Oak Leaf Blister

Oak Leaf Blister , caused by the fungus Taphrina caerulescens is a common disease affecting many species of oaks. Members of the red oak group are particularly susceptible to infection. Disease development is favored by cool, wet springs and, in years when such conditions occur, noticeable leaf deformity results. White oaks are rarely infected, even in years with cool, wet springs. Heavy infections of red oaks impair their appearance but do not endanger the tree health.

Symptoms appear in early summer as yellow, blisterlike, circular, raised areas, 1/16 to 1/2 inch in diameter. The blisters are scattered over the upper leaf surface with corresponding gray depressions on the lower surface. They turn from yellow to reddish brown with pale yellow margins, then become dull brown with age. Several blisters may merge and cause the leaves to curl.

Rounded pale-green bulges develop on leaves soon after infection, while adjacent, healthy, leaf tissue remains flat. As the fungus grows in the leaf blisters, it utilizes materials in the cells as a food source, which kills them. The dead blisters turn gray-green and then brown.

Disease Cycle :In the Midwest the Taphrina fungus overwinters as microscopic ascospores lodged under the bud scales. The spores germinate in the spring as the buds break open and the young leaves are expanding. The germ tubes of the spores penetrate young leaves directly through the cuticle as emerging hyphae grow intercellularly mainly between the epidermal cells. A layer of asci forms in late spring or early summer between the outer epidermal wall and the cuticle.

The asci, which contain the ascospores, push through the cuticle and rupture releasing tremendous numbers of ascospores. The expelled spores cover the surface of the blisters giving them a white to light tan, powdery appearance. They are spread about by air currents, splashing rains, and insects to the buds, where they become lodged under the bud scales, thus completing the disease cycle. The causal fungus may occasionally cause one or more secondary cycles of disease when buds open unseasonably in late spring or summer. Mature leaves are resistant to infection.

Control: Because oak leaf blister does not seriously affect the overall health of the tree, chemical control measures are usually not recommended. Cultural controls tend to be ineffective because of the nature of the fungus and its method of infection and transmission. On small, newly established or especially valuable specimen oak trees previously damaged by leaf blister, apply a protective fungicide at budswell.

Fungicide, such as mancozeb or chlorothalonil, can be used as protectants. Preventative fungicide should be applied just prior to budbreak and through early leaf development for effective control.

If you ever have any bug related issues in New York City, feel free to call us either at Beyond Pest Control. Once again, and I can’t stress this enough we are on call twenty four hours a day seven days a week to kill those bugs, we aren’t kidding whether you call us at 9 am or midnight we will be available to take your call and either get rid of the bug infestation, or answer any questions you may have concerning the bug issue. I can honestly guarantee that there will be someone to answer that call. We make it our business to make you bug free!

If you have any questions about how to get rid of ants check out the rest of our website or go to our blog at http://nypestpro.blogspot.com.

Beyond Pest Control.

Our pest control specialists service all NYC boroughs, including Queens, Brooklyn, Bronx, Manhattan, Long Island (both Nassau & Suffolk counties), Staten Island and even both Westchester & Rockland counties.