How to Protect Cucumber and Squash Plants from Powdery Mildew: Causes, and Treatment

Symptoms of Powdery Mildew are similar across plants and are caused by a group of related fungi. Powdery Mildews on ornamentals does not necessarily spread to vegetable gardens since they are plant-specific. This fungal disease affects various edible crops, flowers, and ornamental plants despite this. The condition is quite common and can be caused by various fungi. Let’s check out how to protect cucumber and squash plants from Powdery Mildew below.

As its name suggests, a Powdery Mildew patch looks like a white mold spot on a leaf. Infections that cause stress and damage plants aren’t a big deal if only a few spots exist. Although this is true, Powdery Mildew spreads easily from plant to plant, and its spores can travel through the air easily.

Plants indoors are just as at risk as those outdoors because they can move through screens. Each type of Powdery Mildew is tailored to thrive on only one or two plants, but no type of plant is safe from it. Garden pests such as Powdery Mildew may be the most common. Some plants are less susceptible to it despite its widespread prevalence.

How to protect cucumber and squash plants from Powdery Mildew

Ideal conditions for Powdery Mildew and how it spreads

The Powdery Mildew grows virtually every growing zone but thrives in warm, dry climates. Powdery Mildew also loves humidity, like any good fungus. During the day, warm, dry air promotes spore distribution because of the dampness of humid air.

Despite living on plants, Powdery Mildew spores can survive or overwinter the soil, compost, mulch, and other plant debris. Spores transmit from plant to plant by wind, insects, splashing water, or direct contact with infected plants. The Powdery Mildew risk is increased under crowded conditions, when there is little airflow, and when it is shaded.

How does Powdery Mildew harm your squash and cucumber plants

Powdery Mildew rarely kills plants. It does not mean you should let it go unchecked just because it is not fatal. In the beginning, a few minor spots won’t harm the host plant, but they can spread spores to other plants. The fungus robs nutrients from the plant as the disease progresses, causing it to become stunted and less productive.

Powdery Mildew can inhibit photosynthesis when it covers a significant portion of leaves. The plant suffers from slow starvation due to this disease. As a result of a change in photosynthesis, fewer sugars will be produced by the plant, which can affect crop flavor. Finally, Powdery Mildew infections stress the plant, making it susceptible to other diseases or pests.

In case you missed it: Cucumber Farming in Polyhouse (Kheera) for Profit

Cucumber Garden
Image Source

It is true that Powdery Mildew on squash leaves does affect their ability to photosynthesize and can, over time, reduce the plant’s productivity and yields. Severe cases may result in wilting and death of leaves. In addition, a plant’s crown can be infected with rot if its dead leaves develop rapidly. Squash plants can also become susceptible to other pests and diseases if infected with Powdery Mildew. In addition to squash bugs and vine borers, squash plants are more vulnerable to botrytis and squash bugs when weakened by the disease.

How to identify Powdery Mildew in plants

  • When plants are infected with Powdery Mildew, they appear floured.
  • Mildewy powdery spots often appear on leaves, stems, and fruit when Powdery Mildew is present.
  • Powdery Mildew usually covers the upper surface of the leaf, but the underside can also be affected.
  • Damage to young foliage is most likely to occur. It turns yellow and dries out the leaves.
  • Some leaves may be twisting, breaking, or disfigurement due to the fungus.
  • Most of the affected leaves will have white spots of Powdery Mildew.
  • As a result, the leaves, buds, and growing tips will also become disfigured. As the growing season progresses, these symptoms usually appear.

Tips for Preventing Powdery Mildew

Powdery Mildew damage can be prevented by preventing the disease from infecting plants in the first place. You can avoid infection by following several good strategies, such as:

Plant Powdery Mildew resistant varieties:

If Powdery Mildew is a major issue in your garden, choose plant varieties and species naturally resistant to it. Wide-resistant varieties are available on the market today, and they are often marked “PMR,” indicating their resistance to Powdery Mildew.

In case you missed it: Organic Cucumber Farming In Greenhouse

Cucumber Plant
Image Source

Use the recommended seed spacing

In humid, crowded conditions, Powdery Mildew thrives. By reducing overcrowding, Powdery Mildew can’t spread between plants. Plants should be spaced for each type and pruned as needed to increase airflow and reduce touching. Shade also encourages mildew growth, so make sure susceptible plants receive plenty of sunlight. It is easy for Powdery Mildew to spread from plant to plant and leaf to leaf.

Plant in full sun and avoid over-fertilization

Choosing a sunny location is perhaps the most important aspect of growing plants. As the sun’s heat burns away humidity, temperatures rise above the moderate level that mildew spores prefer. Sunlight will also boost the plant’s vigor to withstand the damage caused by an infection. The germination of spores is increased in shady conditions. Moving the affected plants to a sunny location is recommended to expose the affected area to direct sunlight. Fertilization overstimulates tender new growth that is more prone to infection.

Clean your garden tools

 Regularly sanitizing garden tools, such as pruning shears, is a good idea, especially when working with diseased plants. Wipe down the tools before moving on to the next plant to prevent Powdery Mildew from spreading. Rub alcohol, white vinegar, hydrogen peroxide, dilute bleach, and other sanitizing agents are effective.

In case you missed it: Top 20 Steps to Boost Cucumber Yield: How to Increase Cucumber Size, Quality, and Production

Pumpkin Garden
Image Source

Wet the soil, not plants

Avoid watering plants overhead as much as possible. Powdery Mildew grows and spreads when leaves are constantly damp or splashed with water from an already-infected plant. Instead of watering the plant, water the soil below it. It is ideal to use drip irrigation. The spores prefer humid air for reproduction. In addition, they thrive on drier, weaker leaves, complicating matters further. Finally, it means getting the cucurbit watering technique right. It is better to channel water to roots instead of letting it evaporate into the atmosphere by adding an organic mulch layer.

Use wise companion planting and polyculture

Don’t plant many plants prone to Powdery Mildew in one bed if you know you struggle with it. Instead, interplant them with species that are resistant instead of buffering them.

Promote overall healthy plants and immune systems

Plants that receive the nutrients and conditions they need to grow big and strong are more resilient to disease, including Mildew. We regularly amend our garden soil with organic fertilizers, well-aged compost, homemade compost tea, and aloe vera extract to keep it funky and fresh. Maintaining a consistent watering schedule and avoiding drought stress are also important.

In case you missed it: How to Start Cucumber Farming in USA: A Step-by-Step Guide to Planting to Harvesting

Cucumber Farm
Image Source

Ways to get rid of Powdery Mildew in Squashes and cucumbers

Powdery Mildew can be removed in several ways, ranging from hippie-dippie to toxic fungicides.

Cut and remove infected leaves.

A few infected leaves can often halt or drastically slow the spread of Powdery Mildew to the rest of the plant if caught early enough and if the plant can survive without them. Therefore, before and after using pruning shears, be sure to clean them thoroughly.

Spray the plant with baking soda

Sodium bicarbonate (baking soda) changes the pH of plant leaves, making them more alkaline and less hospitable for fungi. Blight and Mildew prefer a neutral pH of about 7. Mix 1 to 2 tablespoons baking soda into four liters of water thoroughly. The baking soda will spread and stick to the leaves better if you add a tablespoon of liquid castile soap or dish soap. Next, you should spray the plant thoroughly, saturating the tops and bottoms of the leaves.

Use potassium bicarbonate.

Spraying with this solution is the most effective way to treat Powdery Mildew. Baking soda and potassium bicarbonate have similar action mechanisms, but potassium bicarbonate is stronger and lasts longer. In one case, we treated young seedlings that developed Powdery Mildew very early, and they remained free from the disease for the entire growing season after only one application. A tablespoon of powder and a tablespoon of liquid soap should be mixed in four liters of water. After adding it to your sprayer, spray everything down, coating all parts of the plant.

In case you missed it: Cucumber Farming; Planting; Care; Harvesting Guide

Squash Vegetable
Image Source

Neem oil spray

Powdery Mildew can be controlled with neem oil, but it doesn’t always eliminate it. That is unless you treat your plants early and often throughout the growing season. For example, when used directly on tender foliage that people eat, such as kale leaves and veggies with nooks and crannies, such as broccoli, neem oil can leave an oily residue that is hard to wash off. The leaves of squash plants, however, benefit from it. In the same way, that bicarbonate must be diluted before application, and neem oil must be diluted before use. Water, however, is even trickier to mix with oil since it is an oil.

Trash-infected plants

If all else fails, significantly infected plants should be removed from the garden to prevent disease spread. It is best to avoid shaking, dragging, or dragging the plants over other plants, prime soil, or anything else that could cause the fungi spores to fly. Composting these should not be done. It is wise to replace the mulch around severely infected plants after they have been removed from the garden. Baking soda, potassium bicarbonate, or neem can spray the soil surface.


Once plants are heavily infected, eradicating the disease is difficult, so prevent it from spreading. First, remove infected foliage, stems, and fruit and destroy them. Next, throw away or burn all infected foliage, stems, and fruit. Composting infected plants are not recommended, as the disease can still be spread by the wind and survive in composted materials. However, following the abovementioned methods can prevent Powdery Mildew in its early stages.


Please enter your comment!
Please enter your name here