350 



STATE BOARD OF AG-RICULTURE 



begins in late May, in Michigan, and continues to late June. The largest 

 part of the crop is planted before the 15th of June. 



In those sections of the state that have longer growing seasons than are 

 required to mature the crop, the time of planting the late crop should be 

 largely determined by the climatic conditions that can normally be expected. 



Oct. 10 



Oct'. 20 



Fig. 14. Chart showing average date of first killing frost in autumn. 



Many sections of the state are subject to periods of drought during July and 

 the first half of August. The critical period in the life of the potato plant is 

 when it is setting its tubers. If tubers set during a hot, dry spell, the yield 

 is likely to be low. In many sections, late potatoes are usually planted about 

 the middle of June so that they will be setting tubers during the latter part 

 of August and first half of September, when temperature and moisture condi- 

 tions are generally more favorable for potato growing. 



