6 
1ST. C. Agricultural Experiment Station 
for successful fruit production tlie presence of male vines in large vine¬ 
yards is absolutely essential. 
Even the growers of small fruits are not immune from the harmful 
effects of sterility when certain varieties are planted in solid blocks. 
Fortunately for the commercial growers in the eastern States, the leading 
varieties of dewberries and blackberries are self-fertile and produce 
abundantly even when planted in large solid areas. However, there 
are many excellent varieties on the markets which are more or less 
influenced by the factor of sterility, and which, with judicious care in 
the selection of varieties with regard to pollination, can be made to yield 
profitable crops. In fact, there are a number of varieties which are 
likely to prove to be just as good as the chief commercial varieties of 
the present day, barring this one defect. 
Object of the Experiment .—The prime object of the experiment under 
discussion was to investigate the question of sterility among varieties 
of dewberries and blackberries. This question resolves itself into the 
following three lines of investigation: first, to ascertain which varieties 
of dewberries and which varieties of blackberries are self-fertile and 
which are self-sterile; second, to discover, if possible, the cause or 
causes of this sterility; and, third, if possible, to suggest remedies. 
STERILITY AMONG DEWBERRIES AND BLACKBERRIES. 
Varieties Tested .—In order to provide sufficient material in the way 
of varieties to carry on this sterility test, the following varieties were 
and planted under 
ordinary 
field conditions: 
Dewberries 
Hybrids 
Blackberries 
Austin 
Cox 
Blowers 
Chestnut 
Ruth 
Dallas 
Grandee 
Haupt 
Early Cluster 
Limekiln 
Rathbun 
Early Harvest 
Lucretia 
McDonald 
Eldorado 
Manatee 
Wilson 
Illinois 
Munroe 
Sorsby 
Kenoyer 
Rogers 
Spalding 
King 
Elijah, No. 2 
Mersereau 
Premo 
Minnewaski 
San Jacinto 
White 
Snyder 
Method of Procedure .—The method used to test these varieties for 
self-sterility may be stated as follows: whole flower-clusters, and often¬ 
times several of them, were inclosed in bags so as to exclude all foreign 
pollen. Some of these bags were ordinary half-pound paper sacks, 
while others were made of cloth. The latter were made of Pacific lawn, 
which is a light, gauzy, but very fine-meshed fabric, and which success¬ 
fully keeps out all foreign pollen. 
