362 



FUNDAMENTALS OF FRUIT PRODUCTION 



Table 68. — Percentage of Open and of Unopened Blossoms Killed by the 



Freeze of Apr. 4, 1908 (24°F.) 



(After Chandler^^) 



green fruit well protected with foliage survived January, 1904, the mercury falling 

 to 14 at the ground one night, 16 one night, 17 two nights, 18 one night and 19 

 three nights; and a few berries ripened during the early part of the month." 



Varietal Differences. — Varietal differences in hardiness are sometimes 

 apparent in apples. 



In one case in Missouri the greatest injury in Jonathan seemed to be in the 

 stamens while in Oldenburg the pistil was damaged. It may be suggested that 

 this type of injury might have some interesting bearing on the pollination of 

 mixed orchards. 



In Iowa many of the Russian varieties were hardier in blossom than standard 

 varieties in better locations. Similarly among the native plums a freeze that 

 killed the ovaries of several varieties such as Rollingstone which, incidentally, 

 is very resistant to winter cold, injured only a part of the blossoms of De Soto, 

 Cheney and other varieties. These in turn were surpassed in resistance by the 

 Russian plums which were said to have been "less exposed than our native 

 plums. "28 The Bosc pear has been reported as more tender in blossom than the 

 other pears. 2*^ Chandler states that among peaches " the large flowered varieties 

 seemed uniformly to be the most hardy, probably because the petals remained 

 closed over the pistils longer."^' This statement was in reference to resistance 

 to frosts at blossoming time; after that period no determining factor could be 

 found. Elberta, tender at some other stages, seemed to resist very late frosts as 

 well as most varieties. 



Some varieties of strawberry are more susceptible to frost injury 

 than others because their flower stalks are longer and more inclined to 

 raise the blossoms above the protection of the leaves.^ 



Schuster"'* reports on the Ettersburg No. 121 strawberry: "The first blos- 

 soms being below the foliage are quite well protected from ordinary frost. Foli- 

 age protection is quite a factor when comparing this variety with other varieties 

 of hght fohage, as the primary blossoms are very apt to be fully protected during 

 the frost, while the secondary blossoms that extend beyond the foliage will 

 usually be frosted. Due to the extended blossoming period, it will take repeated 

 frosts to destroy the crop unless there is a heavy freeze." 



Some interesting studies have been made in an attempt to correlate 

 varietal morphological peculiarities with differences in hardiness. 



