Fall is a good time to spot, and eradicate, invasive buckthorn

Buckthorn is an invasive tree that is common throughout the Chicago area. It tends to hold green leaves later than other deciduous trees in fall, so it is easy to spot at this time of year. Cut them at ground level and treat the stump with an herbicide quickly to kill the root system. Smaller trees can be dug out with a sharp spade.

• Shredded leaves make good mulch for your garden beds. For the serious gardener, a shredder can be rented, but they are very noisy, so it is best to use ear and eye protection when shredding the leaves. Using a shredder is a time-consuming process that results in finer leaf mulch. For the average gardener, a lawn mower with a bag to catch the leaves is adequate for this job. The mower doesn't cut the leaves up as finely as a shredder, but it works a lot faster. Ground-up leaves decompose more quickly if you are using them in a compost pile. Shredded leaf mulch may also be purchased from garden centers.

• In most garden situations, tree wrap is not needed for newly planted trees. If used, it should be removed within six months to a year at most. Tree wrap is used in certain areas of the Chicago Botanic Garden to help prevent animal damage in winter. These trees are wrapped in October and November and the wrap is removed in April. Both paper and burlap tree wrap work well. When using paper tree wrap, place the printed side against the trunk so it cannot be seen when wrapping is completed. Start the wrap at the bottom of the trunk and finish at the top. Paper and burlap tree wraps do not adequately protect young trees with smooth bark from deer rubs. Use chicken wire or hardware cloth to wrap these trunks.

• Plants you have installed over the last two years may still need supplemental water if the weather is warm and dry. Evergreens should not go into winter under drought stress.

• Tim Johnson is director of horticulture at Chicago Botanic Garden,

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