Be­ware haz­ardous, ob­vi­ous tree de­cay

Winnipeg Free Press - Section G - - HOMES - MICHAEL ALLEN

AFEW weeks ago, south­ern Man­i­toba ex­pe­ri­enced strong, high-ve­loc­ity winds ac­com­pa­nied by heavy amounts of rain­fall. It did con­sid­er­able dam­age: large trees broke apart and dam­aged prop­erty and ve­hi­cles through­out the re­gion; in some in­stances, per­sonal in­jury was in­volved. From my ob­ser­va­tions driv­ing around the Win­nipeg re­gion and out­ly­ing ar­eas, the trees that tended to do the most dam­age were those that had ob­vi­ous signs of trunk and large branch weak­nesses. The ma­jor rea­son why most trees fail is ex­ten­sive de­cayed heart­wood. How does this weak, de­cayed heart­wood get into the tree? The core-wood de­cay in th­ese haz­ardous trees orig­i­nated from a mul­ti­tude of causes such as bad prun­ing cuts by in­ex­pe­ri­enced tree cut­ters, ex­ca­vated roots of­ten in­ter­fered with by util­i­ties and by prop­erty own­ers in­stalling pools, sun scald­ing, top­ping of trees (which al­ways leaves trees vul­ner­a­ble) and ve­hic­u­lar dam­age. Be­lieve it or not, there are thou­sands of cur­rently stand­ing haz­ardous trees lo­cated on pri­vate prop­er­ties, in­sti­tu­tional and ed­u­ca­tional prop­er­ties, com­mer­cial prop­er­ties, mu­nic­i­pal parks and boule­vards through­out south­ern Man­i­toba ready to fall and do dam­age. Ev­ery day that I am out on call, I wit­ness a num­ber of trees I would cat­e­go­rize as haz­ardous. On oc­ca­sion, I will leave a note in the owner’s mail­box stat­ing my con­cern for par­tic­u­larly danger­ous trees. How­ever, I do not have the time to do this for all the prob­lem­atic trees I see. Prop­erty own­ers must be vig­i­lant. Wood-de­cay fungi can pen­e­trate the dam­aged wood of a tree from the air in un­be­liev­able amounts. Some trees — such as the or­na­men­tal po­plars, as­pens, Man­i­toba maples, wil­lows, elms and ashes — are fre­quently tar­geted by the de­cay fungi. Trees can read­ily be in­vaded through cracks and holes in their branches, trunks and dam­aged roots in for­merly ex­ca­vated soils. As many of th­ese trees age, es­pe­cially the po­plars and wil­lows, wood de­cay sets in quickly. The tree can fail even with a full canopy of healthy look­ing leaves. Most wood fungi do not di­rectly kill trees, as they are na­ture’s cleanup squad whose ul­ti­mate pur­pose is to de­grade dead, dis­eased and dam­aged trees to fine wood par­ti­cles that will be in­cor­po­rated one day into the soil. Want to safe­guard your home and prop­erty? If you have a large tree that you are con­cerned about, call a pro­fes­sional ar­borist to have it prop­erly as­sessed. I rec­om­mend only those that have a valid cur­rent Man­i­toba ar­borist li­cence and at least $2 mil­lion in gen­eral busi­ness li­a­bil­ity in­sur­ance. Th­ese are manda­tory min­i­mum legal re­quire­ments for com­mer­cial ar­borists. In ad­di­tion, I would rec­om­mend you use cer­ti­fied In­ter­na­tional So­ci­ety of Ar­bori­cul­ture (ISA) ar­borists who es­pouse ISA’s phi­los­o­phy, art and science of whole tree care. Michael Allen M.Sc.F., RPF (ret’d) is a con­sult­ing ur­ban forester, tree di­ag­nos­ti­cian and cer­ti­fied ar­borist. He owns Vibur­num Tree Ex­perts. His re­cent book, Dr. Tree’s Guide to the Com­mon Dis­eases of Ur­ban Prairie Dis­eases, is avail­able in lo­cal book stores. He can be reached at 204-831-6503

or 204-223-7709


This split Amer­i­can elm tree shows a large area of fun­gal de­cayed wood.

The ma­jor rea­son why most trees fail is ex­ten­sive de­cayed heart­wood.

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