The content of this article 'Ten common plant diseases and disorders you can diagnose by eye' was prepared by Brian Hudelson for the University of Wisconsin-Madison and has been revised and republished by FreshFruitPortal.com.

Powdery Mildew

Hosts: Herbaceous and woody ornamentals, fruits, vegetables

Pathogens: Miscellaneous powdery mildew fungi

Signs/Symptoms: Powdery white growth on leaves

For more information: UW Garden Facts XHT1005a/b/c

Tar Spot

Hosts: Maples

Pathogens: Rhytisma spp.

Signs/Symptoms: Tarry areas (either sold spots or clusters of small spots) on leaves

For more information: UW Garden Facts XHT1126

Peach Leaf Curl

Hosts: Peach

Pathogens: Taphrina deformans

Signs/Symptoms: Light-green, yellow or purplish-red puckered areas on leaves

For more information: UW Garden Facts XHT1069

Sooty Mold

Hosts: Any plant

Pathogens: Miscellaneous sooty mold fungi

Signs/Symptoms: Powdery black growth on leaves or needles

For more information: UW Bulletin A2637

Chlorosis

Hosts: Oak, red maple

Cause: Iron or manganese deficiency, often induced by high soil pH

Signs/Symptoms: Yellow leaves with dark green veins

For more information: UW Garden Facts XHT1002

Gymnosporangium Rusts

Hosts: Juniper, apple, crabapple, hawthorn, quince

Pathogens: Gymnosporangium spp.

Signs/Symptoms: Brown blobs with orange gelatinous masses (juniper); yellow/orange leaf spots (other hosts)

For more information: UW Garden Facts XHT1009

Black Knot

Hosts: Prunus spp. (plum and cherry)

Pathogens: Apiosporina morbosa

Signs/Symptoms: Black growths on branches

For more information: UW Garden Facts XHT1056

Elderberry Rust

Hosts: Elderberry

Pathogens: Puccinia sambuci

Signs/Symptoms: Light yellow, powdery growths on branches

For more information: UW Garden Facts XHT1280

Golden Canker

Hosts: Pagoda dogwood

Pathogens: Cryptodiaporthe corni

Signs/Symptoms: Gold-colored branches with orange spots

For more information: UW Garden Facts XHT1125

Dog Vomit Slime Mold

Hosts: Any plant and on mulch

Cause: Fuligo septica

Signs/Symptoms: Scrambled egg-like masses on mulch or at the base of plants

For more information: UW Garden Facts XHT1091

For more information on common plant diseases contact your county Extension agent.