INSECTS, FUNGI, PLANT DISK ASKS, ETC. 173 



genous organic fertilizers, and allowing the land to grow 

 up in weeds, will sometimes remedy the evil. In renew- 

 ing the fertilizing materials use potash and phosphoric 

 acid, and, as the tree begins to recover, add a little nitrate 

 of soda or sulphate of ammonia until the tree is brought 

 to its normal condition again. Low, wet soils will also 

 produce this disease, and in that case, thorough drainage 

 must be resorted to. 



Scab of the Lemon {Verrucosis)* The leaves affected 

 with this disease exhibit small, wart-like excrescences 

 of various sizes; in some cases running together and 

 covering a large portion of the leaf or fruit. At first these 

 warts look like small semi-transparent pimples of a 

 slightly lighter shade of green than the surrounding sur- 

 face. In a few days these warts assume a more prominent 

 form, and present a watery cast. Then a fungus makes 

 its appearance, which is at first gray, then dusky, and 

 at last black. Finally the tissue covering the tips of the 

 warts is cut off from the healthy tissue below by the for- 

 mation of cork, and ultimately this cork formation be- 

 comes so abundant as to give a dingy white color to the 

 old warts. 



Treatment. — Proper application of ammoniacal solu- 

 tion of copper carbonate will be found efficient. Remove 

 all infected fruit from the tree and the ground before 

 the blooming begins. Destroy all sour orange trees in 

 the vicinity of the lemon trees, because these are very 

 susceptible to the disease, and will give trouble. Spray 

 with the ammoniacal solution of copper carbonate first 

 when the fruit begins to appear; spray a second time two 

 weeks after; and a third spraying may be required two or 

 three weeks later, when the blooming season is over. 



The ammoniacal solution of copper carbonate is made 



*Bulletin 8, Vegetable Physiology and Pathology, U. S. Dept. Agri. 



