ANTHRACNOSE

Anthracnose may cause defoliation on most maple, oak, elm, walnut, birch, sycamore, and hickory trees. Occasionally, it can affect ash and linden trees.

May infect leaves, twigs, buds, shoots, and even the fruit of various landscape trees

Raking and removing infected leaves will remove the main source of spores that could infect the tree next spring

APPLE SCAB• Most severe during spring and early summer

when the humidity is high and the temperature is moderate

• Most obvious symptoms occur on leaves and fruit in the spring and summer, and look like small velvety brown-olive green spots that enlarge and darken to become more or less circular

BLACK SPOT• Roundish black spots with fringed margins that

can be up to ½’’ in diameter

• Spots form on the upper sides of leaves

• The disease is caused by a fungus called Diplocarpon rose

• To control black spots, rake fallen leaves and remove infected canes

• Avoid wetting leaves when watering and maintain air circulation around within the plants to promote drying

BOTRYTIS• Found virtually everywhere plants are grown

• Can attack many different types of plants

• Signs of Botrytis:

• Fading flowers

• Leaves on which fading infected flowers have fallen

• Broken stems or injured leaves

MANAGEMENT Remove dead or dying tissue from the

plants and from the soil surface

Heat and ventilate greenhouses to prevent high humidity conditions

Avoid injuring plants in any way

o Commonly called gray mold

CANKER

• Common, widespread, and destructive to a wide range of trees and shrubs

Symptoms Brown/reddish lesions on the

bark of trunks or branches, or as injured areas on smaller twigs

New leaves appear smaller than normal, often curled or sparse, and pale green/yellow/brown in color.

Management• Keep plants healthy through proper planting,

mulching, watering, soil management, pruning, and winter protection practices

• Do not prune when bark is wet• Avoid all unnecessary bark wounds

CEDAR-APPLE RUST

Can defoliate trees and blemish fruit making them unmarketable

Before an apple can be infected, adequate moisture must be present in a temperature range from 46-75F to allow for formation of basidiospores on cedar galls

• Leaves are most susceptible to infection when 4-8 days of age

• Fruit are susceptible from tight cluster through bloom

Control• Fungicides• Using resistant

varieties

CROWN GALL• Can infect a wide range of herbaceous and woody plants

• Usually restricted to the roots, lower stems, and lower branches of infected plants

• Caused by the soil-borne bacterium Agrobacterium tumefaciens

Management

• Avoid wounding plants near the soil line• Prune infected plants (Disinfect cutting tools

between each cut)

FIREBLIGHT A bacterial disease that can kill branches and whole plants of

many members of the rose family, including apple, pear, quince, and crabapple

Can be spread by insects, splashing rain or contaminated pruning tools

Symptoms• Dead branches• Water-soaked

blossoms• Light brown/blackened

leaves• Discolored bark• Black “shepherd’s

crook” twigs• Dried fruit

Management• Pruning (Sterilize all tools after each cut)• Chemical Sprays

POWDERY MILDEW

• Lilacs, crab apples, phlox, monarda, roses, grapes, squash and cucumbers are all likely targets for powdery mildew

• Looks like powdery splotches of white or gray, on the leaves or stems of plants

• Different powdery mildew fungi infect different plants

Causes• Dampness• High humidity• Crowded plantings • Poor air circulation

Management• Avoid overhead watering• Remove and destroy all

infected plants• Prune overcrowded material

ROOT ROT Plants affected by root rot will start losing

their leaves, yellowing, drooping, and look like they’re dying

Affected plants will drink less water

Symptomso Appear overwatered

or droopyo Brown, slimy, smelly

rootso Plant leaves start

turning yellowo Plants drink much less

water than usual

Management• Keep growing area

clean• Add beneficial bacteria

to the water• Try to get as much

oxygen as possible dissolved in the water