Hurricane "Bob," A Lesson in 

 Tree Support 



Wesley R. Autio 



Department of Plant & Soil Sciences, University of Massachusetts 



During the third week of August Hurricane 

 Bob swept through the region with winds of 

 nearly 100 miles per hour. Many trees were 

 seemingly unaffected, but others were either 

 snapped off or tipped severely. Probably every 

 tree in Bob's path was in some way damaged; 

 however, at least 10,000 trees in Massachusetts 

 either required straightening or replacement. 

 The long-term effects of this severe storm will be 

 with us for many years. Some good, however, 

 can be derived from this catastrophe; we were 

 able to take a close look at the stability of the 

 many tree support systems used for intensive 

 plantings. 



In the September issue of The Great Lakes 

 Fruit Grower, an article written by Phil 

 Schwallier details some of the effects of a storm 

 with winds in excess of 85 miles per hour which 

 swept through a portion of Michigan in July, 

 resulting in the loss of 5,000 trees. Several of his 

 comments very closely parallel my observa- 

 tions. In Michigan, the most commonly lost 

 trees were four to five years old, on either Mark 

 or M.26, and of the cultivars Gala, Northern 

 Spy, or Jonagold. These trees generally were 

 supported artificially; however, various tech- 

 niques were used. Conduit pipe or bamboo 

 simply bent over and provided no support under 

 the high winds. Steel fence posts or wooden 

 posts fared much better than conduit. The use 

 of a single wire to support trees on Mark was of 

 no value; trees snapped off, slid down the wire, 

 and piled up at the end of the row. 



In Massachusetts, Hurricane Bob resulted 

 in a great deal of damage among trees on M.7 in 

 addition to dwarfed trees. We have known for 

 many years that M.7 produces a free standing 

 tree, but it often is not extremely well anchored. 

 With Delicious as a scion, an experiment termi- 



nated after Hurricane Gloria (1985) showed 

 that trees on M.26 with no artificial support 

 withstood the effects of Gloria significantly bet- 

 ter than similar trees on M.7. Granted, Deli- 

 cious on M.7 is known to be a particularly bad 

 combination, but other trees on M.7 also appear 

 relatively weakly anchored. 



Among dwarf trees in Massachusetts, Mark 

 seems to have done poorly, as did Gala on Mark 

 or M.26; however, it is not possible to separate 

 this relationship from the type of support system 

 used. Most of these trees have been planted 

 within the last five years, and most were sup- 

 ported by a conduit pipe. Under the severe 

 strain, the conduit pipe bent very easily and the 

 tree often snapped at the union. As Phil 

 Schwallier suggested, Mark produces a chars c- 

 teristically brittle union, as does Gala with 

 M.26; however, it is not clear whether or not 

 these trees would have broken if a more substan- 

 tial support system was used. Little damage 

 was seen in three- and four-wire trellis systems 

 or with more substantial posts. 



These observations lead to several recom- 

 mendations: 



1. Conduit pipe should be used for support for 

 no more than one to two years. 



2. If you wish to use conduit pipe, within the 

 first two years after planting add a support 

 wire at six to seven feet from the ground, 

 attached to pressure-treated wooden posts 

 every 20 to 40 feet. Adding this wire is not 

 cheap ( as much at $ 1 ,4 00 per acre); however, 

 losing trees is not cheap either. 



3. If individual support with no wire is desired, 

 you must consider pressure-treated wooden 

 posts. Three-inch posts seem to be adequate 

 to provide a high level of support. 



Fruit Notes, Fall, 1991 



