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), said 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, yellow, grey or black and with or without margins.
Stump said late-season leaf spots are typically more unsightly than harmful, while those beginning early in the season can severely weaken a tree or shrub, especially if it occurs in two or more successive years.
Stump suggests 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, said Stump.
These conditions are typically found in spring and/or fall for the intermountain regions of Wyoming.
Contact Stump at 307-766-2062 or email@example.com for more information.