Removing Poison Ivy and Squirrel-Proofing the Tomatoes

If poison ivy is too mature and can't be pulled, perhaps it can be dug up. (Photos By Sandra Leavitt Lerner For The Washington Post)

You must be careful with any solution over 11 percent vinegar because it can burn you. Higher concentrations than the 5 percent white distilled vinegar found on grocery store shelves will give better weed control. They can be found at food manufacturers such as Fleischmann's Vinegar Co. Call 1-800-443-1067 or visit http://www.fleischmannsvinegar.com/ . Also look for BurnOut II Weed & Grass Killer, a solution of vinegar and citrus, that can be found at health food stores and garden centers.

You must use vinegar as carefully as other non-selective herbicides. It can kill any plant it contacts. Find more information about vinegar as an organic herbicide by surfing the U.S. Department of Agriculture's research site at http://www.ars.usda.gov/ and searching for "vinegar herbicide."

Please help us all by providing information on nontoxic ways to keep our gardens growing beautifully. -- Karen Berry

I appreciate your concern about the use of toxic chemicals to control problems in the landscape, and I always consider the least toxic methods of controlling pest problems. If there are no natural products available, I will choose a material that the academic, scientific community considers to have the least negative effect on the environment. As more natural methods are discovered and approved for use, the safer our environment will be. To that end, readers might peruse some of the Web sites listed below that specialize in information and environmentally friendly materials to control pests in the landscape:

· http://www.centralsan.org/education/ipm/resources.html

· http://www.gardensalive.com/

· http://www.montereylawngarden.com/

· http://www.saferbrand.com/lawncare/lawncareproducts.htm

I have a Japanese maple that seems to be dying off bit by bit each year. It is 15 to 20 feet tall. At the base of the trunk, there is some extensive decay and stripping of the bark just above the soil. Leaves are sparse, and the branches have a black coating on them. Do you have any sense as to what may be happening? Is there any treatment for it? -- Devon Brown

My first speculation, if the tree is planted in lawn, is physical mower damage, especially considering the extensive stripping of bark that you describe at mower height.

If Japanese maples are planted in hard clay and are subject to periods of drought, they will be stressed. They do not like afternoon sun and are sensitive to heat. These conditions make them susceptible to a variety of insect and disease problems, and they will decline because of their tender nature. Plant in an eastern exposure with protection from western sun, and keep a bed around them as a buffer from lawn mower damage.

If your Japanese maple is ornamental enough to try saving, help it along by watering whenever the soil begins to dry. With every other watering, supplement with a water-soluble fertilizer for acid-loving plants, such as Miracid. Also, water in a mixture of growth stimulants, such as Roots, Superthrive, Bio-Plex or a seaweed-and-fish meal-based product. If you lose this tree, try again. Install the new one in a well-drained site. Dig the hole four times as wide as and no deeper than the root ball. Fill with one part compost, two parts native soil and keep moist.

Joel M. Lerner is president of Environmental Design in Capitol View Park, Md. E-mail or contact him through his Web site,http://www.gardenlerner.com.