sanddan said:

I'm thinking of starting a new grow (haven't grown for 2 years) and have questions on avoiding PM during flowering stage. In the past I've had issues with PM during the flowering stage, anywhere from 6 weeks up to 8 weeks of flowering. I have a dehumidifier, 4x4 tent and 600 watt light. I ran at least 4 clip on fans and one floor standing column fan in the tent 24/7. Heat was an issue as the room the tent is in is in an unheated pole barn. Night time temps got as low as 65-68 deg. I had the dehumidifier in the room but not in the tent. Typical humidity in the tent was 45-55%. The last run I attempted I was spraying nukem every 4-5 days and still got PM showing at the 7 week point. Any ideas on how I can get through a crop without the dreaded PM?

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Heard nice things about “actinovate”. I can’t get it here but seems like it works.

Baking soda water and soap, hit the search bar I’ve posted many times about it. Remember pm is systemic. Once it’s in the plant you have to fight to rid it.

1diesel1 said:

Baking soda water and soap, hit the search bar I’ve posted many times about it. Remember pm is systemic. Once it’s in the plant you have to fight to rid it.

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In that symptomatic treatment i would suggest potassium bicarbonate instead of sodium bicarbonate (baking soda).

Don't treat the PM... PREVENT IT... Get your environment under control... I would heat the tent at night. Keep your temperature swing under 10 degrees. Looks like everything else is in order.
I use a 24 hr programmable electric heater. The ones without their own timer had to have the power button reset every time my external timer shut off.
Hope this helps. Best of luck.

1diesel1 said:

Baking soda water and soap, hit the search bar I’ve posted many times about it. Remember pm is systemic. Once it’s in the plant you have to fight to rid it.

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How do you know PM is systemic? Just curious. The consensus of any university study that I’ve read says that PM is not systemic. I know PM is host specific (acting like a parasite). Maybe I missed something?

Also, I’m curious because whether PM is systemic or not is a highly debated topic. I was just curious about what you’ve read or heard....

It’s a hot topic.
w Systemic?


Cannabis growers are divided when it comes to powdery mildew, one of the plant’s most notorious pathogens. In one camp, there are those who believe PM is a systemic pathogen that permeates via the plant’s vascular system. Others believe is it superficial pest that spreads across the plant’s surface?

It turns out, there is a good reason for the debate. Based on the available literature and the tests we have conducted at Medicinal Genomics, it’s not clear whether PM is systemic. The science is still out. But here is what we know so far.

The Powdery Mildew that infects Cannabis is a novel organism


The powdery mildew species that infects cannabis is a different organism than the organism that infects other plants, such as tomatoes or cucumbers.

We genetically sequencing infected cannabis plants from the United States and Canada and found that the DNA didn’t match any known PM sequences. Further complicating things is the possibility that there could be more than one PM species infecting cannabis, but we would need to collect more samples from Europe and Asia in order to sort that out.

There has been no published research into how this novel PM organism infects the cannabis plant. For now, the best we can do is look to studies on how other PM species infect other plants for clues. However, until similar studies are conducted on cannabis, we can’t be sure how the pathogen behaves.

Powdery mildew can create an invisible network before spores are visible


Powdery mildew is an obligate biotroph, which is a fancy way of saying it cannot survive without taking nutrients from a host. A 2012 studyshowed how the Golovinomyces orontii species of PM does just that. After dying an infected leaf, the researchers observed that spores penetrate the leaf and the cell wall with a taproot called a haustorium, which serves as its primary feeding mechanism. The pathogen then forms secondary taproots into neighboring cells, creating a mycelium network over a period of several days before producing the tell-tale white powder.

Again, it’s important to note that Golovinomyces orontii is not the same organism that infects cannabis. However, we have designed test that can detect the unique DNA signature of the PM species that infects cannabis from a 4mm leaf punch. In fact, our youPCR Powdery Mildew detection assay can detect powdery mildew DNA from cannabis leaves that show no visual signs. This suggests that we are detecting the DNA from the mycelium network that the pathogen creates prior to sporulation. This early detection can be useful to growers who can remove and quarantine infected plants so they do not further infect the grow room.

Powdery Mildew can be detected elsewhere in an infected plant


If powdery mildew penetrates the plant, the next question is whether it gets into the plant’s vasculature and infects other parts of the plant. There is no published literature that supports that theory, and it is likely the mycelium network is made externally.

However, we collected four samples from visually clean leaves off a plant that had visual PM elsewhere on the plant. Of those four samples, three tested positive. This does not prove the theory that PM can travel through the plant’s vascular system. It could be that the other parts of the plant were infected by a separate event. It may also be that some powdery mildew DNA gets into the plant’s bloodstream when the haustorium penetrates the plant. In any case, it is a topic that warrants further study.

Cannabis can be bred for powdery mildew resistance


Powdery mildew does not affect all cannabis varieties equally. Some varieties of cannabis are resistant, while others are very susceptible to the pathogen. We also believe that PM resistance is not binary. In hops, we have seen there are lines that are partially resistant.

In any case, PM resistance is a trait that can be selected. Using early detection technology, such as the youPCR Powdery Mildew assay, growers can screen plants for infection before visual signs are present. By continuing to screen for PM infection, and selecting against plants that test positive, breeders will enrich their resistance.

Conclusions
As you can see, there is still much to be learned about powdery mildew on cannabis. As with most plant pathogens, the best defense is prevention. This can be done with strict environmental controls, periodic screenings of grow rooms, and screening of incoming clones

Regalia, Suffoil X and Green Cleaner in an IPM rotation and you'll be just fine as long as you're circulating air well and keeping proper environmental conditions

CrimsonEcho said:

Heard nice things about “actinovate”. I can’t get it here but seems like it works.

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Works and look for it under lawn care section, branded for yellowing lawn and it’s active ingredients are the same

DetGrnThumb said:

Regalia, Suffoil X and Green Cleaner in an IPM rotation and you'll be just fine as long as you're circulating air well and keeping proper environmental conditions

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How far into bloom do you take that regimen?:)

As far as you want. I cut the Suffoil and Regalia after week 3/4 indoors, but the Green Cleaner can go all the way to finish.

Jack og said:

Works and look for it under lawn care section, branded for yellowing lawn and it’s active ingredients are the same

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Are you saying there is something at Home Depot that is similar to Actinovate? What do they call it? I pay an arm and a leg for Regalia/Actinovate and would love to just pay an arm. Thanks

3 balls said:

Are you saying there is something at Home Depot that is similar to Actinovate? What do they call it? I pay an arm and a leg for Regalia/Actinovate and would love to just pay an arm. Thanks

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Here it is.
It’s not a beneficial but it’s a great chemical equivalent.

Here are the specs on actinovate
Walmart has these as well

Regalia is a great product but Procidic2 is hands down the best. I do use both.

Here is some good reading on
Actinovates main ingredient

https://res.mdpi.com/ijms/ijms-19-00952/article_deploy/ijms-19-00952-v2.pdf?filename=&attachment=1

DetGrnThumb said:

As far as you want. I cut the Suffoil and Regalia after week 3/4 indoors, but the Green Cleaner can go all the way to finish.

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I like regalia and microthiol for pm. Last spray of anything, if all goes well, day 13. Got some milstop for emergencies

Jack og said:

Here is some good reading on
Actinovates main ingredient

https://res.mdpi.com/ijms/ijms-19-00952/article_deploy/ijms-19-00952-v2.pdf?filename=&attachment=1

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Thanks, I appreciate the trouble.

CaliRooted said:

Regalia is a great product but Procidic2 is hands down the best. I do use both.

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Got something similar, based on your comments on procidic, called cyclone (it’s the closest I could get)..... Works great, smells nice too haha