1142 WlTHER-TlP AND BROWN ROT OF PlAJMS. [MaR., 



WITHER-TIP AND BROWN ROT OF 



PLUMS, 



The decay of ripe plums known as Brown Rot is a disease 

 familiar to all growers. It is a serious trouble wherever this 

 fruit is cultivated, and the losses due to the disease, both on the 

 trees and in market consignments, are often very heavy. The 

 attack by the Brown Rot fungus on the flowers and shoots of 

 the Plum Tree, which is known as " Blossom-Wilt and Wither- 

 Tip " respectively is quite as serious, and at times more serious, 

 and has only recently been recognised and carefully studied. 

 The details of the various Brown Rot fungi and their method 

 of attack have been followed with extreme care and minuteness 

 by Dr. H. Wormald, of Wye College, to whom practically the 

 whole of our knowledge of Brown Rots, as they occur on fruit 

 trees in this country, is due, and on wmose work this article is 

 based. 



The fungus concerned in the various attacks on plums is 

 Monilia cinerea, forma pruni. It is a form of this same species 

 (M. cinerea, forma mali) which causes the Blossom-Wilt of 

 apple. The two forms, however, are quite distinct. The plum 

 form is apparently unable to cause Blossom-Wilt of apples and 

 the apple form has not been found on plums. This should be a ' 

 matter of considerable satisfaction to growers when the number 

 of apple orchards interplanted with plums is considered. 



Brown Rot of cherries is caused by the same fungus as Brown 

 Rot of plums, and in this case, also, it attacks the blossom and 

 the wood as well as the fruit. The description given in this 

 article, and also the control measures recommended, would apply 

 equally to cherries. 



Blossom- Wilt. — The Brown-Rot fungus produces a Blossom- 

 Wilt of plums similar to that found on apples (see Leaflet 312). 

 In the spring, spores derived from the mummied plums on the 

 trees, and from spore -pustules on infected wood, are blown on 

 to the flowers. The spores readily infect the stigma, and the 

 mycelium of the fungus passes down the style and causes the 

 death of the flowers (Fig. 1 and 2). The mycelium subsequently 

 passes through the flower-stalk into the wood and attacks the 



All the photographs used in this article are bv Dr. Wormald. and the first 

 five are reproduced from the Annnls of Applipd Biology, Vol. V, by kind 

 permission of Dr. Wormald and the Cambridge University Press. 



