Powdery mildew

Powdery mildew, mainly caused by the fungus Podosphaeraxanthii, infects all cucurbits, including muskmelons, squash, cucumbers, gourds, watermelons and pumpkins. In severe cases, powdery mildew can cause premature death of leaves, and reduce yield and fruit quality.

Plants infected with powdery mildew look as if they have been dusted with flour.

  • Powdery mildew usually starts off as circular, powdery white spots, which can appear on leaves, stems, and sometimes fruit.
  • Powdery mildew usually covers the upper part of the leaves, but may grow on the undersides as well.
  • Young foliage is most susceptible to damage. Leaves turn yellow and dry out.
  • The fungus might cause some leaves to twist, break, or become disfigured.
  • The white spots of powdery mildew will spread to cover most of the leaves or affected areas.
  • The leaves, buds, and growing tips will become disfigured as well. These symptoms usually appear late in the growing season.

What causes powdery mildew

  • Powdery mildew infections favor humid conditions with temperatures around 68-81° F.
  • In warm, dry conditions, new spores form and easily spread the disease.
  • Symptoms of powdery mildew first appear mid to late summer in Minnesota.  The older leaves are more susceptible and powdery mildew will infect them first.
  • Wind blows spores produced in leaf spots to infect other leaves.
  • Under favorable conditions, powdery mildew can spread very rapidly, often covering all of the leaves.
  • Although powdery mildew primarily infects leaves and vines, infections occasionally occur on cucumber or melon fruit. Powdery mildew does not directly infect squash fruit.
  • Fewer and smaller fruit grow on infected plants. Reduced fruit quality occurs due to increased sunscald, incomplete ripening, poor storability and poor flavor.
  • Powdery mildew is more likely to infect densely planted vines, plants crowded by weeds, plants in shaded sites and over-fertilized plants



  • Remove all the infected plant parts and destroy them. Remember, do not compost any infected plant, as the disease can still be spread by the wind and persist in the composted materials.
  • Spray infected plants with fungicides. Effective organic fungicides for treating powdery mildew include sulfur, lime-sulfur, neem oil, and potassium bicarbonate.


  • Choose plants that are resistant or tolerant to powdery mildew. Many mildew-resistant varieties of cucurbits (melonscucumberssquash, etc.) have been developed and can be bought from major seed suppliers.
  • Avoid watering plants from overhead in order to reduce relative humidity.
  • Selectively prune overcrowded areas to increase air circulation; this also helps to reduce humidity around your plants.
  • Spray your plants with the fungicides mentioned above according to the directions included with the products.
  • If you don’t want to use fungicides, try spraying your plants with a bicarbonate solution:
    • Mix 1 teaspoon baking soda in 1 quart of water. Spray plants thoroughly, as the solution will only kill fungus that it comes into contact with.

Mix 1 gram of  Powmel -CDM in 1 ltr of water, stir it well and the solution is ready for spray.

The mixed solution should be sprayed on the entire plant. Make sure you are covering the under surface of the leaves while spraying.

When you observe the disease symptoms that are mentioned on the label, you can go for the spray. Generally it can be sprayed once in 15 days interval to prevent these diseases and to have healthy crops.


Powmel Controls spreading of White or brown mealy growth which will be found on upper and lower surfaces and stems. Gradually plants foliage recovers its green color and also increasesphotosynthesis efficiency in the plant


Gradually plants foliage recovers its green color and also increasesphotosynthesis efficiency in the plant resulted in higher yield and quality production..