Cucumber mildew is not only a nuisance, if left unchecked it can even kill the crop. A first sign are spots on the plants. It is important to distinguish which form the disease is in. There are two different forms of fungal infection, which can be combated in a similar way, but require different conditions for growth.

Distinguish between powdery mildew and downy mildew

Both fungal diseases affect cucumber plants and have similar symptoms, including white discoloration. The fungal disease should not be underestimated, because within a very short time not only a whole row of leaves but the entire plant is affected. The advantage, however, is that cucumber powdery mildew only affects cucumbers and does not affect other vegetable crops. If other cultures have comparable symptoms, it is indeed the same fungal disease, but again a form that is specialized for this genus.

Powdery mildew fungus:

  • occurs in dry and warm climates
  • white mealy spots on the upper side of the leaves
  • Transmission by wind or insects

The damage caused by the downy mildew fungus looks similar, but it develops much faster and often goes unnoticed, especially in the early stages.

Downy mildew fungus:

  • formation on the underside of the leaf
  • white to yellowish spots
  • occurs at very high humidity
left: powdery mildew
right: downy mildew

combat powdery mildew

immediate measures

As soon as an infestation is detected on the cucumbers, you should act immediately. The mildew fungus spreads very quickly and can kill the plant within a few weeks. As soon as color changes are detected on the leaves, action must be taken. If you wait until the leaves die off, it is often too late and the plant is already largely infested. Therefore, the underside of the cucumber plants should also be checked regularly in order to also discover the false powdery mildew fungus. Affected plant parts are removed and disposed of as an immediate measure. The fungus can also attack flowers and fruits, which are also no longer eaten but disposed of.

Plants or parts of plants that are infested must not be disposed of in the compost as the fungal spores can withstand even low temperatures unscathed. In the worst case, they are distributed over the entire garden via the compost and can infest cultures again and again, even if they change location. Therefore, you should only infest infected parts of the plant residual waste to dispose.

home remedies

milk

A successful remedy for fungal diseases of any kind is milk. Ideally, raw milk is used directly from the farmer, but commercially available milk can also be used. However, milk from the supermarket should be left in a warm place for at least 24 hours so that enough lactic acid bacteria can form. The lactic acid cultures form a protective layer around the plant parts. On the one hand, this prevents the fungus from spreading and also fights the infestation, even if effects such as white spots are not yet visible.

The lactic acid bacteria themselves do not harm the plant - on the contrary, they even promote the organisms in the soil. For use, the milk is diluted 1:1 with water and sprayed onto the plant. It smells a bit unpleasant for the first few days, but the smell goes away after a while.

tip: You can already use the mixture of milk and water on young plants to prevent infestation. With repeated use, however, you should avoid fruits that are about to be harvested so that they do not have an unpleasant taste.

garlic

Garlic is also a good home remedy for various fungal diseases. Roughly chop the garlic, pour boiling water over it and spray the affected plants with the cooled broth.

nettle manure

Nettle manure has proven itself both for strengthening plants and in the fight against powdery mildew. To do this, roughly chop the stinging nettles, put them in a bucket and fill it up with water. The broth is left covered in a sunny to partially shaded spot for several weeks. If odors form, you can use stone dust to bind them. Once the nettles are mostly decomposed, you can spray or water the broth on the plants at a dilution of 1 part nettle broth to 10 parts water.

tip: Baking soda can also be used to combat powdery mildew. To do this, dissolve 2 teaspoons of baking soda in one liter of water and spray the plants with it again.

fungicides

As an alternative to home remedies, commercially available fungicides can also be used. However, since cucumbers are foodstuffs, instructions for use and, above all, waiting times must be observed exactly. Therefore, only use fungicides in extreme emergencies. Commercial products based on sulfur have proven their worth.

Control in the greenhouse

A particular area of concern is the control of powdery mildew on cucumbers in the greenhouse. Due to the almost closed space, the fungi often spread much faster. You should therefore take special preventive and control measures in the greenhouse:

  • air regularly and thin out plants
  • remove diseased plant parts
  • Disinfect plant sticks before use
  • Change binding material annually

tip: Greenhouses are more likely to create ideal climatic conditions for fungal growth. With a weather station that measures humidity and temperature, you can react in good time and critical climatic areas that promote the spread of mildew can be avoided in advance.

prevent infestation

Gardeners can already prevent powdery mildew on cucumber plants. Above all, strengthening the immune system of the plants has proven itself. If an initial infestation occurs, you can prevent it from spreading by strengthening the cucumber plants and removing the affected parts of the plant.

The following preventive measures are taken:

  • Field horsetail broth for pouring to strengthen the cell structure
  • Water close to the ground and avoid moisture on the leaves
  • Plant cucumbers far enough apart
  • Avoid over-fertilization
  • Plant mixed culture partners such as onions or garlic
  • Keep cucumber plants weed-free

When choosing cucumbers, you should use only healthy and strong plants. Already sickly looking or weak plants should not be planted in the first place. They offer the fungal spores a good surface for attack and can thus promote spread to neighboring plants.

comply with crop rotation

A very decisive factor in combating the powdery mildew fungus in the long term is compliance with crop rotation. Due to the fact that the fungus can survive in the soil for several years without any problems, you should definitely change the location in the event of an infestation.
Do not plant cucumbers in locations where carrots or potatoes used to be. The nematodes that form around the carrots can damage the cucumber plants. In turn, fungal diseases can form in the potatoes, which, like powdery mildew, can damage the cucumbers.

As a successor to locations with cucumber plants, you can plant broad beans, various types of cabbage, radishes or leeks, for example. In this way, you do not offer the cucumber powdery mildew a breeding ground again next year and can fight it in the long term.

Use resistant varieties

Powdery mildew is a fungal disease that can occur again and again due to its resistance. Especially in gardens with limited space, where crop rotation is hardly possible, it causes major problems. Even those who consistently fight mildew can sometimes despair at the persistent occurrence of the fungal disease. Varieties with limited or very high resistance to this fungal infection bring relief. This reduces the effort involved in prevention or control.

Resistant varieties of pickling cucumbers:

  • Charlotte
  • Excelsior
  • Hok
  • zircon

Resistant varieties of snake cucumbers:

  • Cordoba
  • flamingo
  • Hayat
  • Sudica

notice: Although these varieties show a certain resistance, selection should also be made when planting. The healthier and stronger the plants are, the greater their chance of resisting not only mildew but also other pests and diseases.

Category:

Vegetable garden