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Real Solutions: Home & Garden Tips

Decks, bamboo, and oak trees

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We practically live on our outdoor deck from spring through fall. By this time of the season, it's showing wear. How best to care for our deck? -- A.G., Fitchburg, MA

Decks are constantly exposed to the elements and therefore will quickly show signs of weathering. If the wood is dirty (bird droppings, pollen, mud), sponge-mop your deck with a mild detergent and rinse well (I simply hose it off). Mineral spirits will remove tree sap, but be sure to rinse those spots well, as the solution can stain.

If your deck's in the shade, mold or mildew may form. To remove it, mix a solution of 3/4 to 1 cup of bleach with a gallon of hot water. Sponge-mop and rinse, taking care not to splash too much bleach solution onto any plants bordering your deck.

If water's soaking in and darkening your deck (rather than beading up on the surface), it's time to treat the wood. Clean the deck first; then apply a stain according to the manufacturer's instructions. Some homeowners like to use a wood brightener after cleaning but before applying the stain. Brighteners and stains are often sold as companion kits. We recommend using stain with a commercial sealant rather than treating wood with a clear finish such as shellac or varnish, because these tend to peel under too much sun and moisture. -- Polly Bannister, Yankee Home Editor

A tall, grassy plant we call "bamboo" has been spreading like wildfire near a brook on our property, and we can't control it. We don't want to use anything that will affect our water, wells, or wildlife. -- P.D.S., Agawam, MA

Polygonum cuspidatum, commonly known as Japanese knotweed or Japanese bamboo, was introduced from eastern Asia in the late 19th century. It's not a true bamboo; it's an aggressive member of the buckwheat family. It takes over stream banks, forming dense thickets that crowd out all other vegetation. Its extensive, deep, brittle root system grows vigorously, tolerating shade, drought, brackish conditions, and high temperatures, and spreading rapidly in wet soils and adjacent areas.

Controlling this species without using chemicals requires perseverance. Digging out the plants with hand tools may control it if you're persistent. But each root piece that breaks off has the potential to sprout again and grow into a new plant. This invader has become a pervasive and serious enough environmental threat that even most conservation groups agree that chemical controls are necessary. I know of no biological control.

Several herbicide formulations are available that, when handled properly, will cause minimal damage to animals, water, and other plants. You apply these chemicals to either cut stems or foliage, depending on the situation, and repeat treatments are usually necessary. Contact your local extension service or state fish and wildlife department for recommendations. And make sure you always follow the directions on the label. -- R. Wayne Mezitt, Chairman, Weston Nurseries, Hopkinton, MA

I'm surrounded by oak trees here, and last year I noticed numerous solid, Ping-Pong-sized balls dropping from them. Does this happen every so often, or is it a fluke of nature? -- M.G., Wilmington, MA

You're describing "oak apple galls," which commonly form on oak trees and sometimes on plants in the willow and rose families. They're actually deformed leaves that have been modified by secretions from the larvae of a tiny, stingless gall wasp species, Amphibolips confluenta. In the spring, a female wasp injects an egg into an oak-leaf bud; after the larva hatches, the gall structure begins to develop, protecting and nurturing the immature wasp until it emerges as an adult in June or July. The gall is green and spongy at first during the insect's larva and pupa stages; it becomes brown and papery after the adult emerges in summer, and eventually drops off the tree in fall or winter.

The oak apple gall wasp is considered a minor pest; it causes minimal damage to the health of the tree, although infestations may look unsightly. Heavy populations may cause early leaf drop. Minor occurrences may be managed by picking the galls off by hand, but you have to do it before the adult emerges, or the cycle may repeat. Chemical controls aren't necessary or even very effective.

For more information, visit the U.S. Department of Agriculture's Forest Service Web site at fs.fed.us and type "oak apple gall" into the search box. -- R. Wayne Mezitt, Chairman, Weston Nurseries, Hopkinton, MA

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