-CtliiEAL INVESTIGATIONS. 
Nov. i, 1925 Fruit-bud Formation of Pear and Apricot 867 
On the way up the foothills surrounding the valleys the seasons 
become increasingly distinct, mildly cold winters and warm summers 
being experienced. Hardy apples and pears grow well up to 4,000 
feet elevation or somewhat higher. However, the chief fruit-growing 
sections of the mountains are found in the foothills at elevations of 
not higher than 2,500 feet. The climate in the foothills is a modi¬ 
fication of the interior-valley climate. Temperatures are slightly 
lower, and the rainfall increases at the rate ol about 1 inch to each 
100 feet of elevation (fig. 1). 
MATERIAL 
The pear and apricot were chosen for study. These fruits were 
selected not only Ibecause of their commercial importance in Cali¬ 
fornia, but because one was a pome and the other a drupe. It was 
thought that other fruits of these classes might tend to be influenced 
in much the same way even though differentiating at very different 
times. 
Pear and apricot buds were collected from three typical fruit¬ 
growing districts, namely: Sonoma County north and east of Santa 
Rosa, as representative of coastal valley chmatic conditions; univer¬ 
sity farm at Davis, Yolo County, as representative of interior- 
valley climatic conditions; and Eldorado County east of Placerville, 
as representative of foothill climatic conditions. 
Buds were collected in Sonoma County from Bartlett pear trees 
growing under three cultural conditions—heavily pruned and irrigated, 
heavily pruned and nonirrigated, and lightly pruned and nonirrigated. 
The trees were typical, heavily pruned specimens in good health, 
growing on Dublin loam, and were about 20 years old. The non¬ 
irrigated and lightly pruned tree was in good health, 8 or 10 years 
old, and was growing on yellow clay loam. 
Bartlett pear trees growing on the unviersity farm, Yolo County, 
under these three conditions were compared: Lightly pruned and 
irrigated, heavily pruned and irrigated, lightly pruned and non¬ 
irrigated. The first two mentioned were within 50 feet of each other 
and growing under apparently identical field conditions, except for 
pruning treatment. Tne soil was a Yolo sandy loam. The heavily 
pruned tree was typical, but the lightly pruned one was perhaps 
more vigorous than the average tree thus pruned. The lightly 
{ >runed and nonirrigated tree was located about one-quarter mile 
rom the others, on Yolo clay loam, but under much the same condi¬ 
tions except for irrigation. The trees were all 7 years of age, and 
showed vigorous growth. 
Collections of buds were made from only one tree in Eldorado 
County, at an elevation of approximately 2,400 feet. The tree was 
lightly pruned and irrigated, 7 or 8 years of age, and in a vigorous 
condition. 
Apricots are not widely grown in Sonoma and Eldorado Counties, 
and it proved difficult to find suitable examples of this fruit under 
coastal valley and foothill conditions. However, collections were 
taken from the best trees that could be found in these locations. 
The Royal apricot tree chosen in Sonoma County was 10 or 12 
years old, lightly pruned and nonirrigated, and grew on a gravelly, 
fine, sandy loam. 
