42 



Cherries. Cherry trees attacked by die-back usually show 

 a general yellowing or withering of the leaves, commencing 

 at the tips of the shoots. This may commence in spring and 

 may spread so rapidly (see Fig. 2) that by autumn the whole 

 of the upper part of the tree may be dead. When this takes 

 place cracks, from which a viscid gum oozes, often appear in 

 the bark (usually at the crown or at the base of the trunk) and 

 at the same time young shoots arise from the base. On the 

 dead wood the fungus produces spore-pustules abundantly, 

 and in moist weather reddish, tendril-like threads of spores are 

 extruded as in the case of other varieties of fruit trees. The 

 varieties " Noble " and " Napoleon " suffer the most 

 seriously.* 



Measures of Control. 1. Die-back Form. If tackled 

 promptly the disease can to a certain extent be controlled. In 

 the case of a die-back, it is of the utmost importance that the 

 diseased portion should be cut away and burned as soon as it is 

 noticed. The longer it is left, the greater is the amount of 

 damage done. The shoot should be cut back to the still healthy 

 region and the wood painted over with tar. 



2. Canker Form. Where the fungus has formed cankerous 

 wounds on the main branch or on the trunk, the affected part, 

 if observed early enough, may be cut out with a knife or chisel, 

 taking care to remove all the diseased tissue. As the fungus 

 is a wound parasite, the trees should be damaged as little as 

 possible during these operations; all rough wounds should 

 be pared over with a knife and protected immediately with a 

 coating of tar. In order to prevent further spore-liberation 

 great care should be exercised to collect and burn all diseased 

 wood. 



3. Badly Attacked Trees. If the disease once obtains a firm 

 hold and the case is beyond recovery, the trees should be taken 1 

 up at once and the branches cut off and burned to prevent the 

 liberation of further spores. 



PEACH LEAF-CURL. 



(Exoascus deformans.) 



Peach leaf -curl attacks peaches, nectarines and, less fre- 

 quently, almonds; it occurs constantly in this ^ country 

 wherever these plants are grown in the open, but is much 

 less prevalent on trees under glass. The disease is caused by 

 a fungus and, in seasons which favour the fungus, the attack 

 may prove very destructive. It is now known that Peach 

 Leaf-curl can be controlled effectively by spraying. There is, 

 therefore, no necessity for the extensive outbreaks which in 

 the past have so often annoyed and baffled the grower of out- 

 door peaches. 



* For details of the disease on cherries see Wormald, H., Jour. South 

 Eastern Agric. College, Wye, Kent, No. 21, 1912. 



