I recently looked at some elms on Columbus city streets and took some images of two insects on one leaf, though mostly on lower leafs and trunk sprouts. One insect was a wasp leafminer, Fenusa ulmi.  The larvae of this insect “mine” plant leaf cells for their nutritive value. It is a native insect and generally is worse on non-native elm species and those hybrids with some Asian or European elm genetics. Typically, insecticides are not recommended but labeled systemic insecticides may be useful in situations where applications are warranted.

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The 9th time you have explained that soil and its effects on roots are the key to plant health… Your new landscape company and the difficulty of explaining your well-grounded vision of plant health management…Trying to convince your friends of the elegance of Townes Van Zandt’s lyrics…Getting everyone to see how cool byglalerts are as they show up on your phone…Sometimes only time will tell your truths to the rest of the world.  Do not despair: it is always thus.

As such, I started reading the book Mozart in the Jungle by Blair Tindall the other day and the lead quote was...

While hiking (sweating!) along a forested walking trail near my home over the weekend, I came across several types of oak apple wasp galls on their namesake hosts.  These unusual plant growths can range in size at maturity from 1/2 - 2" in diameter and are named for their resemblance to apples.  The galls are constructed of leaf tissue that has been hijacked by a gall wasp (Family Cynipidae) to surround a single wasp larva located within a seed-like structure positioned at the center of the gall.  The exact species of gall-wasp that is responsible for producing the oak-apple gall can be...

Lace bugs were very successful with overwintering in southwest Ohio and high populations are now producing noticeable symptoms.  The most obvious lace bugs include:  basswood lace bug (Gargaphia tiliae), hawthorn lace bug (Corythucha cydoniae), and oak lace bug (C. arcuata).  Sycamore lace bug (C. incurvata) is showing up on trees that were less affected by sycamore anthracnose this spring.

We are all used to seeing cedar apple rust, cedar hawthorn rust and cedar quince rust fungi on their dual hosts of junipers and Rosaceous hosts such as apple, crabapple, the occasional quince, and perhaps serviceberry in Ohio. I was much surprised to see what I think are Callery pear trees speckled with bright orange-red rust symptoms in German Village in Columbus this past week, however.

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Fireblight on Callery pear is highlighted against the blue sky in Columbus’s German Village this past Thursday in the lead photo of this byglalert, with a different look in the second photo taken with a different sun angle, important to remember when seeing images and thinking “it doesn’t look quite like what I saw”. Fireblight symptoms of “shepherd’s crook” shoots and discolored leaves are common to see now, following infections which occurred weeks, even months earlier in cool, warm weather during bloom. 

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The other day I was chatting with Joe Boggs after a program at OSU-Mansfield and regaled the beautiful white firs (Abies concolor) on the campus there. I mentioned that I thought this species of fir was the best-suited for Ohio landscapes, channeling a long-held and repeated opinion that other firs, such as Fraser do not do as well here due to hot summers, preferring North Carolina mountain country and New Hampshire and northern Michigan climes.

For the first times in our lives (not!) Joe disagreed with me. He has considerable cred here, having worked on Christmas tree...

Oak leaf blister is a disease is caused by the fungus, Taphrina caerulescens.  The fungus overwinters in infected buds and twigs.  Leaf infections occur during moist periods in the spring as leaves emerge.  Early symptoms appear as raised, blister-like, light-green to yellowish-green spots on the upper leaf surface matched with deep depressions on the lower leaf surface.  Eventually, the leaf "blisters" become very apparent as they turn dark brown to brownish-black.  The blisters may be evenly distributed across the leaf and are distinct from the angular, vein-based symptoms...

I planted a multi-stemmed Canada red chokecherry (Prunus virginiana 'Shubert') years ago in my landscaping so I could admire the deep, purplish-red foliage; a signature display of this selection.  Of course, that was before anyone knew it’s a magnet for the fungus, Apiosporina morbosa; the plant pathogen that causes black knot.  The disease is characterized by thick, corky, elongated gall-growths on twigs and branches that become coal-black late in the growing season; thus the common name for the disease.  Black knot is now the signature display of many Canada red...

First generation fall webworms (Hyphantria cunea) are appearing in central and southern Ohio.  Fall webworm moths typically have two generations per year in Ohio and despite their common name, first generation nests usually appear in late spring.  Fall webworm caterpillars only feed on the leaves that are enveloped by their silk nest.  As caterpillars grow in size, they expand their nest by casting silk over more leaves to accommodate their expanding appetites.

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