A NEW APPLE TREE CANKER. 



By V- A. PuTTERiLL, \[.A., Division of Botany, Pretoria. 



IVHh 6 Text Figures and Plates XXI-XXX. 



Read July ii, 1919. 



In February of this year a parcel of diseased apple tree ' 

 branches was received at the Phytopathological Laboratories 

 from the Vereenig-ing" Estates, Ltd. Mr. Brandmuller, the 

 manager of the Estates, wrote of them as follows :— 



" The disease frequently occurs in our old apple 

 orchards, but I have not yet noticed it in our younger 

 orchards, in which the trees are from two to ten years old. 

 All varieties of apples planted here are subject to it, but 

 chiefly White Winter Pearmain. The trees are sprayed 

 regularly with fungicide, in earlier years with Bordeaux 

 mixture, in latter years with commercial lime-sulphur. All 

 diseased branches are cut out and burned. I shall be glad 

 if you can recommend me any other measures of control, as 

 the disease appears to get more troublesome every year." 

 In a later letter the. manager writes :— 



" I made an inspection and foimd 58 trees out of 2,500 

 trees in our older orchard affected, which I had burned 

 before taking them out." 



In June I paid a visit to the Vereeniging Estates to see the 

 extent of the disease in the orchards. The disease ,has been 

 giving trouble in the oldest orchard of 2,500 trees ; 58 of these 

 haA already been burned, but a nimiber showing the disease still 

 remained. The majority of these were the Vellow Bell Flower 

 variety on non-blight proof stock, some 20 i^ears old, which had 

 been cut down and worked over to Versfeld, White Winter Pear- 

 main, Cellini, and Rome Beauty, etc., about nine years before. 

 The disease was especially bad on the Yellow Flower part of 

 the trees, in many cases confined to it, ofte?i almost completely 

 girdling the six-inch diameter trunk; whereas the to()s looked 

 particularly hcaltlw, though cankers were p'-esent on some of 

 the younger limbs. (See plates XXI, XXII, and XXVII (b).) 



Mr. Brandmuller states that the disease first came to his 

 notice, as something which might i^ossibly be harmful, about two 

 years ago, through the dying of branches when the trees were in 

 leaf. Prior to this, he is of oi:)inion that possibly the disease 

 was overlooked owing to its being confused with sun scorch. 

 The control measures he has used consist largely in cutting out 

 diseased branches and cankers, and jxiinting over the wound, 



