200 A Blossom Wilt and Canker of A^jple Trees 



indicate where pruning is necessary. If the operation is left over until 

 the winter or spring very careful search is necessary to avoid overlooking 

 some of the dead spurs and cankers, although even in winter the diseased 

 s])urs are often easily recognised from the fact that at leaf-fall the leaves 

 and remains of flowers on such spurs still remain on the trees, and the 

 pedicels and petioles may still be found on them in the spring. 



When, owing to difficulty in obtaining the necessary labour, the 

 removal of the spurs and cankers cannot be carried out before leaf-fall 

 it may be done any time during the winter, but it is imperative that all 

 diseased parts be cut off before any of the flowers begin to open. 



It is important to emphasise the fact that the operation whenever 

 carried out must involve the removal of all brown and dead wood and 

 bark. Thus it is not sufficient merely to break off the withered trusses. 

 In one experiment six withered trusses were broken off from their 

 spurs early in June 1915, at the base of that season's growth, the spurs 

 being then labelled for future reference; in April 1916 four of these 

 bore Monilia pustules. 



As already shown the disease occasionally appears on the young 

 apples causing them to become dry and withered, and such " mummified " 

 apples may be retained on the trees until the following year. Since it 

 is impossible to distinguish, without close examination, between this 

 form of Brown Rot and Monilia fructigena when occurring in this way 

 it is necessary that all "mummies" be picked and destroyed during the 

 winter, especially as Monilia fructigena itself is the cause of a serious 

 fruit rot. 



The cutting out of all affected parts before the blossoms open is the 

 only treatment that can be recommended with confidence until further 

 investigation is carried out. Owners of large standard Lord Derby 

 apple trees have in some cases found, however, that to cut out all the 

 dead trusses (which in serious attacks often number some hundreds per 

 tree) is not practicable especially when skilled labour is difficult to 

 obtain^. In those cases where the disease is very severe, "top-grafting" 

 with a less susceptible variety is to be recommended. 



Whether spraying is of value in controlling the disease is at present 

 uncertain. As infection takes place through the open flower the use 



^ Our Sussex correapondent writes: "To cut off and burn the millions of diseased 

 spurs and shoots on apples and plums is quite impracticable here." 



" Millions" is probably no exaggeration in the case of large orchards, for the writer has 

 counted over l.'^O wilted trusses (or about one-third of the whole) on a small bush tree, and 

 has seen large standard trees where the proportion of dead to living trusses was even 

 higher. 



