Hi. I’ve been growing for over 15 years and the dreaded mildew has found me. Any cures? Ideas? No chemicals.
All help appreciated
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Make sure your plants have adequate calcium and silica throughout their development. Strong leaves and stems help keep issues to a minimum. Common practice to treat powdery mildew on greenhouse cucumbers is to spray the affected leaves daily with water. Seems counter intuitive, I know. Below is an excerpt from a disease and pest management textbook.
Spraying affected cucumber plants with water every two to three days will control powdery mildew.
Plants should be sprayed in the morning, so they can dry in two to three hours. This prevents infection by other disease-causing
organisms. Fogging considerably reduces disease severity.
Other cultural control techniques involve environmental management and sanitation procedures. Greenhouse temperatures
should be maintained at about 21°C by heating and ventilation. Growers should avoid conditions that promote excessive
succulent growth, such as excessive fertilization. Overcrowding, shading and overwatering also should be avoided. Allowing a
period of two to three weeks when the greenhouse is thoroughly cleaned and empty between successive crops helps to prevent a
carry-over of powdery mildew from an infected crop to a new one. Greenhouses and the surrounding area should be kept clear of
susceptible crops, weeds and trash piles.
The amendment of hydroponic nutrient solutions with 100 ppm of soluble silica helps to control powdery mildew. The silica
can be added in the form of potassium or sodium silicate. For effective control, silica must be constantly supplied to the plants.
Silica sprays (1000 ppm) applied to the foliage may also reduce powdery mildew, but the solution must be adjusted to a pH of 5.5
using an acid such as phosphoric acid.
I’ve had it twice and both times a couple of applications of 50% milk/water solution took care of it. I’m a very small grower so application was easy and quick. Sprayed some on my hand and applied to hard to reach areas.
It is so rampant here on outdoor this season… every grower has some… strain resistants exempt… we are so close to finish we are all just trying to stop it… and WPM becomes systemic… if you cloned that plant it might have it… if you clone the only plant not to have it… it never should or be at a far less of a chance…
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Yes. I am growing outside and my plants are so close that I’m just trying to keep it in check. Weather is a big factor and it’s only on a few plants. But we’re running out of time to finish the plants before the weather hits us. I’m looking into a hoop house a little late I know. But a few plants are not ready
PM is non systemic. All plants infected should be killed if you dont want it to spread but in reality once spored release it is everywhere