Marsonnina Leaf Spot Diagnostics chatfield.1 Sun, 06/26/2016 - 19:10

Marsonnina leaf spot of aspen is something I used to see out West when I lived and worked in Colorado, and maybe once or twice in Ohio, but the example I saw yesterday in Vermont was more about diagnostics. As you can see from this image the Marsonnina fungus causes considerable leaf blotch damage on aspen leaves. Note the pattern however.  The fungus overwinters on twigs and buds and then infects leaves during cool, wet conditions at first leaf emergence. Typically, and as seen here, damage is less or non-existent on subsequent leaf emergence. This pattern is common with many (...

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Jim Chatfield

Ailanthus Webworm Moths

Ailanthus webworm moths (Atteva aurea) are flying to porch lights in southwest Ohio.  In my opinion, this is one of the most beautiful moths found in Ohio both because of their coloration and because of what their caterpillars eat.  Caterpillars of this ermine moth (Family Yponomeutidae) feed exclusively on the non-native, highly invasive Tree of Heaven (Ailanthus altissima).

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Joe Boggs

Sneaky Caterpillars

There are over 1,400 species of moths in North America that belong to the family Geometridae; it's one of our largest families of moths and butterflies.  Yet, their caterpillars often remain undetected until missing parts of leaves draws attention to these sneaky general defoliators.  Look closely at the above image:  can you see the caterpillar?

 

I took this picture after first seeing the leaf damage then finding the caterpillar; however, I almost completely overlooked the culprit.  That's the M.O. of these caterpillars.  Their camouflaged coloration and sneaky behavior...

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Joe Boggs

Japanese Beetles are on the Wing

This past Thursday, I posted that Northern and Southern Masked Chafers (Cyclocephala borealis and C. lurida) were appearing around my porch lights at night in southwest Ohio.  I noted that owing to consistently low Japanese beetle (Popillia japonica) populations in recent years, the two masked chafers have largely supplanted Japanese beetles as the dominant "white grub producing" beetles in my part of the state.  However, that may change this season.

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Joe Boggs

Crabapple Scab in Ohio

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...

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Jim Chatfield
Erik Draper
Curtis E. Young
Crazy Caterpillars Consuming Crabapples! draper.15 Fri, 06/24/2016 - 15:18

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.

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Erik Draper
Jim Chatfield

Light, Camera - Crabapple!

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.

 

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Jim Chatfield
Erik Draper

Apple Scab, Rust and Frog-eye Leaf Spot- Which is What?

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...

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Erik Draper
Jim Chatfield

Fireblight, Crabapple, Crablandia. One Strike...

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...

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Jim Chatfield
Erik Draper