Powdery Mildew on Calibrachoa (Million Bells)

— Written By
en 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.

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 ▲

A calibrachoa (million bells) with dried, brown lower leaves was submitted this week to the NCSU Plant Disease and Insect Clinic by a commercial grower (Fig. 1). Slightly younger leaves were turning yellow and had fine necrotic flecks (Fig. 2). There was no evidence of disease in the roots or stems. In this situation there are three likely causes: nutritional problems, spider mites, and powdery mildew. It was the latter. The powdery mildew fungus was present on both sides of the leaves, but the colonies were so thin that they were not visible to the unaided eye or even with a 10x hand lens. It took a microscope to confirm the diagnosis (Fig. 3).

An e-Grow Alert on this problem was published in May 2015. You may also be interested in the new Calibrachoa sheet in the e-Gro Nutritional Monitoring Series.

Note that a similar situation was encountered on greenhouse-grown dahlia plants on the NC State University campus last month (Fig. 4).

drying lower leaves

Fig. 1. Powdery mildew symptoms on greenhouse-grown calibrachoa

Leaf with moderate symptoms, not yet dried out

Fig. 2. Incipient symptoms of yellowing and blotchiness on a mid-level leaf.

chain of five barrel-shaped spores (conidia) on a small conidiophore

Fig. 3. Chain of microscopic spores (conidia) of the powdery mildew fungus Podosphaera

Lower leaves of potted dahlias starting to turn yellow and dry out.

Fig. 4. Greenhouse-grown dahlias with powdery mildew.