Mistletoe is easy to spot in leafless trees

Mistletoe usually grows from the top side of limbs, where birds have deposited the seed. (Walter Reeves for The Atlanta Journal-Constitution)
Mistletoe usually grows from the top side of limbs, where birds have deposited the seed. (Walter Reeves for The Atlanta Journal-Constitution)

Credit: Walter Reeves

Credit: Walter Reeves

Q: What are the little green leaf clumps visible in winter in leafless trees? Ned Morrell, email

A: I believe you’re seeing clumps of mistletoe. This small, evergreen shrub is seen most often growing high in the branches of bare pecan, hickory, oak, red maple and black gum trees. Mistletoe sends root-like structures into tree branches, from which it steals water and nutrients. It is semi-parasitic: It derives much nutrition from the host tree’s sap, but it manufactures some of its own food too. When birds feed on mistletoe berries, the seed inside the berry passes through the bird’s gut surrounded by a sticky film that helps the seed stick to tree branches when it comes out the other end. Areas where trees are heavily infested with mistletoe are indicative of a healthy bird population. Mistletoe spreads and grows relatively slowly and is rarely an immediate threat to tree health. Healthy trees are able to tolerate a few mistletoe plants with little harmful effect, but a heavy infestation may cause decline.

Q: My Georgia-born daughter has bought a home in Martin, Tennessee, west of Nashville. Is there much difference between your advice for Georgia and for west Tennessee? Lynne Connolly, email

A: The best way to compare different gardening spots is to determine their respective USDA Cold Hardiness zones. Martin is in Zone 7a. Comparatively, downtown Atlanta and northward is Zone 7a. Head south and you are in Zone 7b. I think your daughter would be able to plant anything that says it’s hardy in Zone 7, but she should monitor winter weather for a few years if she lives high on a hill or low in a valley.

Q: I’m using hay bought from a local feed and seed store to use as a garden mulch. Should I be worried that the hay may have been sprayed with an herbicide and the damage that may do to my vegetables? Bob Parsons, Cobb County

A: Yes, you should be worried unless you know specifically who provided the hay. It is not unusual for hayfields to be sprayed with herbicide to control weeds. If your store unknowingly buys it, your garden might suffer. It’s simple to do a bioassay to detect contamination. Buy a six-pack of tomato seedlings and pull out two. Jab a hole in a hay bale that’s large enough to hold the tomato roots. Place the two plants into the hay, leaving the leaves showing. Water a couple of times in the next few days. Tomatoes are very sensitive to herbicides and will let you know within a week if the soil is contaminated. The leaves will become thick and twisted and will be obviously malformed.

Walter’s email address is georgiagardener@yahoo.com. Listen to his comments at 6:35 a.m. on “Green and Growing with Ashley Frasca” Saturday mornings on 95.5 WSB. Visit his website, www.walterreeves.com, follow him on Twitter @walterreeves, on Pinterest, or join his Facebook Page at bit.ly/georgiagardener.

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