FRUIT SETTING AS AN ORCHARD PROBLEM 539 



to be planted in limited numbers for the benefit of a main sort is its 

 pollen -bearing qualities. Some varieties are heavy pollen producers; 

 others bear only limited amounts. Thus IVIeylan is one of the best varie- 

 ties of the Enghsh walnut and Glen Mary one of the poorest strawberries 

 to plant for pollinating other varieties. 



The Number of Pollenizers. — The question often is raised as to the 

 number or percentage of pollenizers necessarj^ when business considera- 

 tions make it desirable to limit them as much as possible. No very 

 definite rule can be given. In most deciduous tree fruits every third 

 tree in every third row will furnish all the pollen necessary for the remain- 

 ing 89 per cent. This proportion, however, would not be practicable in 

 the strawberry plantation when it is desired to grow pistillate varieties 

 mainly. Much depends on the provision for cross pollinating agents. 

 If it is an insect-pollinated plant and pollen-carrying insects are numerous 

 (say amounting to one swarm of bees for each 1 or 2 acres of fruit trees) 

 fewer trees of the less valuable pollenizers are necessary than if the bees 

 are few. 



In cases where large blocks of a single self unfruitful variety have been 

 planted and the trees have been in the orchard for a number of years 

 much quicker results can be obtained by grafting over some of them than 

 by removal and replanting. Occasionally growers solve the difficulty 

 by grafting over a limb or two in each tree, but this usually complicates 

 the problem of harvesting and from an economic standpoint is less satis- 

 factory than changing the entire tops of certain trees. 



Temporary Expedients. — Immediate results are often obtainable in 

 self unfruitful orchards through securing from trees of other varieties large 

 branches containing nvmierous flower buds and placing them here and there 

 in the self barren orchard. This permits pollen-carrying insects to effect 

 a transfer of pollen from these branches to the pistils of the orchard trees. 

 Such branches should be cut just as their flowers are starting to open and 

 stood in buckets of water so that they will keep fresh while their flowers 

 are opening and shedding pollen. This is only a temporary expedient, 

 for it is troublesome and often rather expensive ; however, it has been the 

 means of insuring a good set of fruit in many cases when there would have 

 been a crop failure otherwise. It really is a kind of artificial pollination, 

 comparable to practices in vogue for thousands of years in the produc- 

 tion of dates and many varieties of figs. 



Pollinating Agents. — Wind and insects have been mentioned as the 

 chief pollen -carrying agencies for deciduous fruits. Of the two, insects 

 are by far the more important except in some of the nut crops. In fact 

 the amount of cross pollination effected through the agency of the wind 

 in apples, pears, peaches and other insect-pollinated fruits is practically 

 negligible. This has been shown experimentally for the plum by 

 Waugh^^*^ and for other fruits by other investigators. Among pollen- 



