634 Report oF THE HORTICULTURIST OF THE 
to loss of foliage from insect pests and fungous diseases; to a 
lack of fertilizers and to absence of cultivation. But there is no 
difference in treatment of different portions of the orchard, so 
far as pruning, spraying, cultivation and fertilization of soil 
are concerned, and, therefore, the causes enumerated do not 
seem sufficient to satisfactorily account for the unproductive- 
ness of varieties in certain sections, while the same varieties in 
other portions of the orchard are comparatively productive. The 
unfruitful portions consist of separate blocks of Baldwins and 
Greenings unmixed with other varieties, and some have thought 
that possibly on account of this isolation of each variety their 
blossoms have failed to set fruit. 
A similar idea with regard to certain cultivated varieties of 
the native plum has long been entertained by some growers of — 
that fruit in the Mississippi valley and other portions of the Great 
Central plain.® This idea is founded on observations that 
varieties such as Wild Goose and Miner set but little fruit when 
standing alone, although they blossom abundantly, while they 
are more productive when standing near other varieties, from 
which their flowers may be assisted to set fruit. 
Prof. Goff has shown’ that with some kinds of native plums 
failure to set fruit may be partly due to imperfections in the 
flowers, which render them incapable of setting fruit, but this 
does not account for those instances where a tree that was 
formerly barren becomes fruitful when another variety, blossom- 
ing at the same time, is planted near it. In such cases it appears 
that the flowers are capable of setting fruit although they are 
incapable of setting fruit of themselves. 
Some horticulturists have for many years believed that a sim- 
ilar condition of affairs also exists with certain cultivated grapes, 
especially with some of the hybrid varieties. Within the last 
three years I have been able to demonstrate that this belief is, 
in many instances, well founded. Mr. M. B. Waite, of the United 
States Division of Vegetable Pathology, began a similar line of 
investigations in 1891, which resulted in showing that many 
varieties of pears, including some of the standard sorts, are 

ee 
incapable of setting fruit of themselves, a condition, so far as I 
am aware, that was wholly unsuspected by either practical or 
scientific horticulturists. } 
5 Hansen, N. E. The Blossoms of Orchard Fruits; Trans. Iowa Hort. Soc’y, 1893, p. 155. 
6 Flowering and Fertilization of the Native Plum. Garden and Forest, vol. VII, 1894, pp. 262,263, 

