CAUSES OF PEACH TREE DECLINE 



William J. Lord 

 Department of Plant and Soil 



Sciences 



"Peach tree decline" is a major problem for fruit growers, 

 and also a frustrating problem because its cause is often difficult 

 to diagnose. Factors causing peach decline were discussed in a sympo- 

 sium on peach problems and published in Proceedings of the New 

 York State Horticultural Society , Volume 119, 1974. Some of the 

 pertinent facts presented at the symposium are discussed below. 



Factors contributing to peach tree decline in the Hudson Valley . 

 A peach orchard survey conducted in 1973 by Dr. R.C. Pearson, New 

 York State Agricultural Experiment Station, Hudson Valley Labora- 

 tory, showed that Valsa Canker (Cytospora Canker) was perhaps the 

 most important problem. It was present on 26% of the trees exam- 

 ined. Five percent of the trees were damaged by peach borer, and 

 only 3% were suspected (though not confirmed) of having X-disease. 

 It had been generally thought that X-disease was the most important 

 problem associated with peach decline, but the survey by Pearson 

 indicates that this may not be true. 



Minimizing peach decline . According to Dr. G.H. Oberly, Cornell 

 University, winter injury to the wood which permits penetration of 

 the organism causing canker is perhaps one of the greatest contri- 

 buting factors in shortening the life of peach trees in New York. 

 Methods of reducing winter injury and Valsa canker are discussed in 

 an accompanying article entitled "Let's Reduce the Damage to Peach 

 Trees from Cytospora Canker." 



X-Di sease . Research on X-disease has been renewed at a number of 

 Universities and Experiment Stations. Perhaps the most significant 

 finding at present is that the causal organism of X-disease is not 

 a virus but a mycoplasma, an organism which can be controlled by 

 antibiotics. Chemical therapy of X-disease is being researched by 

 Dr. David Sands, Department of Plant Pathology, Connecticut Agricul- 

 tual Experiment Station, New Haven. In tests of injection methods 

 and antibiotic preparations. Dr. Sands has found that tetracyclines 

 (being used for treating pear decline in California) show promise 

 for the control of X-disease of peach. 



Other methods of X-disease control also are under investigation, 

 such as control of the leafhopper vector of the disease and the use 

 of resistant rootstocks such as wild black cherry. Until methods of 

 X-disease control are perfected, growers should renew their efforts 

 at chokecherry eradication. Chokecherries are the main source of 

 inoculum for X-disease and according to Dr. Allen S. Jones, Michigan 

 State University, they should be eradicated from areas bordering 



