54 



scattered here and there over its surface. These tufts of the 

 fungus occur both on the main branches nearly down to their 

 base (see Fig. 3), and frequently also on the younger wood. 



Small hard, blackish bodies, of irregular shape, named 

 sclerotia are also produced in the bark. They are the resting 

 bodies of the fungus and on subsequent germination give rise 

 to multitudes of spores which spread the disease. They are 

 extremely resistant to climatic conditions such as frost, drought, 

 &c. , and serve to carry the fungus through all vicissitudes from 

 one growing season to the next. 



(b) The Young Wood. In the case of young bushes 

 especially, a considerable proportion of the young shoots 

 may be affected by Botrytis and much weakened or killed 

 a fact which has caused growers to speak of the disease as 

 " die-back "'(see Fig. 4). The dead shoots may constitute a 

 prolific source of infection. Prunings of Bon/ts-afiected 

 bushes left lying in a heap in a corner of the plantation or 

 garden may develop during the following spring an 

 abundant crop of powdery tufts of Botrytis, the spores 

 of which, carried by the wind in countless numbers, will 

 spread the disease through the plantation. There is also 

 the danger of cuttings having been taken from Botrytis -infected 

 bushes, when many of the young bushes resulting therefrom 

 will become diseased. 



(c) The Leaves. Very commonly Botrytis infects the 

 leaves, which soon become discoloured at their edges, at 

 first turning yellowish, and finally ashy-grey or whitish 

 (see Fig. 3). If the attack extends from the edge of the 

 leaf inwards until the greater part of the leaf is affected 

 the fall of the leaf soon takes place ; if, however, as is often 

 the case, the injury remains restricted to the edges of the 

 leaves, they remain on the bush until they drop in the normal 

 way. Whebher the injury spreads over the leaf to such an 

 extent as to make it fall prematurely seems to depend on the 

 climatic conditions which prevail at the time. 



(d) The Berries. Lastly, the fungus occasionally attacks 

 the berries and causes them to rot. The first sign of disease 

 on the berry is the browning of the skin; this browning 

 gradually extends until one side of the berry shows obvious 

 signs of softening and of being badly diseased. The Botrytis 

 fructification, in the form of the characteristic ashy-grey 

 " mould," then appears on the surface of the discoloured 

 portions and in about a week the berry becomes completely 

 rotten. 



Measures of Control 1. Sanitation. The most effective 

 treatment is to remove and burn all dead bushes or branches 

 in the plantation. As soon as the edges of the leaves show 

 si^ns of discoloration, all the bushes in the plantation should 

 be examined and any found with the main stem diseased 



