-2- 



Frost. Injuries from lew temperatures range from actual freezing 

 of the developing fruit bud, either before or after the blossom opens, to a 

 mere "touch of frost" which damages to some extent certain tender parts of 

 the flov.-er, including the pistil. Blossoms damaged in the latter way may 

 open and appear quite normal, although the injury may be sufficiently severe 

 to render the blossom incapable of setting fruit. This probably happened 

 in many Massachusetts orchards this spring. Several growers have reported 

 a better i^et on "frost pocket" trees than on those of higher elevation. The 

 reason may be that the latter trees were a little farther advanced and thus 

 suffered more on a frosty night. Heavy frosts n;ust be considered as one of 

 the factors responsible for crop reduction. 



Leaves in 1946 , Apple buds undergo a change beginning around 

 mid-June which sets' the stage for bloom the following spring. The develop- 

 ment of the fruit bud, hov;ever, continues during the suirmer and fall. This 

 development requires a supply of raw materials, including starch. If the 

 foliage is badly infected by apple scab, as was the case in many orchards 

 in 1946, it stands to reason that there is serious interference with the 

 starch making program. And if the tree is actually defoliated in August 

 or Spptember, development of the fruit buds, v,-hich are due to become 

 blossoms the fullov.'ing spring, suffers a severe setback. Many of the buds 

 may fail to open at all while others may develop into fairly normal looking 

 blossoms which are incapable of setting fruit. The condition of the 1946 

 foliage is apparently an extremely important factor in the 1947 crop. 



Scab Infecti on During B loom . V.'ith an abundance of overwintering 

 scab spores~in Massachusetts orchards last spring, and one or tv/o infection 

 periods v.rhile the trees were in bloom, there v/as ample opportunity for 

 v;hat might be termed "pedicel infection" in unprotected orchards, the 

 pedicel being the stem of the blossom. To what extent this happened is a 

 question, although if an apple blossom suffers pedicel infection it tends 

 to drop off. Studies in another state show the loss of as much as lb% 

 of the blossoms by this means. 



Nitroge n Supply During Bloom, A starved tree is inclined to 

 set only an occasTonal cropT It may bloom heavily and still set relatively 

 few apples. The amount of nitrogen actually available in the tree during 

 bloom plays an important role in the setting of apples. The nitrogen 

 supply in many trees was probably rather lov/ at blossoming time because 

 of heavy rains which tended to wash nitrates out of the soil, and because 

 less nitrogen was applied in early spring due to late delivery. It is  

 reasonable to assurae that some Mcintosh trees v;ere deprived of an adequate 

 supply of nitrogen during the blooming period. This factor, however, is 

 probably less significant than the loss of leaves in August, 1946, 



A vaila ble Polle n, Although many tilings about the Hdntosh variety 

 are unknovm,' it Ts"a weir~e3tablished fact that this variety is almost 

 entirely self-storilg. Pollen of another variety, must be brought to the 

 stigma of the Mcintosh blossom if a set is to be obtained. Many varieties 

 are satisfactory, including Cortland, Delicious, Astrachan, Y,"ealthy, 

 V.'agener, Duchess, Ben Davis, etc. Among the unsatisfactory varieties 

 are Baldwin, Gravenstoin, Rliode Island Greening, and the V.'inesap group. 



