FERMENTATION 



337 



wrapped in paper. Why? Mold spores may be killed in a few 

 minutes with dry heat at 212° F. Dry dusting or sweeping will 

 raise dust, which usually contains spores of mold and bacteria. 

 Use a dampened broom or dust cloth frequently in the kitchen, if 

 you wish to preserve foods from molds. 



Other Moldlike Fungi. — Mildews are near relatives of the 

 molds found in our homes. Some of them attack leather, cloth, 

 etc., in a damp house. Other allied forms do damage 

 to plants such as the lilac, rose, and willow. These 

 fungi do not penetrate the host plant to any depth 

 but cover the leaves of their host with the whitish 

 threads of the mycelium and obtain food from the 

 outer layer of cells. Hence they may be killed by 

 application of some fungus-killing fluid, as Bordeaux 

 mixture.^ Among the useful plants preyed upon by 

 mildews are the plum, cherry, and peach trees. The 

 diseases known as black knot and peach curl are 

 caused by similar fungi. 



Among other parasitic fungi are rusts and smuts. 

 Smuts attack corn and other cereals and may be 

 recognized by the black smutty appearance of the 

 mass of ripened spores on the host plant. Wheat 

 rust, so called because of the rusty brown appear- 

 ance of the wheat attacked by it, is probably the 

 most destructive parasitic fungus. It does millions 

 of dollars of damage each year to wheat. Indirectly 

 this parasite is of considerable importance to city dwellers because 

 of its effect upon the price of wheat. 



Fermentation. — It is of common knowledge that the juice of 

 fresh apples, grapes, and some other fruits, if allowed to stand 

 exposed to the air for a short time, will ferment. That is, the 

 sweet juice will begin to taste sour and to have a peculiar odor, 

 which we recognize as that of alcohol. The fermenting juice 

 appears to be full of bubbles, which rise to the surface. If we col- 



Oat smut, on 

 the lower grains. 



A formula for Bordeaux mixture is 



Copper sulphate 1 pound 



Stone lime 1 pound 



Water 10 gallons 



