Watch­ful eye nec­es­sary to pre­vent fire blight

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

THIS win­ter, I have re­ceived sev­eral calls and emails from prop­erty own­ers con­cerned about the de­te­ri­o­rat­ing con­di­tion of their ap­ple and crabap­ple trees. Last year, there was a sharp in­crease in cases of fire blight on ap­ple and crabap­ple trees. Vir­tu­ally ev­ery tree showed signs of this po­ten­tially deadly dis­ease. Some peo­ple thought their trees were re­sis­tant to a dis­ease such as fire blight, but no tree is truly re­sis­tant to dis­eases. Fire blight is an ag­gres­sive fun­gal dis­ease that can be spread by con­tam­i­nated prun­ing tools, pol­li­nat­ing in­sects or even small birds. Early signs of the dis­ease can be al­most in­vis­i­ble to most peo­ple, but that is the stage where the dis­ease is best treated. Curled red­dish-brown or medium brown to dark brown leaves near the end of twigs is a clas­sic sign of this dis­ease. Look for it on your trees as the leaves ap­pear from the buds in May. Early in­fected flow­ers will usu­ally have a brown­ish, shriv­elled ap­pear­ance. With ad­vanced in­fec­tions, the ends of the in­fected twigs of­ten have a curled ap­pear­ance like shep­herd’s crook. If any of th­ese signs show up, you must prune out the in­fected ar­eas. Make sure you do it at least 30 cen­time­tres away from the near­est in­fected lo­ca­tion, and ster­il­ize your prun­ing tools with di­luted bleach, methyl hy­drate or rub­bing al­co­hol af­ter each prun­ing cut. This is very im­por­tant, be­cause your next cut might oth­er­wise in­fect a healthy part of the tree. If you have made a prun­ing cut on a small branch that is more than two cen­time­tres in di­am­e­ter, I rec­om­mend you im­me­di­ately seal the cut with an ap­proved tree-prun­ing sealer such as Green Earth’s. This will pre­vent re-in­fec­tion by fire blight or other dis­eases. You might want to con­sider one or two re­peat treat­ments about one week apart. Re-ap­ply if there is any rain within 24 hours of treat­ment. Two or three spray treat­ments of an ap­proved fungi­cide such as a cop­per­based prod­uct about two to three weeks apart should be con­sid­ered be­gin­ning in late May, es­pe­cially if your tree has many vis­i­ble signs of the dis­ease. If you see any pre­ma­ture drop­ping of the leaves, be sure to col­lect them and place them in sealed trash bags and con­tain­ers for col­lec­tion. Michael Allen M.Sc.F., RPF (ret.) is a con­sult­ing ur­ban forester, tree di­ag­nos­ti­cian and cer­ti­fied ar­borist. He can be reached at 204-831-6503 or 204223-7709 vibur­numtrees@shaw.ca. His

web­site is www.tree­ex­perts.mb.ca.

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