Nov., 1923] DORSEY-STERILITY AND HORTICULTURE 481 
One phase of sterility quite disappointing to growers, and due primarily 
to deficient nutrition, is the production of a heavy bloom from which no 
fruit is set. This is encountered in the apple, in the plum, and probably 
to a lesser extent in other fruits, and may include a part of the flowers or 
all of them. While the effect of deficient nutrition may be different in the 
several fruits, in the plum the method of expression is pistil abortion (Dorsey, 
1919 b). The same is also probably true in the apple. In the strawberry 
and the raspberry, deficient nutrition may result in imperfect berries on 
account of the poor set of achenes or drupelets. A different condition is 
encountered in the currant, in some of whose varieties there is as much as 
ten days to two weeks between the time of opening of the basal and of the 
terminal flowers. In such instances, the currants at the base enlarge con¬ 
siderably before the terminal flowers open, with the result that the latter 
drop leaving the bare stem of the cluster. The status of individual flowers 
in the currant has much in common with the more extreme condition en¬ 
countered in the apple or plum. In all the fruits which produce an excess 
of bloom, the position of the individual flower appears to have much to do 
with its opportunity for development. In the plum, for instance, the flowers 
borne on the terminal growth come into competition with fruiting laterals, 
formed soon after bloom at each node, with the result that flowers borne 
in this position seldom set. Some tests were made at the Minnesota 
station with the currant to determine the relation between the position of 
the flower and setting. When the basal flowers were removed from selected 
clusters before they opened, the terminal ones set, although they had fewer 
seeds and were smaller. On the same bush under the same field conditions, 
terminal flowers on clusters not so treated dropped. 
With the carbohydrate-nitrogen conception as a background, the trend 
of the more recent investigations may be illustrated by the work with the 
apple. Some varieties are known to growers as annual, and others as “ off- 
year” or biennial bearers. For a long time thinning has been advocated 
as a means of preventing exhaustion and consequently inducing annual 
bearing. In New York, four years’ thinning did not make Baldwin more 
regular in bearing (Gourley, 1915). Similar results were obtained in West 
Virginia with Grimes and Delicious (Auchter, 1919). Spurs which fruit 
one year seldom bloom the next (Auchter, 1919; Roberts, 1920), and recent 
investigations indicate that, if thinning is to influence fruit-bud formation 
on spurs which have bloomed, the removal of buds or flowers at least before 
they set (Roberts, 1920) rather than of the fruit, is required (Crow and 
Edit, 1921). The suggestions which have come from the later studies as to 
methods of correcting the “off-year” include good cultural methods 
(Gourley, 1915), pruning out crowding branches and cutting back to re¬ 
juvenate the spurs (Roberts, 1920), stimulation of alternating spur blooming 
by pruning and fertilization (Roberts, 1920; Crow and Edit, 1921), and 
obtaining the normal fruit-spur formation on the two-year-old wood 
