DISEASES INJURIOUS TO FRUITS. 121 



and drop off and the wood fails to mature. In bad cases the 

 berries become discolored and perhaps ruined. As a rule, this 

 disease does not cause serious injury in good locations in this 

 section; but in wet seasons, or on wet land in any season, or 

 where there is a poor circulation of air it may be very destruc- 

 tive. 



Remedies. These should be preventives largely, and con- 

 sist of allowing plenty of room between the plants for a good 

 circulation of air and keeping them in as vigorous a state of 

 health as possible by manuring and cultivating. If the disease 

 makes its appearance in the face of these precautions, recourse 

 should be had to the following remedy, which is very satis- 

 factory: Spray the plants in the spring as soon as the young 

 leaves begin to unfold, and repeat it as often as once in eigh- 

 teen or twenty days, except in times of heavy rains when it 

 must be done oftener. For this purpose use liver of sulfur 

 (Potassium sulfide) dissolved in water at the rate of one-half 

 ounce to the gallon. 



Leaf Spot (Septoria ribes). Both currant and gooseberry 

 are injured by what is termed leaf spot, which causes deadened 

 spots in the foliage. It may be prevented by spraying with 

 Bordeaux mixture before the fruit begins to color and again 

 after the fruit is picked. 



QUESTIONS CHAPTER VII. 

 Diseases. 



1. What portions of the plant are most susceptible to disease? 



2. How are the majority of plant diseases propagated? 



3. What is meant by the alternation of generations? 



4. How are plant diseases generally treated? 



5. Describe the injury caused by the following diseases of the 

 plum and give remedy for each: Plum Pocket, Leaf Curl, Black Rot, 

 Brown Rot, Shot Hole Fungus, Crown Gall. 



6. What diseases are injurious to the pear? 



7. Describe the injury caused by the following diseases of the 

 apple and give remedy for each: Apple Blight, Bitter Rot, Black Rot, 

 Crown Gall, Leaf Rust, Apple Scab, Powdery Mildew, Fruit Scald. 



8. How does spraying sometimes injure the trees? 



9. How does frost affect the trees? 



10. What is sunscald and how does it Injure the trees? 



11. How may it be remedied? 



12. Describe the injury caused by the following diseases of the 

 peach and give remedy for each: Brown Rot, Crown Gall, Leaf Scald, 

 Scab, Yellows. 



