284 FUNDAMENTALS OF FRUIT PRODUCTION 



evident beyond 7 rods. Unfortunately these figures were made in an 

 open field and there is at present no means of stating just to what extent 

 the orchard will protect itself at points beyond the sheltering effects of 

 the windbreak, though observation indicates that it does to a considerable 

 extent. Injury from cold drying winds in the 1903-1904 winter was 

 found to be more severe in the outside rows of many orchards. 



INJURIES CHARACTERISTIC OF LATE WINTER CONDITIONS 



Primarily all winter injuries are induced by cold. This fact should 

 be kept in view though for convenience the late winter injuries are treated 

 as due to warm weather. It is not the heat that does the harm but cold 

 weather, even in moderate degree, following warm weather. In one 

 form or another, all fruit growing sections in temperate regions suffer 

 through injuries proceeding from these causes. 



The Rest Period 



Discussion of the rest period at this point should not be taken to mean 

 that it is regarded among the effects of temperature; it is considered here 

 very briefly because of its relation to them. Periodicity of growth is 

 found in plants wherever they are; equatorial regions with uniform 

 temperatures present the phenomenon of plants in the resting stage while 

 others are in growth. Sometimes on the same tree one branch is resting 

 while others are growing. Other factors than temperature are undoubt- 

 edly concerned with the inception and with the end of the rest period. 



The dormant season should not be confused with the rest period, 

 though the two overlap more or less ; in temperate regions the former may 

 begin after — or before — and generally extends beyond, the latter. In 

 the peach, for example, the rest period may begin to ''break" in January 

 though the temperatures prevailing may prolong the dormant season 

 into April. The rest period is not a time of complete cessation of plant 

 activities. The activities commonly recognized as growth are at a 

 standstill, but other functions, undoubtedly of equal necessity to the 

 l^lant, are active. The beginning and end are probably gradual processes. 



If an attempt is made to force peach trees into growth in a greenhouse 

 during November or early December little success is attained; if the 

 attempt is made in late December less difficulty is encountered while in 

 January there would be still less difficulty. In the first instance the 

 trees are in the rest period; in the second, the rest period is breaking. 

 In the first case, no matter how favorable the environment, there is no 

 response; in the second, the response is rapid whenever the environment 

 is suitable. 



Chandler^^ shows an interesting parallelism between the percentage 

 of buds killed in 1905-1906 and the percentage of buds of the same 

 varieties that could be forced into development early in the following 



