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<br /> <br />IVll[llle~U1U uefJU! 1111\:::111 UI I\lUIUIUI l<e~UUlces <br />DiviSIOn of Foresliy <br /> <br />Internet address: http://www.dnrstale.mnuslfidlindexlhtml <br /> <br />In this issue: <br /> <br />Fall Roundup <br />Can it really be falP <br />Two-lined chestnut borer <br />Maple decline <br />FTC in 2003? <br />Sudden oak death: Nursery survey <br />Orangestriped oakwonns <br />Redhumped oakwonns <br />Leaf tiers on oak <br />Leaf disease on bur oaks <br />Scale insects <br />Spruce with the Midas touch <br />Red pine cone beetle <br />Wood that glows in the dark? <br />Japanese beet les <br />Website Review <br />BUGWOOD <br />Forest Entomology Research <br />Small oak bark beetle, a potential <br />vector of oak wilt <br />News from Elsewhere <br />Emerald ash borer <br />A comparison of 20 deer repellants <br />Feature Article <br />Gypsy moth program update <br /> <br />November 18,2002 <br /> <br />Fall Roundup <br /> <br />Can it really be fall if the leaves haven't <br />fallen off the trees? <br /> <br />The fulling snow, the lakes freezing over, the frost on the <br />windshield, the geese and ducks flying south and deer season <br />all tell us it must be full in northern Minnesota. Then why <br />do so many of the hardwood trees still have leaves? The <br />leaves are dead. They are brown or some shade of sickly <br />green. They are also dry and crumbly, but they are still <br />attached to many of the Irees. Shaking the Iree doesn't <br />dislodge the leaves, the petiole is still finnly attached to the <br />tree. <br /> <br />This is not expected to have any adverse affect on the trees <br />next year. However, if we get a freezing rain followed with <br />wet snow that sticks to the tTees, it is possible that the trees <br />with leaves still attached could suffer more branch breakage <br />due to the extra weight of the snow sticking to the leaves. <br /> <br />One suggestion to explain this phenomenon might be that a <br />hard frost killed the leaves before the abscission layer was <br />fully developed. Here's lhe reasoning. The firsllhree weeks <br />of September were very wann with temperatures in the 80's <br />and 90's common across the state. The last week of <br />September cooled off with high temperatures in northern <br />Minnesota in the 60's. Only a few low laying areas of <br />northern Minnesota experienced a killing frost in September. <br />Cold weather came quickly in October with lows moving <br />inJo the upper 20's Ihe "'first week and into the mid 10 low 20's <br />i.n the second week. Perhaps the wann temperatures <br />delayed formation of the abscission layer and the frosts <br />in early October killed the leaves before the abscission <br />layer was fully formed. <br /> <br />If you have a better guess or actually know why leaves <br />stayed on Irees this year we would like 10 hear from <br /> <br />VOII <br />