348 



The Spraying of Plants. 



leaves (Fig. 80) ; the affected portions may be small, or they 

 may extend over the entire leaflet. Tn this respect it differs 



FIG. 80. Potato foliage attacked by Phytophthora infestans, a fungus which 

 causes rotting of the tubers. 



plainly from the early blight, which progresses slowly, and 

 causes distinct, circular spots, while those produced by the 

 rot are at first small and irregular but they rapidly extend 



