Further Studies of the ‘Brown Rot’ Fungi. 
I. A Shoot-Wilt and Canker of Plum Trees caused by 
Sclerotinia cinerea. 
BY 
H. WORMALD, 
Research Department , South-Eastern Agricultural College , Wye, Kent . 
With Plates XIII and XIV. 
Contents. 
PAGE 
I. General Observations 305 
II. Isolation and Cultural Experiments 308 
III. Inoculation Experiments 310 
(a) On Plum Leaves ............ 310 
( b ) On Plum Fruits 3 r 4 
( c ) On Apple Flowers . • 3*5 
IV. Comparative Tests for Presence of Oxidase in Cultures . . . . 316 
V. ‘Shoot-Wilt’ and ‘Wither-Tip’ compared 3 X 7 
VI. The Economic Importance and the Control of the Disease . 318 
VII. Summary 319 
I. General Observations. 
ABOUT the middle of May 1919 a row of Victoria plum trees in the fruit 
l \ plantation at Wye College was examined for the early symptoms of 
‘ Wither-Tip a disease from which some of the trees had suffered in 
previous years. This disease, described fully elsewhere, 1 is characterized, 
as the name implies, by a withering of the tips of the young green terminal 
shoots of the branches. In the present case the terminal shoots had made 
but little growth at the time the examination was made and typical 
instances of Wither-Tip were not seen. It was found, however, that a 
number of short leafy shoots had been recently killed ; these shoots were 
borne laterally on the twigs produced the previous year, and they were such 
as would have remained short and become ‘ fruiting spurs ’ in the following 
season. 2 The largest leaves on these wilted shoots were only from 2 to 
1 Wormald, H. : A ‘Wither-Tip’ of Plum Trees. Ann. Appl. Biol., v, 1918, pp. 28-59. 
2 Each of these lateral shoots consists of a number of leaves borne on a very short axis ; the 
buds which develop in the axils of these leaves give rise to leaves and flowers the following spring 
(Plate XIII, Fig. 6). 
[Annals of Botany, Vol. XXXVI. No. CXLIII. July, 1922.] 
