4 N. H. Agricultural Experiment Station [Bulletin 274 



older fruit gardens. As the years passed, fewer and fewer varieties were 

 planted. Local demands and the profit from the different varieties in the 

 market governed the planter's choice. Varieties tender to cold or unpro- 

 ductive of large and regular crops, were culled from the orchard. Those 

 especially subject to disease and insect attacks and those not universally 

 popular because of color, flavor, or keeping qualities, came to be placed in 

 the catalog of obsolete varieties. 



New varieties were eagerly sought in order to obtain apples better in 

 some respect than those already established. These changes finally led to 

 conditions occasionally found in the last of the 19th century and often dur- 

 ing the present century, where apple plantings that bloomed heavily failed 

 to produce fruit. 



One of the earliest examples of this condition appeared in the pear 

 industry. Many plantings of Bartlett pears in large blocks were made in 

 the 70's and 80's. When they reached bearing age they produced little or 

 no fruit. The trouble was traced to the fact that under most conditions the 

 Bartlett is partially or wholly self-sterile. The remedy was to plant some 

 other variety with the Bartlett to provide pollen for its flowers, thus insur- 

 ing a crop of fruit. 



This discovery was made and published by M. B. Waite (1) in 1892-3 

 and the knowledge has since been invaluable to fruit growers. Even now 

 self-unfruitful varieties are occasionally planted in solid blocks. In New 

 England the Mcintosh falls in this class. History will without doubt repeat 

 itself in this respect whenever new varieties are introduced that are more 

 profitable than existing ones. 



When the error of planting a self-unfruitful variety in a solid block is 

 discovered perhaps 10 or 15 years later, the remedy is to graft pollenizers 

 into certain trees in the orchard and to include pollenizers in future plant- 

 ings. The mistake is costly because five or six years pass before the pollen- 

 izers grafted into the orchard bloom sufficiently to be effective in cross 

 pollination. This would make the tree needing pollination at least twenty 

 years old before a full crop could be produced. 



Not so well known is the fact that good pollenizers themselves may not 

 be readily pollenized by the main crop variety which has shown need of 

 pollination. Although Delicious wall pollenize Mcintosh, for example, this 

 is no indication that Mcintosh will in turn pollenize Delicious. Further- 

 more, inter-sterility may exist between two varieties. 



Several varieties of apples in New England produce paying crops, even 

 when i)lanted in large blocks without pollenizers. They may therefore be 

 considered self-fruitful sorts. Baldwin is outstanding in this class. 



The fact that a variety may be self-fruitful does not signify that it is also 

 a good pollenizer. The self-fruitful Baldwin is practically useless as a pol- 

 lenizer for any other important commercial variety grown in New 

 Hampshire. 



Darwin emphasized in 1859 that "Nature . . . abhors perpetual self- 

 fertilization." He indicated in his work that cross- fertilization is of value 

 in the plant kingdom. Half a century earlier investigators were aware that 

 bees carried pollen from one flower to another but were unaware of the 

 exact nature of the benefit. 



(1) M. a. Waite. The pollination of pear flowers. U.S.D.A. Bur. Veg. and Plant Path. 

 Bui. 5 (1893) 



