Termites, Mulching Trees and the Urban Legend

Lee Royer
Frederick County Master Gardener

We've all heard the stories that termites are being transported from Katrina areas in mulch made from the wooden debris. Rest easy, your chances of getting termites from mulch, any mulch, are slim. Not impossible, but unlikely. The basis of this rumor begins in truth, as many do. Louisiana has a serious problem with an invasive termite, the Formosan subterranean termite that was introduced accidentally into the US probably from China in the 1940s. This termite is now well established in California, Hawaii, and the south in general. After Katrina, Louisiana officials became worried that the reuse of wooden materials would spread this pest to other areas of the country so they imposed a quarantine on several parishes which were known to be infested heavily. This is the beginning of the urban legend.

The rumor mill added to this truth the incorrect assumption that consumers in the rest of the country were going to be infested with termites from the mulch they would purchase from major retailers. E-mails circulated scaring people away from buying mulch at their local mega retail stores. Well, calm down, America! It's just not true.

The mulch in sealed bags has been heavily shredded and termites don't last long under those conditions. Your local mega mart is one of the safest ways to buy mulch, but stay away from "bargains" on open bags because you really could get termites from mulch that has not been sealed or stored properly. Unsealed bags or mulch piles stored too long on the ground are vulnerable to our own native termites. Best advice for buying mulch is to buy in bags or, if you need a large amount, buy from a retailer who is selling properly stored mulch that doesn't sit around on the ground for long periods of time.

Maryland is home to the genus Reticulitermes that you can see in their native state by taking a drive down RT 355 to Little Bennett Regional Park in Clarksburg. Once there, take a short, no hills, walk to observe them and their interesting colonies creating the typical termite mounds which look like they belong in an African documentary rather than our Maryland forest. This trip is much more fun than observing them under your deck.

Termites do cause a lot of damage, an estimated $1 billion in the US alone, so it is a good idea for homeowners to keep an eye out for them. Identification can be tricky. Most colonies have three forms: workers, soldiers, and swarmers, each looks different from the other and ants, especially flying varieties, are often confused with termites. One way to tell the difference is that in general, termites have straight antennae with a beaded look, while ants have a bend like an elbow in theirs. If you find swarming, flying insects you would like to positively identify (free without a sales pitch), capture a few in a jar and bring them to the extension office at 330 Montevue Lane, or to one of the Master Gardener plant clinics held each Saturday at the local farmers market on Baughman's Lane, or to our annual plant sale on April 29, also at Montevue Lane.

Having obtained termite-free mulch, you now want to mulch your trees so that you create safe space around them, reduce competition with grass, and thereby help them to grow faster and healthier. First thing to remember is a little bit goes a long way. Don't use too much or you will invite the local termite population along with many other diseases and pests. An inch or two deep is fine, no more than three. Where you want to be generous is when creating a circle around the tree as wide as the branches themselves, if space allows.

Second thing to remember is to always keep mulch from direct contact with trees, plants or buildings. Just as you can kill a tree with a weed whacker by cutting a deep line through the bark all the way around the tree, you can kill a tree by girdling it with a layer of mulch touching the bark. Master Gardeners feel great pain when driving through Frederick and observing the many trees surrounded by volcanoes of mulch slowly but surely destroying their bark and inviting pests and diseases.

Read other articles about controlling insects & garden pests

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