What Is the Treatment for Downy Mildew?
Plants become infected with downy mildew as a result of pathogens similar to fungi that attack the leaves and other above-ground parts of the plant. As for its treatment, it is important to know that fungicides usually cannot cure this disease, but there are several methods that help limit its spread and prevent it from infecting plants in the first place. This article explains these methods.
Removing Infected Plant Parts
All infected parts of the plant should be removed as soon as symptoms appear. This includes fallen leaves on the ground. Plants with severe infections should be completely removed.
It is also recommended to dispose of infected material by burying it deeply or burning it to prevent further spread.
Spraying Plants With Organic Treatments
Below are some organic solutions that can help limit the spread of downy mildew or protect plants from infection:
Neem Oil
Neem oil is considered the first line of defense against downy mildew. It helps reduce its spread—though it does not cure it—especially when applied in the early stages of infection.
Copper-Based Fungicides
It is recommended to apply copper fungicides to infected plants and repeat the application every 7–10 days, or until the plant shows clear recovery.
Baking Soda (Sodium Bicarbonate)
Baking soda can be used to treat infected plants by dissolving one tablespoon of baking soda in one liter of mineral water, then spraying the mixture on all upper and lower leaf surfaces.
It is best applied during dry weather.
Bordeaux Mixture
This mixture is a preventive treatment applied regularly in early spring and fall, and during the plant’s vegetative growth stage. It should also be reapplied after rainfall.
Note: A layer of mulch can be placed around infected plants to contain the disease in a localized area and prevent its spread to other leaves or nearby plants.
Improving Air Circulation Around the Plant
Follow these tips to improve airflow around infected plants, which helps speed up the healing process:
- Remove weeds and unwanted grasses regularly.
- Clear dead plant material during fall to reduce the chances of infection in the following spring.
- Train vines and climbing plants on trellises to enhance airflow, and plant crops in well-spaced rows.
- Add fans to create moving air currents in closed environments like greenhouses, and ventilate the space by opening windows or doors periodically.
- Prune plants regularly by removing dead, broken, or diseased branches to reduce the movement of pests from dying tissues to healthy ones.
Reducing Humidity Levels
Once plants become infected with downy mildew, the best approach is to reduce moisture around the plant. Here are some helpful tips:
- Water plants only in the early morning, allowing them to dry during the day.
- Use drip irrigation or a soaker hose to minimize water contact with leaves, reducing the chance of infection.
- Avoid overhead watering, as standing water on leaves encourages the spread of the disease.
