Q: Any idea what's going on with my arborvitae screen? — Frank Chiodo, email
A: Hot, dry weather is the Grim Reaper when it comes to separating well-rooted plants from poorly rooted ones. Arborvitae is an excellent screening plant, but it requires good soil preparation and regular watering for a year after planting for it to thrive. My bet is that yours was planted in an inadequate hole. That said, there's not much you can do about an arborvitae that's this far gone. Dig this one out and loosen an area 6 feet wide before planting a replacement.
Q: How deep do pine tree roots grow into the ground? I have a sewer pipe located 5 feet underground and want to know if the pipe will be damaged by the tree roots. The nearest tree is 6 feet away. — Sal Pirzad, Norcross
A: In undisturbed clay soil, pine tree roots rarely go deeper than a couple of feet. But when the soil has been disturbed, as in digging a sewer trench, they can grow deeper, because they have sufficient oxygen in the soil. It is hard to predict whether the roots will hurt the sewer pipe or not. The damage I typically see is roots that grow alongside a pipe and thicken with age. The expansion impinges on the pipe, particularly at joints, and can cause leaks. If there's a leak, the roots can go into the pipe, causing great tribulation. You probably need to hire a consulting arborist from georgiaarborist.org.
Q: I was planning to put down a 28-0-6 fertilizer when my zoysia grass goes dormant this year. I see that you do not recommend putting down fertilizer after mid-September. — Michael Pisani, Decatur
A: Keep in mind that, as day lengths shorten, zoysia grass and Bermuda grass stop absorbing much nitrogen. Generally speaking, winterizer-type fertilizers applied after mid-September have less and less benefit to a lawn as time goes on. The fertilizer also can predispose a lawn to spring diseases. I recommend you reconsider.
Q: I applied pre-emergent to control annual bluegrass for my Bermuda lawn in early September. Do I need to reapply the pre-emergent one more time in November or December? — Thu Pho, email
A: Much depends on how heavy your annual bluegrass infestation is. If you had a lot, then two applications make sense. If you had not many weeds last spring, then one application usually will be fine if you watered it into place after application. Remember that if you do have a lot of annual bluegrass, it indicates the Bermuda is not growing strongly. Your maintenance schedule should be adjusted to help the lawn grass be part of your weed control program.
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