Tag Archives: ornamental diseases

Gaura Rust

Posted on July 16, 2012 by Don Ferrin

Gaura lindheimeri is a plant native to southwestern Louisiana and Texas that is becoming increasingly popular as a landscape plant because it is a sun-loving, summer-flowering perennial that once established is fairly drought tolerant. For more on the horticultural merits … Continue reading →

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Cercospora Leaf Spot of Hydrangea

Posted on July 6, 2012 by Don Ferrin

Received these photos of Cercospora leaf spot on hydrangea from Gerald Roberts, county agent in Lafayette Parish.  This disease is caused by the fungus Cercospora hydrangeae, which reproduces on infected leaves that have fallen to the ground. The spores produced … Continue reading →

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Powdery Mildew Blighting Crape Myrtles Now

Posted on June 25, 2012 by Don Ferrin

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 Update

Posted on June 5, 2012 by Don Ferrin

Downy mildew was observed on Impatiens walleriana in a residential landscape in New Orleans today. The affected plants had been purchased at a “big box” store in the area, but it was not the same chain as the store in the … Continue reading →

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

Posted on May 21, 2012 by Don Ferrin

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 Oomycete-specific Fungicide from Syngenta

Posted on April 10, 2012 by Don Ferrin

Micora™, a new fungicide from Syngenta, is now registered for use on greenhouse and outdoor ornamentals and vegetable transplants to be sold to retail consumers. Micora™ contains the active ingredient mandipropamid (a carboxylic acid amide), which is specific for the … Continue reading →

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Rose Downy Mildew Is Active in Louisiana

Posted on April 3, 2012 by Don Ferrin

Received a call from a local garden center last week regarding downy mildew on a shipment of roses from California that they had hoped to sell for Mother’s Day. Symptoms on the somewhat resistant cultivar Mr. Lincoln could easily be mistaken for … Continue reading →

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Disease Du Jour (May 9, 2011)

Posted on May 9, 2011 by Don Ferrin

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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Disease Du Jour (April 20, 2011)

Posted on April 20, 2011 by Don Ferrin

I’ve heard that azalea leaf gall is quite prevalent in the Feliciana parishes this spring.  Some people considered these galls to be unsightly, but I guess that a matter of personal perception.  The fungus that causes them,  Exobasidium vaccinii, only invades the young expanding leaves during … Continue reading →

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Entomsoporium Leaf Spot Is Active

Posted on April 6, 2011 by Don Ferrin

Received the photo on the left from Al Orgeron in St. James Parish of Entomosporium leaf spot that showed up recently on red tip photinia. Also had some show up recently on my Indian hawthorn at home. There’s still time to spray to … Continue reading →

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