ACCIDENTS, DISEASES, PARASITES. 157 



White frosts are produced by the cooling of the soil 

 resulting from the radiation of the heat from the soil towards 

 the sky. The young shoots close to the soil are influenced by 

 this cold and die if it falls below zero. Low and damp sites 

 are generally more exposed to the action of frosts, and it is 

 in April or May,* towards four or five in the morning, that 

 they are most severe. Farmers have noticed that this 

 phenomenon occurs regularly at certain dates. Edouard 

 Koche established in his studies on the cjimate of Montpellier, 

 resulting from records spreading over 100 years, f that in 

 the He*rault late forests were to be feared towards the 10th 

 or 14th, the 18th or 

 19th, to the 24th \ A 



April ; from the 2nd 

 to the 4th or 5th, and 

 from the llth to the 

 13th of May. Similar 

 observations have 



been made in other Fig 138 ._ Brou8sin Cau8ed by frost, 



vine-growing coun- 

 tries. There is only one means of diminishing the effects 

 of black frost, and that is by trying to throw back the 

 bursting of the buds as far as possible, by cultivating special 

 varieties, or by pruning late, as we have already explained 

 (fall pruning, page 137)4 



These prosecutions may also be useful against white frosts, 

 but other means may be used. Some are permanent, 

 and result from the way the vines are planted ; others are 

 only temporary, and may be repeated every time the frost 

 appears. 



Among the first we may mention planting on hills, 

 where the effect of radiation is lessened. This is generally 

 done in the North, Bourgogne, Champagne, <fcc. The crown 

 may be kept at a certain height above the soil, placing the 

 shoots at a distance from the soil sufficient to diminish the 

 influence of the decrease of temperature. In Savoy vines are 

 trained on high trellises with the object of preventing the 

 action of frosts. 



In countries where spring frosts are prevalent one should 

 not build walls or grow hedges about the vineyard, which 



* October and November in Victoria. 



t Edouard Roche. Les variations pModiques de la temperature dans le cours de 

 I'annee d Montpellier. Messager Agricole du Midi, 10th Mai, 1883. 



J It has been noticed that sulphate of iron used in concentrated solutions to protect 



vines against cryptogamic diseases greatly retards the bursting of 

 therefore be used successfully in certain circumstances. 



solutions to protect 

 the buds. It may 



