64 THE RAISIN INDUSTRY. 



crop for a week or more. Smoking of vineyards can only be success- 

 fully carried out in small valleys sheltered from heavy winds, but on 

 the open plains such smoking is accompanied with difficulties, and its 

 effect is uncertain. The growing of a limited number of windbreaks 

 has in the Fresno district no doubt modified the climate, and made 

 spring frosts rarer and less to be feared. 



While the spring frosts are injurious to the grapes, winter frosts are 

 on the other hand most beneficial, if not necessary to a continued 

 raisin cult. The raisin grape must have a season of recuperation, and 

 winter frost is the only climatic phenomenon which, without injury to 

 the vine, can procure it that rest which is so necessary for all decid- 

 uous trees, by nature destined to enjoy alternate periods of growth and 

 sleep. The absence of frost causes the sap of the vine to circulate more 

 or less in the wood, and the vine never ceases to grow. This is one of 

 the reasons why our deciduous vines do not succeed well in the tropics, 

 where there are no cold seasons to cause the leaves to fall and the sap 

 to become dormant. In the tropics, therefore, our deciduous vines keep 

 on growing, set little or no fruit, and prove unprofitable. This phe- 

 nomenon is shared there with other trees, and peaches, pears and apples 

 act in the same manner. They all appear to need the rest afforded 

 them by the winter frosts. It is also a question of very great import- 

 ance, whether the continued and unnatural activity of the vine, at a 

 time when it should be dormant, does not invite diseases of various 

 kinds, which find the exhausted vines unfit to withstand their ravages. 

 It may be possible that mat nero, the vine plague and other similar 

 and as yet insufficiently understood diseases, are especially destructive 

 to vines growing in frost-free climates, while in colder climates they 

 make but little headway, the vines as it were being protected by the 

 heavy frosts, which either kill the enemies of the vine or enable the 

 latter to gather the necessary strength to battle with them through the 

 growing season. There can be little doubt that at present the 

 healthiest vineyards are those growing in countries where winter frosts 

 are severe, but on the other hand we know that grapevines have 

 been growing for ages in temperate climates, where the frosts, even if 

 not entirely unknown, are still of very rare occurrence. 



Summer Temperature. The temperature in summer time must be 

 sufficient to properly ripen the grapes, but must not be so great as to 

 injure them either while they hang on the vines, or while they are 

 exposed to dry on the trays. The average heat required to do the 

 work of maturing is not exactly known, but it is certain that a very 

 high degree is not absolutely needed to produce sweet grapes. As far 

 as our experience goes, it seems that cool weather, with the average 

 temperature of ninety degrees Fahrenheit, v/puld be most beneficial in 

 the fore part of the season, while when the grapes begin to ripen a 

 greater heat is desirable. It is not the warmest countries nor the 

 warmest seasons which produce the earliest grapes. Thus while the 

 season of 1888 was in California unusually cool, with the thermometer 

 seldom reaching one hundred degrees in June and July, the raisin sea- 

 son was nevertheless a very early one, and much earlier than seasons 

 remarkable for their early high temperature. In Malaga and Smyrna, 



