284 PLANT DISEASES 



If the spraying had been done a month earlier, it is reason- 

 able to suppose that with proper care in application the 

 rot could have been almost entirely prevented. 



* Where copper remedies are used for black rot or mildew, 

 it is not unlikely that the grapes are in danger from the 

 ripe rot [= apple rot], and in cases where no remedies 

 have been used, two or three sprayings will probably pro- 

 tect the grapes. For this it will not be necessary to go to 

 the expense of preparing the Bordeaux mixture, but the 

 ammoniacal solution, or even the potassium sulphide 

 solution, will probably be satisfactory.' 



Galloway, U.S. Dept. of Agriculture, Bull. No. 8, p. 61 ; 

 and in Ann. Rep. U.S. Dept. Agric.^ 1889, p. 412, figs. 

 Southworth,ybwr. My col. ^ vol. vi. p. 164. 



PLANE LEAF SCORCH 



(Gloeosporium nervisequum, Sacc.) 



A destructive fungus, causing defoliation of planes in 

 Europe and the United States. When the leaves are just 

 full-grown, scattered brown spots appear, often following 

 the veins ; sometimes the patches become very large, 

 from the meeting and blending of originally distinct areas 

 of disease. The mycelium passes from the veins into the 

 leaf-stalk, when the leaf soon falls before it is dead ; 

 by this means trees are often destitute of leaves at mid- 

 summer. Minute blackish pustules containing the spores 

 are formed on the veins on the under surface of the leaf. 

 At maturity the spores ooze to the surface in a mass, held 

 together by mucilage, are dispersed by rain, and, being 

 capable of germinating at once, infect fresh leaves. 



Platanus occidentalis, L., and P. orientalis, L., suffer 

 severely, P. occidentalis, the American species, being most 



