UVA UVB Lighting To Kill Powdery Mildew And Mold

I have been doing some research into the use of UVA UVB lighting to either control, kill or eliminate powdery mildew and mold on medical marijuana cannabis plants.

I recently along with just about everyone else have been struggling with powdery mildew this past year.

Powdery Mildew Myth Debunked

I would first like to dispel some of the myths that are associated with powdery mildew.
Many people believe that powdery mildew is caused by too much humidity or that temperature issues can cause it. This is not true. Powdery mildew is caused by poor air quality control and is usually contracted through another plant that was introduced into your room or from the outside air coming into your room. It is critical that your outside air is filtered and not allowed to just free flow into your room. If you are growing in organic soil it is always possible to contract any number of pests, diseases or viruses. Many of them are present at all times on our plants and in our grow media. Just like the human body many diseases and viruses exist in our body but never become a full blown outbreak. Given the right environment the virus will accelerate. With poor air quality control you are providing the environment powdery mildew needs to explode. Once it starts it is nearly impossible to eliminate.

Excellent air quality means that you have the correct humidity, optimal temperature, excellent airflow, air movement and good air exchange. If you run a closed room you will need to supplement with CO2. Fans need to be located above and below your plants to eliminate stagnant air and provide the plant with CO2 that it needs. The slight flutter of the leaves allow the marijuana plant to uptake CO2.

How to Control The Spread Of Powdery Mildew

I have found that if you isolate the cannabis plant and treat it regularly it is possible to finish the plant or plants off and lower the chance of exposure to the rest of your crop. The mold thrives in darkness and the lower branches of your plants. It is critical to lollipop or strip off as much of the lower branching as possible followed by thinning the plant out either by deleafing the larger fan leaves or at the very least remove as many of the infected leaves as possible. If your plants are touching they will transfer the powdery mildew or mold at a much faster rate. I usually deleaf my plants in week 3 or 4 anyways with no adverse effects whatsoever. This allows more light to reach the lower branches and increases bud size. I will write up a separate blog about deleafing at a later date. I use a mix of products to control and eliminate the powdery mold but it is not a sure thing. I mix up a 5 gal bucket of Mighty Wash. I add in 80 ml of SM90 which can also be used as a root drench by itself to control and eliminate the mold or mildew. In addition I add in 40-80 ml of Neem oil, 32 oz of peroxide, 40 ml of Organocide and I have a petroleum base product I add 40 ml of that as well. I also add Coco Wet. Each of these products are comprised of different ingredients and serve a different purpose in the control or elimination of pests and disease. I have never had any one of my 22 strains show any adverse effects from this mix. I also spray with my lights on so I can get every nook and cranny of my plants top and bottom of the leaves and stalks. Another option would be to fog it in with a fogger which uses a lot less product and does a better job with coverage. Make sure you where a mask so as not to taste this in your mouth for next couple of days. All products are organic and will not hurt you or your plants. I have even sprayed all the way up to my 7th week in bloom and had no issues. My only concern was taste. I couldn't taste anything maybe just a little more harsh than normal at most. If desired you can also add in your foliar sprays such as Liquid Light, Sea Green or Magic Green at the same time.

During my fight to save my crop all my strains and mother plants I have researched many methods of control or elimination. What I have found is early treatment can control it or maybe eliminate it. Once the plant has become covered in powdery mildew it gets into the root system and becomes systematic. Once the powdery mildew becomes systematic it is nearly impossible to eliminate.

UVA UVB Lighting Research To Eliminate Powdery Mildew On Vegetable Crops

My research led me to some studies that had been done on lettuce plants cucumbers and tomatoes. The research had found that with a minimum exposure of 15 min per day from the UVA UVB lighting the powdery mildew was in some cases controlled and other cases eliminated. I found this to be very interesting because for the past 3 years I had been using my UVA UVB lighting to increase THC up to 5% UVB UVA Study Results Increses Marijuana Cannabis Potency By 3-5% and never had any powdery mildew issues during that entire time. When I moved my room to a new location I discontinued use of the lighting and within 3 months started having issues with powdery mildew. I never made the connection.

This makes complete sense because many companies sell uva uvb filters for fish tanks and ponds that filter out and kill algae and other unwanted micro organisms. They also purify and clean the water of unwanted bacteria.

Test Results In My Grow Room With The Ultraviolet Lighting

I have since then installed the new T5 HO 54w Reptisun 4ft bulbs in my room which are 2x more powerful than the T8 Reptisun bulbs I used last time. Link to Reptisun 10.0 UVA UVB T5 HO 4FT bulbs I will be doing some further testing with these bulbs as compared to the T8's I was using before to increase the cannabis potency. Stay tuned for the results!

I run my UVA UVB bulbs during the full 12 hr bloom cycle. Since installing the bulbs I have had no further progression of the Powdery mildew and it seems to have killed off all remaining mold spores on my plants. It has been 2 weeks since I installed them over the plants. If your plants are really tall you may have to position the UVA UVB lighting near the bottom of the plants so it penetrates down into the canopy or near the underside of the plant where the majority of the mold will grow.

My plants that are in the vegetative stage have been mostly cleaned of the powdery mildew but every now and then I would get a few spots here and there. I placed my veg plants under the same lighting and have not had any signs of mildew since.

Due to the fact that powdery mildew is a viral infection and can not be killed off without damaging or killing the plant I am waiting to see if my new clones develop any new mold spores. If not that means the powdery mildew is wiped out of the plant completely. This would be a revolutionary finding because many growers have lost entire marijuana crops due to powdery mildew. There is no product on the market that can eliminate it in bloom. Some claim to eliminate it in vedge but this has not been proven to be effective 100% of the time.

How to Dry medical marijuana with powdery mildew

In addition I have found even if you can control the mold or mildew once you cut the plant down and start the drying process the powdery mildew explodes all over the buds and the rest of the plant that was not previously contaminated. I found that if I dry with a light on or a set of lights on in my drying room the powdery mildew does not continue to grow. I have had no adverse effects from drying with my lights on contrary to popular belief that you must dry in the dark. So there goes another myth busted!

The mold only grows in humidity above 10-15% however if we kept our rooms at this level we would have some serious issues to deal with. Plants will not root, they grow very slow, buds do not swell and when drying the finished medical marijuana would be dust! So even though humidity does play some role it is not a path we can travel down.

Further Testing Needed With UVA UVB Lighting

I would like to see more testing done on other forms of mold and mildew such as bud rot mold, grey mold, blight, downy mildew etc. I am confident the the UVA UVB lighting would eliminate all of these as well.

In closing it seems that we as growers need to plan on adding UVA UVB lighting to their rooms. It has been proven to have many positive effects on the marijuana plant when grown indoors. After all in nature all plants need this light spectrum. This spectrum triggers growth responses and protects the plants from immune deficiencies as well as unwanted pathogens.


Links to related blogs:

How To Grow Marijuana Like A Pro

UVA UVB Lighting To Kill Powdery Mildew

UVB UVA Study Results Increses Marijuana Cannabis Potency By 3-5%

How to achieve uniform THC and CBD results with the use of UVA UVB lighting.

Here is a quick update about how to achieve a uniform consistency when using UVA UVB lighting to grow medical marijuana.

Based on my last two years of testing I have found that using UVA UVB lighting will increase THC % by 3-5% on average.

Additionally we found where the light is placed makes a big difference as well as where the sample taken for testing or consumption also makes a noticeable difference. 

The lighting must be over top of plants and only the part of the plant receiving direct lighting from the UVA UVB bulbs increases. Which means the bigger the plant the more UVB UVA lighting you will need. Nowhere else on the plant does it show any increases in potency other than where the light is directly applied.

Also the location of the cutting taken for testing or consumption varies 3-5% as well. With this information it is possible that the top 6 inches of the plant could be 6-10% higher in THC than the lower branches.

Using the UVA UVB lighting in vedge or seed stage makes no difference on potency only some minor leaf curl is noticed if used in bloom only. All new leaves will adjust and not show any curling.

SCROG For Best UVA UVB Light Coverage And Uniformity

Based on this knowledge it would be best to grow medical marijuana plants in a technique called SCROG or screen of green. 

Basically you are growing a plant out wide not tall. A plant could be five feet wide but only 12- 18 inches tall. What this does is allow all the light to be used by the plant evenly and uniformly. This will eliminate the huge variance in THC and CBD potency. It will also eliminate all those small airy, fluffy flowers that are no good to consume other than maybe edibles. Resulting in large easy to trim flowers that all have the same flavor, taste, smell, hardness, density, potency and bag appeal.

 It also allows you to increase your yield by at least double if not more while growing fewer plants. This is a benefit if you live in a state where the legal limit of plant count is very low. To achieve this plants will need to be vedged longer and allowed to get fuller and taller. Top and crop as much as possible to make the plant short and wide.

Here is an example of a five foot SCROG set up in a 20 gal pot grown in a soil or soilless media. The pot size can be dropped to a 10 gallon or 15 gallon size with similar results.

It is my hope that all my research and testing will benefit everyone as well as advance the growth and knowledge of the industry resulting in better medicine and less chronic pain patients loaded up on highly addictive pain killers.

Links to related blogs:

How to Grow Medical Cannabis Like A Pro

UVB UVA Study Results Increses Marijuana Cannabis Potency By 3-5%

Updated UVA UVB Medical Marijuana Study Results

Updated UVA UVB Medical Marijuana Study Results

I am pleased to say I have done another round of UVA UVB testing and it has been completed.

The objective was to determine if the location of the UVA UVB lighting effects the entire plant or just the area in which the lighting was placed.

I had the lighting placed on one side of the plant for the entire bloom cycle. Normally I would have them overhead. Then after the cycle was over I took samples from both sides of the plant. I sent in both samples that I had taken for testing.

The test results showed that only the side facing the lighting increased 5% from 23% to 28%!

This is a very important finding. Not only is the fruit closest to our grow lighting 3-5% stronger with the addition of UVA UVB lighting it will also increase the potency another 3-5% only where the UVA UVB lighting is placed.

With this testing completed it will be important to locate lighting all around the plant as much as possible or directly overhead. I previously used the Reptisun 10.0 UVA UVB 4ft T8 bulbs. I am now using the Reptisun 10.0 UVA UVB T5 4ft bulbs. They are 2x stronger and will penetrate deeper into the canopy.

Next round of testing will be to see if waiting till last 2 weeks of bloom to turn on the UVA UVB lighting will still result in the dame 3_5% increase.

Link to Reptisun 10.0 UVA UVB T5 HO 4FT bulbs UVA

How To Grow Medical Marijuana Like A pro

UVB UVA Lighting Study Results Increases Medical Marijuana Potency 3-5%

UVA UVB Lizard light testing results.  Date Feb 2013- Dutchman Enterprises

I just completed 2 full years of testing on over 10 different strains and have reached the conclusion that the UVA UVB light spectrum will add 3-5% THC and .0-.5% bcd over all strains tested.

I have done 6 complete grows from veg through bloom each one tested with the lighting and without the lighting alternating each crop. One on and one off. Each time the crop with the lights on would jump 3-5% with the lights off it would decrease 3-5%. I have assumed an error margin of 2%

My test results seem to be right in line with what other people have experienced over the years. I could not find any recent data online so I Decided to do my own research and testing.

Some strains tested are as follows when under Lizard Lights.

Chem dawg 27%

OG-18 25%

Holy grail Kush 28%

Critical + 23%

Tohoe OG 24%

Grape Ape 23%

White Fire OG 25%

Dead Head Og  24%

Chem Valley kush- shit pheno 15%

The difference in potency is so obvious that all my patients would complain about the lack of potency on the crops that I did not use the UVA UVB lighting!

UVA UVB Light Exposure

I have found it is best to expose them to it from time they are rooted. This will give them time to acclimate to the lighting. It does not make any difference to the potency if you use the lights in bloom only. The only difference is if you do it in bloom only you will get leaf curl but it does not seem to stress the plant or hurt it in any way. I would start them off slowly and build up to the full 12hrs in bloom if you are not going to veg them under the UVA UVB lighting.

I started off my strains in low doses on a timer in 2 hr increments on and off and slowly each day increased them as I was scared to kill them initially due to some research I had done on this topic in online forums. 

I soon found that it did not matter at all. You can hit them with the lighting 24hrs in veg and 12 hrs in bloom with no adverse effects except a little leaf curl at the ends if they had not been previously acclimated to it at the beginning of life stages (rooted). This is why I would recommend exposure as soon as possible.

I purchased the new 4 ft Zoo MedReptiSun 10.0 UVB/UVA Bulbs 

These bulbs were chosen because they reach the deepest and furthest away.

With these 10.0 bulbs penetration is 18-24 inches from the light. 

The older 8.0 or 9.0 bulbs were 12 inches or less which did not give much room for plant location in my 8x15 room.

UVA UVB Light Test Results

I had every batch of plants tested by Cannalytics for accuracy. I have also found that where you take your sample on the plant also plays a role in test results. The THC % plants can vary anywhere from 3-6% difference based on where sample was taken top, side or bottom of plant. 

I am no scientist so I can't say 100% that it does not alter the plants genetics but based on my knowledge of genetics and my own research I do not believe the genetics have been altered at all. What has happened is just a natural stress response by the plant to protect itself from the ultraviolet rays. 

To prove this even more is the fact that each strain dropped back 3-5% when it was not under the UVA/UVB lights. Even when I had them under the UVA/UVB lights in veg but not under the lights in bloom they did not increase in potency enough that I could measure a change.

Further UVA UVB Questions To Answer

Some further questions I would like to get an answer to is if the light is positioned on one side of the plant instead directly over top of the plant does the whole plant respond to the uva uvb stress the same throughout or does it only increase potency on the side the light is on? I will need to take two samples off one plant and have them analyzed.

I was able to get the double 4ft fluorescent light fixtures for $50 each that had a 15ft electrical chord plug attached. I found the ReptiSun 10.0 4ft bulbs for $18.95 each plus a few bucks shipping. I will find who it was and post it when I do. My total cost for 6 fixtures and 6 bulbs was around $400. 

I have used them for 2 years on and off so pay off has been good. In my opinion it is well worth it to run the UVB UVA bulbs. It will set your product apart from every one elses in your area. Think about it to be a beginning grower and have strains testing out at 27-28% and seeds were gathered from online seed banks is pretty darn good!

UVA UVB Lighting To Kill Powdery Mildew

YouTube Channel How To Grow Marijuana Like A Pro

I hope this helps someone, happy growing

Dutchman Enterprises

UVA UVB MEDICAL MARIJUANA LIGHTING LIZARD LIGHTS THC POTENCY INCREASE