Powdery mildew is a fungal plant disease, common among a wide range of plant species. Many species of ascomycete fungi (Erysiphales order) cause this disease. However, it is easy to identify this disease.
Depending on the infecting strain and severity, the infected plants produce a lesser quantity or quality of fruits or flowers. Although no accurate treatment is available, you can control the powdery mildew plant disease with some proven methods.
How Does this Disease Spread?
There are two ways, in which the disease spreads primarily.
1.) The wind carries the powdery mildew spores and drops them on the plants in its way. This is how the disease approaches your garden plants, initially.
2.) In the past seasons, if your garden had been infected with this disease, dormant spores may reside in weeds or old vegetative materials nearby. In favorable environments, these spores outbreak, infecting nearby plants.
During warm (60-80°F / 15-27°C), dry, humid summer days, this disease infects susceptible plant species readily. Therefore, you must be wary, looking for the symptoms of this disease in late spring to early summer climates. The warm, dry days and slightly cool nights of this season provide a perfect environment for this disease to thrive.
Other factors that contribute to conditions favoring this disease include inadequate sunlight and poor air ventilation.
Contrarily, Powdery mildew cannot spread well in rainy, cool areas. The high temperatures (above 90°F or 32°C) also slow down the intensity and spreading of this disease.
This rarely fatal disease tends to rob off water and nutrients from your plants, thereby causing harm to them. In most cases, the leaves turn yellow and become distorted or withered. Eventually, the plants become weak, grow slower, and bloom less.
How to Identify Powdery Mildew Plant Disease
You can identify this disease with visual inspections.
1.) The Infected portions of the plant have a dusty’ appearance. Usually, this disease starts with circular, powdery light grey or white spots on leaves, stems, flowers, or fruits. These spots, generally, cover the upper portions of the plant leaves. Sometimes, they may grow on the undersides of the leaves as well.
2.) The infected leaves turn yellow. They can also break, twist, dry out, or become disfigured. Similarly, other infected portions like buds, growing tips, stems, etc. can show many visual signs including disfiguration.
3.) With time, more and more asexual spores grow in the infected portions, making the spots larger and denser. If not treated, this disease can spread to the entire plant. New plants are most susceptible to these kinds of diseases.
How to Prevent Powdery Mildew Plant Disease
As a popular saying goes, “Prevention is better than cure.” Proactive prevention helps to maintain the plants healthy. It also saves money, time, and energy spending on treating diseases.
Choosing Disease-Resistant Varieties:
Leading nurseries and garden centers sell disease-resistant varieties of plants. You can also opt to buy seeds from some major seed suppliers. Mostly, they have both online and offline shops, making shopping easy for their customers.
Choosing the Right Planting Spots:
Powdery mildew develops often in shady areas, with inadequate sunlight. Hence, grow your plants in spaces that get the most light.
Providing Air Ventilation:
Gap the plants as per the recommendation. If needed, prune them regularly. This provides sufficient air ventilation, thereby reducing relative humidity near plants. This reduces the disease-favoring environment to a large extent.
Watering Plants:
Water the plants in the early morning hours. While doing so, aim at the bottom of plants. This helps plants to dry themselves as the sun rises. Some people try to wash off the spores, watering overhead. This is not a recommended practice, as wet leaves invite other disease-causing agents.
Keep Your Garden Clean:
The powdery mildew spores often tend to overwinter in plants. Hence, when the season ends, remove all the fallen leaves and debris. Make sure to dispose of them in a professional way.
Other Prevention Techniques
Generally, solutions available in the market focus on the prevention of plant diseases. However, there are many homemade remedies that can be effective in both preventing and treating existing infections.
Spray mixtures usually kill pathogens that they meet with. Hence, coat the infected portions thoroughly with these mixtures. Depending on the infection, you may have to spray multiple coatings at regular intervals. Apply the mixture about one or two times a week for about a month. If needed, you may extend the application periods for better results.
Baking Soda Solution:
In a gallon of water, mix baking soda (1 tablespoon) and non-detergent liquid soap like Castile (½ teaspoon). Stir the mixture well. Spray the mixture liberally on all affected areas, including under side of the leaves.
Potassium Bicarbonate:
In a gallon of water, mix potassium bicarbonate (1 tablespoon) and non-detergent liquid soap (½ teaspoon). Mix well and spray on all areas of the plant, liberally. In most cases, this mixture works better than baking soda solution on existing infections.
Milk:
Mix milk (1 part) with water (2 to 3 parts). Stir well and spray liberally on all portions of the plant. This treatment seems to work better, especially on cucumbers, melons, and zucchini. Most gardeners believe that milk compounds boost the immune system in plants, in addition to combating common diseases.
Neem Oil:
Neem oil, by itself, can combat various plant diseases and avoid common plant pests. You can also add neem oil to the above solutions. It helps increase their effectiveness.
Powdery Mildew Fungicides:
You can purchase many types of sulfur-containing organic fungicides in the market. These fungicides have no residue, low toxicity, and are effective for longer durations. However, check with your local garden centers for ‘approved to use fungicides’ in your area.
How to Control Powdery Mildew Plant Disease
It is difficult to treat heavily infected plants. Therefore, it is best to focus on preventing the infection from spreading to other healthy plants. Collect all the infected stems, foliage, fruits, etc., and thrash them or burn them completely.
Never compost the infected plant, as the spores can persist in them. Make sure to sterilize your equipment like pruning shears before, after, and in between usage. This helps spreading of powdery mildew spores to other healthy plants.
Frequently Asked Questions
Powdery mildew, a fungal plant disease, often hits gardens, hurting plant health and lessening blooms and fruits.
The fungal spores travel through winds. vegetative materials or nearby weeds might hold dormant spores that can outbreak in favorable conditions
Powdery mildew grows best in warm, dry places but needs humidity to spread, It struggles in cool, wet, or scorching weather, and prefers shade over sun.
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