Tag Archives: Louisiana State Horticultural Society

Powdery Mildew Blighting Crape Myrtles Now

Powdery mildew, caused by the fungus Erysiphe lagerstroemeriae, is once again wreaking havoc on the blooms of susceptible crape myrtle varieties. The warm, humid weather during late spring and early summer has been ideal for disease development on plants in partially … Continue reading

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Impatiens Downy Mildew Makes Its First Confirmed Appearance in the Louisiana Landscape

We had our first confirmed report of downy mildew on Impatiens walleriana here is south Louisiana this weekend. My wife commented that one of the double impatiens that she’d gotten at one of the big box stores a couple of weeks … Continue reading

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New Online Citrus Disease Identification Tool

The U.S.D.A.’s Center for Plant Health Science and Technology has added a new online tool to aid in the identification of 24 diseases and common disorders of citrus. This new site contains an interactive key for identification based on symptoms as well … Continue reading

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A New Boxwood Blight in the U.S.

As if boxwoods didn’t have enough problems already with diseases caused by Phytophthora and Volutella, a new boxwood blight, caused by the soilborne fungus Cylindrocladium pseudonaviculatum (= Cylindrocladium buxicola), was confirmed on nursery plants in North Carolina last month. It was subsequently found in a nursery in … Continue reading

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Disease Du Jour (June 22, 2011)

I taught a Master Gardeners class in Avoyelles Parish yesterday evening and in appreciation Dr. Carlos Smith and members of the class presented me with this beautiful bouquet. It’s not everyday that you get a bouquet of tomato flowers, especially … Continue reading

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Citrus Post-Harvest Fungicide Now Registered in Louisiana

Graduate A+, a combination of the fungicides fludioxonil and azoxystrobin, is now registered for use in Louisiana as a post-harvest fungicide treatment on citrus.  As part of the federal quarantine for Sweet Orange Scab, all citrus fruit being shipped out of the quarantined … Continue reading

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Disease Du Jour (May 9, 2011)

Received this photo of what appears to be powdery mildew on Sedum from Bobby Fletcher, Jr.  This disease is quite common in nurseries and unlike most powdery mildews on other hosts, very little mycelium is present and is usually only visible with the … Continue reading

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