Craven County Center will be closed today, 12/25/2024 for the holiday.
Algal Leaf Spot
Find this article at: go.ncsu.edu/readext?765987
— Written By Thomas Glasgow and last updated by Jami Hooperen Español / em Português
Español
El inglés es el idioma de control de esta página. En la medida en que haya algún conflicto entre la traducción al inglés y la traducción, el inglés prevalece.
Al hacer clic en el enlace de traducción se activa un servicio de traducción gratuito para convertir la página al español. Al igual que con cualquier traducción por Internet, la conversión no es sensible al contexto y puede que no traduzca el texto en su significado original. NC State Extension no garantiza la exactitud del texto traducido. Por favor, tenga en cuenta que algunas aplicaciones y/o servicios pueden no funcionar como se espera cuando se traducen.
Português
Inglês é o idioma de controle desta página. Na medida que haja algum conflito entre o texto original em Inglês e a tradução, o Inglês prevalece.
Ao clicar no link de tradução, um serviço gratuito de tradução será ativado para converter a página para o Português. Como em qualquer tradução pela internet, a conversão não é sensivel ao contexto e pode não ocorrer a tradução para o significado orginal. O serviço de Extensão da Carolina do Norte (NC State Extension) não garante a exatidão do texto traduzido. Por favor, observe que algumas funções ou serviços podem não funcionar como esperado após a tradução.
English
English is the controlling language of this page. To the extent there is any conflict between the English text and the translation, English controls.
Clicking on the translation link activates a free translation service to convert the page to Spanish. As with any Internet translation, the conversion is not context-sensitive and may not translate the text to its original meaning. NC State Extension does not guarantee the accuracy of the translated text. Please note that some applications and/or services may not function as expected when translated.
Collapse ▲
January is a good time to inspect southern magnolias (Magnolia grandiflora) for the presence of algal leaf spot. According to Clemson University and other sources, the specific algae is most likely Cephaleuros virescens, which is the only species of plant parasitic algae that is common in the U.S. Pictured below is an infested leaf taken from a Craven County landscape in mid-January.
One good reason for inspecting your magnolias in winter is that the removal of fallen, infested leaves prior to the return of warm weather can help to reduce the severity of the problem. While algal leaf spot is usually not a serious issue, it’s best to not just ignore it. In addition to the removal of fallen leaves, you may be able to improve sunlight penetration and air movement by selective pruning of adjacent vegetation. You will likely notice that even on the same individual tree, the number of infected leaves will vary with more or less exposure to sunlight and air movement. (Copper-containing fungicides can also be applied, but this should probably be limited to commercial applicators, and becomes impractical on the larger magnolias.)
Close study of an infested magnolia leaf will reveal that there’s more going on than just the growth of the algae. In the close up below (taken from the same magnolia tree), you will note an orange/yellow algal growth to the right; and to the left, a couple of larger grayish/white splotches. These grayish/white structures are “lichenized” algae. In other words, as explained in a Clemson University information note, “Older algal colonies may become colonized (or lichenized) by a fungus and are then classified in the genus Strigula. This is the only lichen that is parasitic on plants. Lichens are composite organisms that include an alga and a fungus.” Visit Clemson University Cooperative Extension to review the Clemson note and to compare their images with the ones we’ve obtained from Craven County.
Thanks to Mike Munster/NC State University for his assistance on this topic.
