196 



REPORT OF STATE BOARD OF HORTICULTURE, 



73— Winter-in. I urf'd fruit bud.-- 

 Bletigbelmer apple. 



WINTER AND SPRING FROST MAY INJURE THE BLOSSOMS. 



The unfruitlvilness arising- from winter or .spring- frost injury is some- 

 times confused with self-sterility. Various forms of winter injury to fruit 

 buds are shown in Figs. 72-77. At A in Fig. 72 is a fruit bud which has 

 been completely winter-killed and has no growth whatever. B and C are buds 

 which will never be able to open ; while D is a very weak blossom which can- 

 not set fruit. The single open flower on this branch is the only one which can 

 possibly set fruit, A winter-injured cluster of Bietigheimer blossoms is seen 

 in Fig. 73, with a section of one bud in Fig. 74 to show the shriveled stamens 

 and pistils. The leaves in this cluster came through all right, but the 

 flowers were injured. The single flower which has expanded is too small and 



Aveak to develop into fruit. These winter- 

 injured clusters were common on all va- 

 rieties of pears, particularly Angouleme 

 and Manning Elizabeth, and on some va- 

 rieties of apples, in the spring of 18!j9. 



Two forms of winter or spring frost ii> 

 jury to the pistils are seen in Figs. 75 and 

 76, with a normal blossom for comparison 

 in Fig. 77. A common form of injury is 

 that in Fig. 75, in which the pistil is 

 blackened and stunted, having made no perceptible growth during the 

 opening of the flower. These jjistils always drop from the tree soon after 

 the petals have fallen. Another and not less common form of injury is that 

 in Fig. 7(), in which the pistil has made a partial growth 

 but has no well-developed ovary. Unless a careful exam- 

 ination is made, blossoms like this would not be consid- 

 ered as winter-injured. Of flfty which were tagged, none 

 gave fruit, although several fruits grew to the size of 

 peas. The killing of the pistils is the most common form 

 of winter-injury to fruit buds. Some of the native and 

 Japanese plums had as high as eighty per cent, of defec- 

 tive pistils last spring, but with their enormous amount 

 of bloom this did not materially decrease the crop of 

 fruit which' the trees were able to carry. The Japanese 

 plums bloom so early that their blossoms are liable to be injured by frost in 

 the middle states and south. 



It is thus seen that the injury to fruit blossoms from cold is of all degrees. 

 During the opening of a normal flower, the pistil grows. It is often taken 



for granted that if this growth occurs the pistil is 

 uninjured ; but it may be that even though a pistil 

 reaches its full size, it may yet be so injured that it 

 cannot develop into fruit. In 1899 about ten per 

 cent, of the blossom buds of a Royal apricot opened 

 fully, like the one in Fig. 72. All of these blossoms 

 appeared to be perfect, with long pistils, plump 

 ovaries and well-developed stamens. Yet hardly a 

 dozen fruits set on the whole tree, although the 

 weather during the blooming season was ideal, bees 



74 — Section of one 

 bud in Fls. 73. 



7.') — Catherine apricot: 

 injured pistil. 



