Q. I had a large oak taken down and noticed light-colored worms crawling under the bark. Did they kill the tree? Can we use the wood for firewood?
A. The worms -- most likely beetle larvae -- did not kill your tree. Many types of beetle larvae will bore into severely stressed trees and feed on the cambium -- the area under the bark.
You can burn the infested firewood but bring it into your home only as you need it. Keep it stored outside and away from your house.
Q. I love vinca and plant it in garden beds and different types of containers. This year, half the potted plants wilted and turned brown, even though I planted them in rich garden soil and watered them once or twice each day. The others were beautiful. What mistake did I make and how do I avoid making it next year?
A. Vinca is susceptible to different types of root rots, including phytophthora. These fungi occur naturally in all soils and thrive under moist conditions. Your garden soil probably drained poorly and allowed one or more of these root-rot organisms to gain a foothold.
Next year, use a soilless potting mix that drains well, and be sure your pots have several holes in the bottom.
Q. My neighbor's very tall and invasive bamboo grew into my yard this summer. We want to know the best way to keep it at bay. Are herbicides the only solution?
A. Herbicides will not reliably control bamboo and may also damage your neighbor's plants. The best solution to your problem is a solid barrier. The first step is to dig a 2-foot-deep trench by hand or with a trenching machine. This will immediately sever the thick underground rhizomes that support the growth in your yard.
Angle the trench outward from the bamboo and line the trench with a root-barrier product that is at least 40 mil thick. Rolls of rubber matting used on roofs and as pond liners will work well. Cut the material 2 feet wide and lay it in the trench, allowing the top to stick out above ground level. Backfill the trench, and leave no gaps in the barrier.
THIS WEEK'S CHECKLIST
1. Plant tulips at a depth of three to four times the height of the bulbs. Be sure to incorporate a balanced fertilizer before planting.
2. Place a netted cover over your backyard pond to keep leaves from falling in.
3. Use a mulching lawn mower with a bag attachment to collect and chop all diseased leaves that have fallen from shade and fruit trees. Compost the chopped leaves.
Garden tips are provided by the Home and Garden Information Center of the Maryland Cooperative Extension. For additional information on these questions, or if you have questions of your own, call the center's hot line at 800-342-2507, or visit its Web site at www.agnr.umd.edu/users/hgic.