GOOD FRUIT REQUIRES ENOUGH HEAT J9 



Lowest Temperatures at Several California Points Continued. 



San Miguel 11 Tulare City 18 Porterville 22 



Los Angeles 28 Colton 19 Redlands 25 



San Diego 32 Imperial 20 Riverside 21 



These records will show any one familiar with winter killing of 

 the leading orchard fruits that such disasters are not to be feared 

 in the chief fruit regions of California. Local temperature is largely 

 controlled by local conditions, as has already been pointed out, and 

 in the districts named in the table there are special locations where 

 the lowest temperature may have been a few degrees higher or lower 

 than figures given. 



NECESSITY OF ADEQUATE SUMMER HEAT 



Passing beyond the freedom from winter killing it may be re- 

 marked that the influences of certain degrees of heat upon the 

 growth of the plant and the perfection of its fruit, has been the 

 subject of much close observation. Boussingault conducted careful 

 experiments, and showed that a temperature above a certain mini- 

 mum of heat is found necessary for germination, another for 

 chemical modification, and a third for flowering, a fourth for the 

 ripening of seeds, a fifth for the elaboration of the saccharine juices, 

 and a sixth for the development of aroma or bouquet. 



Originally the mean annual temperature was alone observed, and 

 the polar limits of plants, it was presumed, could be thereby deter- 

 mined. More recently it was taught that the mean temperature of 

 seasons is of more importance than that of the year, and it is be- 

 lieved that to the relative distribution of heat over the seasons 

 rather than to the absolute amount received during the year, we are 

 to attribute the fitness or unfitness of a region for the growth of 

 certain kinds of vegetation. 



It is held in Europe that the mean heat of the cycle of vegetation 

 of the vine must be at least 59 degrees Fahr., and that of the summer 

 from 65 degrees to 66 degrees Fahr. It is stated to be impossible, 

 for instance, to cultivate the vine upon the temperate tablelands of 

 South America, where they enjoy a mean temperature of 62.6 de- 

 grees to 66.2 degrees Fahr., because these climates are characterized 

 by a constancy of temperature, never rising to the higher heats 

 necessary to the process of sugar forming ; and the vine grows and 

 flourishes, but the grapes never become thoroughly ripe. Boussin- 

 gault shows that, in addition to a summer and autumn sufficiently 

 hot, it is indispensable that at a given period that which follows 

 the appearance of seeds there should be a month the mean temper- 

 ature of which does not fall below 66.2 degrees Fahr. As will appear 

 presently, this temperature test should not be taken alone, but it 

 will serve as a standard to show one feature of the horticultural 

 adaptation of the California climate. Boussingault claims the need 

 of 66.2 degrees Fahr. for a single month. To be sure to include this, 

 the accompanying table gives the average summer temperature at 

 the leading fruit-growing centers named. 



