What to do against powdery mildew?

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What to do against powdery mildew?

We have spotted an infection of powdery mildew on one of our cucumber plants.
powdery mildew
leaf infected with powdery mildew
Luckily we saw it early, so we still have time to control the damage.
Nevertheless, we want to conduct a small experiment with the infected plant. Reason for this experiment is rumors and some scientific tests that were conducted, using a mixture of water and cow milk. It is said that powdery mildew can be prevented and even stopped when already present by using this mixture of water and milk.
I don’t know if it’s fact or fiction because results tend to differ. We have started the experiment anyway because it could be a good solution for organic gardening. (We really don’t like chemicals in our garden and even biological treatments can be devastating for nature.)
So, we currently have one plant infected with powdery mildew. This is what we did: we made a mixture of water and milk 1:1 and we sprayed it all over the plant.
Although powdery mildew only starts on one side of the leaf, we sprayed both sides of the leaves and the stem (because the stem is infected too).
powdery mildew on stem
stem infected with powdery mildew

Symptoms of powdery mildew:

We started seeing small white spots on the upper side of the leaf. These spots grew larger until the whole top side of the leaf became grayish white. After a while, the infected leafs dry out and fall off the plant.
In case of powdery mildew, we really need to do something as quickly as possible. Under normal circumstances, we have to cut off the infected parts (don’t throw these on the compost pile because it will infect the whole pile) and spray the rest of the plants.
In our case, for the sake of the experiment, we didn’t cut the infected leaves but let them stay on the plant. Now we’re waiting to see if the infection will spread or not. If the mixture is effective, the powdery mildew will at least be blocked to spread further.
The problem we face at this moment is the fact that different sources tell different stories. For instance, the amount of milk and water varies from source to source.
Also, the time between treatments differs from source to source. Some sources tell to treat the plants every two weeks. Other sources say the plants have to be treated two times a week.
treating powdery mildew
spraying milk mixture
against powdery mildew
In this experiment, not knowing what to do precisely, we start with our mixture, as said before, on a ratio of 1 to 1. And we use the mixture two times a week.
So, after reading all the above mentioned, you know, we’ll be back soon with an update. I guess the success is up to the cow now.


I have to be honest, the milk and water solution did stagnate the growth of the fungus but it didn’t eliminate the disease. I didn’t carry on with the test as the calculated price for the milk would be more expensive than pulling out the plant and sowing a new plant.


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