Powdery Mildew Fungus on Japanese Honeysuckle

Diseased plants are normally a disturbing sight.  My initial reaction when I saw pale, shriveling plants in this jungle of greenery was dismay.  That feeling dissipated quickly as I realized that all of the sickly plants were Japanese Honeysuckle.  Anything that weakens an invasive plant species has got to be good.

Closer examination revealed a velvety covering of mold on leaf and stem.  The condition is commonly referred to as Powdery Mildew and is the result of a fungus growing on the surface of the plant.  Powdery Mildew is an affliction shared by many species of plants, but for most plant species, there is a specific fungus that produces the condition.  Spores produced by the fungus on the Japanese Honeysuckle will only grow if they happen to land on another honeysuckle vine. 

Powdery Mildew definitely weakens the plant and it can cause death in severe cases.  Shade, humidity and temperature are the three factors affecting the growth of the fungus.  Spores ride the wind and blanket the countryside.  I’m certain that all honeysuckle has been in contact with the spores.  When conditions are favorable, the fungus thrives and the plants suffer. 

The fungus is only present in a few small patches of Japanese Honeysuckle at Blue Jay Barrens. The plants probably won’t die, but I’m hoping to see a significant reduction in competition between honeysuckle and the desired native plants.  Powdery Mildew has long been known to people who cultivate Japanese Honeysuckle.  Those people are happy to share methods of saving the plants, but I haven’t found any who have recommendations on how to encourage the fungus.

I’ll be keeping a close eye on this honeysuckle area as the summer progresses.  I would love to discover a method of growing the fungus on all of the Blue Jay Barrens honeysuckle.  Since the fungus growth is more a function of weather conditions, there’s no way that I can control its spread.  About the best I can hope for is the elimination of honeysuckle in these small areas.  I’ll certainly keep hoping for the best.