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Bark and Wood Diseases Spread by the Pruning 1 Shears. 



I am inclined to think that the method of pruning may have had 

 much to do with the diseased condition of occasional specimens sub- 

 mitted to me. It not unfrequently happens that diseases of the bark 

 and wood are unwittingly spread through pruning with infected shears 

 or other tools. To give an illustration, suppose that at the first cut 

 the shears pass through a pustule of some disease, such as is to be 

 occasionally found on almost any tree, in connection with the dead or 

 weakened branches that need cutting away. The shears thus become 

 smeared with the spores of the disease, and at the next cut these 

 spores are transferred to another part of the tree, where they may have 

 a good chance to establish themselves so as to do much harm. The 

 operation just described constitutes an almost ideal method of spread- 

 ing the disease by inoculation, and there can be little doubt that in the 

 case of certain diseases, especially of the bark, this is one of the most 

 common methods by which the disease is spread. The obvious remedy 

 is to disinfect the shear cuts, and this can be done by the application 

 of any one of several substances, such as good white lead paint, white- 

 wash, thick Bordeaux mixture, or even hot grafting wax. 



Of course, after the disease has got a good hold at an old pruning 

 mark it is not easy to eradicate it. The best way to proceed is to 

 scrub or scrape down the trunk and larger branches so as to remove 

 all the old bark possible. These scrapings should be burned. After- 

 wards apply the lime, sulphur and salt mixture, or thick Bordeaux 

 mixture to the trunk and branches, preferably in the winter. If it 

 appears on the preliminary examination that the old marks of pruning 

 present rotten and soft wood, and there are no signs of the wound 

 healing over properly, it would be well to give these special attention 

 by cutting away until the wood looks fresh and healthy. If these new 

 uts are treated with paint as mentioned above nothing further can be 

 done for them. In the case of roses and some other plants, if the tree 

 has become much weakened, it would be well to keep it well pruned so 

 as to encourage it to throw new shoots from below. These, if the roots 

 are still good, will in time in certain instances replace the old trunk. 



TECHNICAL NOTES ON CITRUS DISEASES. 



Notes on the Gray Scab of the Orange. 



THESE notes have reference to the scab on the fruit of the orange 

 that afterwards becomes cracked, and which ultimately scales off, and 

 leaves a smooth depressed scar, often of an elongated shape. A few 

 weeks after its formation the scab contains minute black perithecia, 

 carrying oval unicellular spores. 



As soon as the scab is well formed, it will be found possible to 

 remove it in a cleanly manner by working patiently with a small 

 scraper. The scab comes away rather easily, except at certain points 

 which are concentric with a darker colour, as if the new skin were 

 attempting to form new oil glands. Even these parts can be 

 removed by patient scraping, leaving the new skin quite whole and 

 with a good natural-looking surface. 



