Pest & Disease Anthracnose

Anthracnose

Colletotrichum graminicola

What is Anthracnose leaf blight (Colletotrichum graminicola)?

Anthracnose leaf blight, caused by Colletotrichum graminicola (formerly known as Glomerella graminicola). It affects various crops, particularly cereal grains. Early in the season, it manifests as small, oval water-soaked lesions on lower leaves, which enlarge to ¾ inch with tan centers and red to reddish-brown or yellow-orange borders. Severe blighting results in yellowing and death of entire leaves. Late in the season, upper leaves are affected.

How does Anthracnose leaf blight (Colletotrichum graminicola) occur?

Colletotrichum graminicola reproduces through two methods: asexual and sexual. In asexual reproduction, the fungus produces spores called conidia, which are spread by wind, rain, insects, or machinery. Sexual reproduction involves the formation of special structures that produce spores called ascospores. These ascospores are also dispersed by wind. Both methods help the fungus survive and spread, with asexual reproduction being the main way it spreads and sexual reproduction adding genetic diversity.

Symptoms

1 - Effects on Crops

• Anthracnose leaf blight can cause significant yield losses in affected crops. • The disease affects leaf function, reducing photosynthesis and weakening plants, leading to reduced grain quality and yield.

2 - Effects on Soil

• Colletotrichum graminicola overwintering on crop debris leads to infected residue accumulation, increasing disease risk. • Severe infections disrupt nutrient uptake and cycling, affecting the availability of future crops. • Disease outbreaks can impact soil biodiversity and ecosystem interactions.

Solutions

1 - Cultural Practices

1. Practice crop rotation, avoiding consecutive maize and other susceptible crop plantings. 2. Use maize hybrids that are resistant or tolerant to anthracnose leaf blight. 3. Remove and destroy crop debris after harvest to reduce overwintering fungal spores. 4. Incorporate crop residue into the soil through tillage to accelerate decomposition and reduce the survival of fungal pathogens. 5. Use high-quality, disease-free seeds from reliable sources to minimize the introduction of fungal inoculum.

2 - Fungicides Applications

• Common fungicides active ingredients used for the control of anthracnose leaf blight caused by Colletotrichum graminicola in corn and cereal crops include azoxystrobin, pyraclostrobin, propiconazole, tebuconazole, thiophanate-methyl, and mancozeb (contact fungicide). • It is important to note that the availability and specific recommendations for fungicides can vary by region and may be subject to local regulations.

Susceptible Species

Flamingo Boxelder

Kelly's Gold Boxelder

Japanese Maple

River Birch

River Birch (clump)

Summer Cascade Weeping River Birch

Eddie's White Wonder Flowering Dogwood

Cherokee Brave Flowering Dogwood

Cherokee Chief Flowering Dogwood

Cherokee Daybreak Flowering Dogwood

Cherokee Princess Flowering Dogwood

Cherokee Sunset Flowering Dogwood

Red Flowering Dogwood

Cornelian Cherry Dogwood

Golden Cornelian Cherry Dogwood

Variegated Cornelian Cherry Dogwood

Leprechaun Green Ash

Patmore Green Ash

Sweet Gum

Round Leaf Sweet Gum

Silver King Sweet Gum

Slender Silhouette Sweet Gum

Worplesdon Sweet Gum

Tuliptree

Arnold Tuliptree

Yellow Variegated Tuliptree

Fastigiatum Tuliptree

Alexandrina Saucer Magnolia

Rustica Rubra Magnolia

horse chestnut

horse chestnut

snapdragon

European white birch

silver birch

false aster

false aster

false chamomile

false aster

camellia

tatarian dogwood

flowering dogwood

flowering dogwood

flowering dogwood

flowering dogwood

flowering dogwood

flowering dogwood

flowering dogwood

flowering dogwood

flowering dogwood

flowering dogwood

flowering dogwood

mountain dogwood

red twig dogwood

yellow twig dogwood

winter creeper

white ash

European ash

European ash

European ash

flowering ash

English ivy

common hop

common St. John's wort

black walnut

common privet

Chinese tulip tree

big blue lilyturf

star magnolia

spearmint

oriental plane tree

Kentucky bluegrass

common pear

white oak

scarlet oak

pin oak

pin oak

willow oak

English oak

English oak

English oak

red oak

weeping willow

dragon's claw willow

rough goldenrod

European mountain ash

snowberry

David viburnum

Red-Flowering Currant

Vine Maple

variegated bulbous oat grass

silverleaf dogwood

Silver King euonymus

Idaho fescue

narrow-leafed ash

Transvaal daisy

Oregon grape

peppermint

London plane

Garry oak

tomato

Pink Pagoda mountain ash

piggyback plant

Pink Dawn chitalpa