Powdery Mildew and Aquaponics

Fri, 13 Jan 2017


We had an email from one of our regular aquaponics customers, concerned about his cucumber plants in his aquaponics system. His system is fairly new, but whatever stage you’re at, there’s always things to learn.

"I had a cucumber plant that was going great guns, but all of a sudden the leaves have started to turn brown at the edges, and there is a white powder like substance in the middle of the leaves. Plus all the baby cucumbers have shrivelled up and died."

Sound familiar? Welcome to the world of powdery mildew which affects only certain plants, cucumber, rockmelon, watermelon - actually all melons, zucchini, most vine crops. Is there a pattern emerging?

Powdery mildew is a fungus which spreads a whitish film over the upper and lower surfaces of the leaves of plants. It favours high humidity and dry conditions.

powdery_mildew_leaf.jpg     powdery_mildew_leaf_spray.jpg


Our resident horticulturist Delia said that this usually occurs when it’s humid and dry. It’s difficult to control, especially in climates like we’ve had lately. The weather just seems to be a little nuts!

As our customer is doing aquaponics (growing fish and vegetables together), finding a natural solution that works successfully is difficult. The last thing we want to do is kill our precious fish from using a chemical treatment.

Delia’s advice was to carefully trim off the affected leaves as you don’t want the spores to be floating around ready to spread, and harvest what fruit you can until the plant has pretty much given you it’s best days. You’ll then need to remove the plant and hope that it hasn’t spread to other similar plants.

The problem can quite often be quality of seeds or seedlings as well. Inferior seeds or seedlings can be more susceptible to disease. Always try to get the best organic seeds or seedlings available, assuming that we can be bothered with actually propagating our own seeds. However, I'm time poor (aka lazy) and find it easier to purchase seedlings. From there, it’s just a matter of rinsing the soil off and voilà - instant vegetable garden. Until trouble strikes.

So, what can we do to treat this nuisance? We’ve tried a few different natural remedies such as full cream milk / water spray as we prefer don’t want to add use chemicals. Aside from this, vigilence is key.

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