PROTECTION AGAINST FROST 



369 



If late blooming is urgently needed it is best secured by selecting late 

 blossoming varieties, planting them on a north slope and keeping them 

 growing vigorously. The last two measures are effective only within 

 comparatively narrow limits, leaving the first as the best method of 

 evading frost damage. In certain fruits the present varietal range in 

 blossoming season is hardly sufficient to secure protection through the 

 selection of the later blooming sorts, but in others practical immunity 

 from damage may be obtained in that way. There is reason to believe 

 that late blooming varieties of many fruits may be bred and the ultimate 

 solution of the frost problem lies in that direction. 



Indices to Blossoming Periods in New Location. — Sometimes in 

 considering locations where fruit has not been grown it is desirable to 

 know at what time the trees may be expected to bloom. It is possible 

 that phonological observations on native plants in different sections 

 would show a degree of correspondence with the various fruits so that 

 certain native plants might serve as indicators of what fruit trees would 

 do in the same locality. 



Figure 37, arranged from the Mikesell Records, '^^ shows the overlapping of 

 the King apple in the stage from first blossom to full bloom with poison ivy, a 



?0 IZ 24 Z6 ?8 JO 2 4 6 8 10 \Z 14 IG IS 20 22 

 April f^ a y 



Fig. 37. — Comparable phenological stages in apple and poison ivy. (Apple from first 

 blossom to full bloom; poison ivy from starting of buds to first fully formed leaf). 



fairly common wild plant, in the stage from buds starting to the first fully formed 

 leaf. It will be observed that the correspondence, though not invariable, is 

 rather close. Some plants show better correspondence with the King apple than 

 others; several recorded in the Mikesell records show less than the poison ivy. 

 This instance is but suggestive of many other parallels or overlappings in 

 blossoming seasons that may be estabhshed— parallels that in many cases would 

 repay careful study. 



FROST PREDICTION 



It is frequently important to know a few hours in advance whether 

 or not a frost will occur, so that final preparations for protection against 



24 



