Plant Diseases. 49 



Lettuce. MILDEW (Peronospora gangliformis, De Bary). 

 A delicate mildew, attacking lettuce leaves and causing 

 yellow or brown spots, and finally killing the leaf. 



Preventives. (According to Maynard.) Grow at a low 

 temperature (35 to 40 at night, 50 to 70 during day); give 

 abundance of plant food ; give abundance of water, but 

 apply it in morning and bright days only ; avoid sudden 

 extreme changes of temperature. 

 Remedy. Fumes of sulphur. 



Maple. LEAF-SPOT (Phyllosticta acericola, C. & E.). 

 Attacks the leaves of red, silver, and striped maples in 

 spring, causing them to become spotted and unsightly, 

 and lessening the vigor of the tree. 



Remedies. Rake and burn the leaves in autumn. When 

 the leaves are two-thirds grown spray with sulphide of 

 potassium, and repeat every three or four weeks as long 

 as necessary. 



Onion. RUST (Peronospora Schleideniana, Unger). The 

 leaves turn yellow about the time the onions begin to bot- 

 tom, or a little later, and wilt and die. 



Preventive. There is no remedy known. Exercise care 

 to grow on land not infected, and destroy all affected 

 onions. 



Orange. ORANGE-LEAF SCAB (Cladosporium). The leaves 

 become yellow and distorted. 



Remedy. Spray with Grison liquid, or carbolic acid and 

 glycerine mixture. 



Peach. BROWN -ROT. See under Cherry. 



CURL, LEAF-CURL OR "FRENCHING," (Taphrina deformans, 

 Tul. ; written also Ascomyces deformans and Exoascus de- 

 formans}. The leaves become blistered and crumpled early 

 in the season and fall off. 



Remedy. It seldom does much damage, and the trees 

 usually renew their foliage the same season. Good cult- 

 ure, to enable the tree to put forth new leaves, is to be 

 recommended. 



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