492 REpoRT OF THE HORTICULTURAL DEPARTMENT OF THB 
which govern the distribution of plants. Few species are more 
decidely influenced than the culivated grape by latitude and 
altitude, temperature, water supply, air currents, the chemical 
and physical properties of the soil, insects and fungi,— the 
natural factors which determine local environment. 
Altitude and latitude The temperature of a place, as well 
as the amount of sunlight and the length of the growing sea- 
son, is largely determined by the latitude and altitude. Local 
modifications often counteract these. In general, cultivated 
varieties are more exacting in their demands than native 
Species; because such plants are usually removed from their 
natural habitat, and their growth attempted in places having 
a different elevation, a longer or shorter growing season, or 
a higher or lower annual temperature. Similar susceptibility 
to environmental variations is also shown in the case of grapes 
from crosses between species long adapted to different climatic 
conditions. 
Temperature.— The grape requires a relatively even air tem- 
perature. In the latitude of New York, regions and seasons 
having a comparatively low temperature during the growing 
season of May, June and July, with much sunshine during the 
maturing months of August, September and October, produce 
the best grapes. Grape growing is perhaps dominated more by 
air temperature than any other single factor. This largely 
determines the northern range and hardiness of varieties, 
which ones can be grown successfully in any region, and in 
many seasons where and when there shall be a crop. Its in- 
fluence is seen at different periods of the year in winter killing, 
damage by late spring or early frosts, shrivelling and drying 
up of the leaves or sunscald of the fruit. In the control of 
air temperature lies the value to the grape of large bodies of 
water, like lakes and wide rivers, which temper the cold winter 
and hot summer weather, equalize night and day temperatures 
and lengthen the growing season by warding off frosts in the 
spring and autumn. 
