Plants as Affected by Fungous Parasites. 171 
makes it preferable to the latter for use upon plants of 
which the fruit is nearly mature. To make this solution, 
dissolve one and a half ounces of precipitated copper carbon- 
ate in one quart of strong commercial ammonia, and add 
this solution to 25 gallons of water. The ammonia should 
be procured in a glass or earthen vessel, and should be 
kept tightly corked. To prevent waste of the ammonia by 
evaporation, add the solution to the water immediately be- 
fore spraying. 
332. Potassium Sulfid Solution is used to some ex- 
tent to prevent gooseberry mildew (330), and a few other 
diseases, but it is less enduring in its effects than the cop- 
per compounds. To prepare it, dissolve one-half ounce of 
potassium sulfid (sulfuret of potassium, liver of sulfur) in 
one gallon of water and apply immediately. The sulfid is 
best dissolved in a little warm water and then diluted. 
333. Moisture Favors Spore Germination, hence a 
free circulation of air through the orchard and vineyard 
tends to prevent fungous diseases, Branches of fruit trees 
should not be permitted to hang near the ground, and 
weeds should be kept down. 
Bunches of grapes are sometimes inclosed on the vine, in 
paper bags, to keep them dry, and thus preserve them from 
fungous attack. Grape vines sheltered from rains by a 
cornice are seldom much troubled with fungous diseases, 
334. Fungi that Develop chiefly on the Outside of the 
Plant (epiphytic (ep-i-phyt’-ic) fungi), are as a rule readily 
controlled by sulfur, either in the form of ‘ flowers of sulfur,” 
or the solution of potassium sulfid (332). To this class be- 
long the powdery mildews of the grape,* apple ¢ etc, 
* Uncinula spiralis. + Podosphera oxycanthe. 
