240 EXPERIMETTT STATION EECORD. [Vol.41 



to the variety tbiin iit New Brunswick, wliere the soil is ^'ravelly red shale luaiu. 

 Cousideral)le vai'iatioii in total twitr growth was found to occur between in- 

 dividual trees at tlie close of the first season. Tliis apparently had no influence 

 upon the growth of the trees in the second season, for whereas between some 

 groups an average difference of 50 in. the first season was appreciable in the 

 second season, between other groups an average difference of 100 in the first 

 season was not noticeable the second season. In both the Vineland and New 

 Brunswick experiments the smaller the circumference in 1912 the greater the 

 percentage increase in circumference in 1913. 



The data already secured indicate that permitting the development of 

 branches, shoots, or suckers on the lower part of the trunk during the growing 

 season tends to increase the girth of the trunk more rapidly than where such 

 growth is removed and where the trunk is longer and the branches higher 

 above the ground. In the summer pruned treatments the shoots are removed 

 fi'om the trunk, giving in almost every case a greater twig growth to each inch 

 increase in trunk circumference. In the no pruning and winter pruning treat- 

 ments the twigs were allowed to remain on the trunks, resulting in a narrow 

 ratio of increase in trunk circumference to increase in twig growth. "Where 

 most of the growth is made at the very top of the tree it will have proportion- 

 ally less influence upon the circumference of the trunk near the ground. 



Sunnner pruning reduces the amount of the necessary thinning of twig 

 growth in winter, but increases the amount of clipping back due to the in- 

 crease in vigor of the secondaiy twigs on the leaders. The summer pruning of 

 the combined winter and summer treatment reduced the pruning required in 

 A^anter to about one-lialf at Vineland and from one-third to one-half at New 

 Brunswick as compared with the winter and cut back treatment. Pinching 

 back the main twigs increases the number of secondary or side twigs. 



Tlie summer pruning only treatment at Vineland made the greatest average 

 total growth and the winter cut back treatment was second. At New Bruns- 

 wick the no pruning treatment made the best total growth and the summer prun- 

 ing only treatment was second. KSununer pruning appan^ntly did not affect or re- 

 duce the amount of twig growth made by the tri'os during the second season. 

 Of the various treatments tlie winter pruning without cutting back was the 

 cheapest and the combined winter and summer pruning the most expensive. 

 Tlie data thus far secured indicate that varieties having an upright habit with 

 numerous twigs and branches are more expensive to prune than varieties with 

 spreading, open habit growth. 



Pollination of the Bartlett pear, W., P. Tufts {California Sta. BuL 307 

 {1919), pp. 369-390, figs. 8). — The results are given of pollination studies con- 

 ducted during the tliree seasons 1916-1918, to determine the relative sterility 

 or fertility of the Bartlett pear under both foothill and valley conditions in 

 California. Tests were made of suitable pollinizers for the Bartlett pear and 

 the pollen viability of pears in general was also studied. The results of early 

 investigators are briefly noted. 



The Bartlett was found to be self-sterile under foothill conditions and self- 

 sterile to a liniited degree under valley conditions. Since no cases of inter- 

 sterility were found to exist between pear varieties it is concluded that any 

 variety overlapping in blooming period with the I'.artlett may be expected to 

 be an efhcient iiollinator. Pears resulting from cross-pollination did not appear 

 to exhibit the same tendency to fall at the .Tune drop as those resulting from 

 self-pollinatioTis. It is recounnended that all P.artlett orchards should be 

 provided with facilities for cross-pollination, and pollinating agencies such as 

 the honeybee should also be provided. A list of varieties pollinating the Bart- 

 lett successfully is given. 



