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ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



well as some more or less connected ex- 

 perimental work done by several persons 

 in different localities and widely differ- 

 ing conditions show that the control of 

 this disease is by far more important than 

 suspected at an earlier date. It is now 

 definitely Icnown that the fungus has two 

 stages, one of which may be termed the 

 conidial and the other the ascigerous. 

 Also that the fungus attacks the prune, 

 plum and pear causing shallow cankers 

 in the outer bark of the trunks and larger 

 branches; will induce Gummosis of the 

 cherry and in addition to the destruction 

 wrought upon the apple tree, also causes 

 the most serious loss of apples in both 

 common and cold storage due to a fungus, 

 as well as causing a similar decay of the 

 fruit of the quince. 



The recognition and control of the dis- 

 ease caused by this fungus which is now 

 known under the scientific name of Xe- 

 ofdbraea Malicorticis (Cordley), Jackson, 

 is of greatest importance as a disease of 

 the apple since the fungus attacks the 

 body of the tree directly threatening the 

 life of the plant and later produces 

 spores which lodge upon the fruit causing 

 serious losses of the fruit after it has 

 been placed in common or cold storage. 



The discovery that there are two spore 

 forms developed in a canker and that the 

 conidia mature the first year while the 

 bark is dying or a little later and that 

 the second year another crop of spores 

 (ascospores) are thrown out. should make 

 the orchardist doubly cautious in attempt- 

 ing to eradicate the disease since the dis- 

 tribution of spores continues for so long 

 a period. 



Thorough applications of fungicides 

 during the autumn applied previous to 

 the early rains of winter do control the 

 disease. Owing to the late date apple 

 harvesting continues, it is sometimes true 

 that the autumn rains are heavy enough 

 to make the soil so muddy that it is im- 

 possible to spray following the gathering 

 of the fruit. Owing to the fact that tests 

 with lime-sulphur and Bordeaux mixture 

 made on mature fruit shortly be- 

 fore picking time have at least 

 indicated that the fruit may be sprayed 

 without the slightest injury, it seems ad- 



visable to spray the fruit before gathering 

 it. Such applications should control the 

 spread of the fungus for a short period at 

 least and kill all the spores of the fungus 

 (anthracnose) adhering to the fruit as 

 well as in part preventing the late infec- 

 tion of apple scab which sometimes takes 

 place upon the fruit after the same has 

 been wrapped, packed and placed in stor- 

 age. 



A thorough spraying with double 

 strength Bordeaux mixture, applied in 

 spring before the buds began to open, has 

 also given the desired results. At this 

 time the entire tree is exposed to the 

 direct drive of the spray and the trees 

 may be so thoroughly coated that the 

 amount of spray that will adhere to the 

 bark during the entire season is sufficient 

 to give as good results as have been ob- 

 tained through applications during au- 

 tumn. This spring spraying admits of 

 thoroughly soaking all the cankers which 

 if in a dry condition have been observed 

 to become a deep blue color, due to the 

 dead bark absorbing large quantities of 

 the spray. 



In cleaning up a badly infested orchard 

 the dead bark should be torn from all 

 the cankers and as many of the new cank- 

 ers scraped as practicable, after which 

 one or more thorough sprayings, prefer- 

 ably with Bordeaux, should be made. 



Black Spot Fungus or Scab 



Fusicladium detidriticum 

 During recent years the apple scab 

 fungus has been very troublesome in 

 Canada, often injuring the fruit so badly 

 that it is quite unsaleable. The disease 

 attacks the tree in early spring and is 

 first noticeable as light green patches 

 on the young leaves. The fruit may be 

 affected as soon as formed and if badly 

 diseased will drop off. As the fruit in- 

 creases in size the diseased patches en- 

 large and nearly all the surface is often 

 covered with the black spots before the 

 fruit is picked. In addition to the dis- 

 figured appearance of the fruit, caused 

 by this disease, the apples do not reach 

 their full size. The apple spot develops 

 most rapidly in moist weather. This 

 disease may be almost entirely prevented 



