23 



The regular spraying, as outlined under spraying, should keep it under control. 

 Sometimes, however, rot will develop as the fruit is ripening and sprays that 

 mark the fruit can not be used. At this time use ammoniacal copper carbonate. 



Copper carbonate, 5 ounces. Ammonia, (20° Baume) three pints. "Water, 

 forty-five gallons, 



Eefer to Bulletin 195, Ontario Department of Agriculture, page 36, for full 

 instructions in making. 



Black Knot^ PloiorigJitia morbosa. — This is the most serious disease affecting 

 the tree. It is a fungus that works in the inner tissues of the limbs and twigs 

 and cannot be controlled by spraying. It shows itself quite plainly by making 

 rough looking knots in various places. 



Control: All diseased parts must be cut out and destroyed in late fall or 

 winter. Don't wait till late spring or early summer. If the trunk or main 

 limbs are affected the diseased parts may be cut out as thoroughly as possible and 

 the wound painted with red lead. It is recommended, however, that when the 

 trunk is badly affected, to remove the tree entirely to prevent the spread of in- 

 fection. If a large limb is badly affected it is safer to cut out and destroy than 

 to attempt a remedy. The orchardist can not be too careful about the removal 

 of all infested parts as fast as they appear. Oontrol will not be complete unless 

 the methods are thorough. 



Leaf Spot oe Shot-Hole Fungus, Cylindrosporium padi, is a fungus which 

 shows itself by making somewhat cylindrical holes in the leaves. It is not com- 

 paratively serious and is controlled by good orchard methods and the regular 

 sprays applied thoroughly. 



Plum Pockets, Exoascus pruni, is not common in Ontario, but is worthy of 

 mention. The small green plums become enlarged, soft and spongy. The nu- 

 trition of the stone seems to be interfered with, as it does not develop. It also 

 causes a curling of the leaves similar to peach leaf curl. 



Control : Eemove or cut out all signs of disease. The first spray should keep 

 it under control if applied just as the buds are beginning to swell. 



Sun-Scald is injury caused by the rays of the sun blistering and destroying 

 the exposed trees and limbs. It might be considered a form of winter injury. 

 The bark cracks and shells; breaking away from the wood beneath, exposing the 

 tissues. When once the bark is broken disease spores are likely to get in and 

 start decay. 



Control: Prevention is the only remedy. Bank up the tree with earth to a 

 height of about eight or ten inches. Cut ordinary rolls of building paper into 

 about four lengths with a saw and use this to wrap the trunks from the top of the 

 bank to the lower limbs. Put on the paper much the same as' a bandage or legging 

 and tie at the top with twine. Wrap loosely but tie tightly. 



If the tree is already damaged cut away the loose bark and all decayed and 

 dead parts, if possible, and paint with white or red lead. Or if you prefer it, cover 

 the whole of the exposed tissues with grating wax. Low heading lessens the 

 liability to the trouble, Gummosis or gumming of the wood, is somewhat common 

 and where common is serious. It apparently is the result of mechanical injuries, 

 though it is not proven, Hedrick in ''Plums of New York" says, "The disease 

 i^ least common in specfes and varieties having hard wood ; on trees on soils 

 favoring the maturity of wood; under conditions where sun and frost are not 

 injurious; and obviously, in orchards where by good care the primary causes of 

 gumming are kept out. 



