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Five Things To Know About Oak Wilt <br />1. 4. <br />Every year, Minnesota loses a large number <br />There are ways to minimize the spread of <br /> <br /> <br />of oak trees to oak wilt. <br />oak wilt. <br /> Oak wilt is caused by a non- <br /> They include mechanically cutting grafted roots <br />native fungus that affects all types of oaks found in <br />between diseased and healthy oaks and/or chemically <br />Minnesota. We are now in the “High Risk” timeframe for <br />injecting trees to protect against infection. If oak wilt is <br />potential Oak Wilk infection (generally April through <br />present, injections should be repeated every other year for a <br />June). <br />total of three injections over a 6-year timeframe. If possible, <br />avoid pruning oaks between the months of April and June <br />(later if possible) and do not transport infected firewood to <br />other locations (e.g. don’t bring it up to the cabin). <br />5. <br />Proper disposal of infected wood is very <br /> <br />important. <br /> Options include debarking the trunk, chipping <br />the wood or cutting it into firewood-sized lengths and <br />stacking and covering. The stack should be covered with 4-6 <br />mil clear plastic for a full growing season. The edges of the <br />plastic should be buried in the ground several inches to create <br />a tight seal and this should be in place before April 1. <br />2. <br /> <br />The oak wilt fungus actually travels within a <br /> <br />tree through its water conducting system. <br /> In red <br /> <br />oaks, wilting begins at the top and outer portions of the tree. <br />In white oaks, browning sections of the branches are <br /> <br />scattered. In both red and white oaks, the leaves will brown <br /> <br />from tip and margin inward toward the base of the leaf. <br />The fungus affects the red oak group quickly, with complete <br /> <br />wilting and defoliation in as little as four weeks. In the <br /> <br />white oak group, the disease progression is slower, with <br /> <br />death often occuring over the course of a growing season or <br /> <br />Image courtesy of plantdiseasehandbook.tamu.edu <br />longer <br />. <br /> <br /> <br />3. <br />The fungus spreads both below ground <br /> <br /> <br /> <br />through connected (grafted) roots and above ground <br /> <br />by certain insects. <br />Below ground, roots from trees of the <br /> <br />same species can fuse or graft together. Oak wilt not only <br />moves within a tree, but can also move between trees through <br />grafted roots. Above ground, the fungus is spread by certain <br />insects as they feed on sap flowing from fresh wounds on oak <br />trees(asaresultofstormdamage,pruningactivities,etc.). <br />If you have questions about oak wilt or suspect oak wilt on <br />your property, contact the City Planner at 763-433-9817 or <br />canderson@cityoframsey.com. <br />14 Ramsey Resident • May/June 2019 <br />