Powdery Mildew?

Dr. Frescho

Member
Ey guys, i recently saw some white tiny points on my leaves.... My plants are currently at the third week of flowering and i'm pretty scared it could be PM.

Since i wasn't sure of what to do i applied a solution for PM by sprayin the leaves; i should repeat the process 10 days after that...
Anyway here are som picsIMG_20200308_014804.jpgIMG_20200308_014738.jpgIMG_20200308_014733.jpgIMG_20200308_014716.jpg

As you can see they're small,i only see tiny white points without magnification, there are no big white spots yet
 

Attachments

RainmakerJ

New Member
Turn the leaves upside down and check for spider mites. They appear as dark specs. Use your smartphone video recording with magnification to see them move around.
 

Cannablitzz

Member
Definitely not powdery mildew.
Powdery mildew would cause the leafs look like chicken skin before major infection.

Preventative maintenance/measures
Keep canopy, trim underneath get rid of older mature leafs and any that truly isn’t getting light.
If it’s shaded completely get rid of it or move the canopy around to allow light to penetrate.

make sure RH is 30-40-% imo for safe coasting.
I live in the desert so that also plays a roll into my RH.

Now adequate air flow.. don’t allow pockets of humidity to build. Any blockage of air flow leads to stagnation of humidity which means powdery mildew.

Don’t forget you set the best conditions for your plant and supply ample nutrients..
which means if you conditions can be right for other pathogens, pest. Do your best to be proactive and you’ll never have to worry bud.

enioy that sweet plant looks like thc glands.. which means that baby is dank
 

MICHI-CAN

Well-Known Member
Definitely not powdery mildew.
Powdery mildew would cause the leafs look like chicken skin before major infection.

Preventative maintenance/measures
Keep canopy, trim underneath get rid of older mature leafs and any that truly isn’t getting light.
If it’s shaded completely get rid of it or move the canopy around to allow light to penetrate.

make sure RH is 30-40-% imo for safe coasting.
I live in the desert so that also plays a roll into my RH.

Now adequate air flow.. don’t allow pockets of humidity to build. Any blockage of air flow leads to stagnation of humidity which means powdery mildew.

Don’t forget you set the best conditions for your plant and supply ample nutrients..
which means if you conditions can be right for other pathogens, pest. Do your best to be proactive and you’ll never have to worry bud.

enioy that sweet plant looks like thc glands.. which means that baby is dank
Excuse me please. Powdery mildew thrives on dry warm conditions. It spreads by means of air currents. It cannot grow or spread when wet. Please read up on it.
 

Renfro

Well-Known Member
Excuse me please. Powdery mildew thrives on dry warm conditions. It spreads by means of air currents. It cannot grow or spread when wet. Please read up on it.
PM requires times of high RH% and times of low RH%. For example, I never saw powdery mildew in over 20 years of growing in Missouri. After moving to Colorado I experienced it for the first time. This is because we NEVER had low RH% in Missouri but in Colorado it's the normal and the grow room caused times of higher RH%, usually lights out situation when temps drop, cooling isn't required and RH% spikes. So you definitely need the low RH% times for the spores to spread and the high RH% times is when it's shows up.
 

MICHI-CAN

Well-Known Member
LOL. Rampant here in the late summer / early fall. Gourds are hell to grow. And buds mold from the outside if you're not on it.
 

Cannablitzz

Member
Excuse me please. Powdery mildew thrives on dry warm conditions. It spreads by means of air currents. It cannot grow or spread when wet. Please read up on it.
PM requires times of high RH% and times of low RH%. For example, I never saw powdery mildew in over 20 years of growing in Missouri. After moving to Colorado I experienced it for the first time. This is because we NEVER had low RH% in Missouri but in Colorado it's the normal and the grow room caused times of higher RH%, usually lights out situation when temps drop, cooling isn't required and RH% spikes. So you definitely need the low RH% times for the spores to spread and the high RH% times is when it's shows up.
Well said.
 

Cannablitzz

Member
Excuse me please. Powdery mildew thrives on dry warm conditions. It spreads by means of air currents. It cannot grow or spread when wet. Please read up on it.
The key to mildew control is moisture control
Mildew growth requires fungal spores, organic material, and sufficient moisture. In actual practice, you can only control your moisture level. Experts agree that 50% relative humidity or lower is a good target for preventing mildew.
If you have a moisture problem, solve it before it becomes a mold or mildew problem.
Humidity equalizes rapidly
Air movement is needed to equalize temperature in the grow room but humidity diffuses rapidly throughout a room all by itself. This means dehumidifiers require no ductwork in most grow rooms.
Ventilation sometimes helps
Ventilation can work well for hobbyists and small grow rooms. Ventilation works best in dry climates with moderate temperatures year round, but comes up short during humid seasons or in humid climates. The incoming air must be filtered to keep out pests, mold spores, and other contaminants.
Ventilation does not work well for growers using supplemental CO2 and it adds cost when odors need to be filtered out of the exhaust air.
Air Conditioning sometimes helps
Air conditioning can remove some moisture when lights are on, temperatures are near 80F, and there is a need for cooling. Using an air conditioner to dehumidify a room when the lights are off is not a good idea. Running an air conditioner to dry a room when the lights are off will often freeze-up the A/C system and will certainly consume excessive energy.
It isn’t wise to force your cooling system to play at being a moisture management system.
Dehumidifiers give positive control
Dehumidifiers are a sure way of controlling humidity at all times. Most commonly available dehumidifiers are designed for light use in residential settings. For hobbyist grow rooms, light-duty dehumidifiers can be used as-is or modified by removing the condensate bucket and running a garden hose to a drain. A more professional operation should consider the extended reliability, much greater energy efficiency, and higher moisture removal capacity of commercial grade dehumidifiers.
How much moisture must be removed?
Plants transpire over 97% of the water they receive, so, for most grow rooms—the amount of water you give your plants is approximately the amount you must remove each day. For example 30 plants each receiving 1/2-gallon per day comes to 15 gallons water removal per day.
Dehumidifiers are rated by their water removal capacity in pints per day, operating in an 80F/60%RH environment.
Dehumidifier sizing
The best starting point is the concept of, “What goes in, must come out.” Almost all the water you give your plants must be removed from the air after the plants use it.
For the example above: (15 gallons) x (8 pints / gallon) is 120 pints per day of water. You would use a 120 ppd dehumidifier.
The air conditioner argument
Some growers may argue that their A/C system removes some water…so the dehumidifier wouldn’t need to have all that capacity. The fact is, A/C systems are optimized to reduce the temperature in a room (they remove sensible heat.) That’s what you want to use them for.
A/C systems can sometimes remove some water but while they are removing water, they cannot do much cooling. And, normally, if you’re A/C system is running, it’s because your room needs cooling.
Environmental control strategy
The best strategy for precise, efficient environmental control in a grow room: Use your A/C system to control room temperature and use your dehumidification system to control room humidity. Anything less is a gamble.
 

MICHI-CAN

Well-Known Member
The key to mildew control is moisture control
Mildew growth requires fungal spores, organic material, and sufficient moisture. In actual practice, you can only control your moisture level. Experts agree that 50% relative humidity or lower is a good target for preventing mildew.
If you have a moisture problem, solve it before it becomes a mold or mildew problem.
Humidity equalizes rapidly
Air movement is needed to equalize temperature in the grow room but humidity diffuses rapidly throughout a room all by itself. This means dehumidifiers require no ductwork in most grow rooms.
Ventilation sometimes helps
Ventilation can work well for hobbyists and small grow rooms. Ventilation works best in dry climates with moderate temperatures year round, but comes up short during humid seasons or in humid climates. The incoming air must be filtered to keep out pests, mold spores, and other contaminants.
Ventilation does not work well for growers using supplemental CO2 and it adds cost when odors need to be filtered out of the exhaust air.
Air Conditioning sometimes helps
Air conditioning can remove some moisture when lights are on, temperatures are near 80F, and there is a need for cooling. Using an air conditioner to dehumidify a room when the lights are off is not a good idea. Running an air conditioner to dry a room when the lights are off will often freeze-up the A/C system and will certainly consume excessive energy.
It isn’t wise to force your cooling system to play at being a moisture management system.
Dehumidifiers give positive control
Dehumidifiers are a sure way of controlling humidity at all times. Most commonly available dehumidifiers are designed for light use in residential settings. For hobbyist grow rooms, light-duty dehumidifiers can be used as-is or modified by removing the condensate bucket and running a garden hose to a drain. A more professional operation should consider the extended reliability, much greater energy efficiency, and higher moisture removal capacity of commercial grade dehumidifiers.
How much moisture must be removed?
Plants transpire over 97% of the water they receive, so, for most grow rooms—the amount of water you give your plants is approximately the amount you must remove each day. For example 30 plants each receiving 1/2-gallon per day comes to 15 gallons water removal per day.
Dehumidifiers are rated by their water removal capacity in pints per day, operating in an 80F/60%RH environment.
Dehumidifier sizing
The best starting point is the concept of, “What goes in, must come out.” Almost all the water you give your plants must be removed from the air after the plants use it.
For the example above: (15 gallons) x (8 pints / gallon) is 120 pints per day of water. You would use a 120 ppd dehumidifier.
The air conditioner argument
Some growers may argue that their A/C system removes some water…so the dehumidifier wouldn’t need to have all that capacity. The fact is, A/C systems are optimized to reduce the temperature in a room (they remove sensible heat.) That’s what you want to use them for.
A/C systems can sometimes remove some water but while they are removing water, they cannot do much cooling. And, normally, if you’re A/C system is running, it’s because your room needs cooling.
Environmental control strategy
The best strategy for precise, efficient environmental control in a grow room: Use your A/C system to control room temperature and use your dehumidification system to control room humidity. Anything less is a gamble.
Enjoy the balancing act. It's an art. Thank you for pasting this. Heard too many too wet stories. Peace.
 

Cannablitzz

Member
Enjoy the balancing act. It's an art. Thank you for pasting this. Heard too many too wet stories. Peace.
Excuse me please. Powdery mildew thrives on dry warm conditions. It spreads by means of air currents. It cannot grow or spread when wet. Please read up on it.
Another bit of info


Powdery mildew is the scourge of agricultural producers everywhere, and marijuana cultivators are no exception. While it is often believed that mildew and mold thrive at higher temperatures, they actually have an affinity for moderate temperatures like the typical range used for growing marijuana. This makes it tough to outsmart and stop powdery mildew. Understanding the most common causes of powdery mildew can help you prevent it from taking over.
Common Causes of Powdery Mildew
1. Poor Air Circulation

Overcrowded plant spaces are an excellent place for powdery mildew spores to develop. Keep plants evenly spaced. This will help isolate any infections and reduce the risk of the fungus spreading as quickly. Often, an air ventilation system or fans can promote healthy air circulation. These will also help push air toward your AiroClean420 air purification system to remove all airborne threats in your grow environment.
2. Insufficient Light
Plants need plenty of light to grow and produce buds. Insufficient light is one of the common causes of powdery mildew, and it can also lead to plants appearing weak or anemic. If you’re growing cannabis indoors, ensure your grow light timers are set accurately to give plants the light they need. This also prevents water from pooling in soil, which can promote fungus development.
3. Over-Fertilization
There is a tricky balance between providing plants with the nutrients they need and overdoing it. Powdery mildew tends to target new plant growth. Giving plants too much fertilizer may cause them to grow too quickly, which can cause a powdery mildew outbreak. Carefully monitor your delivery of nutrients to keep plants growing at a steady pace. AiroClean420 units have no harsh chemicals, harmful emissions or ozone, so your cannabis can stay fresh and vibrant.
4. Compromised Air Quality
Although fans or ventilation systems are a good way to improve air circulation, they can cause powdery mildew spores to quickly spread throughout your entire cannabis crop. It’s vital to kill powdery mildew with powerful air purification before it kills your crop. Compromised air quality can turn a mild powdery mildew outbreak into a catastrophic event. To prevent a disaster, invest in an air purification system such as AiroClean420, which neutralizes spores and bacteria as they enter the reactor chamber.
5. High Humidity
Powdery mildew thrives in humid environments. Using a hygrometer can help you monitor the humidity levels in your grow room. Seedlings require higher humidity, close to 70%. As plants mature, however, you may drop humidity levels toward 40%. During the seedling phase, carefully monitor your plants for early signs of powdery mildew. They are particularly vulnerable during this time. Through each stage of cannabis growth, AiroClean420 can provide your plants with pure, clean air to flourish.
Prevent Causes of Powdery Mildew
Although compromised air quality is one of the most common causes of powdery mildew, it is also among the easiest to correct. Our proven cannabis air purificationsystem, AiroClean420, is the solution to your air quality problems and an efficient way to stop powdery mildew. Contact the experts at AiroClean420 today to learn how this industry-leading technology can benefit your growing environment.
Go ahead and do some research
 

Cannablitzz

Member
This is a sales brochure. Incorrect.
Powdery mildew, a common and tenacious pathogen that
infests cannabis, can germinate at typical relative humidity levels of 50-70%.22 Although powdery mildew and most of the other mould and mildew species found on cannabis are not human pathogens,23 an infested cannabis crop may nevertheless contribute to indoor mould and particulate matter, with potential impacts on respiratory health through allergic sensitivity or irritation.17 Mouldy plants should be disposed of immediately, and in a way that does not allow unsuitable material to be reprocessed (e.g., the use of waste plant material for hash oil).
Cannabis-related odours derive from a complex mixture of hundreds of volatile compounds (terpenes and terpenoids) that are produced alongside odourless cannabinoids in the resinous secretion of the flower.24 Thus, odours increase with flowering and may also intensify during drying, curing, and processing as essential oils are volatilized. The combination of volatile compounds expressed varies among species and hybrids and may be subjectively more or less pleasant. To date, there is no evidence to suggest that cannabis odours are specifically detrimental to human health25; however, as with any strong odour, it can be argued that odour itself impacts well-being through annoyance, disruption, and stress.26,27
Carbon monoxide (CO) is a hazardous by-product of propane- or natural gas-powered carbon dioxide (CO2) generators or “burners” that are sometimes used to enhance plant growth and increase yield.28 CO accumulation within the home may also be affected (positively or negatively) by modification of the home’s ventilation capacity.29 Ignition devices also create an explosion hazard in the event of a fire due to the presence of compressed gas. Other hazardous practices include venting furnaces or water heaters directly into the grow room to increase CO2.3
National Collaborating Centre for Environmental Health
4

Policy considerations for indoor air quality
A great deal of attention has previously been focused on both the indoor and outdoor air quality concerns related to commercial cannabis facilities, and a number of regulations, technologies, and best practices have been developed to mitigate these issues.30-33 However, very different approaches are required to address these issues in private homes:
• Limit plant numbers. Because impacts on indoor air quality scale up with the number of plants, low plant limits should minimize risks for home growers. However, even a few plants may create or exacerbate moisture issues in some homes. Furthermore, Canadian law enforcement has indicated that plant limits under the proposed Cannabis Act will be difficult or impossible to enforce, and overgrowth is considered likely.5 Thus, plant limits alone are insufficient to mitigate the indoor air quality risks of indoor cultivation.
• Grow outside of the home. Cultivation-related humidity and mould issues can be avoided by growing outside of the home. Several provinces have indicated that they will permit outdoor or open-air growing on private property,34,35 although this increases the risk of theft and may exacerbate odour issues. A second option is to allow or encourage growth in secure, non-attached structures on the same property, which would also allow for the installation of odour control technology, if necessary.
On the left, four three week old cannabis plant seedlings in plastic pots. On the right, three fully mature cannabis plants budding under grow lights.
• Consider use of indoor air cleaners. Although air filtration units are typically limited in their ability to capture mould spores, which tend to settle before they can be entrained and removed,36 the use of additional ventilation in the grow space (fans, etc.) may create a more turbulent environment in which air filtration could help to reduce airborne spores. However, to date there has been no formal evaluation regarding the efficacy of portable air filtration units or air cleaners in the context of indoor cannabis cultivation.
b For example, incense, perfumes, or scented candles.
• Implement odour-reducing techniques and technologies.
Low-cost options that can be implemented without structural alterations include choosing low-odour varieties, storing cannabis in air-tight containers, and using masking agents,b deodorizers, ozone generators, and small-scale activated carbon filters to decrease odour.37 Activated carbon filters are widely promoted by the cannabis community as the most effective means, but have not been formally evaluated. Masking agents and ozone generators are not recommended as they may
National Collaborating Centre for Environmental Health

 

MICHI-CAN

Well-Known Member
It was fun. I'll check actual scientific sources. You may also try. Non profit university archives are good. If I am wrong I will apologize.
 

Renfro

Well-Known Member
Something to consider if you are in an environment that's prone to PM outbreaks, and for dipping incoming clones prior to quarantine, is a product called Actinovate. It is a bacterial fungicide that will prevent PM from growing. It can be applied in flower right up to harvest should the need arise. 1 teaspoon per gallon as a preventative and 2 for an existing infection. pH any and all foliar applications to 11.0 to prevent creating an acidic environment favorable to PM.

It can also be used to help prevent other molds that plague growers such as botrytis. You do have to apply it as a preventative as you won't be able to get it inside the buds later.
 
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