452 notes on uromyces amgydali, cooke, 



Treatment. 



The treatment must be preventive, and spraying with ammoniacal 

 solution of copper carbonate and modified eau celeste has been 

 found successful in the United States. The improved form of 

 Bordeaux Mixture, as given in Guides to Growers, No. 15 (see 

 Literature at end), has been found effectual with us, and since the 

 lower surface of the leaves is affected, the spraying should be 

 specially directed there. 



There is another preventive measure which should never be 

 neglected, and that is the burning as far as possible of the 

 affected leaves in order to destroy the winter spores. So important 

 and so generally applicable is this advice, that the remarks of the 

 late Baron von Thuemen on this particular disease may be quoted 

 in full : — " The surest and most effectual means of combating this 

 rust, as well as other rust fungi, is to destroy the resting-spore 

 generation as far as possible. The purpose of the special spore 

 appearing in the autumn is to tide the species over the winter. 

 On the leaves lying on the ground, even if they are decayed and 

 decomposed, the spore-clusters remain for the most part com- 

 pletely safe. So when the trees put forth their young leaves next 

 year they are infected afresh from the soil, by means of the spores 

 present there in unlimited quantities, on little bits of the leaves 

 hardly recognisable. These spores, on account of their tenacity 

 of life, have received the name of 'resting-spores.' Hence the 

 imperative necessity for the fruit groM^er to destroy the leaves 

 covered with heaps of spores, in order to prevent fresh infection. 

 This is best done in the autumn when all the leaves have fallen 

 from the tree, and they may then be carefull}^ collected and 

 burnt. Or if this is impracticable, the land under the trees 

 should be deeply dug so that all affected leaves may be buried 

 deeply in the soil, where they can do no further mischief." 



Since writing this paper I have seen the Report of Professor 

 Scribner^' for 1887 on "Leaf Rust of the Cherry, Peach, Plum, 



* Report of the Commissioner of Agriculture, U.S.A., for 1887, pp. ^)58 

 to 355. 



