What to Do When Bougainvillea Gets Brown Spot Disease? Symptom Identification and Treatment Methods

Bougainvillea is also called paperflower. Because its appearance is very unique and its bracts look very much like leaves, it was named this way, so the main ornamental part of bougainvillea is the bracts. However, if bougainvillea suffers from brown spot disease, its ornamental value will be greatly affected. If not treated in time, the plant may even die. The editor will now introduce the symptoms and control methods of bougainvillea brown spot disease for you.

Bougainvillea

I. Symptoms

When bougainvillea suffers from brown spot disease, it mainly appears between the veins of the leaves. In the early stage of the disease, there are yellow-brown or dark brown round spots on the leaves, surrounded by yellow-green halos. Later, the spots become irregular in shape and gradually deepen in color. In the later stage of the disease, black granular substances appear on the spots, and finally the leaves fall off. Brown spot disease is more commonly seen in spring and early autumn.

II. Control Methods

1. Keep the plant well ventilated and exposed to light;

2. Pay attention to increasing or maintaining leaf humidity;

3. When infection occurs, promptly prune diseased branches and leaves and destroy them;

4. In the early stage of infection, spray a 1000-fold solution of 50% Tuzet or other fungicides to inhibit the development of the disease.

Causes of Brown Spot Disease in Gardenia

Although gardenia flowers are elegant in color, white as snow, the appearance of brown spot disease on the leaves will greatly affect the gardenia's ornamental image, and the gardenia's appearance will be compromised. How should brown spot disease in gardenia be solved?

Prevention of Brown Spot Disease in Gardenia

Symptoms and pathological changes: In the early stage, the leaves have pale yellow round spots with orange-red halos, which gradually expand into round or irregular brown spots with faint concentric rings, causing the leaves to dry up. This disease is a fungal disease caused by infection with Glomerella cingulata.

The pathogen mainly overwinters as mycelium lurking in diseased leaves. When temperature and humidity are suitable in the spring of the following year, the disease develops. A characteristic of this pathogen is that it can also form a large amount of the sexual state during the growing season. High temperature and high humidity conditions favor the onset of the disease. During the transport of gardenia seedlings, poor ventilation and a hot, humid environment result in a high incidence rate.

Control methods for gardenia brown spot disease:

1. Remove and destroy diseased leaves at any time to reduce sources of infection.

2. Carry out chemical control. Before the disease occurs, spray 1% Bordeaux mixture to protect the plant from infection; during the disease period, spray 75% chlorothalonil wettable powder at 500-800 times dilution for control. Or use alum fertilizer water (made by mixing 2.5 kg ferrous sulfate, 5 kg soybean cake, and 15 kg pig manure, fermenting and decomposing for 10-15 days before use) and alternate watering with clean water. A 0.1%-0.2% ferrous sulfate aqueous solution can also be sprayed on the leaf surface.

Gardenia brown spot disease should be prevented in time. One of the causes of gardenia brown spot disease is poor ventilation. It is recommended that everyone must maintain ventilation for gardenias during cultivation. Especially under high temperature conditions, you must pay special attention to this point!

What to Do When Azalea Leaves Turn Black: Causes and Solutions for Blackened Leaves

Azalea is one of the most common indoor plants, but during cultivation, improper plant care and other reasons may cause azalea leaves to turn black. So what should be done when azalea leaves turn black? Let's take a look below at the causes and solutions for azalea leaves turning black.

What to Do When Azalea Leaves Turn Black

Azalea leaves turning black may be caused by improper watering, improper fertilizing, too low humidity, improper lighting, disease invasion, and other reasons. Below, the editor will introduce in detail the causes and solutions for azalea leaves turning black. Only by identifying the cause of azalea leaves turning black and finding the corresponding solution can the problem of azalea leaves turning black be thoroughly solved.

One: Greenhouse Cultivation

Most azaleas are grown in greenhouses. They have relatively high requirements for soil moisture and temperature. In addition, forced flowering and rapid growth drain the plant's life, which can cause azalea leaves to turn black. This kind of azalea basically cannot be kept alive unless you repot with new soil immediately after buying it, prune most of the branches and leaves, remove all the flowers, and let it grow for one or two years. But that takes too much time and energy.

Two: Improper Watering

Watering azaleas too much or too little can both cause azalea leaves to turn black. Do not water too frequently. Water thoroughly only when the soil surface is slightly dry. The interval between waterings should be determined by the substrate. Peat soil has strong moisture retention, so the watering interval should be longer; pine needle soil has slightly weaker moisture retention, so the watering interval should be slightly shorter. It is best to adjust flexibly.

Three: Improper Fertilizing

Fertilizing too much or too little can also cause azalea leaves to turn black. Azaleas are not tolerant of heavy fertilizer. It is best to fertilize lightly, and do not apply too much or too concentrated fertilizer. The fertilizing principle for azaleas is light fertilizer applied frequently, that is, apply a little at a time and apply it more often.

Four: Humidity Too Low

Air humidity that is too low can also cause azalea leaves to turn black. This is also related to care and management. During growth, it is necessary to spray water frequently to keep environmental humidity stable, preferably between 60-80%. This symptom is prone to appear in dry environments.

Five: Improper Lighting

Azaleas require semi-shade or scattered light. They should not be placed in a shaded place. Strong summer light can also easily cause azalea leaves to be damaged and turn black, with growth stagnating, and in severe cases the whole plant may die. After summer begins, place azaleas in a ventilated and cool place. In the hot summer, use reed curtains, bamboo curtains, or shade nets for shading, and open the curtains before 8 a.m. and after 5-6 p.m.

Six: Brown Spot Disease

Azaleas may be infected with brown spot disease, which can cause azalea leaves to turn black. In the early stage of the disease, brown spots appear on the edges of azalea leaves. The boundary between diseased and healthy tissue is not obvious, showing a transition from light green to brown to rust-red. As the disease spreads, the spots expand or the entire azalea leaf turns brown, causing the leaves to fall prematurely, and even the whole azalea plant to wither and die. The disease is most severe from July to August. Provide appropriate shade during high temperatures, enhance azalea growth, and apply more organic fertilizer to improve disease resistance.

Adhere to the principle of prevention first. Spray the protective fungicide 80% Dacotech wettable powder at 600-800 times dilution, or 75% chlorothalonil wettable powder at 600-800 times dilution. In the early stage of the disease, spray the systemic fungicide 12.5% Likejun wettable powder at 2500 times dilution, or 25% Tilt emulsifiable concentrate at 1500-2000 times dilution.

Seven: Red Spot Disease

If azaleas are infected with red spot disease, it can also cause azalea leaves to turn black. In the early stage, small rust-red spots appear on azalea leaves, mostly on the edges or tips of the upper leaves. The spots gradually expand into nearly round or irregular rust-red spots. The boundary between diseased and healthy tissue is obvious and dark brown. In the later stage, black dots appear on the diseased areas. The affected leaf areas become brittle and easily crack. Finally, the spots expand to most of the azalea leaf or the entire leaf, causing premature leaf drop. Late June to August is the peak period of the disease. Cut off diseased leaves and burn them. In the early stage of the disease, spray 70% thiophanate-methyl wettable powder at 1000 times dilution, or 12.5% Likejun wettable powder at 2500 times dilution, or 25% Tilt emulsifiable concentrate at 1500-2000 times dilution.

How to Prevent Azalea Leaves from Turning Black

Azaleas prefer a warm, humid, semi-shaded environment and require good ventilation. Normally, they can be placed in a bright location for care. During the high-temperature seasons of summer and early autumn, shading is necessary to avoid direct sun exposure, otherwise strong light will scorch the leaves. However, they should not be placed in too much shade either, lest the azaleas grow leggy and flowering be affected. They can be placed under a shade canopy or under tree shade for care. During the growing season, keep the soil moist but not waterlogged. Pay attention to drainage during the rainy season. When the air is dry, sprinkle water on the azaleas and the surrounding ground to increase air humidity and prevent azalea leaves from drying up. A layer of soft grass can also be spread on the surface of the potting soil to prevent the strong sun from scorching the fine fibrous roots on the soil surface. Apply a fully decomposed, dilute liquid fertilizer about once every 15 days. To prevent chlorosis, add a small amount of black alum to the fertilizer solution to make the leaves dark green and glossy. During the bud stage, apply 1 to 2 additional applications of phosphorus fertilizers such as bone meal or superphosphate to promote larger and more colorful azalea flowers.

Summary: The above is an introduction to what to do when azalea leaves turn black, and the causes and solutions for azalea leaves turning black. We hope it will be helpful to everyone.