Frost-Killing of Bulbs 



309 



FIG. 115. A strawberry 

 nubbin, due to frost. 



were permanently discolored. The buds swelled with the 

 freezing, but returned to their previous size when thawed 

 out, and they looked as if withered for several days, or 

 until active expansion began. 



When the flowers have fully expanded, a comparatively 

 light frost will destroy them. This is shown in the fact 

 that a very slight elevation in a black- 

 berry or strawberry patch is often suffi- 

 cient to avert injury. The pistils seem 

 to suffer first. A strawberry nubbin is 

 shown in Fig. 115. The top of the 

 berry (or the bottom, as it hangs) is 

 flattened and deformed. This is usually due to the freezing 

 of the upper pistils in the flower, as it stood erect. Nubbins 

 are sometimes the result of imperfect pollination, but in 

 such cases the deformity is more likely to be on the sides 

 than on the top, for the top pistils are the ones that are 

 very likely to be pollinated by insects. 



A similar case is reported on blackberries at Cornell. 

 The only serious accident known to injure the blackberry 

 crop in New York (aside from hail) is frost; and in most 

 cases the injury is unavoidable, even 

 though the grower has warning of 

 its approach. In six crops grown 

 in a certain patch, only one was 

 injured by frost, and even this one, 

 when the cold wave was unusually 

 late and severe, suffered seriously 

 only in the lowest places. Drawings 

 of blackberry flowers were made on 

 the spot, two or three days after the 

 frost, and they are here reproduced, 



y . - * . . i Fia. 116. Normal blackberry 



natural size. A normal, uninjured flower; fuii size. 



