When the weather is cool and wet, the plants in your garden will be more susceptible to plant diseases. One of these diseases is white spots on leaves. It affects various plants. You will likely see it on leaves of flowering plants, vegetable plants, and even trees. Therefore, every gardener must know how to deal with this problem.
What is White Spots on Leaves?
In general, white spots on leaves are caused by fungus or other parasites. The fungus is different from one plant to another. It depends on the host plants. This parasite grows uncontrollable when there is a combination wet environment and cool temperature.
Wet environment is mostly caused by rain and dew. However, wrong watering method will also cause the plant to become wet. Therefore, fungus will grow easily on it. Meanwhile, cool environment at temperature of 12oC to 18oC is favorable for the fungus to grow. In addition, certain fungus grows uncontrollably when the weather is warm.
The plants in your garden get white spots on leaves from the spores of the fungus that are blown by the wind. And when the spores are on the wet or moist leaves, fungal infection will occur. In some cases, they are already in the soil. And when the environment is favorable, they will cause this infection. To cope with this infection on different plants, you need to understand more about it.
White Spots on Rose Leaves
1. Downy Mildew
On this plant, this infection is caused by Peronospora sparsa. This fungus will damage this flowering plant quickly. At first, the plant shows a symptom in the form of blotches on its stems, blooms, and leaves. The color of these blotches is varied, such as dark purple, brown, or purplish red.
When the infection becomes worse, you will find yellow spots of dead tissue on the leaves. If your rose bush gets white spots on leaves, it is essential for you to treat them as soon as possible. If it is left untreated, your flowering plant will die rapidly. On the other hand, treating this fungal infection is not easy.
Therefore, some gardeners choose to use more than one product to cope with this disease. A combination of different treatments, such as picking off the leaves, applying copper fungicide, and neem oil, will be able to get rid of white spots on leaves more effectively. However, you need to apply the fungicides in different time, about a week apart.
2. Powdery Mildew
Podosphaera pannosa is the cause of powdery mildew on roses. Rose leaves which suffer from this fungal infection will have spots of white powder on the surface of the leaves and stems. Rose bushes that suffer from prolonged powdery mildew will not be able to bloom.
In addition, these white spots on leaves will cause the leaves to crinkle. And later on, they will fall off from the stems. That’s why you need to treat this disease with the best fungicide right away. Rose bushes that have been cured will still have the appearance of crinkled leaves though.
White Spot on Cucumber Leaves
White spots on leaves also affect cucumber plants. On this plant, the cause of this fungal infection is Erysiphe cichoracearum and Sphaerotheca fuliginea. At first, the fungi will cause the leaves to have white powdery spots. If it is not treated quickly and effectively, the white spots will get larger and cover the entire leaves. Then, the spots will spread to the stems and fruits. As a result, the plant will not be able to function well.
Treating these white spots on leaves is not always an easy thing to do. Therefore, you must do some prevention steps to avoid it. One of the things you can do is growing cucumber in a sunny spot. You also need to avoid getting the plant wet when watering it. And most importantly, you have to spray the cucumber plant with fungicide when the weather is damp.
White Spots on Zucchini Leaves
It is normal for a zucchini leaves to have white spots on leaves. They are natural and parts of the coloration of the leaves. However, in certain condition, zucchini leaves can suffer from two fungal infections.
1. Zucchini powdery mildew
Erysiphe cichoracearum is the cause of powdery mildew. This fungal infection is pretty common in zucchini plant. Moreover, it usually appears in the fall. At first, the leaves show yellow spots. After that, you will see white powder-like substance on the leaves.
To control the white spots on leaves, you must remove the affected leaves. In a severe case, especially on zucchini seedlings or young plant, you need to remove the plants entirely. It is also important for you to spray the plant with fungicide.
In addition, you must do some prevention steps. It is because most fungicides are only capable of preventing the fungus to grow. Growing resistant zucchini varieties in a sunny spot and performing crop rotation are some of the steps you need to do. Moreover, you also need to spray the plant with organic fungicide.
2. Zucchini downy mildew
Zucchini plants will suffer from downy mildew or white spots on leaves. Though they are called white spots, they are actually pale green or yellow. If this fungal infection happens for a prolonged period, the spots will be bigger and spread to all the leaves on the plant. As a result, they will not be able to perform photosynthesis properly which resulted in bad harvest.
You can get rid of this fungal infection by removing the leaves and applying various fungicides. However, it is better for you to prevent this fungal infection before it appears. Providing enough space between plants, watering the plant at ground level, and applying fungicide spray beforehand will help the plant to avoid white spots on leaves.
White Spots on Tomato Leaves
Checking on white spots on your tomato leaves is an essential thing to do. Leaves play an important role for the quality of the tomatoes and the live of the plant itself. Therefore, if you see any white spots on leaves, you must do something to control it immediately.
Tomato plants get these white spots from Oidium lycopersicum. On an early stage, the symptom of this fungal infection is only white spots on the surface of the leaves. But, when it is uncontrolled, powdery white spots will also occur on the stems. If it is not treated, this infection will lead to withering leaves and dying plant.
One of the easiest things to do when you found those white spots on leaves is removing the leaves and then destroying them. Moreover, you need to spray the plant with fungicide. You can make the fungicide on your own or buy the commercial one. For a homemade fungicide, you can mix 3 tablespoon of horticultural oil, 1.5 tablespoon of baking soda, and 1 gallon of water.
White Spots on Plant Leaves
Various houseplants suffer from white spots on leaves during certain conditions. This fungal infection is in the form downy mildew, white rust, and powdery mildew. They may appear on the undersides of the leaves at first and then appear on the tops of the leaves. Moreover, the fungus will spread to other parts of the plants if it is left untreated.
Aside from removing the affected parts or even the whole plants, you can use several choices of natural fungicide to deal with this fungal infection.
1. Neem oil
This natural fungicide is made of neem seeds and safe for bees, birds, and humans. The best time to apply neem oli spray is when the weather dry without wind. To get rid of white spots on leaves, apply the spray once a week. And for prevention, you must spray the plant with neem oil every two weeks.
2. Baking soda
Baking soda is not very effective in killing fungus since it will be washed off by the rain. This fungicide will stop the growth of this parasite. But, once the rain washes the baking soda off, the fungus will grow again.
3. Baking soda and horticultural oil
A mix of baking soda, horticultural oil, and water can control powdery mildew and downy mildew effectively. In order to control fungal infection on your houseplants, you can spray the whole plant with this mix until it is drenching wet. In the summer, you must not apply it too often. Moreover, you cannot apply it on young shoots and open flowers.
4. Sulfur spray
This particular spray is a great fungicide. It is especially effective in preventing fungal infection if applied in early spring. Sulfur spray is safe for bees and birds. However, you need to protect yourself with respirator, glasses and long sleeve shirt because it can cause irritation. Moreover, you must not apply it when the temperature is above 29oC.
5. Copper fungicide
If you look for effective fungicide to control downy mildew, powdery mildew, and rust, you can opt for copper fungicide. It is relatively safe for bees. But, it may harm pets, fish, and people. Moreover, applying this fungicide too often can cause copper accumulation which can cause root damage on your plants.
White Spots on Squash Leaves
Some varieties of squash are resistant to fungal infection, such as powdery mildew. However, some others may fall prey to this kind of infection. Because of it, squash leaves have white and powdery spots. They will disturb the photosynthesis process on the leaves. In consequence, the plant will not be able to bear high quality fruits.
To control the fungus on this plant, you must prune the affected parts of the plant. After that, spray the plant with effective fungicide. To prevent fungal infection in the future, you must not use the same spot to grow squash for the next three years.
White Spots on Pumpkin Leaves
White spots sometimes appear on pumpkin leaves. This fungal infection or powdery mildew usually happens when the weather is warm and there is high humidity. Mild cases of powdery mildew are not dangerous. However, the severe one can cause smaller and less tasty pumpkins.
To deal with this fungal infection, you can do the same steps of dealing powdery mildew on squash. First of all, you need to remove the affected leaves and stems. In addition, you must apply fungicide spray on the plant. Sulfur spray can control the powdery mildew pumpkin leaves effectively and has been used for a long time to deal it.
White Spots on Orchid Leaves
Orchid is beautiful and makes your exterior and interior looks charming. However, this beauty can be damaged by white spots on leaves. This particular disease is often mistakenly caused by fungus. However, it is mostly caused by mealy bugs. This small insect hides itself in its white secretion. As a result, it looks like powdery mildew.
If the infestation is mild, you can get rid of these bugs using a toothbrush and 70% isopropyl alcohol. Dip the toothbrush in the alcohol and use it to swab the bugs. In severe cases, you can remove the bugs using neem oil, horticultural oil, or insecticide.
White Spots on Mint Leaves
Growing mint in the kitchen garden is very advantageous. Unfortunately, white spots sometimes appear on its leaves. In consequence, this herb has weaker aroma and flavor. White spots on mint can be caused by spider mites or leafhoppers. To deal with these pests, you need to apply insecticide or pesticide.
White Spots on Weed Leaves
Weed or cannabis is also susceptible to white leaf spots. This fungal infection is mostly powdery mildew. Weeds will catch this fungal infection if the cannabis plants are not spaced properly. It can also be caused by poor ventilation and high humidity.
Coping with powdery mildew on weeds is almost similar as coping with this fungal infection on other plants. Removing the white spots is an important thing to do. After that, you need to spray the plant with fungicide, increase airflow, and improve the ventilation system.
White Spots on Basil Leaves
Downy mildew also affects basil leaves when the environment is overly wet. This fungal infection can be effectively treated using fungicide. In addition, you can prevent this disease by planting it in well-drained soil. Moreover, he plant must get enough sun, good air circulation, and preventive fungicide spray.
White spots are a common problem of various plants. It can be treated and prevented through various steps. One of them is through applying fungicide spray. When you are applying this spray, you must remember to consider its safety and amount. Therefore, you can get rid of this infection or infestation effectively.