BULLETIN 197. 



GRAPE CULTURE IN CALIFORNIA. 



155 



Swabbing with lime, sulfate of iron, and other antiseptics has proven 

 useless. 



Couture of Muscats. The Muscat of Alexandria, from which the 

 bulk of our raisins is made, has a. tendency to drop its blossoms without 

 setting. This trouble is usually known in California by the French 

 term of "coulure," which may be translated "dropping." The first 

 crop is particularly subject to this defect, which is often so serious 

 that a large part and sometimes the whole of the first crop is lost. 



The trouble has been investigated during the last twenty-five years 

 by a large number of observers, and various causes assigned. Among 

 these causes may be mentioned unfavorable weather, improper prun- 

 ing, fungous attacks, unsuitable or exhausted soil. These causes and 

 others may intensify the 

 trouble, but the primary and 

 essential cause has lately 

 been demonstrated by P. 

 Viala and P. Pacottet, and 

 published in the "Revue 

 de Viticulture." 1 



According to these investi- 

 gations the cause of the 

 dropping lies in the peculiar 

 structure of the flower itself. 



The flowers of most culti- 

 vated varieties of grapes are 

 what the botanist calls * ' per- 

 fect." That is, each flower has the two elements which are necessary 

 for the development of the perfect fruit. These elements are the pollen 

 contained in the anthers and the ovules contained in the pistil. Unless 

 the ovules are fertilized by normal pollen the pistil will not develop 

 into a normal grape berry. 



There are several defects in the Muscat flower which make this 

 necessary pollination more uncertain than with most varieties, and it 

 is only under the most favorable conditions that the ovules are prop- 

 erly fertilized. 



In the first place, owing to the shortness of the filaments supporting 

 the anthers, the position of the pollen is such that it may all fall off 

 without reaching the stigma, which is a part of the pistil through 

 which the pollen tube obtains access to the ovule. 



In the second place, the pollen is not powdery as with most vines, 

 but waxy and with a tendency to cohere in masses. This renders its 



A B C 



FIG. 19. (After Viala and Pacottet.) 



Normal flower of the vine, with filaments as long 



as the pistil. 

 Defective flower of the vine, with filaments shorter 



than the pistil. 

 Defective flower of the vine, with abortive pistil. 



1 "Sur la Fgcondation Artificielle de la Vigne," Revue de Viticulture, T. XXII, 

 No. 551, pp. 5-10. Paris, 1904. 



