as expensive. 



If the increased control can more than pay for itself, it 

 is worthwhile. For example, if the material reduces the 

 number of rotted peaches by 1 peach per tree, it will 

 increase the production of an acre of peaches by approxi- 

 mately 1 bushel. This result will earn an extra $15.00 to 

 $20.00. Ifthepostharvestrotisdecreased, extramoneyand 

 extra customer satisfaction will be added. If this extra 

 money exceeds the extra material cost, obviously the treat- 

 ment is worthwhile. 



By those criteria, our data from last year indicated that 



the Ronilan treatments were not economically justified. 

 However, it is important to stress that this is only one year, 

 and that we do not know how well captan might have 

 controlled brown rot. In addition, this analysis does not 

 consider what might happen under heavy brown rot pres- 

 sure. 



This year we hope to carry out the economic analysis 

 more completely and include captan treatments for com- 

 parison. Only by determining the ultimate Tmancial benefit 

 can we judge whether or not a more effective chemical is 

 indeed a more cost effective fungicide. 



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Mauget Microinjection for Peach X-Disease Therapy 



Julianne Schieffer, Terry A. Tattar, and Daniel R. Cooley 

 Department of Plant Pathology, University of Massachusetts 



Introduction 



Since the first report in Connecticut in 1933, X-disease 

 has become a serious disease of peach. Originally thought 

 to be caused by a virus, X-disease was shown to be caused 

 by a mycoplasma-like organism living in the phloem. 

 Infection occurs from chokecherry to peach through trans- 

 mission by leafhoppers. 



An infected tree breaks out of dormancy with healthy 

 foliage and flowers. After seven to eight weeks, sections of 

 the tree begin to show a diffuse yellowing. Soon the leaves 

 become brittle, develop red spots, tatter, and curl upward. 

 Diseased leaves fall, often leaving a rosette of yellowed, 

 dwarfed leaves at the tip of each infected branch. This 

 process produces a "rat tailing" effect as the terminal bud 

 breaks prematurely. Diseased trees have reduced growth 

 and lower yields. Unaffected scaffolds within the same tree 

 may continue to grow and bear, but this fruit often lacks 

 flavor or is bitter. Death of the tree, or winter kill of 

 affected sections, often follows within one to four years. 



Attempts to control peach X-disease have had mixed 

 results. Pruning diseased limbs is not successful, as the 

 disease appears on other limbs the following year. Chemo- 

 therapy of X-disease with oxytetracycline (OTC) has 

 shown much promise, but traditional injection methods 

 have a number of disadvantages. Injection techniques such 

 as gravity infusion, pneumatic pressure, and pipettes, have 

 proven labor intensive, ineffective, or detrimental to tree 

 health (Lacy, 1982; Rosenbergcr & Jones, 1977). Mauget 

 microinjection has been used widely to deliver effectively 



chemicals to shade trees with little injury. The objective of 

 this study was to determine if Mauget microinjection of 

 oxytetracycline could be used in commercial peach or- 

 chards for remission of peach X-disease symptoms. 



Materials and Methods 



The Mauget microinjection system consists of a small 

 disposable capsule. In our research, these capsules con- 

 tained 4 ml of 4% OTC solution. Each capsule is attached 

 to a beveled feeder tube and pressurized with a mallet to 

 approximately 10 to 12 pounds per square inch. One or 

 more 3/16 inch holes, depending on tree diameter, are 

 drilled approximately 1/2 inch deep at the tree base with a 

 portable drill. The capsules are inserted immediately and 

 tapped with the mallet to break the internal membrane, 

 thereby forcing the OTC solution into the xylem of the tree. 

 The appropriate dose rate is one capsule per two inches of 

 trunk diameter. Most trees in this study received 2 or 3 

 capsules. The contents of most of the capsules was taken 

 up by the tree within a few hours. Empty capsules were 

 removed within a week. 



Four Massachusetts orchards were chosen for injec- 

 tion in September, 1986. Each diseased tree and each 

 healthy control tree was rated with the following scale: = 

 outwardly healthy, 1 = foliar symptoms on 10% or less of 

 the canopy, 2 = symptoms on 10 to 50% or less of the 

 canopy, 3 = 50 to 90% affected, and 4 = over 90% affected 

 or dead. Approximately half the trees in each rating class 

 then were injected after fruit harvest. 



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