Skip to content to avoid repetitive links

Oak Pests - A Guide to Major Insects, Diseases, Air Pollution and Chemical Injury


[ Contents ] [ PreviousPrevious ] [ NextNext ] [ Go Back to DigitalArborist.com ]

MINOR DISEASES

Note: see bottom of page for figure descriptions.

Disease Agent

Injury

Control

Leaf spot, Septoria spp.
The fungus overwinters on dead leaves; spores are wind disseminated to young leaves in the spring.

Small round spots with straw- colored centers may be numerous; (figure 74); red oaks are preferred; defoliation may result in growth loss, but no mortality.

4
5
14
15

Powdery mildew, Microsphaera alni and PhyIlactinia guttata. These fungi overwinter on dead leaves and their spores are spread by the wind to healthy leaves.

White, powdery mold patches on leaves and buds (figure 75); leaves may be distorted, stunted and dropped prematurely.

5
15

Twig canker, Botryodiplodia gallae .
The fungi overwinter on dead tissues; in the spring, spores are wind disseminated to wounds and twigs.

Small sunken branch cankers and twig dieback (figure 76).

8
14
15

Spot anthracnose, Elsinoe quercus-falcatae. The southern red oak is preferred host; spreads by wind disseminated spores.

Very small spots on leaf upper surface starting about mid-summer.

5
15

Smooth patch, Aleurodiscus oakesii (figure 77).The fungus survives on the bark surface and releases spores which continues its spread.

Outermost bark sloughes as a result of fungal activity giving rise to slightly sunken lighter colored, smooth patches in the bark. Has no significant impact on the tree.

 

Iron-deficiency chlorosis (figure 78); iron deficiency may be a common problem with pin and willow oaks in some of the less acid soils.

Yellow-green discoloration between veins; leaves may curl, turn brown along margins and between veins.

16

Figures 74 - 78. --

(74) Septoria leaf spot
(75) Powdery mildew
(76) Twig canker
(77) Smooth patch
(78) Iron-deficiency chlorosis

 
[ Contents ] [ PreviousPrevious ] [ NextNext ] [ Go Back to DigitalArborist.com ]