Getting rid of mildew can keep pumpkin plants growing strong.

How to Kill Mildew on a Pumpkin Plant

by Kimberly Caines

If the supermom in you wants to surprise your kids with homegrown pumpkins (Cucurbita pepo) for Halloween, closely observing your pumpkin plants as they grow is essential to your success. Pumpkins are susceptible to powdery mildew, a disease that causes white, powdery mold to grow on the shoots and leaves. Ultimately the leaves can die and fall off the plant, yields can be reduced, and the fruit can lack flavor. If your plants are infected, learn how to properly eliminate the mildew.

Prune infected leaves and stems, and excess plant material from the pumpkin plant as soon as you notice them, and discard them. Wipe the pruning shears with alcohol to disinfect them after each use to prevent spreading the disease. Also discard plant material on the soil around the plant to prevent further infestation. Pruning promotes air circulation, which reduces humid conditions in which the disease thrives.

Mix 1 1/2 tablespoons of baking soda and 3 tablespoons of horticultural oil in 1 gallon of water. Pour the mixture in a spray bottle, and thoroughly spray the plants with it when the temperature is below 90 degrees Fahrenheit. This mixture combats mildew and can eliminate mild to moderate infections. Use it every seven to 14 days.

Water pumpkin plants early in the morning so any wet foliage can dry before nighttime. Ideally, use drip-irrigation or manually water the soil around the plants. Avoid getting the leaves wet, because although the water washes away mildew, it can trigger other pest problems.

Items you will need

  • Pruning shears
  • Alcohol
  • Baking soda
  • Horticultural oil
  • Spray bottle


  • Grow pumpkin varieties that are resistant to powdery mildew.
  • To prevent powdery mildew, apply a protecting fungicide, such as Serenade, which contains the bacterium, Bacillus subtilis, before any disease symptoms appear. Since fungicide is only effective on contact, spray it thoroughly on all plant parts. Also, spray any new growth with the fungicide. Reapply it every seven to 10 days.

About the Author

Kimberly Caines is a well traveled model, writer and licensed physical fitness trainer who was first published in 1997. Her work has appeared in the Dutch newspaper "De Overschiese Krant" and on various websites. Caines holds a degree in journalism from Mercurius College in Holland and is writing her first novel.

Photo Credits

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