Don Kinzler, Published November 22 2013
Fielding questionsQ I am concerned that I have oak wilt spreading in my yard. My smaller oaks start out fine, but by July the leaves curl and turn brown, and it’s moving to other trees. I read an Extension office article that said the only remedy is trenching 5 feet down to separate the roots. Can you help me diagnose and remedy this problem?
– Melanie Cole, Fergus Falls, Minn.
A Oak wilt can be a quickly fatal disease caused by a fungus spread both by beetles and through the roots of one tree to adjacent trees. Leaves rapidly discolor, wilt and drop beginning at the top of the tree. The disease progresses rapidly on red oak types, characterized by pointed lobes. White oak types, with rounded lobes such as bur oak are slower to wilt, and survive longer once infected.
The most recent information from the University of Minnesota indicates that oak wilt has not been found north or west of the St. Cloud area, so I don’t think it has reached Fergus Falls. I also don’t believe it has been diagnosed in North Dakota, where most oaks are of the less-susceptible white bur oak type.
There are many factors that cause similar symptoms such as anthracnose, which doesn’t do permanent damage. Drought, insects, water-logged soil, chemical injury and construction soil disturbance can look like oak wilt. A test from a university’s diagnostic lab might be in order, but in the meantime you might watch for other causes.
Q I have a question about the replanted Easter lilies in your Nov. 16 column. Are they hardy enough to survive the winter in North Dakota or would they only rebloom that first fall?
– Vic Peterson, Fargo
A Great question. The Easter lilies pictured were obtained from our church, planted in May and bloomed in late September.
Easter lily (Lilium longiflorum) normally blooms in mid-summer along with its Asiatic relatives. Easter lilies are definitely borderline in hardiness in our Zone 4, but they will survive winter if protected with fall mulch and good snow cover. I haven’t mulched the lilies pictured, as I got side-tracked with our house fire, but I better get a layer of leaves added very soon.
Q In a recent column you mentioned grow lights. I start plants from seed in March and April in my basement and have always used grow lights in shop light fixtures. Can I really get by with regular fluorescent tubes? It would be a lot cheaper.
– Deb Larson, Pequot Lakes, Minn.
A My columns are usually a combination of what works for me blended with literary research to be certain I’m keeping up with new recommendations and findings.
I’ve used ordinary fluorescent tubes for our basement growing for 30-some years, mostly because I’m too frugal to pay the price of the more expensive plant grow tubes.
Recent research conducted by the University of Alaska demonstrated equal success with ordinary tubes compared to special plant lights. Some sources recommend using one cool white paired with one warm white tube.
However, I hate to advise anyone to change a successful practice, and you’re doing well with your system. This spring I’m going to buy some plant tubes and do a side-by-side comparison.
If you have a gardening or lawn care question, email Don Kinzler at firstname.lastname@example.org. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.