Farmers spend billions of dollars are on disease management, often without adequate technical support, resulting in poor disease control, pollution and harmful results. In addition, plant disease can devastate natural ecosystems, compounding environmental problems caused by habitat loss and poor land management.

Aristotle, Plato’s student, recorded plant diseases as early as 350 B.C., and his colleague Theophrastus observed and speculated about diseases of cereals, legumes, and trees. Evidently, plant diseases were destructive in ancient times and the people lived in fear of famine.

Where Do Plant Pathologists Work?

• Colleges and universities (research, teaching, and extension)
• Agricultural consulting companies.
• Agrichemical companies.
• Seed and plant production companies.
• Tissue culture laboratories.
• Diagnostic laboratories.
• International agricultural research centers.
• Botanical gardens and arboreta.

The toxin (com- posed of ten linear polyketols) affects leaf func- tion, including photosynthesis and respiration, and inhibits closure of stomata. In addition, membrane permeability is increased, resulting in leakage of potassium, and root growth is also impared.

In general, pathogens that infect plants do not specialize in infecting people. You are not likely to catch a disease from working with diseased plants in your garden, but it is a potential risk (depending on the infection), and consideration should be taken.

A symptom of plant disease is a visible effect of disease on the plant. Symptoms may include a detectable change in color, shape or function of the plant as it responds to the pathogen. Leaf wilting is a typical symptom of verticilium wilt, caused by the fungal plant pathogens Verticillium albo-atrum and V.

Most Common Plant Diseases and Solutions

1. Powdery Mildew. Most powdery mildew are very host specific, mildew on cucumbers will not infect roses.
2. Black Spot. This is a common fungal disease of roses.
3. Bacterial Canker or Blight.
4. Shot Hole.
5. Black Knot.
6. Rust.
7. Late Blight / Early Blight.
8. Apple Scab.

Diseased plants can be identified by abnormal growth or by signs of the disease-causing organism, such as bacterial slime (an external sign of a disease called bacterial wet wood) or insect larvae which hatches from eggs and feeds on leaves. Symptoms of common plant infections are shown in the slideshow below.

Know What is Normal

1. Proper plant identification.
2. Recognize healthy plant appearance.
3. Identify characteristic symptoms.
4. Identify symptom variability.
5. Look for signs of biotic causal agents.
6. Identify Plant Part Affected – Are symptoms associated with specific plant parts?
7. Check distribution of symptoms.

Symptoms of bacterial infection in plants are much like the symptoms in fungal plant disease. They include leaf spots, blights, wilts, scabs, cankers and soft rots of roots, storage organs and fruit, and overgrowth.

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.

Symptoms of bacterial leaf spot

1. Bacterial leaf spot diseases often start as small dark brown to black spots with a halo of yellow tissue surrounding each spot.
2. In some cases, the center of the leaf spot will dry up and fall out, giving the leaf a “shot hole” appearance.

The most common method to rid plants of leaf miners is to spray general pesticide on the infected plants. The trick to this method of how to kill leaf miners is to spray at right time. If you spray too early or too late, the pesticide will not reach the leaf miner larva and will not kill the leaf miner flies.

1. Live with the disease. Most trees tolerate leaf spots with little or no apparent damage.
2. Remove infected leaves and dead twigs.
3. Keep foliage dry.
4. Keep plants healthy.
5. Use fungicides if needed.
6. Replace the plant.

Some fungal diseases occur on a wide range of vegetables. These diseases include Anthracnose; Botrytis rots; Downy mildews; Fusarium rots; Powdery mildews; Rusts; Rhizoctonia rots; Sclerotinia rots; Sclerotium rots.

Wheat leaf rust is a disease caused by Pucciniatriticina fungus. This rust disease happens where maize, barley and other cereal crops are cultivated. Thus, the correct answer is A i.e., Black rot of crucifers.

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 …

For a look at the different ways fungal pathogens operate, consider these common fungal diseases: Black spot: Dark spots on the upper sides of leaves reveal black spot in action. Never on leaf undersides, the spots expand until the leaf is yellow and dotted with black.

Prevention & Treatment Water your plants in the morning because it gives the plant leaves all day to dry out. Fungal diseases can only infect the plant foliage if it’s consistently moist during the day. Spacing the plants and removing weeds can also reduce humidity around the plants and provide good air circulation.

Make a typical baking soda spray by dissolving 1 teaspoon of baking soda into one quart of water. You can add a few drops of insecticidal soap or liquid soap to help the solution spread and stick to the leaves. Only use liquid soap, like Ivory, and not laundry detergent.