Fungal Diseases

There’s a fungus among us!

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In truth, there are more fungal species and individual fungi than anyone could imagine. Fungi are the most common cause of plant disease and crop loss.


Did you know that fungi are more closely related to animals than plants? 

Mycologists are scientists who study fungi. They are still debating where fungi fall in the world of taxonomy because fungi have characteristics of both plants and animals. Like plant cells, fungal cells contain mitochondria, ribosomes, vacuoles, and a cell wall. But they lack chloroplasts, the same as animal cells. Most fungi lack a vascular bundle, so they use tiny structures in the base, similar to roots, to suck nutrients out of whatever is beneath them. Fungi can reproduce sexually or asexually, depending on the species, using spores or similar structures. Those spores are where problems in the garden start happening.

Strawberry fruit with fungal growth (Kate Russell)

Spores in spring

As the weather starts warming and rains fall in spring, fungal spores take to the skies with every breeze. A single citrus mummy can hold billions of fungal spores that can infect nearby fruit, trees, and other plants. If you see a mummy in the garden, get rid of it. Also, don’t count on drier summer weather to clear out fungal diseases - powdery mildew loves dry weather!


Common fungal diseases

Fungal plant diseases can be difficult to defeat once they take hold. Fungal infections include blights, blotches, molds, mildews, rots, rusts, scabs, scurfs, and spots. You can find a more detailed list below.


How to control fungal diseases

The most common response to fungal infestations is the use of fungicides. As quickly as fungi evolve, however, applying fungicide too frequently or incorrectly creates resistant varieties that are even more difficult to control. These good cultural practices can help your garden plants protect themselves without chemicals:

• Prune regularly and correctly to remove infected or damaged areas, increase airflow, and improve plant health.
• Irrigate deeply in the early morning, but do not create mud. Roots, tubers, and tree trunks will rot if the soil stays wet too long. 
• Keep sprinkler sprays off tree trunks.
• Improve soil structure with  compost for better porosity and drainage.
•  Keep plants healthy with regular, appropriate feeding. Stimulating too much tender new growth can invite disaster when fungal spores are abundant.
• Install resistant varieties. Plant labels that carry “VF” after the plant name are resistant.
• Control pests that spread fungal diseases, such as soft scale and aphids.
• If you must use fungicides, follow the directions exactly, completely, and without fail.

When it comes to fungal diseases, prevention is far more effective than trying to get rid of them.

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Detailed list of fungal diseases:
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• Alternaria blotch of apple
• Alternaria leaf blight
• Alternaria rot
• Anthracnose
• Apple blotch
• Apple measles
• Apple scab
• Apricot gummosis
• Armillaria root rot
• Ashy stem blight
• Ascochyta blight
• Basil downy mildew
• Bean rust
• Belly rot
• Black mold
• Black root rot
• Black scurf
• Black spot
• Blackleg
• Blossom brown rot
• Bottom rot
• Brown rot
• Butt rot
• Cane blight
• Canker rot
• Cavity spot
• Cedar apple rust
• Chocolate spot
• Chocolate tube slime
• Crown rot
• Cucurbit scab
• Cucurbit wet rot
• Cytospora canker
• Damping off
• Diebacks
• Downy mildews
• Early blight
• Eutypa dieback
• Frenching
• Foamy bark canker
• Frogeye leaf spot
• Fusarium wilt
• Fusicoccin
• Gray leaf spot
• Gray mold
• Gummy stem blight
• Hull rot
• Johnson spot
• Late leaf rust
• ​Leaf rots
• Leaf spot
• Measles
• Mummy berry
• Onion white rot
• Peach leaf curl
• Pink root
• Powdery mildew
• Purple blotch
• Ramularia leaf spot
• Rhizopus head rot
• Rhizopus soft rot
• Ringspot
• Root rot
• Rust
• Sclerotinia blight
• Seed rot
• Septoria leaf spot
• Shot hole disease
• Silver leaf
• Sooty blotch and flyspeck
• Sooty mold
• Spur blight
• Stem blights
• Sudden wilt
• Sweet potato scurf
• Tomato ringspot
• Verticillium wilt
• White rust
• Yellow rust