The Smallest of Living Things 249 



U. S. D. A. 



FIG. 200. Disinfecting seed wheat for smut. The United States Department 

 of Agriculture estimates that $35,000,000 worth of cereals could be saved 

 annually by disinfecting seed. 



mixture early in December ; for curl leaf, spray just 

 before the buds open in spring (Fig. 199). 



Scab of apple and pear are caused by fungi. Spray Scab on 

 with Bordeaux mixture about three times during early ^ rmt 

 spring. 



There are two kinds of potato blight, " early " and Potato 

 " late," and these are caused by two different fungi. a ^ d l cab 

 For both kinds of blight, spray once in ten days or two 

 weeks with Bordeaux mixture. Potato scab is a fungous 

 growth that roughens the skin of the potato. Soak 

 seed potatoes for two hours in formalin, one pint to 

 thirty gallons, or in bichlorid of mercury with a strength 

 of one to one thousand. 



