Summer is a time for enjoying the outdoors and spending time in the garden. However, it’s also a time when plants can be vulnerable to diseases, including cercospora leaf spot. This disease can affect bean plants, causing significant damage if not treated promptly.

What is Cercospora Leaf Spot?

Cercospora leaf spot is a fungal disease that affects bean plants. It can cause a variety of symptoms, including:

• Leaf spots: Small, circular spots with a reddish or purplish discoloration.
• Discoloration: Sun-exposed leaves may develop a leathery appearance and turn a deep purple color.
• Defoliation: Severely affected upper leaves may drop, leaving the petioles (leaf stems) intact.
• Pod damage: As the disease spreads, lesions and discoloration can also appear on bean pods.
• Seed damage: If the disease infects the seeds, they may develop purple discoloration on their surfaces.

How Does Cercospora Leaf Spot Spread?

Cercospora leaf spot is spread by spores that are carried by wind and water. The spores can survive in soil and plant debris for several years, making it important to take steps to prevent the disease from spreading.

Conditions that Favor Cercospora Leaf Spot

Cercospora leaf spot is most common during warm, humid weather. Temperatures between 75 and 85 degrees Fahrenheit and high humidity levels create ideal conditions for the disease to develop.

How to Prevent Cercospora Leaf Spot

There are several steps you can take to prevent cercospora leaf spot in your bean plants:

• Use disease-resistant varieties: Choose bean varieties that are resistant to cercospora leaf spot.
• Practice crop rotation: Avoid planting beans in the same location year after year. Rotate beans with corn, grain, or grasses to help reduce the buildup of spores in the soil.
• Remove infected plant debris: Remove and destroy any infected bean plants or plant debris to prevent the disease from spreading.
• Water plants at the base: Avoid watering plants overhead, as this can splash spores onto the leaves.
• Provide good air circulation: Space bean plants properly to allow for good air circulation, which can help prevent the buildup of moisture and disease.

How to Treat Cercospora Leaf Spot

If your bean plants do develop cercospora leaf spot, there are several fungicides that can be used to treat the disease. Some of the most effective fungicides for cercospora leaf spot include:

• Tetraconazole
• Flutriafol
• Axoxystrobin
• Difenconazole

It’s important to follow the instructions on the fungicide label carefully to ensure proper application and effectiveness.

Additional Tips for Managing Cercospora Leaf Spot

In addition to using fungicides, there are several other things you can do to manage cercospora leaf spot in your bean plants:

• Remove infected leaves: Remove any leaves that show signs of infection to prevent the disease from spreading.
• Apply mulch: Mulching around bean plants can help suppress weeds and retain moisture, which can help reduce the risk of cercospora leaf spot.
• Avoid overwatering: Overwatering can create conditions that favor the development of cercospora leaf spot. Water plants only when the soil is dry to the touch.
• Keep garden tools clean: Clean your garden tools with a disinfectant solution between uses to prevent the spread of disease.

By following these tips, you can help prevent and manage cercospora leaf spot in your bean plants, ensuring a healthy and productive harvest.

What is Citrus Melanose?

Citrus melanose is a disease that affects all types of citrus trees, including oranges, grapefruits, and lemons. It causes damage to the leaves and fruit rinds, making the fruit look unattractive. Although the pulp of the fruit is usually not affected, the disease can weaken the tree and reduce fruit production.

What Causes Citrus Melanose?

Citrus melanose is caused by a fungus called Phomopsis citri. This fungus grows on dead twigs and branches of citrus trees. When it rains, the spores of the fungus are spread by water droplets to other parts of the tree and to other trees. Grapefruit and lemon trees are most susceptible to citrus melanose.

Symptoms of Citrus Melanose

The symptoms of citrus melanose are most visible on the leaves and fruit.

• Leaves: Small red-to-brown spots appear on the leaves. These spots are often surrounded by a yellow ring, but this coloring fades as the disease progresses. The surface of the leaf becomes rough and bumpy.
• Fruit: Brown spots or pustules develop on the fruit. These spots grow together and crack, creating a condition known as “mudcake.” The spots may also spread down the fruit with dripping water, forming “tear stains.”

Preventing Citrus Melanose

There are several steps you can take to reduce the risk of citrus melanose in your garden:

• Trim dead branches and twigs: The fungus that causes citrus melanose grows on dead wood. By removing dead branches and twigs, you can help to prevent the spread of the disease.
• Disinfect pruning shears: Before using pruning shears on healthy branches, disinfect them with a bleach solution. This will help to prevent the spread of the fungus from infected branches to healthy ones.
• Avoid overhead watering: Overhead watering can spread the spores of the citrus melanose fungus. Instead, water your citrus trees at the base of the trunk.

Treating Citrus Melanose

If citrus melanose develops in your trees, you can use fungicides to control it. Copper fungicides are the most commonly used type. You can get recommendations and instructions for use from your local nursery or agricultural extension office.

When to Use Fungicides

Fungicide treatment is not always necessary for citrus melanose. The disease does not make the fruit inedible, and in most cases, it does not cause serious damage to the tree. However, if the infection is severe, it can weaken the tree and reduce fruit production. Fungicides can be used as a last resort if prevention and control methods don’t keep the disease under control.

Additional Tips

• Inspect your citrus trees regularly for signs of citrus melanose.
• Remove any infected leaves or fruit from the tree and dispose of them in the trash.
• Keep your citrus trees healthy and vigorous by providing them with proper care, including regular watering, fertilization, and pruning.

Dahlias are beautiful flowers that can add a splash of color to your garden from midsummer to autumn. They come in a wide range of sizes, colors, and shapes, so you’re sure to find one that you love.

But even though dahlias are relatively easy to grow, they can be susceptible to certain diseases. In this article, we’ll discuss the most common dahlia diseases and how to prevent and treat them.

Common Dahlia Diseases

The most common dahlia diseases include:

• Powdery mildew: This fungal disease is easy to spot by the white, powdery growth that appears on leaves. It can affect the appearance of the plant, but it’s rarely fatal.
• Botrytis blight: Also known as gray mold, this fungal disease causes brown, water-soaked spots on leaves and stems. As the disease progresses, the spots enlarge and develop a fuzzy, gray or tan mold. Botrytis blight is often a problem in humid weather conditions.
• Wilt: Fusarium wilt and verticillium wilt are two fungal diseases that cause wilted, yellowing leaves. The plant may eventually turn dark brown or black and die. Fusarium wilt is most severe when the soil is warm, while verticillium wilt often appears when the weather turns warm after a cool period.
• Stem rot: This deadly disease causes stems to become mushy and rotted. It’s most common in dahlias that are planted in poorly drained, soggy soil.
• Viral diseases: Viral diseases are often transmitted by thrips, which are tiny insects that burrow into the stems and buds of plants. Symptoms of viral diseases include lines, rings, a mottled appearance, and streaks of dark and light green. Infected plants are usually discarded, as thrips are notoriously difficult to control.

Dahlia Disease Control

Most common dahlia diseases are caused by damp, humid conditions, overwatering, or poorly drained soil. The best way to prevent disease is to:

• Plant dahlias in well-drained soil.
• Avoid overwatering.
• Water at the base of the plant and avoid wetting the foliage.
• Keep plants spaced apart so that air can circulate freely.
• Remove any diseased plant material from the garden and dispose of it properly.

Treating Dahlia Diseases

Some dahlia diseases, such as powdery mildew and gray mold, can be treated with fungicides. Fungicides can also be used as a preventive measure. However, many dahlia diseases are fatal, and the best recourse is to start fresh with new, disease-resistant tubers.

If you think your dahlias may be diseased, it’s important to diagnose the problem correctly so that you can take the appropriate steps to treat it. A local nursery or gardening center can help you identify the disease and recommend the best course of action.

With proper care, you can help your dahlias stay healthy and beautiful all season long.