Disease Du Jour (July 15)

 Today’s disease images come to us by way of Rusty Batty in St. Tammany Parish. With the abundant moisture and humidity we’ve had recently, conditions have been ideal for a disease like fig leaf and web blight to exhibit itself. This disease is caused by the fungus Rhizoctonia solani, which we typically think of as causing root and crown rots. However, it is also capable of causing aerial and web blights in crops like beans, azaleas and others. The pathogen survives from one season to the next as sclerotia on the plant , in plant debris or in the soil. Symptoms first appear on the leaves as yellowish, water-soaked lesions that enlarge rapidly with the upper leaf surface taking on a silvery appearance. The white to light brown fungal mycelium is readily visible on the underside of the infected leaf, which may shrivel up and die. Occasionally, the fungal mycelium may actually “tie” the leaves and stem together as in the photo below. There are no fungicides registered for use on edible figs, so disease control relies solely on the removal of infected tissues to prevent further spread. 

Fig leaf and web blight (photo by G. Ballanco)

Fungal mycelium associated with fig leaf blight (photo by G. Ballanco)

  

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About Don Ferrin

I am an associate professor and extension specialist in the Department of Plant Patholgy & Crop Physiology with the LSU AgCenter in Baton Rouge. I have statewide responsibility for issues and educational programs related to diseases of all horticultural crops in Louisiana.
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