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Pear Decline in Connecticut and Response of Diseased Trees to Oxytetracycline Infusion. John L. McIntyre, Department of Plant Pathology, Connecticut Agricultural Experiment Station, New Haven 06504; H. Schneider(2), G. H. Lacy(3), J. A. Dodds(4), and G. S. Walton(5). (2)Department of Plant Pathology, University of California, Riverside 92521; (3)(4)(5)Department of Plant Pathology, Connecticut Agricultural Experiment Station, New Haven 06504. Phytopathology 69:955-958. Accepted for publication 12 March 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-955.

Pear decline in Connecticut orchards is evidenced by symptomatology, graft transmission of symptoms to indicator hosts, mycoplasmalike organisms in sieve tubes of leaf tissue from diseased trees, and symptom remission after infusion of diseased trees with oxytetracycline (OTC) for two consecutive years. Of 5,318 trees observed in 18 orchards throughout Connecticut, 33% had symptoms of pear decline. Connecticut and California sources of pear decline could not be differentiated by symptoms on indicator pear cultivars. After 1 and 2 yr of treatment, trees infused with OTC showed significant remission of foliar symptoms. After 2 yr of treatment, tree yield (kg/cm2 trunk area at 30 cm above the soil) and weight of individual fruit were significantly increased. Tree vigor, evidenced by increased trunk circumference and shoot growth, also improved significantly, so fruit yield should increase in the future.