Disease Digest

Gallignostics

  Let us call this A Case of Gallignostics. Plant galls are defined as abnormal plant growths caused by a gall-maker; the gall-maker being certain insects, mites, fungi, and bacteria. From horned oak gall to bacterial crown gall, from maple bladder galls to cedar-apple rust galls, there are many galls of interest to horticulturists. Relative to all this, Joe Boggs recently got an e-mail from Michael Goldman of the Grange Insurance Audubon Center:

 

  I'm a big fan of the BYGL, and found something here that might be interesting for it.  The pictures I took look like some...

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Jim Chatfield
Joe Boggs

Oak Leaf Blister Disease

  Oak leaf blister, a fungal disease caused by Taphrina caerulescens, is widespread this year on a range of oak species, both in the white oak and red oak groups. Symptoms include raised, blistered, greenish-yellow spots on upper leaf surfaces and darker, corresponding sunken spots on lower leaf surfaces, though sometimes the raised and sunken aspects may be obscured. Fungal growth can sometimes be seen on undersurfaces of leaves.

 

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Jim Chatfield

Sycamore Anthracnose Symptoms Fade

  This morning I got a message from Frank Leon, horticulturist with Barnes Nursery, complete with the above image showing the thinning of sycamore (American planetree; Platanus occidentalis), a common sight seen in northwest Ohio this Spring. The problem is sycamore anthracnose, caused by the fungus Apiognomonia veneta.

 

 

  This particular anthracnose fungus occurs on planetrees, including our native sycamore, but less so on Platanus orientalis and the hybrid between these two planetrees, Londone planetree (PlatanusX acerifolia...

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Jim Chatfield
Yellow Polka Dotted... Tomatoes?? draper.15 Tue, 06/27/2017 - 20:16

I was called out to visit a high tunnel vegetable grower, who was concerned about what he was seeing on tomato leaves, which he hadn’t seen before on the plants.  He told me that spots had suddenly began to appear on his tomato plants, and that he really didn’t want to lose the plants or the huge crop of tomatoes that the plants had set.

 

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Erik Draper
Rosaceous Rusts Rampage chatfield.1 Mon, 06/19/2017 - 14:00

Rust on serviceberry? Yes. Has the whole world gone mad? No. It just reveals itself to each of us in manageable gulps.  We talk frequently of three “cedar rusts” on BYGL: cedar apple rust, cedar hawthorn rust, cedar quince rust, all caused by separate species in the fungal genus Gymnosporangium (bygl.osu.edu/node/781).  In fact, it is not as simple as this – there are over 40 species of the Gymnosporangium fungus. 

 

  Not only that, but there are over 480 species in 11 genera of the rose family (Rosaceae) that are affected by Gymnosporangium ...

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Jim Chatfield
Maple Anthracnose chatfield.1 Sat, 06/10/2017 - 23:55

Jeff Stachler, OSU Extensioneer in Auglaize County sent the following message this past Tuesday on June 6:

  “A maple tree in the front of a home yard has leaves with the symptoms you see in the photos.  Veins and leaf tips are black with yellow and brown colors below the black.  Is there anything that can be done or should be done?” He also sent the tell-tale photo above, showing “water-soaked” darkish lesions along leaf veins.

 

Right on time. Last June 5, I took a picture of a neighbor’s red maple in Doyletown in northeast Ohio of the same problem: maple...

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Jim Chatfield
Rusty Hawthorns boggs.47 Sat, 06/10/2017 - 11:28
It’s easy to spot wild hawthorns growing along Ohio trails at this time of the year if they sport gaudy orange-spotted leaves. The spots are the telltale leaf symptoms of Cedar-Hawthorn Rust and the leaf infections can cause hawthorns to stand out among other understory trees and shrubs.
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Joe Boggs
A Case Study: Peach Leaf Curl on Ornamental Peach Trees boggs.47 Wed, 05/17/2017 - 10:38
Peach Leaf Curl is a springtime disease caused by the fungus Taphrina deformans. The fungus can infect peach (Prunus persica) as well as a few other members of the Prunus genus. The disease can be devastating in fruit orchards, but it can also appear on ornamental (flowering) peach trees in landscapes and nurseries; the "ornamental" designation does not impart resistance.
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Joe Boggs

Rusty Junipers

Junipers in southwest Ohio are being garnished with tangerine tentacles and orange goo; the calling cards of rust fungi. The three fungi producing the colorful displays belong to the genus Gymnosporangium and each must alternate between a member of the plant genus Juniperus and members of the rose family (Rosaceae) in order to complete their life cycle.
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Joe Boggs
Signs and Symptoms: A Tale of Two Tar Spots chatfield.1 Wed, 10/19/2016 - 10:13

  As noted earlier (http://bygl.osu.edu/node/525) there are two common tar spots of maple seen in Ohio.  One, that occurs commonly on silver and red maple results in dense, tarry spots caused by the fungus, Rhytisma acerinum. A second tar spot disease is typically found on Norway maple, with multiple tiny tarry spots that eventually coalesce into a larger spot, not quite as “tarry” but nonetheless black in color, caused by the fungus  Rhytisma punctatum.

 

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Jim Chatfield