1556 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



Remedy 



In California it has been found tliat 

 the disease may be kept under control 

 by regular fall spraying with Bordeaux 

 mixture without spring applications. In 

 Oregon the fall application is undoubt- 

 edly the most important, but where the 

 disease is firmly established it is prob- 

 able that spring applications will also 

 be necessary. After the disease is under 

 control, and where fall spraying is regu- 

 larly practiced, it may later be found 

 that the spring spraying may be dis- 

 pensed with. ^^ _, _. 



H. S. Jacksoit, 



Corvallis, Ore. 

 Cankers 



The term "canker" is to be applied to 

 any definite dead area in the bark of the 

 limbs or body of the tree. There are 

 several cankers of the peach tree. The 

 one most frequently spoken of is per- 

 haps the Valsa canker. This is a very 

 common canker on the bodies of the 

 trees just above the ground or on the 

 larger limbs. Sometimes the twigs of 

 the trees appear to be killed by the same 

 disease. The losses from this malady 

 are sometimes serious. 



Symptoms 



The cankers appear as dead, sunken 

 areas in the bark, at first at least, with 

 no definite cracking of the bark along 

 the margins of the diseased area. The 

 bark in to the wood appears to be killed 

 and the depression results chiefly from 

 the formation of a new wood layer over 

 all the parts of the trunk or limb ex- 

 cept where the bark has been killed. 

 The yellowing of the foliage and the 

 dying of the tree follows as the diseased 

 areas enlarge and girdle limbs or body. 

 The surface of the cankers soon show 

 the white tips of the fruit bodies pro- 

 truding through the checks and cracks 

 of the dead bark- 

 Cause 



Whether the fungus Valsa leuoostoma 

 so commonly present in the dead bark 

 of these cankers is the primary cause 

 of the injury is rather doubtful. It ap- 



pears more probable that these cankers 

 or dead areas are the result of winter 

 injury, and the fungus always present 

 on dead limbs and twigs in the peach 

 orchard quickly finds its way to this in- 

 jured bark and there develops rapidly, 

 no doubt extending the original injured 

 area from year to year. Here it pro- 

 duces its spores in the fruit bodies sunk- 

 en in the bark, the white tips of which 

 protruding permit the extrusion and dis- 

 semination of the spores. It is generally 

 observed that this disease is much more 

 severe the season following severe winter 

 injury. 



Control 



The prompt cutting out of the dis- 

 eased bark as soon as the cankers are 

 discovered is the only measure to be 

 suggested. Cut half an inch or so out 

 into the healthy bark all round the dis- 

 eased area. Carefully and thoroughly 

 clean away all the diseased tissue and 

 tar the wound with gas tar or paint with 

 good paint free of turpentine. 



H. H. Whetzel, 

 N. Y. State College. 



A New Disease of Peaches 



The disease occurs in the Niagara dis- 

 trict and extends into New York state 

 wherever peaches are grown. It mani- 

 fests itself by larger or smaller cankers 

 occurring on trees of all ages, often 

 somewhat like the common black knot 

 ot plums and cherries. Closer examina- 

 tion shows, however, that these "knots" 

 are characteristic canker spots. They 

 may occur on all parts of the tree, the 

 main trunk, especially the crotch, smal- 

 ler limbs and quite young wood. In 

 some instances, the cankers encircle the 

 whole limb, rendering it liable to be 

 broken by wind or by the weight of the 

 fruit that may still be produced. As far 

 as could be learned from a personal 

 examination of a number of orchards, 

 the disease is contagious and spreads 

 rapidly. No variety seems exempt from 

 an attack and the age of the tree seems 

 to make little difference. The disease 

 was first observed by growers about four 



