Phomopsis Gall on Hickory. 

An arboretum walk, a mature tree flowering and leafing out, a lovely spring day, a – gall. A bunch of galls, in fact, on this one tree. At first glance, the galls looked like horned-oak or gouty oak galls, round to oblong stem galls that occur on oak. The areas on the stems even looked sort of oak-ish at first, with masses of pollen-bearing male catkins evident. Not an oak, though, as the compound leaves attested. It was a hickory, and the galls, unlike the insect-induced horned oak and gouty oak galls, were caused by a fungus, the Phomopsis  ...

When most people think of horned oak galls, they visualize the gnarled, woody stem galls that form on the twigs and small branches of pin oaks.  This is understandable since the gall-making wasp, Callirhytis cornigera (Family Cynipidae) that's responsible for directing the growth of the stem galls spends 33 months developing inside individual chambers within these very obvious galls.

The galls grow larger in size with each season.  In early spring, as the immature wasps near the completion of their development, the whitish-tan, cone-shaped “horns” that give this gall its...

So-called marginal leaf fold galls are appearing on oaks in the "red oak group" in southwest Ohio.  The galls appear as rolled or folded leaf margins and are produced by a gall-making midge fly, Macrodiplosis erubescens (Family Cecidomyiidae).  As with the vast majority of oak galls, the leaf fold galls cause no appreciable harm to the overall health of affected oaks.  However, the gall has become notorious in recent years for its connection to a non-native predaceous mite (Pyemotes herfsi) that may feed on the gall-making midge fly larvae (maggots).  The mite...

The felt-like erineum patches produced by the eriophyid mite, Acalitus fagerinea, on the upper leaf surfaces of American beech are now appearing in southwest Ohio.  Currently, the patches are light-yellow.  However, they progress through several color stages throughout the season from light green in the spring to brilliant yellow to yellowish-gold then rusty red to reddish-brown and finally dark brown.

Although the patches are located on the upper leaf surface, they cause a dimpling of the lower leaf surface beneath the patch. 

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Last week, we reported that leaf and stem symptoms of the fungal disease known as sycamore anthracnose were becoming evident on the namesake host in many areas of Ohio.  This week, we're adding ash, oak, and beech to the list of foliar anthracnose diseases appearing in the southwest part of the state.  It's important to keep in mind that the anthracnose diseases affecting sycamore, ash, oak, and beech are each produced by a different host-specific fungus.  The fungus that produces anthracnose on sycamore does not infect ash, oak, or beech and vice versa; the fungus responsible for ash...

Wild parsnip (Pastinaca sativa) plants are rising towards their full height and blooms are beginning to appear in southern Ohio.  Landscape managers and gardeners should exercise extreme caution around this non-native invasive plant; the plant's juices can cause phytophotodermatitis (a.k.a. Berloque dermatitis).   If plant juices contact skin and the skin is then exposed to sunlight (specifically ultraviolet light), severe blistering can occur, as well as skin discoloration that may last several months. 

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First generation imported willow leaf beetles (Plagiodera versicolora) are munching the leaves of wild and cultivated willows in southwest Ohio.  This native of northern Europe was first found in the U.S. in 1915.  Since that time, it has become well established throughout most of the eastern and Midwestern states.  Although it has been a number of years since a significant outbreak has been reported in Ohio, this beetle has a history of periodically achieving population outbreak densities and causing significant defoliation of its namesake host.

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Heavy leaf damage from the non-native bristly roseslug sawfly (Cladius difformis) is becoming very apparent on its namesake host in southwest Ohio.  Roses in Ohio may be infested by this sawfly as well as two other non-native species:  the European roseslug sawfly (Endelomyia aethiops); and the curled roseslug sawfly (Allantus cinctus).  Despite their common names, the larvae of these sawflies resemble tiny caterpillars and look nothing like the glistening, elongated pear-shaped "slug sawflies" which do resemble tiny slugs.

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Overwintered common bagworm (Thyridopteryx ephemeraeformis) eggs have hatched in southwest Ohio and 1st instar caterpillars have settled to feed and construct their characteristic sac-like bags.  A percentage of the tiny 1st instar caterpillars produce a strand of silk upon hatching to catch the wind and "balloon" to new locations.  This behavior is one of the reasons bagworms often appear on hosts that were not infested last season.

Some of you might think that I am crazy (most already know that) but I am really getting to the point that I need rain.  Someone told me this morning that we are supposed to have 100% chance of rain today but I won't believe it until I can go out and play in it!

Last Sunday night, there were storms all around Ohio.  Driving back from Akron we hit some really heavy rain in Ashland County.   Friends on Facebook were saying that they got 3" or more in the Enon area.  I thougth for sure that we had to have gotten some at my house in the northern part of Clark County.  Pulling...