The following articles were compiled during the last 7 days by members of the Buckeye Environmental Horticulture Team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer. Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu
For more pictures and information, click on the article titles. To contact the authors, click on their names
Authors Erik Draper
Published on April 23, 2021
How many of us have gone outside to smugly look at our gardens that looked pristine and in excellent shape heading into the winter? Then in the Spring, as we emerge from our winter hibernation to survey our domain… We are shocked! What the heck happened out there because there are tufts of green weeds everywhere! A gardening friend asked me what this green thing was, because he had already pulled or dug up two wheelbarrow loads of them! The prolific green demon belongs to the mustard family (Brassicaceae) and is known as Hairy Bittercress (HB) or Cardamine hirsuta.
HB is typically a winter annual, but it can also be a summer annual and or even act as a biennial—another plant that doesn’t follow the rules! As a winter annual, HB germinates and leafs out as a basal rosette to sneakily and vegetatively pass through winter, soaking up any available sunshine. In early Spring, the tidy green mound sends up flower stalks with tiny, white flowers to begin to create the real mess… seeds. Each plant has the potential to produce 600 to 1,000 little green bombs called seeds!
The flowers form thin, purple, seed pods, which are actually called siliques. This is where HB disguises itself as innocuous and cute with the upright, purplish-green siliques scattered around the flowers, looking so Spring-fresh and nice. As the seeds mature inside of the siliques, these prolific pods begin to coil tightly to create the greatest gardening crime ever—they explode, flinging seeds in all directions!
Well okay, they don’t really explode, but the tension in the ripe silique causes it to suddenly split apart (dehisce), catapulting seeds in every direction. Anything barely touching the nasty pods, like tools, your hands or even the gentle wind stirring through the pods, causes a reaction. The appalling purple silique will violently detonate, whipping the seeds up and out into the blast zone, to sail as far away as sixteen feet! When you weed, they get in your eyes, up your nose, and in your ears and hair—they are everywhere!!
This obnoxious weed can be controlled with various preemergence and postemergence herbicides, but it is all about application timing. Usually late in the year, you are satisfied with the garden season and have put most garden chores and tasks to bed, ready for winter. That is the prime time to become a bound and determined bittercress buster!
To achieve successful control of hairy bittercress, preemergence herbicides applications should be applied in late summer or early fall. Postemergence herbicides applications, using a contact, non-selective herbicide to target tender seedlings, should begin in mid-fall or early Spring. To get ahead of this seed flinging machine, don’t let it flower or mature to develop those blasted purple launch pods! Keep after those tender, germinating seedlings, which shamelessly seem to emerge year-round, with no hesitation whatsoever. Therefore, anytime you get a chance to go outside when the weather warms up… Get outside and begin BUSTING HAIRY BITTERCRESS!
Authors Joe Boggs
Published on April 22, 2021
Temperatures have dropped into the dumpster for a second time this spring throughout Ohio. Of course, it’s spring and it’s Ohio.
Round one turned beautiful magnolia blooms into brown mush in southwest Ohio. Impacts from this second round are yet to be determined but it’s likely some trees and shrubs suffered frost/freeze damage that will eventually be revealed with symptoms ranging from blasted flowers to wilted, blackened leaves, to twig dieback.
However, feeding damage by the buckeye petiole borer (Zeiraphera claypoleana, family Tortricidae) produces symptoms that are a dead ringer for frost/freeze damage. Wilted leaves on buckeyes (Aesculus spp.) deserve a close look.
Dave Shetlar (OSU Entomology, Professor Emeritus) shared images of the caterpillars in buckeye petioles in central Ohio during our BYGL Zoom Inservice on Tuesday morning. Curtis Young (OSU Extension, Van Wert County) showed images of the symptoms on buckeyes in northwest Ohio and I’m finding damage on wild understory buckeyes in the southwest part of the state.
We’ve noted in past BYGL Alerts that the moth appears to prefer small understory trees growing in wooded areas along streams. I’ve rarely seen damage on mature trees or trees in landscapes. Although the literature notes this native moth is specific to Ohio buckeye (A. glabra), I’ve also observed petiole borer activity on yellow buckeye (A. flava).
Petiole Borer Detection
As their common name indicates, the caterpillars tunnel within leaf petioles to feed on vascular tissues. The damage causes leaves to rapidly droop, wilt, and turn dark green to black. Damaged leaves eventually detach producing mild defoliation.
I’ve never found more than one caterpillar per petiole even where populations are high. Look closely for a slight swelling of the petiole on wilted leaves. There may be a small hole exuding granular-like frass (insect excrement). This indicates there is a caterpillar actively feeding within the petiole.
A clean hole in the petiole indicates the caterpillar has completed its development and exited to pupate in the soil. Slicing open the petiole will reveal a short, empty chamber.
Trees usually only suffer a few damaged leaves. The hit-or-miss nature of the wilted leaves provides good evidence that it’s not frost/freeze injury. Damage by this borer may appear conspicuous; however, the caterpillars seldom cause enough leaf loss to affect the overall health of infested trees.
On the other hand, earlier this week, I found and photographed a caterpillar boring into the tender new terminal growth on a small understory tree in southwest Ohio. I’ve never seen or heard of this type of damage. However, damage to main stems represents a potentially more serious impact compared to the loss of a nominal number of leaves.
There are two generations in Ohio with the first generation coming to an end in the southern part of the state. The vast majority of the petioles I inspected earlier this week were empty with only a few petioles and the aforementioned main stem containing mature caterpillars.
There are no chemical control recommendations given that the damage is usually confined to wild buckeyes growing in wood lots and leaf loss from the petiole borer is seldom significant. However, I’ve seen localized populations gradually increase over successive years to eventually produce very noticeable symptoms with the damage caused by the second generation becoming more severe.
Hand-removal of infested leaves can reduce localized petiole borer populations. The first step is to make certain the petioles actually contain caterpillars; a clean hole means the caterpillar has vacated the premises! Removing first-generation caterpillars will decrease damaged caused by the second generation later this spring and the removal of second-generation caterpillars will help to deplete the overall population.
The second step is to destroy the caterpillar within the infested leaves and stomping is highly effective. Thus far, no populations have become resistant to this control method.
Authors Thomas deHaas
Published on April 22, 2021
During the recent snowstorm that hit Northeastern Ohio, some trees and property owners suffered serious damage.
But not all.
Young tree training is the key to providing your trees the best chance at surviving a storm or heaving snowfall. When trees are young, the homeowner can do some of this training themselves. The focus should be on developing a strong central leader and getting rid of weak crotch angles.
As trees age, they typically require the attention of an arborist. The International Society of Arboriculture certify these individuals. It is recommended that you seek the help of an ISA certified arborist. You can search for one in your area by using the following link: https://www.isa-arbor.com/
If you don’t hire a professional, you might end up with something like this:
I am reminded of the Fram Oil commercial “You can Pay me now or pay me later.” I’m dating myself! If trees are left to their own devices, they can form very bad habits (and growth).
In a forest, trees tend to shade each other out and develop a strong canopy. Also, trees growing in a group tend to resist wind damage.
In the landscape, a tree typically gets all the sun, water and food it wants, and therefor overgrows itself. The result is competing leaders, weak crotch angles, and eventual loss of branches.
During the past weather event, the Norway Maples were almost entirely in leaf and suffered much of the damage. But not all Norway Maples. Click here for pictures of a Norway Maple that was trained to have a central leader and one that was trained to have strong crotch angles with room to grow.
Also damaged were evergreens and flowering trees that were in full flower.
The lessons to be learned are as follows:
- Train trees when they are young.
- Hire a certified arborist to prune larger trees as they age.
- Remove trees that are a danger to property or people.
It could save your life and/or your home!