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MAUGBT MICROINJECTION OF OXYTETRACYCLINB FOR THERAPY 

 AND PREVENTION OF EASTERN X-DISEASB OF PEACHES 



Terry A. Tattar, Julianno Schi>5ffer, 



and Daniel Cooley 



Department of Plant Pathology 



University of Massachusetts 



Introduction 



Peach X-disease has been considered one of tiie factors that limits 

 profitability of commercial peach product ion in the Nortlieast. This mycoplasnfia 

 disease has been brought into remission by trunk injection of oxytetracycline 

 antibiotics (2). However, the injection met'nods used were very labor intensive 

 and difficult for peach growers to use in commercial orchards (1). There also 

 is some evidence that these methods have led to significant trunk dam.ige over 

 time (Pierson, personal communication). Mauget (J.J. Mauget Co., 2810 So. 

 Figu<;roa St., Los Angeles, CA 90065) microinjection has been used widely for 

 trunk injection of shade trees by arborists to deliver f ert ili/.ers, fungicides, 

 antibiotics, insecticides, and micrunutrients. Recently, a Mauget capsule //ith 

 4% oxytetracycline (OTC) became available for experimental use in controlling 

 myc»)plasma diseases of trees. If a simple system of trunk injtsction like the 

 Mauget microinjection system could deliver oxytetracycline to peach trees 

 effectively, control of X-disease in peach orchards by trunk injection could be 

 performed by peach growers. The objcsct of this study was to determine if 

 Mauget capsules containing 4% oxytetraoycline could be used to control X- 

 disease in a commc^rcial peach orciiard. 



Materials and Methods 



Green Acres Orciiard in Wilbraham, Massachusetts was the test site for 

 this study. In late summer, 1985 it was noted that a number of trees in the 

 northeast corner of a 5- to 6-year-old peach block (a late variety mixture) 

 vvere exhibiting sy.nijto ns (reduced apical and radial growth, greatly reduc^^d 

 fruit yield, chlorotic and red-spotted foliage, prematire defoliation of inner 

 leav-is, and prematare bud break) of eastern X-disease. At this time several 

 trees in this corner of the block had already died and replacement trees had 

 been planted. A number of other trees had one-t'nird to one-half of their 

 crowns remov'id by pruning. 



Antibiotic therapy was performed in an attemjjt to save the living trees 

 exhibiting X-disease sy^nptjas, and to protect a number of trees growing 

 adjacent to the affected ones. The metliod cliosen for therapy was trunk 

 injection with Mauget capsules, which contain 4 ml of i% oxytetra-cycline 

 (OTC) antibiotic and are disposable after use. On October 7, 1985 twenty-seven 

 trees were trunk injected using a dose rate of one capsul<i per two inches of 

 trunk diameter, measured at approximately one foot above ground. Since most 

 trees were approximately 5 to 7 inches in diameter, three capsules per tree was 

 the most common dose. To place the Mauget capsule in the tree, a drill hole 

 (3/16" in diameter and 1/2" dec^p) was made in the trunk approxim^i tely 2 to 4" 

 aboveground. The delivery tube and capsule were inserted immediately into the 

 hole. Most )f the capsules were einpty within two hours and all were empty by 

 the next day when the capsules were removed. 



