Root Pruning, Part of the Second-level 

 Apple Integrated Pest Management 

 Project 



Wesley R. Autio and Duane W. Greene 



Department of Plant & Soil Sciences, University of Massachusetts 



James W. Gamble 



Department of Plant Pathology, University of Massachusetts 



Margaret M. Christie and Kathleen P. Leahy 

 Department of Entomology, University of Massachusetts 



In the previous article we discussed the 

 growth controlling techniques of scoring and 

 ringing. A third cultural technique, root prun- 

 ing, has been studied extensively by Dr. James 

 Schupp (University of Maine) and Dr. David 

 Ferree (Ohio State University). In 1991, we 

 conducted root pruning experiments as part of 

 the Second-level Apple Integrated Pest Man- 

 agement Project. 



Root pruning was included in the Second- 

 level IPM Project because of a number of re- 

 ported positive effects. Specifically, root prun- 

 ing reduces vegetative growth. The advantage 

 of this effect to the apple grower is twofold: less 

 time is required to prune the trees, and air 

 movement through the tree canopies is en- 

 hanced. The enhanced air movement should 

 result in reductions in summer-disease inci- 

 dence by reducing drying time and relative 

 humidity. Additionally, pesticide penetration 

 into the canopy should be improved. The second 

 reported effect of root pruning is a delay in 

 natural fruit drop. If this effect is consistent, 

 then a larger portion of the crop on the tree will 

 be able to be harvested, significantly reducing 

 economic losses. A second benefit of this delayed 

 abscision relates directly to pest management. 

 Reduced numbers of fruit on the ground de- 

 creases the effort required to remove those fruit 



from the orchard floor, a requirement of second- 

 level IPM for apple maggot control. 



Root pruning is a dramatic treatment, cut- 

 ting off more than half of the feeder roots within 

 12 inches of the soil surface. It is not a treatment 

 to be taken lightly, since it has the potential for 

 reducing growth severely. If trees are overly 

 stunted, then productivity will decline and fruit 

 size will be small. To ere on the side of caution, 

 we decided to study root pruning only on those 

 Second-level IPM sites most severely needing 

 growth control. We wanted to study a number 

 of effects and the consistency of response in 

 order to determine whether or not root pruning 

 should be included in our Second-level IPM 

 Plan. 



The Root Pruning Procedure 



Root pruning is accomplished with a sharp- 

 ened subsoiling blade attached to a tool bar on 

 the tractor. The blade is set so that it penetrates 

 the soil to a depth of 12 inches. The blade is 

 passed by both sides of the tree at a distance of 

 36 inches from the trunk. 



For our study, three of the six full second- 

 level treatment sites were chosen. These sites 

 were Fay Mountain Farm (Charlton), Rice Fruit 

 Farm (Wilbraham), and the University of Mas- 



Fruit Notes, Summer, 1992 



