34 THE PLUM IN KANSAS. 



II, COMMON ORCHARD OBSERVATIONS. 



Among the multitudinous uncertainties of fruit-growing, the pro- 

 duction of a crop of j)lums presents the greatest combination of ob- 

 scure and unmanageable factors. Even if a heavy crop of fruit is set, 

 the curculio, the gouger, and the brown rot — all peculiarly hard of 

 suppression — remain between it and the market. But there are many 

 uncertainties in the setting of the crop. At times plum trees are so 

 greatly overloaded with fruit that the branches may be broken to the 

 ground. Other varieties, or the same varieties in different localities, 

 or the same trees in different years, may show hardly any fruit. More- 

 over this condition of varying fruitfulness is largely independent of 

 the crop of blossoms which the trees may produce. Plums are notably 

 prolific bloomers ; yet many trees are loaded with blossoms year after 

 year without the smallest result in fruit. A crop of plum blossoms is 

 no satisfactory indication of a crop of plums. 



These are matters of common remark. Observant orchardists have 

 long ago learned to shun unproductive varieties and to destroy the more 

 nearly sterile trees. More recently it has become customary to refer 

 cases of total or partial sterility to lack of cross-pollination, and, pro- 

 ceeding on this theory, mixed planting and the intergrafting of differ- 

 ent varieties have been frequently advised and practiced. Cases 

 which lend support to this theory will occur to every horticulturist. 

 Mr. L. M. Macomber, of North Ferrisburgh, Vt., has a tree of natural- 

 ized plum from Minnesota (the typical P. cnnerlcana), which blos- 

 somed heavily each spring but did not bear a fruit for several years. 

 Later a tree of Lawrence variety standing near it began to blossom. 

 The first year after the blossoming of the Lawrence, and each succed- 

 ing year, the Minnesota plum bore heavy loads of fruit. Similar 

 cases could be cited indefinitely. 



III. CROSS-POLLINATION AND FRUITFULNESS. 



The influence which cross-pollination is assumed to have in the in- 

 creased number of plums set in certain cases is analogous to that 

 which has been shown to exist with many other plants. Cross-pol- 

 lination (or cross-fertilization) is associated in the popular mind with 

 the production of wonderful new varieties of fruits, flowers, and vege- 

 tables — with hybrids and colored plates and fruit-tree agents. But 

 in the light of more thoughtful study it seems doubtful whether this 

 is the chief role which nature intended for cross-pollination, or 

 whether, indeed, it is a natural role at all. It seems rather that cross- 

 pollination has its best usefulness in its immediate effects in provok- 

 ing certain flowers to bear fruit which otherwise would have been 

 abortive, or in stimulating certain fruits to a more perfect develop- 

 ment than they would attain through self-fecundation, Waite has 



