Apple scab disease, caused by the fungus Venturia inaequalis, is a common problem resulting in major aesthetic damage to many crabapple types (taxa). However, there is a tremendous range of susceptibility of these crabapple taxa to scab, and this can make all the difference to a landscape designer, a nurseryman, a homeowner, a garden center professional or Master Gardener volunteer making recommendations for plant selection. Got leaves, got ugly leaves, got beautiful leaves – all are options.

This is why the International Ornamental Crabapple Society has...

As Jim Chatfield and I wandered through the “Crablandia” plot evaluating and photographing crabapples today, we noticed multiple stages of the fall webworm munching on some of the foliage of the trees.  We first noticed the initial stages of the fall webworm caterpillars, which were small enough to have congregated on a single leaf.

It is always a revelation when taking pictures, when evaluating plants from catalogue photos, or just in terms of enjoying the nuances of a plant – to realize the importance of light. Backlit photos, the upper and lower surfaces of leaves, outlining against the bright blue sky: come forth and see the light!  Seen here are three views of the same tree, ‘Royal Raindrops’ crabapple.

As Jim Chatfield and I were out in the “Crablandia” plot today, we noticed the onset of multiple foliar diseases.  Many tree lovers at this time of year start to panic as some of the crabapple leaves begin to turn yellow and drop.  They are often frustrated because they were told that the crabapple they chose was scab resistant, but it still gets spots, the leaves turn yellow and then they fall off.  That’s the Apple Scab fungus right… Well, maybe so and maybe not!

All of these fungal diseases cause spots as a result of their infections of leaf tissue and all of them result in the...

We were out in our Crablandia plots at the Secrest Arboretum of OSU’s Ohio Agricultural Research and Development Center in Wooster today. One mission was to check for bacterial fireblight disease on the 76 crabapple taxa in our replicated, randomized plot. This spring we had heard of and seen some fireblight, on crabapples and other related rosaceous plants such as pears elsewhere, and we have susceptible crabapples in the trials so why not here? Yet, cultivar after cultivar, early blooming and late blooming types - no fireblight. Wait, wait, we see one shoot with the tell-tale shepherd’s...

Reports of branch die back in many trees are coming into the Medina Extension Office from around the county.  These brown patches are most likely the result of periodical cicadas laying eggs in the tender branches of trees.  Cicadas prefer laying their eggs in young twigs about 1/4 to 1/2 inch in diameter.  To lay their eggs, cicada stab a needle-like ovipositor into the branch that can cause these tender twigs to break, wither, and die.  The resulting symptom is browning leaves at branch tips known as "flags" or "flagging".  While larger trees have enough foliage to withstand tip dieback...

This digital image of dogwood arrived with the e-mailer asking if the problem was leaf scorch.   Damage seemed too great and too complete to be simple leaf scorch due to some transient heat stress. Further information indicated that someone had suggested that the plant needed potash and the e-mailer applied it and then asked if too much could be applied.  Well, yes. As with anything, even something as useful as fertilizer, “the dose makes the poison.”

The sender had applied 2 pounds of a 6 pound bag of a consumer-product potash (0-0-60) fertilizer. So at 2 pounds...

Earlier this week, Eric Richer (OSU Extension, Fulton County) sent me an image of a maple with almost all of the branches covered with Cottony Maple Scale females that were extruding their elongated, white, cottony ovisacs.  The oval-shaped dark brown females remained highly visible with their ovisacs peeking out from beneath their bodies.  The ovisacs expand to look like 1/4" diameter cotton balls on the branches of their host plants.  The scale has a very wide host range which includes their namesake host as well as ash, basswood/linden, black locust, dogwood, elm, euonymus, hackberry,...

Northern Masked Chafer (Cyclocephala borealis) and Southern Masked Chafer (C. lurida) adults are appearing around porchlights at night in southern Ohio.  It is common for people to assume that white grubs found beneath turfgrass in Ohio are Japanese beetle (Popillia japonica) grubs.  This is no longer a safe bet.  Japanese beetles have largely been replaced by these two chafers as the dominant "white grub producing" beetles in many areas of Ohio including the southern part of the state.  Indeed, I asked an experienced lawn care company last season to collect...

I received several images of white oak leaves from a homeowner who wanted to know why the leaves appeared bleached.  The culprit was Oak Lace Bug (Corythucha arcuata).  This lace bug lives on the undersides of oak leaves where they use their piercing/sucking mouth parts to suck juices from the leaves.  As with all lace bugs, their feeding produces tiny yellow or whitish leaf spots (stippling) that may coalesce to produce large, white patches on the upper leaf surface.  Eventually, the damage becomes yellow-to-copper colored and the overall damage can produce early leaf drop....