Eco-gardening is at its best in The Monday Garden
FEBRUARY 22, 2004, Issue 100
This morning, there’s a breath-takingly beautiful winter tree photo on my cousin Nancy’s site, and she mentioned our mutual love of winter tree viewing, so that inspired me to write about another fine winter-viewing tree, our native locust.
picture: Long Island Sound (Dolphin Cove, Stamford, CT)
North America has two great locust trees that range today from southern Canada to northern Florida. The Black (or Yellow) Locust (robinia pseudo-acacia) was pushed into Appalachia by the Ice Age but was spread back over the Eastern seaboard by the European settlers. The Honey Locust (gleditsia triacnthos) is a mid-westerner.
Both locusts, members of the pea family, leaf out late in spring and drop their leaves relatively early in the fall, which leaves their “bones” exposed for viewing a good part of the year. The spring leaf color is a lovely yellow green and the fall, orange to butter yellow. In summer, the Black Locust is blue green and the Honey, a bright green-green. The Black Locust has grape-shaped leaves; the Honey Locust leaves are more elongated.
picture: Honey Locust, Summer Street Stamford, Summer 2003
Picture: Morgan Street, Stamford CT, fall 2003
Both trees are urban, yard, and beach favorites. They are fast growers that need full sun but are tolerant of all soil types, salt and pollution. They’re subject to a range of icky pests (mites, virus, and fungus) but generally fight them off without help.
The Black is a tall, thin, gothic-looking tree with zig-zag twigs, no visible buds, and short thorns. It reproduces from roots suckers so it’s often found in groves. Older trees will have deeply furrowed bark.
picture: Black Locust, Bedford Street, Stamford, Ct
The Honey Locust has a rounder, spreading shape, big thorns, and the bark comes in large rough scales.
picture: Honey Locust, Morgan Street Ally, Stamford CT
The Black Locust has showy, white sweet-pea like flowers in late spring that, as any bee will tell you, make great honey. The Honey Locust’s flowers are white-green and not particularly noticeable. The both trees’ flowers turn into long, woody pods that the trees hold through winter. The Black’s look like polished mahogany; the Honey’s are lighter and tend to be very curly.
My mother has a Black that every other year produces an astonishing quantity of pods, despite the very young pods being a favorite of numerous birds. The squirrels and crows will eat the mature pods but only as a last resort. This, unfortunately, leaves bag after bag of pods to be raked up. The Honey Locusts, believe it or not, are named for a sweet, edible jelly found inside the pods, coating the seeds.
Locusts are great yard trees (if you get a pod-less, thorn-less cultivar). They grow fast so the nurseries can sell them fairly cheaply and they’ll give you lots of shade pronto. And it’s light shade so it’s OK for the shade garden and the grass. I have noticed that, over the years, the big, shallow locust roots heave up sidewalks and the like; indeed, the ones in front of my condo are doing a number on the driveway. So consider planting them away from paved areas where this could be a problem. Also, locust spread so fast that we have a local invasiveness warning out on them, so make sure to get the pod-less kind.
picture: Locust grove, Cove Island, Stamford, CT October 2003
©Susan W. Sweeney 2004.
___________________________________
What the readers:
Congratulations on Issue 100! That's quite a milestone and I've enjoyed every one. (Brother) Bill (CO)
Wow, 100 weeks already! I can't believe it!. Keep up the good work; I really enjoy the weekly publication! Jennifer (NJ)
Happy 100th issue! And a beautiful picture -- as always -- but I'm not going to use it as wallpaper (which is what I usually do with your pictures) because I want to think about SPRING!!!! Gregg (NY)
Well, this is a very interesting issue. By the way, the backyard is covered with locust pods. I can't believe that they all came
Comments (7)
Enjoyed your page on black locusts. Nice photos!
-- David Beaulieu
Landscaping Editor
About.com Network
Posted by David Beaulieu | November 7, 2005 3:06 PM
Posted on November 7, 2005 15:06
Hi Sue,
We planted a Locust last year and then the builder leveled the back your and left the roots exposed and may have hit it. Most of the trees are starting to bloom but not the Locust. Is it a late bloomer and is there any tree fertilizers I could apply.
Thanks for your help.
Kevin
Kevin -- it's too early to worry; locusts are one of the last trees to leaf out.
Most tree never need fertilizing and fertilizing a sick tree is throwing oil a fire.
If you think the tree may be a bit stressed out, and this one could be, make sure that it has enough water when it doesn't rain. Most trees want about 1 inch a week, depending on humidity, sold drainage, etc-- enough to make the soil moist down 6 to 10 inches.
Water the whole area under the tree out to the edge of the tree's "drip line" (point where the longest reaching branches would drip on the ground).
Mulch is also great to keep the roots cool and moist; the earthworms and other soil critters will slowly digest the mulch and carry nutrients that the tree can safely use down to the tree's roots for you. Spread up to 2" deep (and no more!) and leave an empty space about 6" from the trunk. I personal like cedar mulch or compost (but I must be sure of the source).
Hope this helps and good luck with the tree
Sue
Posted by S. W. Sweeney | April 30, 2006 9:08 PM
Posted on April 30, 2006 21:08
it seems some insect or virus is wiping out the black locust trees all around my neighborhood. i live in buffalo ny, is this just a common pest or a real problem?
Posted by ted | June 6, 2006 7:15 PM
Posted on June 6, 2006 19:15
Ted -- I'm all ears.
For starters, are you certain it is the black locusts, not the honey locusts?
The honey locusts down here get devastated every few years by a late, wet spring like this year, which brings out a host of pests (insects and fungi) that kill the honey locust's whole first crop of leaves. The trees then have to make a whole new set of leaves and don't get fully leafed out until mid-late June but this is "normal" for honey locusts and they live with it. The trees only get weakened if we have 2 or 3 bad years in a row, particularly if the wet spring is followed by summer or fall drought, and then we could lose some.
The thing to do for the honey locusts is to resect the tree's ability to take care of itself. We can assist the trees by mulching the roots out to the drip line, and by giving it supplement water so that, with the natural rain fall, it's getting the equivalent of an inch of rain a week. (Don't fertilize -- that's generally harmful to an ailing plant).
So, first thing is to make sure it's not the honey locusts. If it's the black locusts, I'd like more detail on just what symptoms you're seeing so we can figure out what it is, and then check around the web to see where there have been similar reports, etc.
Sue
Posted by S. W. Sweeney | June 7, 2006 11:38 AM
Posted on June 7, 2006 11:38
I have a locut tree in my yard that has something. The outer branches/leaves are covered with a fine weblike substance and the leaves are rolled over and brown. What could this be. How does this insect or whatever it is, get into my tree. How do i prevent it. What is it??? what can i do about it - it is really ugly stuff and there are tiny extrements all over my deck!!! please email me the answes Thank you
Faye
Posted by faye schlatter | August 1, 2006 1:14 PM
Posted on August 1, 2006 13:14
Faye -- I'm not a tree disease expert so can't tell you exactly what the problem is but it sounds like an insect. If it was me, I'd turn the garden hose on them (every day or two for a few days).
The real thing to check is whether the tree is healthy since healthy trees can usually fight off bugs on their own. Tree health is usually directly related to how it was planted, the growing conditions (e.g sun, drainage), and environmental damage such as heavy equipment compacting the roots or being exposed to lawn chemicals.
Hope this helps
Sue
Posted by S. W. Sweeney | August 2, 2006 8:19 AM
Posted on August 2, 2006 08:19
THANKS, BUT I AM SURE IT IS AN INSECT. WE LIVE ON A LAKE AND IT IS HEALTHY. I USED TANGLEFOOT ON THE OTHER LOCUST IN MY YARD AND IT HARDLY HAS ANY SO I AM THINKING THAT MAYBE IT IS A WORM THAT CREEPS UP THE TREE IN THE SPRING TIME. I THINK I WILL USE THAT AGAIN FOR THIS ONE NEXT YEAR. STILL WOULD LIKE TO KNOW WHAT IT IS EXACTLY. THANK FOR YOU CONCERN. I AM FROM COLDWATER, MI.
Faye -- Interesting -- let me know how the tanglefoot works. If you want to ID the insect try these sites:
http://www.sickplant.com/
http://www.caes.state.ct.us/Plantoffice/plantoffice.htm
http://www.ipm.iastate.edu/ipm/hortnews/indices/plantdisindex.html
http://plantclinic.cornell.edu/
or Google "locust + insect"
Good luck
Sue
Posted by S. W. Sweeney | August 2, 2006 11:48 AM
Posted on August 2, 2006 11:48