Worm aid . — Further Studies of the ‘ Brown Rot ’ Fungi. /. 319 
VII. Summary. 
1. A wilt of the short shoots of Victoria plum trees is described. 
2. The shoots are killed soon after the leaves unfold and mycelium 
extends from the dead shoots into the twigs bearing them, causing cankers. 
3. The disintegration of the infected parts results in gummosis of the 
tissues, and gum often exudes in drops. 
4. A necrosis of the young xylem elements can be traced for several 
centimetres above and below a canker, but the mycelium extends no 
farther than the actual canker. 
5. The fructifications of Monilia cinerea are sometimes to be found on 
the infected leaves during the summer, but they do not appear on the 
cankers until the following winter and spring. 
6. Conidia taken from a canker in winter had an average size of 
n*3 x 8-4 n, but when the fungus was grown on plums (fruit) in summer the 
average size of the conidia produced under these conditions was 16-8 x 1 2*5pi. 
7. Shoot-Wilt has been induced on plum trees by inoculating punctured 
leaves with conidia of the fungus grown in pure cultures. 
8. The fungus causing the disease is Scleroiinia cinerea , (Bon.) Schroter, 
f. pruni , as shown by its — 
(a) morphology, 
(b) mode of growth in pure cultures, 
(c) inability to invade the axes of apple inflorescences when flowers 
are inoculated with conidia, 
(d) comparatively slow rate of secretion of an oxidase when growing 
in liquid culture media. 
EXPLANATION OP' PLATES XIII AND XIV. 
PLATE XIII. 
Fig. 1. Typical example of ‘ Shoot-Wilt 
Fig. 2. Two cankeis, the result of infection through short shoots, showing a copious flow of gum. 
Figs. 3 and 4. Cankers as seen in the winter following infection of the shoots ; at this stage the 
cankers bear conidial fructification of Scleroiinia cinerea . 
Fig. 5. A twig showing the terminal portion killed by infection through a short shoot. 
Fig. 6. Portion of a plum twig at the time of blossoming, showing the remains of a short shoot 
killed during the previous season ; the uninfected shoots have developed into flowering spurs. 
PLATE XIV. 
Fig. 7. Shcot-Wilt cankers showing condition duiing the second winter after infection; the 
lesions are almost covered with callus. 
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