Mold & Mildew, got milk? (2024)

Gray stem mold has been a major problem in my outdoor garden this year.
Fortunately, I've only seen a little powdery mildew but it's definitely getting a foothold on my squash leaves - which is perfectly normal.
It's in the air this time of year for sure.

I've been spraying diluted milk for several weeks in an effort to prevent infections, and I think it worked great for PM but not so much for gray stem mold.
But looking back, I realized that I wasn't spraying the stems until problems had already started.

Hmm... is it really necessary to pay special attention to the stems?
I'm thinking yes, definitely.

In fact, I'm pretty sure that bud rot also starts on stems, not in the bud. It's probably the same mold that's hitting my stems now, but that's just a hunch.

Here's some good news - if you catch stem mold early, it can be successfully removed with a concentrated blast of diluted milk. Get the nozzle less than an inch from the mold and give it a good blast to irrigate the wound.

This has worked surprisingly well. It may take a couple of shots, and there will be a permanent scar, but the plant can recover without amputation.

There is some debate on the ratio of milk to water, but I personally like using 1.5 cups (12 oz) per gallon because it works well and leaves minimal residue.
I've seen recommendations of up to 40% milk, but that will definitely leave a white residue that I personally think looks terrible.

How does it work?
I don't know, and neither do scientists - but it works, and unlike many other sprays, you want to spray milk in full sunlight.

Genetics also play a role. One strain in particular, which I won't name, has been plagued with stem mold and I've had to cull 4 of them.

What are your thoughts?

I'll add pics soon...
— edit —

This has been sprayed with milk but there’s still some mold that needs another shot.

Ditto for this plant. Sprayed yesterday but needs another shot.

Unexpected yellow leaves can be a sign there’s a problem.

Recently I’ve been in the camp of water actually being the anti fungal agent is most sprays. As soon as PM is wet the spores are null and it can’t spread. Just like pollen kinda. So maybe it’s just that the Milk solution is wet just like all the snake oil EPA exempt oils and sprays on the market. They work cause they are wet.

I could be way off but was thinking about setting up a small test this year and seeing if straight water is just as effective as anything mixed and applied. Food for thought.

If water alone was effective, there would be no pm here on my squash, but there is. And it's been raining daily and plenty. So it's being treated daily in effect. The milk treatment is done once every 10 days and it works but it's not the end of the pm but it knocks it back and will get you through your grow.

There's a lot of info on the web of milk being used that has nothing to do with weed plants.
If I see any pm on mine I will certainly be breaking out the milk spray.

I’m a greenhorn outdoor but also have alot invested which has sent me on deep dives for information regarding all disease and pest. But I’ll preface with that so don’t think I’m bashing any style or practice for growing.

But it’s at least worth a friendly conversation.
The main thing I didn’t understand is PM is just the symptom of many strains of mildew. And the Strains in our veg garden is not the same, nor reacts the same to treatments that affects cannibus.

Also it was tad hussey of KIS organics that had mentioned the idea of water being the most effective treatment. I linked a quick reference that’s pretty clear how water on the leaf surface kills and inhibits germination of spores so idk ? The real issue here is still lack of studies regarding cannabis specifically at the university level If it were any other crop there would be better information more readily available.

I’m 100% not bashing anything that works and if it ain’t broke don’t fix it!

Powdery Mildew on Vegetables Management Guidelines--UC IPM

"LAB-derived unsaturated fatty acids and hydroxyl unsaturated fatty acids exhibit antifungal activity."