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Powdery mildew on zucchini leaves

Powdery mildew is one of the most feared fungal diseases among home gardeners. And pumpkins are not spared either. So what to do if the coating is discovered on the leaves or even on the fruits of the pumpkin plant. Control should be carried out immediately so that the harvest is not endangered. However, there are some means available for this that are also ecologically harmless.


Powdery mildew has a particularly characteristic pattern of damage that is usually immediately apparent. This is a fungus that can survive cold temperatures in winter unscathed in the soil or on plants and weeds. Once powdery mildew has been detected in your own garden, it can recur again and again, even if it has been successfully combated on the plants affected at the time.

damage picture

As temperatures warm in spring, mildew cells are transmitted to plants by host animals and the wind. Already at a temperature of 20° Celsius and high humidity, the spread in the garden begins explosively. A distinction is made between two types of powdery mildew. Therefore, if the white coatings on the pumpkin plants appear under or already on the leaf side, then it can be powdery mildew or downy mildew. So the infestation shows as follows.

powdery mildew on plant leaf


powdery mildew

  • white, mealy spots on the upper side of the leaves
  • on stems and fruits as well
  • Leaves turn brown and die
  • The cause is usually prolonged drought
  • Heat helps it spread

Wrong mildew

  • whitish or brownish deposits
  • look velvety
  • are on the underside of the leaf
  • yellow to brown spots on top
  • usually occurs in very humid weather

Pumpkin breeds that are available in well-stocked garden shops are often already resistant to powdery mildew. So if you have to take action against the annoying fungal infestation in your garden again and again, you should buy one of the resistant varieties for the next season.


Downy mildew always occurs when the area around the plant is humid or even very wet for a long time. Therefore, the pumpkins should not be watered too often or too much. The soil can be kept drier by mixing in some rock flour. Fungicides should not be used on the consumable pumpkins, as they could also be harmful to health if ingested. Fertilization with nitrogen should also be avoided at all costs, as this can promote mildew infestation. Furthermore, the following can be done for prevention.

Hokkaido pumpkin
  • vigorous pumpkin plants are more resistant to powdery mildew
  • Strengthen plants with liverwort extract
  • this also prevents the multiplication of the spores
  • Always water plants from below
  • do not let water get on the leaves
  • only water in the morning or afternoon
  • especially in spring the plant should be dry at night
  • Mulch on the ground makes pumpkins more resilient

Bacteria contained in cow's milk are intended to prevent mildew infestation. To do this, milk is mixed with water in a ratio of one to eight and regularly sprayed onto the plants. The bacteria form a dense coating that does not harm the plants, but repels the pathogens of powdery mildew.


Combat biologically

The powdery mildew can be controlled biologically without a chemical mace on the pumpkin plants. But there are some remedies that are environmentally and consumer-friendly and can therefore be used at any time against mildew on pumpkins.

  • Plant mixed crops
  • put garlic between the pumpkin plants
  • Basil and marigolds also keep mildew away
  • Garlic as an infusion together with onion broth
  • always choose an airy location
  • Place plants at a sufficient distance
  • Remove any affected parts immediately
  • don't put it in the compost
  • Spray regularly with a milk-curd soap-alcohol solution
  • Use parasitic wasps and ladybirds

Ichneumon wasps are available in well-stocked garden shops and can be used directly on the infested plants. Even if the insects are called wasps, they are in no way dangerous to humans or animals. Nevertheless, the bed with the pumpkins should be fenced off in such a way that neither small children nor free-roaming pets can enter it, so that they cannot come into contact with any spores that may be on it.

use soda

Soda is already known as an all-rounder from the kitchen, but it can also help against powdery mildew on pumpkin plants. If powdery mildew has already formed on the plants, then soda can be used as a natural fungicide after the affected parts of the plant have already been removed. The mixture is then stirred as follows.

  • a heaping tablespoon of soda
  • alternatively, baking soda can be used in the same amount
  • dissolve in four liters of water
  • Add 15 milliliters each of curd soap and vegetable oil

The mixture is placed in a spray bottle and the affected plants are sprayed several times with it. Also treat the soil around the pumpkins and neighboring plants if necessary.

Herb broths against powdery mildew

Even mixed herbal broths are usually also good against powdery mildew, because they activate soil life and at the same time strengthen the pumpkin plants' defenses. Field horsetail is used for this, which is available in well-stocked shops or in a farm shop in fresh or dried form. The preparation is therefore as follows.

Powdery mildew on a plant leaf
  • 150 grams of dried field horsetail
  • or a kilo of fresh herbs
  • put in ten liters of water
  • Leave to soak for 24 hours
  • then cook for half an hour
  • strain
  • dilute with five times the amount of water for watering

Water the bed with the pumpkin plants regularly with this brew, additional watering with just water is not necessary.


powdery mildew harmful

If the pumpkin plants and perhaps even the fruits are affected by powdery mildew, the question also arises as to whether this is harmful to health. It has been proven that powdery mildew can be poisonous, but this also depends above all on the people who touch an infested fruit. Because powdery mildew can trigger allergic reactions if the gardener suffers from a mushroom allergy. Even a penicillin allergy, which is more common, can be very dangerous if you come into contact with powdery mildew. Therefore, the following precautions should be taken on the squashes affected by powdery mildew.

  • do not eat infected plants
  • children and older people in particular should avoid this
  • Consequences are stomach or digestive problems
  • Breathing problems when inhaling the fungal spores
  • Skin irritation after contact
  • Better to wear gloves and a respirator
Mildew infestation on a grapevine


Discard infected squash

If the pumpkin plants have been attacked by mildew and rescue measures have already been carried out, but the mildew is persistent, then unfortunately these plants can only be disposed of. For this purpose, the entire plants with the fruits should be removed from the infested bed. Please do not put these in the compost, because from here the fungal spores can spread throughout the garden. It is better to put the plants in plastic bags as soon as you remove them, seal them tightly and then dispose of them in the household waste. The bed must also be treated by removing the top layer of soil and disposing of it with household waste. Otherwise the spores can survive in the soil and infect the next plants again in the new season.

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