Q The shady side of my lawn is overrun with wild strawberries. How can I get rid of them?
A Wild strawberries, more accurately known as barren strawberries, are one of the most common turf weeds in our area and are growing merrily through the winter. They signal the presence of shade, acidic soil and excess moisture. Any broadleaf herbicide turf will kill them but unless you correct the conditions they like, they will return.
They are often confused with the true wild strawberry, which hails from the same genus as the strawberry grown for its fruit and similarly has white flowers with aromatic, red fruits. Barren strawberry, however, is a member of another genus, and has yellow flowers and tasteless, aroma-free fruit.
The best way to rid yourself of it is to have your soil tested. I suspect you have sour soil with a pH below 5.5 and that your test results will call for large amounts of lime to sweeten it. Clay soil, most typical for this region, needs much more lime than sandy soil to correct pH.
In dire cases, as much as 400 pounds -- 10 bags -- per 1,000 square feet of lawn may be needed.
The liming will help drainage by improving the soil structure, but you may still need to fix waterlogging by installing drains.
If all this sounds like too much work for a weed-free lawn, there are other options. I'd much rather spend valuable time in the garden creating a shady bed with groundcovers such as Allegheny spurge (Pachysandra procumbens) and variegated sweet flag (Acorus gramineus), perhaps with some English bluebells (Hyacinthoides nonscripta) mixed in for spring color.
I have a climbing hydrangea growing up and across my backyard deck. It starts filling out in April and through mid- to late-May it is really beautiful, with lush, green leaves. In June, the Japanese beetles arrive and attack. I've tried placing beetle bags farther out in the yard (away from the deck), and they fill up, but it doesn't seem to curtail the number of beetles attacking that particular plant. I also spray the hydrangea with Sevin, and although it kills a few it doesn't stop the onslaught.
The end result is a decimated plant that is an eyesore until the following April. I've even considered trying to cover the plant for six weeks while the beetles are at their peak, but I am not sure what to use or how to do this. Any suggestions?
You have planted one of the Japanese beetles' favorite host plants. Forget about the Sevin, unless you want to spray every three days. Toss the beetle traps in the trash -- unless you can place them a quarter mile away from the climbing hydrangea, they serve only to attract more beetles than they kill.
There's a chance that you can keep the beetles under control just by picking them off the plant or knocking them into a bucket of soapy water, but the most effective measure is to treat the vine with a soil drench containing the pesticide imidacloprid. You can find this pesticide in the Bayer Advanced products. Be sure to apply the drench in spring, several weeks before the beetles appear, because it takes some time to get the pesticide into the plant.
I recently purchased a Tamarix ramosissima tree. It's a beautiful cultivar, "Pink Cascade," trained into a standard form. Now I've read that it is highly invasive on the West Coast. Is it invasive in our area as well? I planted it on my farm and would not want it to take over the native fauna.
Tamarisk is invasive in parts of the west, where it grows rampantly along stream courses. It has had a profound ecological impact, since it can send roots deep into the soil to exploit groundwater that native plants are not able to reach. In some areas, it has caused wells to go dry and has reduced stream flows.
In the eastern half of the country, tamarisk is not a problem plant. In fact, it is not able to compete with native vegetation and does not escape into the wild. You can grow it here in good conscience.
Scott Aker is a horticulturist at the U.S. National Arboretum.
