| HOST PLANT |
DISEASE |
SYMPTOMS |
MANAGEMENT |
Maple
Acer spp. |
Anthracnose, Discula species and others |
Tan/brown/black spots and blotches develop on leaves during
wet periods. Spring infections result in leaf distortion. Necrosis may
follow the veins. |
Rake up and destroy or compost fallen leaves. Promote tree
vigor. Not seriously damaging to healthy established trees.
CHEMICAL:
Preventative fungicides should be applied beginning at bud break when
deemed necessary. Bordeaux, chlorothalonil, fixed coppers, mancozeb,
thiophanate-methyl or zyban. |
| Leaf spot, Phyllosticta minima |
Well-defined lesion on the leaf surface with a
light-colored center and dark margin at maturity. Tiny black dots
(fruiting bodies of the fungus) are often visible. |
Rake up and destroy fallen leaves. Avoid wetting the tree
foliage during irrigation. Promote tree vigor. Seldom damaging to healthy,
established trees.
CHEMICAL: Treat preventatively with Bordeaux
8-8-100, fixed coppers or mancozeb. |
| Target-shaped canker, Nectria galligena, Eutypella
parasitica |
Perennial cankers develop around wounds on immature trees,
usually within 10 feet of the ground. The trunk is swollen around the
canker, which often has a “target-like” appearance. |
Plant on good sites in proper zone. Prevent damage to trunk
and limbs. Promote tree vigor. Remove branches with cankers. May become a
hazard tree and should be evaluated as such.
CHEMICAL: None. |
| Tar spot, Rhytisma acerinum |
Roughly circular, raised black spots on the leaf surface
which resemble spots of tar. Seldom a problem. |
Maintain tree vigor. Infected leaves can be raked up and
destroyed or composted.
CHEMICAL: None necessary. |
| Wilt, Verticillium dahliae |
Slow growth, dwarfed foliage and/or wilting. Leaves with
scorched margins. Defoliation. Often occurs on only one part of the tree.
Green to black vascular discoloration may be present in the sapwood of
larger branches and the trunk.
REFERENCE: Verticillium Wilt of Trees
and Shrubs |
Fertilize to promote growth; keep nitrogen to a minimum.
Prevent moisture stress. Remove dead limbs. Do not plant susceptible tree
species where Verticillium is present in the soil.
CHEMICAL:
None.
NURSERY: Preplant fumigation. |
