of the Diligent and Curious." 

 He adds, " 'Tis very serviceable to give the Trees a gentle Refreshing 

 of Water, at the Time you begin to screen them from the Sun, which they 

 will freely imbibe, and [which] very much strengthens Nature in her 

 Productions." 



At the present time the weather is still in many cases held account- 

 able for the failure of blossoms to set fruit. Osterwalder (1907 a), for 

 example, cites the causes which the peasants of Switzerland hold accoimt- 

 able for the wholesale dropping of fruit. Among others, he mentions the 

 "dew rain" of the early morning, which occurs during blooming time 

 and subsequently; the strong mountain winds which prevail shortly after 

 blooming time; and the presence of "honey dew" on the leaves. This 

 honeydew, now known to be the result of aphid work, was formerly asso- 

 ciated with local climatic conditions. 



Hedrick (1908) has given renewed emphasis to the importance of 

 weather in fruit setting. He is of the opinion that unfavorable weather 

 during blossoming time is the predominating factor in the loss of fruit 

 crops. Besides mentioning the direct and obvious damage done by frost, 

 hail, wind, and the like, to buds, flowers, and fruits, this author points 

 out that rain, cloudiness, wind, and low temperatures during blossoming 

 time offer unfavorable conditions for pollination and subsequent 

 fertilization. 



Waite (1894) observed that many varieties of apples and pears are 

 self -sterile. Fruits resulting from cross-pollination were found to be larger 

 and finer specimens than those resulting from self-pollination. The 

 former contained large, plump seeds, and the latter, small and flattened 

 seeds. It was also noted that the ability of a tree to set fruit, either with 

 its own pollen or with that from another tree, was affected by its state 

 of nutrition and its general environment. 



Since Waite 's work, the need of cross-pollination to insure a set of 

 fruit has received considerable attention. While most of the writers or 

 workers on this question — among whom may be mentioned Hansen 

 (1894), Beach (1895), Budd (1896), Waugh (1896, 1901), Munson (1899), 



li 161 



