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Canker and wood decay fungi can be readily isolated from dark brown or 

 red trunk cankers. Later in the season fruiting bodies of the wood decay 

 fungi are very evident. Bacteria can be isolated from these cankers only 

 very early in the season. 



Other people have worked on canker and dieback problems in apples. A 

 study done by Or. George Agrios in Massachusetts during the early IQfiO's 

 showed that several canker fungi were associated with apple. Of these, 

 Cytospora , Phoma , Physalospora , Phomopsis , Gleosporium and Botryosphaeria 

 were found, in order of decreasing frequency. These were associated with 

 cankers which became much more frequent during the drought occurring at that 

 time, and drought stress was believed to be a large factor in the disease, 

 rir. Dale Bergdahl recently completed a study of trees on marginal orchard 

 sites in Minnesota. He found that tree mortality went from less than 10% 

 when the orchards were first observed to over 90% after approximately 10 

 years. He attributed the decline to tohe wood-decay fungi Irpex , 

 Schizophyllum and Coriolus in conjunction with cold and other environmental 

 stresses . 



Several researchers have described a bud blast and canker on deciduous 

 fruit trees induced by Pseudomonas syringae . The disease is not generally 

 reported on apples, but an incidence apparently occurred in New York in 

 1950. Dr. Tom Burr of New York has shown that Pseudomonas syringae often 

 live on the surface of apple tissue causing no apparent di sease. iTrT Chris 

 Goodman of South Africa reports that there is a newly observed twig blight 

 caused by P^ syringae observed in that country. 



Scientists at the HSDA Fruit Research Laboratory in Kearneysvi 1 le, WVA, 

 hosted a conference on peach decline, and suggested that we might find simi- 

 larities between peach tree cankers and the apple disease. Roth appear to 

 have a cold stress component, both have bacteria associated with cankers, 

 particularly a Pseudomonas sp., and both have rapid colonization of cankers 

 by fungi. In peaches, the primary fungus is Cytospora . The success a tree 

 has in walling-off, or compartmentalizing, an infection also plays a large 

 role in determining whether a tree will recover, or continue to decline. 

 Proper pruning decreased the potential for extensive fungus colonization and 

 wood loss in peach. Researchers also reported that wound dressings and 

 fungicides did not significantly decrease pruning cut infections. Figure 2 

 illustrates the many interactions which affect the peach canker disease. 



The bud symptoms we have seen resemble descriptions of Pseudomonas bud 

 blast, as described on stone fruits and pear. Symptoms were widespread this 

 spring, yet not uniform in a given area. With the realization that the evi- 

 dence is still speculative and circumstantial, we suggest that the problem 

 may have been caused by an interaction between abnormal temperature fluctu- 

 ations, heavy rain during spring and autumn, a bacterial organism such as 

 Pseudomonas , and several fungal pathogens. 



To manage the problem, we are suggesting an 8-8-100 Bordeaux Mixture 

 applied from silver tip to green tip. Other growers fire experimenting with 

 a fall application made after trees have entered rest. Others are con- 

 sidering similar applications of copper hydroxide (Kocide)*. These 



*Trade name 



