Powdery mildew is not anything new to growers and gardeners. This fungal plant disease is relatively common, and it is one of the easiest to recognize due to its distinctive symptoms.
The disease first attacks the young, lower leaves, forcing them to curl and leave behind white powdery spots. It then spreads to the buds and the stem, causing them to wither.
Even though powdery mildew is not fatal, leaving your plants untreated will not only weaken them, but also cause them to lose their aesthetics.
Pruning and uprooting infected plants might seem like the ideal solution – however, it is not always practical. Using fungicides such as neem oil is one of the recommended treatment options for powdery mildew.
Neem oil is a naturally occurring extract harvested from the fruits, leaves, and seeds of the neem tree. The oil has several uses but it is more popular as a natural fungicide.
How effective is neem oil for powdery mildew?
The effectiveness of neem oil in treating powdery mildew has never been in question. The oil has several antifungal properties that work against a wide range of fungi that cause powdery mildew.
Spraying your plants with 2.5 tablespoons of neem oil concentrate per gallon of water can go a long way to keep fungi at bay. The solution works by stopping spore production and disrupting plant metabolism, making it impossible for fungi to grow.
This explains how effective the oil is in treating various fungal diseases such as powdery mildew. The oil can also treat and control other foliar diseases like blackspot, rust fungi, and downy mildew.
See other benefits of applying neem oil on houseplants.
What plants should you not use neem oil on?
As much as neem oil is an effective, organic treatment for powdery mildew, you should not use it on very young plants as they may not be able to handle the potent ingredients of the solution. The oil contains active compounds that can burn the foliage of young crops.
You should also avoid using the oil on plants that are visibly stressed and recently transplanted crops.
What if I use too much neem oil?
The recommended proportion of neem oil per gallon of water is 2-4 tablespoons. Ideally you should spray your plants with the solution every 7-14 days.
Applying too much neem oil than the recommended amount can do more harm than good to your farm or garden.
Some plants may wither or develop black spots after heavy application. Other plants, particularly the seedlings, may die due to stress.
The good news is that you can reverse the effects of too much neem oil by rinsing your plants with fresh, warm water, 20 minutes after application.
This will remove the oily coat that forms around the leaves after the application.
Does neem oil need to be washed off?
Yes, and No.
You should wash off neem oil from fruits and vegetables before eating. Neem oil is potentially unsafe to humans when ingested through the mouth. The oil can cause serious conditions such as kidney failure, metabolic acidosis, and severe brain ischemia in kids.
Conversely, you should not wash off neem oil after application. Washing the neem oil off soon after spraying it on your plants will only allow fungi, bacteria, and other disease-causing pests to thrive.
5 Best neem oil for powdery mildew
No doubt, neem oil is one of the best options for treating powdery mildew and controlling pests.
It works effectively as an insecticide as well as a fungicide against a wide range of plant diseases.
Here is a list of the best neem oil products you should consider for your garden.
Should I remove leaves with powdery mildew?
Removing leaves with powdery mildew might be a good option if you are dealing with a small bunch of infected plants.
Although not fatal, powdery mildew can spread to other parts sporadically, causing the entire plant to wither if left untreated.
If the infection has affected your entire garden, removing leaves with powdery mildew might not be a practical solution.
You should instead treat your plants with natural fungicides such as neem oil.
Proper application of neem oil to your plants will help get rid of powdery mildew quickly and effectively.
Can you wash off powdery mildew?
Yes – you can wash off powdery mildew from your plants using non-detergent soap and water or other home remedies like baking soda. This is because the mildew only forms on the surface of the leaves rather than the deeper layers of the plant.
However, the idea of washing your plants to remove powdery mildew is only effective during harvesting.
Washing off powdery mildew from growing plants is not a viable option since it is tedious and time-consuming.
To avoid going through all the trouble, consider spraying your plants with neem oil a few days before harvesting.
Will powdery mildew go away on its own?
Powdery mildew cannot go away on its own. Instead, the fungi will spread to other parts of the plant and other crops in your garden or farm through lightweight spores that travel by wind. The spores can also spread easily to other plants when carried by contaminated garden tools.
Although fungi tend to thrive in warm, humid settings, they can also withstand various weather conditions.
If you are waiting for the powdery mildew to go away on its own during the cold seasons, then you are in for a rude shock.
Infected plants will eventually wither, weaken, turn yellow, or die.
With this in mind, you should enforce quick control measures by pruning or treating infected plants to curb the spread of these fungal spores.
How do you stop powdery mildew from spreading?
Powdery mildew might seem harmless at first, but it can leave a devastating impact on your yields. It can disrupt photosynthesis and cause your plants to wither. It can also yellow your ornamental plants and disfigure the leaves.
The worst part is that powdery mildew spreads very fast by wind or through contaminated farm tools.
This means the rest of your crops are at risk of developing these white spots if left unchecked.
Here are a few tips on how to stop powdery mildew from spreading:
- Selectively prune infected leaves and overcrowded areas
- Remove and destroy infected plants
- Sanitize all garden tools and equipment
- Wash your garden gloves after handling infected plants
- Water your plants from an overhead position to wash off fungal spores
- Use appropriate fungicides such as neem oil
Does baking soda kill powdery mildew?
Baking soda can kill powdery mildew, but it is not an effective treatment on its own. You have to mix it with non-detergent soap and water to make the most of this bicarbonate solution.
Moreover, it is best used as a preventive measure rather than a treatment option.
To prepare this organic mixture, stir one teaspoon of baking soda and one-half teaspoon of liquid soap in one quart of water, and then spray the solution on your plants.
Does sunlight kill powdery mildew?
Although powdery mildew thrives in warm and humid conditions, it cannot tolerate high temperatures. In case you haven’t noticed, powdery mildew is more rampant in shaded areas.
According to a 2005 study, exposing infected plants to direct sunlight can help kill fungi that cause powdery mildew. UV radiation is capable of damaging any cellular structure, including that of fungi.
The strong rays from the sun are able to destroy fungal spores and curtail the growth of fungal colonies on plants.
Does powdery mildew stay in the soil?
Most fungal diseases that affect plants, including powdery mildew, are soil-borne. These diseases emanate from the soil and tend to affect plants from their roots and underground stems as they germinate.
But unlike other fungal diseases, powdery mildew is host-specific. This means after infecting a plant, it does not remain in the soil but on the leaves of the plant. It then spreads to other plants by wind or via contaminated farm tools.
What is the best treatment for powdery mildew?
The best treatment for powdery mildew depends on the infected plant. Some plants “heal” faster with natural, organic treatments like neem oil while others respond well to chemical fungicides.
Natural treatment options for powdery mildew include:
- Baking soda
- Lime sulfur
- Potassium bicarbonate
- Hydrogen peroxide
Examples of commercial, chemical fungicides include BONIDE copper fungicide dust and Monterey Bi-Carb Fungicide.
If you compare the benefits of each option above, neem oil ranks highly as one of the best treatments for powdery mildew. Neem oil is natural, effective, and has no side effects.
Read more about Can you use neem oil on edible plants and herbs?
Besides, it delivers desirable results within a few days as long as you spray the solution appropriately.
All farmers and gardeners struggling to deal with powdery mildew should consider trying out neem oil. This special extract works as an insecticide as well as a fungicide, meaning you can use it to treat all manner of plant diseases and at the same time keep pests at bay.