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Helping trees grow in Minnesota

 

Getting ready for winter

Here are some tips for homeowners who want to get ready for winter and plan ahead for early spring.

Pest or conditionTreeFall activitySpring activity
Rodent damage Young and thin-barked treesRake mulch back away 3 to 4" from tree trunk. Wrap lower 12 to 18" with aluminum foil or enclose trunk with cylinder of 1/4 " hardware cloth, extending slightly into the soil.Remove foil or cylinder.
Sun scald Young and thin-barked trees, recently pruned or transplanted treesWrap trunk with commercial tree wrap or plastic tree guards.Remove all wrappings after the last frost.
Winter drying ConifersWater throughout the fall. Erect temporary barriers around yews, arbor vitae. Keep de-icing salts away from trees. After snow melt and prior to budbreak, rinse de-icing salts off.
Branch removal AllPrune live, dying or dead branches. Always cut outside of the branch collar.Prune dead branches. Always cut outside the branch collar.
Anthracnose HardwoodsRake and dispose or burn fallen leaves and twigs.At budbreak, spray chlorothalonil, mancozeb or zyban.
Black knot CherryPrune away infected branches at least 4" below the knot. Apply lime-sulfur as dormant spray following pruning.At dormant-bud, pink-bud, full bloom and 3 wks. later, apply thiophanate-methyl.
Fire blight Apples, pears and mt. ash Remove and destroy all infected material.Apply basic copper sulfate or copper hydroxide as directed on the label.
Dutch elm disease ElmsRemove dead trees and debark wood to be stored for firewood. If you live in a community with access to it, a vibratory plow line should be installed prior to cutting tree(s) down.Do not prune after April 15th .
Oak wilt. Oaks Remove dead trees and debark wood to be stored for firewood. If you live in a community with access to it, a vibratory plow line should be installed prior to cutting tree(s) down.Do not prune after April 15th
White pine blister rust White pinePrune dying branches anywhere in the crown. Prune lowest whorls of branches to prevent infection. 
Cytospora canker SprucesPrune and destroy infected branches. Disinfect tools between cuts with rubbing alcohol. 
Rhizosphaera needlecast SprucesPrune away lower branches to promote air circulation.Make 2 applications of chlorothalonil as directed on label.
Scab and canker WillowsRake and destroy fallen leaves and twigs. Prune out diseased branches. Apply Bordeaux (8-8-100)after leaf drop. 2 or 3 applications of Bordeaux (6-6-100) starting when leaves first visible.
Tar spot Maples Rake and compost or destroy leaves. 
Birch leaf miner Birches Spray foliage when mines first appear. Use acephate or dimethoate.
Bronze birch borer Prune away dead branches. BirchesPrune away dead branches. Dispose , debark or destroy the wood.Dispose , debark or destroy the wood.
Cankerworms Many hardwoods Spray at leaf expansion using Bt or acephate, carbaryl, malathion, diazinon, insecticidal soap, etc.
Elm leafminer Elms Spray foliage with dimethoate when mines first appear.
Mite galls Maple, elm, ash, hackberry and more. Spray carbaryl or dicofol at or just prior to budbreak.
Two-lined chestnut borer Prune away dead branches. OaksPrune away dead branches. Dispose , debark or destroy the wood.Dispose , debark or destroy the wood by April 15th.
Spruce gall adelgids Spruces Clip and destroy galls.As buds swell, spray acephate, carbaryl or diazinon before galls form.
Pine needle scale Pines, spruces In late May, apply acephate, carbaryl, chlorpyrifos, cyfluthrin, insecticidal soap or malathion.
White pine weevil Pines  Spray terminals with chlorpyrifos in mid to late April.

Information in the above table was derived from the following publications:

Ash, C., M. Draper, H. Laney and D. Gallenberg. 1995. Disease Management Recommendations for Trees and Shrubs. Minn. Ext. Serv. Pub. BU-6659-S.

Hahn, J., R. Wawrzynski and V. Krischik. 1996. Insecticide Suggestions to Manage Landscape Trees and Shrub Insects. Minn. Ext. Serv. Pub. FO-0704-B.

Swanson, B. and R. Rideout. 1992. Protecting trees and shrubs against winter damage. Minn. Ext. Serv. Pub. AG-FO-1411-B.