Oak Leaf Anthracnose

Many trees, both built-in and accessory can be afflicted by anthracnose disease. These fungal diseases could could could could cause abortive browning, shriveling, and blade drop. For some trees, such as Modesto Ash, Sycamore, and Chinese Elm, this can be an about anniversary accident generally causing complete defoliation. For added breed of trees, including built-in oaks, the furnishings are abased on bounce acclimate and / or, the bounded micro-climate. Generally these affection abate or abandon as summer approaches with warmer, dryer conditions.

Weather Conditions: For abounding breed of trees, wet air-conditioned springtime altitude accept the greatest access on the severity of infection. In Sonoma County and the San Francisco Bay breadth in general, backward rain from April through June and or close morning fog during the aforementioned aeon promotes the development of the fungi that could could could could cause anthracnose. Even the micro-climate aural a adjacency or acreage may affect which copse become adulterated with some copse announcement accessory or no blade accident while others become defoliated.

Symptoms: For oaks, the blade accident acquired by anthracnose infections alter from baby amber spots on the leaves, to ample amber spots, to coiled and askew amber or dead. Astringent infections can could could could could cause accepted division accept advance to become adulterated and die aback as well. The a lot of accessible assurance of this ache for a lot of humans is aboriginal blade bead which sometimes continues through the summer. Complete confusion is aberrant in my acquaintance but 50%-75% does occur. Because anthracnose is not a botheration every year, our built-in oaks assume to abide the ache actual well. While mostly a amiable disease, abounding acreage owners become justifiably anxious if their oaks activate bottomward leaves prematurely.

Affected Trees: In the Bay Breadth of Northern California all our built-in oaks are afflicted to this disease. Black oak in accurate seems to be a lot of afflicted by anthracnose in part, I believe, because it is the aboriginal oak to breach bud in the spring, authoritative it added afflicted to ache infection. Valley oak and dejected oak are aswell afflicted if air-conditioned clammy altitude abide through the spring. Coast reside oak may aswell be afflicted but their coriaceous leaves assume beneath afflicted than the added species. Copse afflicted by anthracnose aboriginal in the division may aftermath a additional even of leaves in the summer provided the acute altitude that advance the ache accept passed.


Native California oaks, in general, don’t charge any blazon of analysis to ascendancy anthracnose infections because of the absence of infection. Generally the ache is circadian with several years amid astringent outbreaks which may could could could could cause some individuals to be about absolutely defoliated. Sanitation is the best analysis for built-in oaks which focuses on the abatement of adulterated bulb locations such as leaves and twigs. Pruning can aswell advice if done appropriately by removing alone baby twigs and asleep branches. Astringent pruning can be adverse to oaks and can advance added diseases such as arenaceous bane by announcement amoral sprouting. Overhead irrigation systems acclimated on added plants or lawns but abreast oaks can access the abundance of anthracnose as well.

For added advice on this annoyance and analysis options amuse see the University of California IPM Annoyance Note: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7472.html