What are the 4 common plant diseases?

Author: Prof. Ike Beahan I  |  Last update: Wednesday, October 22, 2025

Common Plant Diseases
  • Anthracnose. Anthracnose is a fungal disease that affects plants, trees, fruits and vegetables. ...
  • Blossom-End Rot. ...
  • Downy Mildew. ...
  • Early Blight. ...
  • Mosaic Viruses. ...
  • Powdery Mildew. ...
  • Rust Plant Disease. ...
  • White Mold.

What are the major plant diseases?

list of plant diseases
  • aster yellows.
  • bacterial wilt.
  • blight. fire blight. rice bacterial blight.
  • canker.
  • crown gall.
  • rot. basal rot.
  • scab.

What are the top 10 viral diseases in plants?

The Top 10 list includes, in rank order, (1) Tobacco mosaic virus, (2) Tomato spotted wilt virus, (3) Tomato yellow leaf curl virus, (4) Cucumber mosaic virus, (5) Potato virus Y, (6) Cauliflower mosaic virus, (7) African cassava mosaic virus, (8) Plum pox virus, (9) Brome mosaic virus and (10) Potato virus X, with ...

What are 4 signs that a plant has a disease?

Symptoms of plant disease
  • Stunted growth from mealybugs. ...
  • Spots on leaves caused by the rose black spot fungus. ...
  • Decay caused by the rice blast fungus. ...
  • Malformed stems or leaves caused by the ash dieback fungus. ...
  • Discoloration caused by the tobacco mosaic virus. ...
  • The presence of pests (aphids)

What are the 3 main disease agents for plant diseases?

A plant disease is any harmful condition that affects a plant's appearance or function. Common pathogens that cause diseases include: fungi, bacteria, and viruses. Some nematodes are plant disease agents.

GCSE Biology - Plant Disease and Defences #46

How do I know if my plant has a bacterial or fungal infection?

Leaf wilting is a typical symptom of verticilium wilt, caused by the fungal plant pathogens Verticillium albo-atrum and V. dahliae. Common bacterial blight symptoms include brown, necrotic lesions surrounded by a bright yellow halo at the leaf margin or interior of the leaf on bean plants.

What is the most dominant plant disease agent?

The majority of plant diseases are caused by fungi. There are well over 100,000 different species of fungi and only a surprisingly small portion of them are capable of causing plant diseases. Fungi are similar to plants but lack chlorophyll and the conductive or vascular tissues that are found in ferns and seed plants.

How do I tell what disease my plant has?

Blackened roots and a sour or ammonia odor are sure signs the root system is unhealthy.
  1. Common Diseases. ...
  2. Gray Mold: Also called Botrytis; a fungal disease that can attack every part of a plant. ...
  3. Powdery Mildew: White powder appears on leaves. ...
  4. Leaf Spot: Yellow, brown, black or water-soaked spots appear on leaves.

How do you tell the difference between a fungal and bacterial leaf spot?

Bacterial leaf spot symptoms typically have a more angular appearance than fungal leaf spot, with the spots bounded between the veins. Fungal leaf spots will cross veins. This is because the bacteria is inside the plant and cannot cross vein easily. Fungal leaf spots grow on the surface and cross veins easily.

What does fungus on plants look like?

Symptoms of a fungal disease on indoor plants

There are many species of fungi that can cause leaf spots on houseplants. Symptoms often include many tan to reddish brown to black roughly circular spots or lesions that may run together to cause large irregular shaped lesions or blighting of the entire leaf.

What is the largest known plant virus?

Potyvirus is the largest genus of plant viruses, posing implicit economical losses to crops mainly in the families Fabaceae, Cucurbitaceae, Poaceae, and Solananceae.

What is the most common source of disease in plants?

Infectious plant diseases are caused by living (biotic) agents, or pathogens. These pathogens can be spread from an infected plant or plant debris to a healthy plant. Microorganisms that cause plant diseases include nematodes, fungi, bacteria, and mycoplasmas.

How do you treat plant viruses?

There is no cure or treatment for virus-infected plants in landscapes, and generally none is needed for woody ornamentals. Provide proper cultural care to improve plant vigor or replace infected plants if their growth is unsatisfactory.

How to treat diseased plants?

Thinning plants or rearranging surroundings can help. Prune infected plant parts promptly and dispose of the debris — don't compost it. Always cut back into healthy tissue, so no disease remains. Sterilize your pruning implements by wiping them with a common household disinfectant.

What disease can cause the rapid withering and death of plants?

Wilt diseases can kill a large, healthy tree during a single growing season. Diseases that affect the vascular system of a plant are called wilt diseases. The attack on the vascular tissue by the fungus causes moisture stress that eventually leads to wilting.

What are the 3 conditions necessary for diseases in plants?

A host, pathogen, and favorable environment are required for the development of a plant disease.

What kills leaf spot fungus?

There are several fungicides registered for use in control including thiophanate methyl, chlorothalonil, ferbam, and mancozeb.

What is a natural fungicide for plants?

A good place to start is a mix of mild liquid soap and water, sprayed onto houseplants. One teaspoon of soap per litre of water will do the job. It sounds simple, but this formula will treat a lot of common houseplant pests. Add just a teaspoon of bicarbonate of soda and it becomes a great fungicide as well.

How to get rid of fungus in plants?

Baking soda is one of the most commonly used and seen indoor plant fungus treatments. For this, you will need one tablespoon of baking soda, mixed with a gallon of water and two and a half tablespoons of vegetable oil. Once the mixture is ready, add it to a spray bottle, shake the contents and spray the affected areas.

What does a sick plant look like?

Abnormal tissue coloration—Tissue color may change (leaves, stems, roots). Examples include: chlorosis (yellowing), necrosis (browning), purpling, bronzing and reddening. Mosaic or mottled patterns may also appear on some tissues. Wilting—Water stress (too much or too little) can cause a plant to wilt.

Can plants recover from disease?

Plants can recover from viral disease and achieve a virus-tolerant state. Virus-induced diseases cause severe damages to cultivated plants resulting in crop losses. Interestingly, in some cases, the diseased plants are able to re-gain health, further grow and develop normally.

How do you diagnose a dying plant?

Signs Your Plant is Dying or Sick
  1. Yellowing or browning on the leaves.
  2. Wilting or drooping leaves.
  3. Leaves falling off.
  4. Roots visible on the surface of the soil or coming through drainage holes.
  5. Brown or black spots.
  6. Flowers blooming and then falling off soon after.
  7. The presence of gnats.

What are the worst plant diseases?

However should a plant disease become introduced in Canada, the Agency's goal is to reduce its impact.
  • Potato spindle tuber viroid (PSTVd)
  • Potato wart.
  • Scleroderris canker – Gremmeniella abietina.
  • Sudden oak death – Phytophthora ramorum.
  • Tomato brown rugose fruit virus.
  • Verticillium stripe – Verticillium longisporum.

What kills fungus in nature?

Laboratory-dish experiments showed that the natural compound, a water-soluble tannin known as PGG, blocks 90% of the growth in four different species of Candida fungi. The researchers also discovered how PGG inhibits the growth: It grabs up iron molecules, essentially starving the fungi of an essential nutrient.

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