White Powder Mildew...it's Everywhere!

[ArcticOrange]

I've read plenty of threads around where people claimed white powder mildew was brought into their grow by X, or "I've never had it before it must have come from this soil or that grow bag" whatever the case may be. White powder mildew is caused by fungi primarily from order Erysiphales. These fungi can reproduce both sexually and aesexually. Fungal spores are resilient and can lay dormant for very long periods of time. The scary thing about WPM causing fungus? They're literally everywhere. I mean everywhere. Are you breathing right now? Cause they're floating in the air! But fear not! They are waiting for the proper climate before they can become active again. This is where all of you come in. WPM likes temperate humid environments (much like our friend Mrs. Cannabis) so when you're dialing in your room for your plants you are often times dialing it in for WPM as well, which is why it is so common in indoor cannabis grows (especially when humidity gets above 50%). I am not trying to scare anyone here I just wanted to clarify that we as indoor growers create a prime environment for some pests and those pests will show their heads. They've been there all along. Create strong healthy plants with thick cell walls and good immune health and you can keep that WPM away.

-ArcticOrange

 

[ArcticOrange]

For tips on naturally boosting plant immune health look into silica, there are plenty of university studies done in the last 10-15 years that suggest it is one very under appreciated micro-nutrient, it can be harvested sustainably from natural sources, or is available in a far less sustainable salt form for anyone in hydro.

 

[cannabeans]

They are waiting for the proper climate before they can become active again

Due tell.... What is the proper climate for them to be active?

 

[ArcticOrange]

50-90 degrees Fahrenheit, and it is uncommon but infection can happen as low as 50% relative humidity. Infection becomes much more likely above that.

 

[mittenmedgrow]

Large environmental swings and low light area of the gardens are more prone.

 

[ken dog]

Maintaining good calcium uptake is very important in preventing powdery mildew... Because the calcium helps make pectin, which is essentially the glue between the cell walls.

When the powdery mildew spore tries to send a feeding tube down into the water between the cell walls, it encounters a high pectin content instead of a high water content, which makes it harder for the feeding tube to be inserted... And that extra time that it takes to penetrate, makes it easier for the spore to dry up and die.

 

[Seamaiden]

50-90 degrees Fahrenheit, and it is uncommon but infection can happen as low as 50% relative humidity. Infection becomes much more likely above that.

Even lower. I see it almost annually on various plants (bull thistle, for example, or Cucurbits) at 30% and below.

When and how it presents depends as much on the particular strain you're growing as environmental parameters. ;)

 

[jumpincactus]

And dont underestimate the power of a well brewed AACT to prevent & combat PM. Regular use will typically keep you free from this malady.

 

[BlackSheepOG]

Ever since I started using osa28 my plants have never been happier and I haven't seen PM since. Of course I foliar all through veg so flower isn't even an issue. But healthy plants help a lot to keep it away. Never throw an unhappy plant into flower either, that's asking for trouble.

As jump said AACT tea can do wonders.

 

[jumpincactus]

Castings Teas suppress disease and pests on vegetation and will boost the crucial microbial activity known as the Soil Food Web (SFW) which is so crucial to organic soils. Perhaps the most widely used and known use of teas is to suppress/eliminate black spot and powdery mildew on roses. By spraying Castings Tea on the surface of leaves, you are doing two things. First, you coat the leaf with millions if not billions of microbes all competing for a food source. Some, for instance protozoa, eat bacteria which may be eating decaying plant material. Others eat other microbes and their wastes. In the end, there are not enough resources for the harmful molds and fungi to flourish. In addition, you are also coating the leaf with a protective surface that protects the leaf cells from attack by foreign spores or airborne microbes. Finally, by inoculating the soil with Castings Tea, microbes break down nutrients for uptake into plants thereby increasing plant health and the plant’s own disease resistance/suppression.

http://yelmworms.com/compost-tea/page3.htm

 

[shemshemet]

I think you're right in the caution, but I disagree the spores are in everybodies room. If I had powdery mildew spores in my grow, my plants would definitey be infected.

#1 control of indoor pests is prevention. I say that every chance I have.

 

[mittenmedgrow]

In my 20 years of indoor growing I have had pm 1 time ,thrips once and spider mites 2 times I have never used any teas or beneficial microbes. I focus on enviroment, cleanliness of grow areas and treating new genetics before bringing them in. Haven't had any insect or plant health issues in a long time. I want to like teas and think it's very interesting seeing this new generation of growers with the teas, Benny's and organics but I have yet to witness the benefits from any of it. Maybe the people in my area suck but I work as a local consultant and visit multiple gardens every week and I haven't been the least bit impressed by the organic tea guys. Fungus gnats, root aphids, thrips and pm seem to run rampant in the organic gardens I visit. One organic guy I know was battling pm for three years he wouldn't do anything to change his environment but would throw just about every organic method known to man at them. He finally broke and hit everything with eagle 20 and hasn't had pm in about a year. One of these days I will switch to organic gardening and start using teas because I believe it's the future of the cannabis industry, but I'm still waiting for the guy who does it right to impress me and teach me the ways. I know he's out there I just haven't met him yet. There seems to be a lot of guys on the farm that have it down but I need to find someone in my area that can teach me.

 

[ArcticOrange]

ALL I was getting at is WPM is literally floating through the air. I'm not saying it's in your grow because I don't know if every single intake for air has a hepa filter on it I'm just saying spores and fungi are naturally occurring and are almost everywhere on the planet.

 

[BlackSheepOG]

In my 20 years of indoor growing I have had pm 1 time ,thrips once and spider mites 2 times I have never used any teas or beneficial microbes. I focus on enviroment, cleanliness of grow areas and treating new genetics before bringing them in. Haven't had any insect or plant health issues in a long time. I want to like teas and think it's very interesting seeing this new generation of growers with the teas, Benny's and organics but I have yet to witness the benefits from any of it. Maybe the people in my area suck but I work as a local consultant and visit multiple gardens every week and I haven't been the least bit impressed by the organic tea guys. Fungus gnats, root aphids, thrips and pm seem to run rampant in the organic gardens I visit. One organic guy I know was battling pm for three years he wouldn't do anything to change his environment but would throw just about every organic method known to man at them. He finally broke and hit everything with eagle 20 and hasn't had pm in about a year. One of these days I will switch to organic gardening and start using teas because I believe it's the future of the cannabis industry, but I'm still waiting for the guy who does it right to impress me and teach me the ways. I know he's out there I just haven't met him yet. There seems to be a lot of guys on the farm that have it down but I need to find someone in my area that can teach me.

Since I've switched to organics I've never looked back. There are just so many natural alternatives to the chemicals ones. I can tell the difference when I smoke none organic buds as well. The terpenes are just so much more pronounced.

If you have any questions don't hesitate to ask. I'm not expert by any means and always willing to listen but I think I know enough to help someone out.

 

[ShroomKing]

I think you're right in the caution, but I disagree the spores are in everybodies room. If I had powdery mildew spores in my grow, my plants would definitey be infected.

#1 control of indoor pests is prevention. I say that every chance I have.

I actually had PM and bud rot effect one plant in my garden at the same time this run. But the rest of my garden unaffected.
I keep a moderately clean garden with High air exchange, and low humidity.
I chalk this one up to weak plant defense not my gardening practices.

 

[BlackSheepOG]

I actually had PM and bud rot effect one plant in my garden at the same time this run. But the rest of my garden unaffected.
I keep a moderately clean garden with High air exchange, and low humidity.
I chalk this one up to weak plant defense not my gardening practices.

Every plant isn't a super star ;)

I've had it happen to bro and just sometimes that's how the dice rolls. Nothing to do but carry on in search of the dank :)

 

[ShroomKing]

Every plant isn't a super star ;)

I've had it happen to bro and just sometimes that's how the dice rolls. Nothing to do but carry on in search of the dank :)

Yep.
The leaves that were growing out of the spot in the bud that had the rot, we're the leaves the pm grew on. I noticed the pm first, pulled the leaf off to find a brown rotten stem.

 

[BlackSheepOG]

You can also take some potassium bicarbonate and mix it with water and little dr bonners soap for a wetting agent and foliar with it is also great for PM.

If you don't want to make your own you can get greencure which is essentially the same thing but more expensive

 

[ArcticOrange]

Afghani straino or strains with afghan parentage will have almost no mold resistance.

 

[BlackSheepOG]

Afghani straino or strains with afghan parentage will have almost no mold resistance.

Yea indica dom plants are bad for high humidity, but damn do I love a good indica :)