382 TEXTBOOK OF BOTANY 



entire fruit. The fruit now decays, and in the meantime 

 the fungus produces an abundance of spores, which may 

 be scattered by the wind or may remain on the stems and 

 leaves to spread the disease the following year. The fruit 

 finally becomes hard, shriveled, and wrinkled (Fig. 216) ; 

 in this condition it either remains on the stem or falls to 

 the ground. The next spring the plant 

 body of the fungus, which has remained 

 dormant in the decayed fruit, develops 

 a saucer-shaped fruiting body on a short 

 stalk. Within this saucer are borne an 

 immense number of small sacs in each 

 of which eight spores are produced. In 

 order to check the ravages of this fungus 

 it is necessary to remove the diseased 

 portions of the plant as soon as they are 

 FIG. 217. Spores of discovered. These, with the decayed 

 the brown rot fungus f m it s f rom the tree and ground, should 

 ^ once be burned, because the spores 

 may be carried to a considerable distance 

 by the wind. Spraying also helps to check the growth of 

 the fungus. For this purpose, modifications of the ordinary 

 Bordeaux mixture and a lime-sulphur wash are probably 

 the best. 1 



386. Powdery Mildews. More than sixteen hundred 

 species of seed plants are known to be attacked by one or 

 another of these parasitic fungi. Although strict parasites, 



1 Lime-sulphur wash. This can be obtained in prepared form, or it may be made 

 according to the following formula : 



Flowers of sulphur, 10 pounds. 

 Stone lime, 10 pounds. 



Water, 50 gallons. 



The lime is poured into a barrel, three to five gallons of water are added, then the 

 sulphur is sifted in and the whole mixture is stirred while the lime is being slaked. 

 More water is added as the mixture becomes heated. When the lime is entirely 

 slaked the rest of the water may be added. 



