121 



down the Brown Rot diseases; it is essen- 

 tial to remove and burn all sources of in- 



FiG. 5. — Two Mummified Plums with Pustules of 

 Monilia Oinerea. 



fection, e.g., mummified fruit (see Fig. 6), 

 dead spurs, twigs and canker. 



Silver Leaf Disease. 



A disease, which must now be familiar 

 to all who cultivate plum trees and against 

 which the grower should exercise drastic 

 measures, is that known as " Silver Leaf 

 Disease," from the fact that the leaves of 

 the affected trees have a silvery sheen, 

 showing a striking contrast with the 

 normal dark green leaves of healthy trees. 

 Victoria Plum trees are very susceptible 

 to attack, and in this variety great 

 numbers of affected trees have been killed 

 outright by the disease in recent years. 

 It is important that growers should realise 

 the infectious nature of the disease and 

 make every effort to stamp it out when 

 it first appears in a plantation. The 



fungus, Stereuni purpureum, which is the 

 cause of the disease, is not found in the 

 leaves, but in the tissues of the branches 

 and stem. Sooner or later the affected 

 branches die, and then the fungus appears 

 at the surface of the bark as bracket-like 

 outgrowths, usually about one ioch in length 

 (Fig. 7) ; these are the fructifications of 

 the fungus, and trees which bear them are 



Fig, 6. — The Blossom Wilt and Canker, Disease 



of the Apple Tree, pustules of the fungus on a 



dead branch in winter. 



a source of danger to those around, for the 

 fructifications produce innumerable spores 

 which are borne on the wind to other trees. 

 Branches or trees with silvered leaves 

 should be promptly removed and burnt 

 before the fungus produces its fructifica- 

 tion. The dead stumps of such trees 

 should not be left, as these often become 

 covered with these fruiting bodies; nor 

 should the dead stems and branches be 

 allowed to remain on the ground after they 

 are cut down, or the fungus will continue 

 to develop and produce its spores. 



Stereum purpureum is a wound parasite, 

 thus care should be exercised to avoid in- 

 juring the trees as far as possible. Where 

 practicable, branches bearing heavy crops 

 should be supported to obviate the rupture 

 that might otherwise arise at the junction 

 with the stem. 



