Skip to Main Navigation. Each navigation link will open a list of sub navigation links.

Skip to Main Content

Apply to the University of Wyoming

Global Resource Navigation

Visit Campus
Download UW Viewbook
Give to UW

UW Extension Diagnostics Team Seeing Spots

September 17, 2014

A growing number of tree and ornamental samples submitted to the University of Wyoming Extension diagnostic team have leaf-spot issues.

A generic term used to describe a number of leaf-spotting disease organisms that can affect all manner of plants, most leaf-spot diseases develop as small, scattered circular-to-oval dead areas in leaves under proper conditions (usually damp weather), says William Stump, extension plant pathologist.

Spots can enlarge and grow together to form large angular to irregular dead areas, and can range in color from tan, brown and yellow to gray and black, and with or without margins.

Stump says late-season leaf spots are typically more unsightly than harmful, while those beginning early in the season can severely weaken trees or shrubs, especially if they occur in two or more successive years.

Stump offers these suggestions to minimize leaf-spot disease:

-- Remove infected leaves and dead twigs before winter sets in.

-- Avoid wetting foliage while watering.

-- Maintain good plant health and avoid over-fertilization.

-- Use fungicides only in cases of severe disease causing defoliation for several consecutive years.

Fungi overwintering in fallen leaves, buds, fruits and twigs can spread leaf-spotting disease. Some fungi have specific hosts or may attack several species and, under proper conditions -- usually extended periods of cool, wet weather --numerous spores are produced that infect leaves, Stump says.

These conditions typically are found in spring or fall for Wyoming’s intermountain regions.

For more information, contact Stump at (307) 766-2062 or email wstump@uwyo.edu.

Photo:
UW plant pathologists say leaf-spotting disease organisms can affect all manner of plants.


Share This Page:

Contact Us

Chad Baldwin

Institutional Communications

Bureau of Mines Building, Room 137

Laramie, WY 82071

Phone: (307) 766-2929

Email: cbaldwin@uwyo.edu

Find us on Facebook (Link opens a new window) Find us on Twitter (Link opens a new window)

1000 E. University Ave. Laramie, WY 82071
UW Operators (307) 766-1121 | Contact Us | Download Adobe Reader

Twitter Icon Youtube Icon Instagram Icon Vimeo Icon Facebook Icon

Accreditation | Emergency Preparedness | Employment at UW | Gainful Employment | Privacy Policy | Accessibility Accessibility information icon