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BUD BLAST, CANKER, AND DIEBACK OF YOUNG APPLE TREES 

 IN MASSACHUSETTS: A PROGRESS REPORT 



Daniel R. Cooley, Franzine D. Smith and William J. Manning 

 Department of Plant Pathology 



and 



Robert A. Spitko 

 New England Fruit Consultants 



During the 1981 and 1982 growing seasons, a bud blast and branch 

 dieback problem occurred on young apple trees in a few scattered orchards in 

 Massachusetts. In the 1984 season bud blast, branch and trunk cankers and 

 terminal dieback were wide-spread in the State and other apple-growing 

 regions of New England. 



Symptoms of bud blast and branch and trunk cankers were first noted on 

 young trees in the third to tenth leaf. Petioles from the previous season's 

 leaves were evident on vegetative shoots. Affected trees were usually less 

 than 10-years-old and had made very vigorous vegetative shoot growth in 

 1983. Symptoms occurred on many apple varieties, but were more prevalent 

 and severe on Mcintosh, especially on Marshall Mcintosh. 



These symptoms ^re illustrated in Figure 1. They resemble winter 

 injury and this was our initial diagnosis. The prolonged warm autumn of 

 1983, a rapid drop in temperature to -1B° F (or lower in places) during 

 early winter, and a February thaw contributed to the diagnosis of winter 

 injury. 



We also noted, however, that unique aspects of some of these symptoms 

 resembled those caused by plant pathogens. Rud blast and canker and dieback 

 can be caused by plant-pathogenic bacteria, while branch and trunk cankers 

 and terminal dieback can be caused by bacteria and/or plant pathogenic 

 fungi . 



Further examination of the symptoms resulted in the conclusion that two 

 different yet related syndromes were present. Rud blast and branch dieback 

 appear to be one problem, while branch and trunk cankers and terminal 

 dieback are probably another problem. Both are different, but share the 

 canker symptom and are probably both associated with winter injury. To 

 identify organisms associated with the problems, samples were taken from 

 affected trees from spring to autumn. Isolations were made in the labora- 

 tory and resulting bacterial and fungal colonies were identified. 



In bud blast and branch canker and dieback, affected vegetative buds 

 are either killed or produce only small distorted leaves. Branch cankers 

 develop and branches may be killed back to the trunk of the tree. In 

 spring, bacteria can be observed in affected buds and in the cambium beneath 

 buds. Of the bacteria isolated, several, such as Pseudomonas syringae , may 

 be plant pathogens. Frequency of isolation of bacteria decreased as the 

 season advanced. Several potential canker fungi such as Sphaeropsis , 

 Cytospora , and Cephalosporium , and some wood decay fungi such as Irpex , 

 Coriolus and Schi zophyllum , increased in frequency as the season advanced. 



