166 THE SOILS AND CROPS OF THE FARM. 



growth lias ceased, usually for a considerable time. 

 Experiments show that the weight of dry matter is 

 increased in the corn up to the time it is perfectly 

 ripe. Indian corn is our only cereal crop in which 

 the harvesting is done almost exclusively by hand. 

 At least two hundred billion ears are separately 

 handled annually. 



When harvesting for fodder the practice is to cut 

 when the ears begin to dent or glaze, and lower 

 leaves begin to get dry. Although less total dry mat- 

 ter is harvested than if allowed to ripen, the assump- 

 tion is that the fodder is more digestible and more 

 palatable than when riper. 



Plant Diiseases. — The most common and gen- 

 erally known plant disease to which the corn is sub- 

 ject is corn smut. {Ustilago Maydis.) The black 

 sooty mass which is familiar to every one is composed 

 of myriads of microscopic spores which spread the 

 disease. These spores are supposed to germinate and 

 penetrate the corn plant when it is small and the 

 smut plant grows inside the corn plant, the former 

 feeding upon the latter. The part which we see 

 coming upon the plant so conspicuously during 

 August is merely the fruiting part of the plant. 



Methods of prevention are not well understood. 

 Sowing with seed and upon land which is free from 

 the spores of the disease should apparently accom- 

 plish the object. Seed corn being hand selected is 

 less likely to have the spores of corn smut upon it, 

 than oats, for example, are to have oat smut upon 

 them. Rotation of crops might be expected to rid the 

 land of the spores. Stable manure, especially where 

 corn fodder is fed, may be expected to contain an 



