Calling all PM experts. How do you deal?

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radmobile

radmobile

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OK, so I’m sure anyone that grows weed has dealt with PM. I’ve been growing for a little over a year and regardless of where I grow (inside or out) I always have PM. Here are things I’ve tried:
Neem Oil - gross smell and if you get it on your buds, your weed tastes like crap and smell like crap
Ph @ 10+ - this is a myth from my experience. I soaked 2 plants with over 11 ph and the alkaline didn’t kill any (literally ANY) of the PM.
Potassium Bicarbonate, 1/4 cup whole milk and a gallon of water - this works. Every time I use this, it kills the PM. This is great in Veg but if you spray your buds it will definitely brown the buds and take away the sweet aroma and terpenes.
Ive bleached my flower room, wipe all the walls and even removed every single thing except the plants. No matter how clean it gets, the PM is back within a couple weeks.

im setup in a 8x13 basement room (finished) with an air intake from outside and an exhaust that goes up the chimney. I know the intake charcoal filter doesn’t block PM so I’m considering a sealed room approach.

before I do that, does anyone have any other tricks to kill/mitigate PM without it affecting the buds? I’m SOOOOOO tired of PM.
Almost quit growing all together because it’s so often an issue. Any help
Would be HUGE!
 
Ponky

Ponky

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Safers 3 in 1 pre mixed. Soak every day for three days. Defoliate damaged leaves. Spray every 4 days there after. If you correct the condition causing the PM like low overnight temps. Stagnant air . Etc. Then it might cure it. However. PM is usually unstoppable. And the plant is weak to it. You can use a UV flashlight to see where you have it the most.

Now. Are you able to have the dwelling unoccupied for a good 12 hours and have no neighbour's close by? It's either the building or set up or the genetics. There's a method for sterilizing you basement thats pretty aggressive. But should work.
 
radmobile

radmobile

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Safers 3 in 1 pre mixed. Soak every day for three days. Defoliate damaged leaves. Spray every 4 days there after. If you correct the condition causing the PM like low overnight temps. Stagnant air . Etc. Then it might cure it. However. PM is usually unstoppable. And the plant is weak to it. You can use a UV flashlight to see where you have it the most.

Now. Are you able to have the dwelling unoccupied for a good 12 hours and have no neighbour's close by? It's either the building or set up or the genetics. There's a method for sterilizing you basement thats pretty aggressive. But should work.
Thanks for the prompt feedback!
I’m in a pretty tight neighborhood and I have 2 kids and 3 pets so I can’t exactly nuke the house.
I have to assume the PM is coming from outside. I read that the standard charcoal filters don’t block pathogens so I’m guessing my intake air contains the PM that keeps spreading?

stagnant air at night? I thought my fans were supposed to be on all the time to help
Mitigate spreading.
 
FOE20

FOE20

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This should be done as a preventative but heres my go to...
Green Cure mixed with Neem both organic solutions......GCure is a Fungicide Surfactant soap(Potassium Bicarbonate also a Organic beneficial)...add it to warm water shake till you have plenty of suds...Add a good amount of Neem which the soap will help to distribute properly...
shake well to emulsify and cover plant and surface of medium...the room..the floor and Lower your Humidity and make it More Dry in the enviro...PM wants moist dark cool conditions...
dont help it thrive..Plus if you already have it...its more of a challenge to get completely rid of it...power to it
FOE20
 
radmobile

radmobile

85
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This should be done as a preventative but heres my go to...
Green Cure mixed with Neem both organic solutions......GCure is a Fungicide Surfactant soap(Potassium Bicarbonate also a Organic beneficial)...add it to warm water shake till you have plenty of suds...Add a good amount of Neem which the soap will help to distribute properly...
shake well to emulsify and cover plant and surface of medium...the room..the floor and Lower your Humidity and make it More Dry in the enviro...PM wants moist dark cool conditions...
dont help it thrive..Plus if you already have it...its more of a challenge to get completely rid of it...power to it
FOE20
I have used the PB and Milk combo and it works. I’ve use neem as a leaf protectant and all of these work well in Veg. I do not want to spray my buds with any of these.
It ruins the buds completely. Maybe after I get through this flower I can try more than just bleach. In the meantime….I want something that’s not going to torch the pistils and kill the quality
 
Ponky

Ponky

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Ok. Second option is bleaching and killex paint. And get the flow down. Can't do an ozone peroxide nuke. Too obvious.
 
Moe.Red

Moe.Red

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Some cultivars are more susceptible than others, but I have found that the environmental control of air movement and humidity to be the answer.

Most people do not adequately remove humidity at night. When the lights go off, humidity goes way up typically. If you don't remove it fast it can get to 100% in a sealed tent pretty quick. Lights out and spiking RH are inviting PM.

This is from my SensorPush right now. It is a 4x8 and I had to upgrade to a 70Liter Dehuy to keep from spiking to well over 80% when the lights go out. I pull a total of over 10 gallons a day when in full tree flower mode out of the air. The little 30L I had in there simply would not ever catch up.

IMG_6A63C758F25B-1.jpeg


The bigger the plants, the more respiration, the worse it is.

Removing lower leaves to minimize that and to allow for more air flow helps too.

Bottom line is I hate putting stuff on my plants, even if it says it is organic. But I have found that if you control the environment the PM problem is virtually non-existent.
 
FOE20

FOE20

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I have used the PB and Milk combo and it works. I’ve use neem as a leaf protectant and all of these work well in Veg. I do not want to spray my buds with any of these.
It ruins the buds completely. Maybe after I get through this flower I can try more than just bleach. In the meantime….I want something that’s not going to torch the pistils and kill the quality
ahhh.....Im with that...didnt realize you were that far in....ya thats a tricky one....but....2 ways around it....1 no neem just use the soap....let it dry off......wash plant down lightly if needed...You dont want more Moisture but your just usinmg it fast as possible....you can do it without hitting budsites...you have to be careful...Foliage only...PM attacks leaves and will rest on stalks and shoots..It wont effect buds till its way past fighting...
So I totally get where your coming from but it is doable....but also dont want to lead you down a bad path so follow your gut..
the lower humidity is a must tho ime....least till your past the point of sweating it...hope it help and power to it
FOE20
 
PizzaBob

PizzaBob

125
43
Been in tough battles before. At some point it’s not worth putting certain stuff on them. Never had luck with the high pH stuff like greencure. Had better luck with lost coast therapy.
But I hear Regalia by Marrone Bio Innovations is worth a look from an outdoor dude. It’s 0 residue so supposed to pass testing too.
 
radmobile

radmobile

85
18
ahhh.....Im with that...didnt realize you were that far in....ya thats a tricky one....but....2 ways around it....1 no neem just use the soap....let it dry off......wash plant down lightly if needed...You dont want more Moisture but your just usinmg it fast as possible....you can do it without hitting budsites...you have to be careful...Foliage only...PM attacks leaves and will rest on stalks and shoots..It wont effect buds till its way past fighting...
So I totally get where your coming from but it is doable....but also dont want to lead you down a bad path so follow your gut..
the lower humidity is a must tho ime....least till your past the point of sweating it...hope it help and power to it
FOE20
Great stuff! Are you suggesting I spray with the PB (trying to avoid buds) and then soak/rinse? Will this keep the buds from burning out?
 
radmobile

radmobile

85
18
Some cultivars are more susceptible than others, but I have found that the environmental control of air movement and humidity to be the answer.

Most people do not adequately remove humidity at night. When the lights go off, humidity goes way up typically. If you don't remove it fast it can get to 100% in a sealed tent pretty quick. Lights out and spiking RH are inviting PM.

This is from my SensorPush right now. It is a 4x8 and I had to upgrade to a 70Liter Dehuy to keep from spiking to well over 80% when the lights go out. I pull a total of over 10 gallons a day when in full tree flower mode out of the air. The little 30L I had in there simply would not ever catch up.

View attachment 1167314

The bigger the plants, the more respiration, the worse it is.

Removing lower leaves to minimize that and to allow for more air flow helps too.

Bottom line is I hate putting stuff on my plants, even if it says it is organic. But I have found that if you control the environment the PM problem is virtually non-existent.
What are your night time humidity settings? I hear it’s good to get them down around 40? I’m somewhere up near 55.

my outside plants have it too. I feel like, if I’m going to spray my buds, I’ve ruined the entire grow. Other than High ph water (which didn’t help) everything has burned the pistils and ruined the quality.
 
radmobile

radmobile

85
18
Been in tough battles before. At some point it’s not worth putting certain stuff on them. Never had luck with the high pH stuff like greencure. Had better luck with lost coast therapy.
But I hear Regalia by Marrone Bio Innovations is worth a look from an outdoor dude. It’s 0 residue so supposed to pass testing too.
Right on. Thanks for the tip. How do you handle outdoor pm?
 
ComfortablyNumb

ComfortablyNumb

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PM is a humidity issue. It starts in the microclimes in the interior of the buds.
You've got to reduce the RH in your grow areas.
 
FOE20

FOE20

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Great stuff! Are you suggesting I spray with the PB (trying to avoid buds) and then soak/rinse? Will this keep the buds from burning out?
Yes ..exactly..........and not to contradict other comments but PM is spore that feeds on the Plant...not the buds until its waaaaay past fixing...
But were talking PM not Bud Rot...
Buds dont rot from the inside on their own which is more of a Botrytis issue, and a whole other thing all together...And starts at the Sexing calyx node point of a inter-node usually off the Meristem...
thats just my 2cents but I'll stand firm on it..
Cause I know these issues very well and how to manage them correctly being a master grower....gl
FOE20
 
Kanzeon

Kanzeon

1,703
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Some cultivars are more susceptible than others, but I have found that the environmental control of air movement and humidity to be the answer.

Most people do not adequately remove humidity at night. When the lights go off, humidity goes way up typically. If you don't remove it fast it can get to 100% in a sealed tent pretty quick. Lights out and spiking RH are inviting PM.

This is from my SensorPush right now. It is a 4x8 and I had to upgrade to a 70Liter Dehuy to keep from spiking to well over 80% when the lights go out. I pull a total of over 10 gallons a day when in full tree flower mode out of the air. The little 30L I had in there simply would not ever catch up.

View attachment 1167314

The bigger the plants, the more respiration, the worse it is.

Removing lower leaves to minimize that and to allow for more air flow helps too.

Bottom line is I hate putting stuff on my plants, even if it says it is organic. But I have found that if you control the environment the PM problem is virtually non-existent.

This. Decreasing humidity all the time won't necessarily help, but keeping plants in VPD will. PM isn't just caused by moisture, it's caused by fluctuations in the temperature and humidity outside of proper VPD.

My flower room is at 60% humidity right now and I haven't seen PM in years. Humidity isn't the enemy with PM (or botrytis), an improper balance of humidity/temperature/airflow is.

The best preventative is proper VPD. The best treatment is micronized sulfur, sprayed regularly.
 
Frankster

Frankster

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Some cultivars are more susceptible than others, but I have found that the environmental control of air movement and humidity to be the answer.

Most people do not adequately remove humidity at night. When the lights go off, humidity goes way up typically. If you don't remove it fast it can get to 100% in a sealed tent pretty quick. Lights out and spiking RH are inviting PM.

This is from my SensorPush right now. It is a 4x8 and I had to upgrade to a 70Liter Dehuy to keep from spiking to well over 80% when the lights go out. I pull a total of over 10 gallons a day when in full tree flower mode out of the air. The little 30L I had in there simply would not ever catch up.

View attachment 1167314

The bigger the plants, the more respiration, the worse it is.

Removing lower leaves to minimize that and to allow for more air flow helps too.

Bottom line is I hate putting stuff on my plants, even if it says it is organic. But I have found that if you control the environment the PM problem is virtually non-existent.

Agreed, it's no doubt a humidity issue, but also a dew point (temperature) issue. Indoors we use dehumidification, or air movement and temperature regulation. Those are the most readily available means of manipulation.

Outdoors those controls fly out the window, so we need to find another source to manipulate these controls.

Water activity (aw) is the partial vapor pressure of water in a solution divided by the standard state partial vapor pressure of water. The standard state is most often defined as the partial vapor pressure of pure water at the same temperature. Using this particular definition, pure distilled water has a water activity of exactly one. As temperature increases, aw typically increases, except in some products with crystalline salt or sugar. (Or glycerin)

Higher aw substances tend to support more microorganisms. Water migrates from areas of high aw to areas of low aw. For example, if honey (aw ≈ 0.6) is exposed to humid air (aw ≈ 0.7), the honey absorbs water from the air.

Definition of aw:
where p is the partial water vapor pressure in equilibrium with the solution, and p* is the partial vapor pressure of pure water at the same temperature.
aw1.JPG


Alternate definition: where lw is the activity coefficient of water and xw is the mole fraction of water in the aqueous fraction.
aw2.JPG


Relationship to relative humidity: The relative humidity (RH) of air in equilibrium with a sample is also called the Equilibrium Relative Humidity (ERH).
erh.JPG


Estimated mold-free shelf life (MFSL) in days at 21° C:
msfl.JPG


Water activity is related to water content in a non-linear relationship known as a moisture sorption isotherm curve. These isotherms are substance- and temperature-specific. Isotherms can be used to help predict product stability over time in different storage conditions. (perhaps even growing conditions)
AW.JPG



There is net evaporation from a solution with a water activity greater than the relative humidity of its surroundings. There is net absorption of water by a solution with a water activity less than the relative humidity of its surroundings. Therefore, a solution can be used to regulate humidity (especially in a closed space)

Most extremophile micro-organisms require sufficient water to be active. The threshold of water activity for their development is around of 0.6
Molds vary in their water activity requirements and this ranges from 0.7 to >0.9. Higher aw materials tend to support the growth of more microorganisms.

The water activity increases with temperature. ... Most plants have a water activity above 0.95 and that will provide sufficient moisture to support the growth of bacteria, yeasts, and mold. The amount of available moisture can be reduced to a point which will inhibit the growth of the organisms. osmotic concentration methods are used to reduce water activity.

Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known as glycerides. Due to having antimicrobial and antiviral properties it is widely used as a sweetener in the food industry and as a humectant in pharmaceutical formulations. Owing to the presence of three hydroxyl groups, glycerol is miscible with water and is hygroscopic in nature.
1920px-Glycerin_Skelett.svg (1).png
 
Frankster

Frankster

dinOmite!
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This. Decreasing humidity all the time won't necessarily help, but keeping plants in VPD will. PM isn't just caused by moisture, it's caused by fluctuations in the temperature and humidity outside of proper VPD.

My flower room is at 60% humidity right now and I haven't seen PM in years. Humidity isn't the enemy with PM (or botrytis), an improper balance of humidity/temperature/airflow is.

The best preventative is proper VPD. The best treatment is micronized sulfur, sprayed regularly.
I agree with the last part Kanzeon, however water is the major x factor IMO, micro-organisms require sufficient water to be active. Lack of water might not kill them, but it will create optimal conditions for encouraging dormancy and arresting (microbial) growth.

Temperature, humidity, air movement and osmotic concentration are among the regulatory factors.

equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature. The equilibrium vapor pressure is an indication of a liquid's evaporation rate. It relates to the tendency of particles to escape from the liquid (or a solid). ie. Even tiny differences in the plant's (body) temp, and the exterior (air) temp's come into play here.

No question proper VDP plays a very major role in all of this, not only inhibition, but also in promoting optimal conditions for the plants to mount an efficient stress response, resulting in optimized metabolic pathway.

Bottom line, the plant needs to be in that proper humidification zone, not too high, not too low. In a targeted range. When temperature, humidity controls go out the window, it makes this ever more problematic. In an outdoor setting, it seems to me that potentially air movement (fans) and osmotic concentrations (foliar) are regulating factors that can be potentially harnessed here, as we no longer control temperature, nor humidity.
 
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ComfortablyNumb

ComfortablyNumb

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I agree with the last part Kanzeon, however water is the major x factor IMO, micro-organisms require sufficient water to be active. Lack of water might not kill them, but it will create optimal conditions for encouraging dormancy and arresting (microbial) growth.

Temperature, humidity, air movement and osmotic concentration are among the regulatory factors.

equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature. The equilibrium vapor pressure is an indication of a liquid's evaporation rate. It relates to the tendency of particles to escape from the liquid (or a solid). ie. Even tiny differences in the plant's (body) temp, and the exterior (air) temp's come into play here.

No question proper VDP plays a very major role in all of this, not only inhibition, but also in promoting optimal conditions for the plants to mount an efficient stress response, resulting in optimized metabolic pathway.

Bottom line, the plant needs to be in that proper humidification zone, not too high, not too low. In a targeted range. When temperature, humidity controls go out the window, it makes this ever more problematic. In an outdoor setting, it seems to me that potentially air movement (fans) and osmotic concentrations (foliar) are regulating factors that can be potentially harnessed here, as we no longer control temperature, nor humidity.
I have to add here that we are unable to control the environment to any real degree. So we use it to our advantage. We know that plants thrive outside here, so we mimic it as best we can with open tents and enough fans to re-create the trades inside. (15-20 mph breeze we usually have.) We have had zero issues with PM or bud rot even though it is insanely humid often.
 
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ComfortablyNumb

ComfortablyNumb

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I bring that up because we don't do anything except keep a high level of airflow 24/7 on them. They have been off the VPD chart so many times but I have learned to ignore it because they just keep growing anyway.
 
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