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Plant Pathology
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Taken from the B.Y.G.L. (Buckeye Yard and Garden Online) Newsletter
Contributing Authors: Pam Bennett, Joe Boggs, Cindy Meyer, Jim Chatfield, Erik Draper, Dave Dyke, Gary Gao, David Goerig, Tim Malinich, Becky McCann, Bridget Meiring, Amy Stone and Curtis Young |
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"Don't get caught with your plants down - Consult a Plant Pathologist." Such are the lessons learned by students in Plant Pathology on the OSU Columbus campus this quarter. Here are a few sample highlights from the class:
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*RUST ON BUCKEYE. A leaf rust was noted on Ohio buckeye on Main Campus and the Chadwick Arboretum on the Agriculture Campus, as well as reported from Joe Boggs in southwest Ohio. This rust appears to be of minor significance. *CEDAR QUINCE RUST. This is a more significant rust disease, one which alternates between junipers (Eastern red cedar) and plants in the Rosaceae family (rosaceous hosts): apples, crabapples, hawthorns, and quinces. It was quite prominent on a juniper in Chadwick Arboretum. Unlike other cedar rusts, this rust fungus does not cause large galls and showy fungal spore horns on junipers, but instead causes oozy spore masses on small cankered areas on juniper stems. These "orange-juice concentrate-like" masses dry to a dark orange-red on juniper stems during drier weather with spores disseminated to the rosaceous hosts now, resulting in symptoms on these plants in a few weeks. Cedar quince rust is also different on the rosaceous host than its cousin diseases, cedar apple rust and cedar hawthorn rust. Cedar quince rust causes spore masses on fruits and galls on stems, rather than the familiar orange spots on upper leaf surfaces and spore masses on lower leaf surfaces typical of these other rusts. *POWDERY MILDEW ON CRABAPPLE was noted on samples in class collected from the OSU Main campus. This seems early, coming even before symptoms of apple scab were observed. Powdery growth (a sign of the pathogen) was noted, as well as distorted new growth (a symptom of the disease). *Symptoms of SYCAMORE ANTHRACNOSE is beginning to show up on sycamores and to a lesser extent on London planetrees. This fungus overwintered on stems and is now spreading by spores to expanding leaves. It is likely that we will see more significant than usual spring anthracnose problems this year on American planetrees (sycamore), white oaks and ashes due to the extended cool, wet conditions that occurred during leaf emergence of these plants in most areas of Ohio. Those are the environmental conditions conducive to these diseases. Typically, though damage may seem severe, these diseases are not deadly relative to plant health, though often plant health managers treat due to customer demand. Remember that once leaves emerge and the season progresses, the leaves become less susceptible to infections. Treatments at this point will have little impact since one cannot eliminate anthracnose disease which has already developed. |
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