1930] PracH CurTurRE IN CALIFORNIA 31 
$15 per acre. Occasionally, however, frost protection may be profit- 
able. As for example, during the spring of 1929, when certain growers 
saved most of their crop by orchard heating, whereas certain others 
not equipped to heat, lost their entire crop. 
When the temperatures are near the danger point or slightly below 
for only very short periods of time, it is claimed by some growers 
that the possible injury may be appreciably lessened by the application 
of irrigation water, especially if all the growers in the neighborhood 
irrigate just previous to the drop in temperature. Water in basins or 
running in furrows liberates heat since it is generally at a tempera- 
ture higher than that of the air and thus may afford a small amount 
of protection. 
Fruit Thinning.'>—In general it is more profitable to thin peaches 
than any other deciduous fruit. Peaches are thinned primarily to 
increase the size of the fruit, inasmuch as it takes two 2-inch peaches 
to equal one 24-inch peach in weight. With experience one man ean 
thin by hand ten or twelve trees in a ten-hour day when from 1000 to 
1500 peaches are removed from each tree. Thinning eosts about 30 to 
40 cents per tree. 
There is usually a dropping of young fruit about the first part of 
June from causes, such as insufficient moisture, inadequate pollination, 
and adverse climatic conditions. Thinning is generally postponed 
until after the fruit drop, when the prospect of the erop can be 
determined. It, however, is usually done previous to the hardening of 
the pit. On the other hand, increase in size may be effected by later 
thinning. Peaches are thinned, four to six inches apart. The actual 
distance of spacing and number of fruits left on the tree varies with 
the variety, amount of crop set, character of twig and branch growth, 
soil, water supply, and other factors. 
Weldon'* suggests thinning so as to leave a given approximate 
number of peaches per tree. For example, if trees are planted 24 by 24 
feet and a yield of 15 tons per acre of size two and three-fourths inch 
peaches is expected, each tree should average about 1155 peaches. The 
number of peaches per tree divided by three will give the approximate 
pounds of fruit, since it takes three normal-size peaches to weigh one 
pound. This multiplied by the number of trees per acre will give 
the total number of pounds, and when divided by 2000 gives the tons 
per acre. Growers are, therefore, advised to thin by count. It is 
~ 1s'Tufts, W. P. Thinning deciduous fruits. California Agr. Exp. Sta. Cir. 
258:1-13. 1923. 
14 Weldon, George P. A new idea in peach thinning. Chaffey Junior College, 
Dept. Agr. Bul. 5:14.