White Powdery Mildew on leaves...

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OGKushman

Don’t eat that pancake.
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So my buddy is having bad issues with mildew. It is growing on all parts of the leaves and even the buds. He ripped his entire grow down and started over with some advice from me. He started a new grow in a new room, from the Black and White poly down to the drywall was replaced!

He is now seeing some lower areas with mildew spots starting again.


His humidity is 20% during day, 40% at night, and get this...his temps are 60-66 degrees MAX. It is freezing in there.

But the mildew is still showing up. What can he do? I am out of ideas. :holysheep:
 
Hello OGK :)

Is he growing in soil?

Is he bringing fresh air in from outside?

What is his weather like outside?

:peace:
 
Bring that heat up....Thats too cold to grow in...I bet they aint even growing...sounds as though he has more issues then just Mildew ....Tell him 4u2sm0ke said bring his arse and his pictures to us here...its best help without middleman...not that your doing anything bad...just he would get Much help..as you all ready know...Take care and be safe
 
HippyInEngland said:
Hello OGK :)

Is he growing in soil?

Is he bringing fresh air in from outside?

What is his weather like outside?

:peace:
1. Rockwool
2. He was but now has CO2
3. Weather is SoCal. Kinda cool lately but when it showed, temps were high as well as humidity.


The plants look great right now. I hear pure indicas like to be cooler.? He just cant seem to stop it from showing up little by little.
 
PM is prominant here in Cali among the MANY clone vendors. I am not sure if you are making your own cuts, or purchasing them thru a club. If you are getting them from a club, my bet is that is where it is all starting.
If not, you need to treat your mother plants consistently until all signs of PM are wiped out.

I have fought PM for many years and there is only a couple of ways to truly eradicate it ,imo.
One, from the source plant of course.

Once you have plants that show signs, running a sulpher burner is really the only way to get trid of it, but I would not reccomend running it after a couple of weeks into flower.
 
Dampness or high humidity
Crowded plantings
Poor air circulation

these things will cause it everytime...plus watering on leaves once they are blooming..no misting.

Improve air circulation by thinning and pruning
Don’t fertilized until the problem is corrected. Powdery mildew favors young, succulent growth
Don’t water plants from above
 
2Dog...GREAT advice. Everything she said will def help keep it from coming back, once u get rid of it.
 
I make him his cuts, and I have no issues?

Humidity is low,
plants were crowded, but he started over and they are still small,
air circ is good....

Will the low temps affect his grow? Will it really help in controlling the PM?

He used a copper soap and has had some inconclusive results.

thanks guys
 
I dont know I have never had mildew but I keep my airflow up and my room is in the 70's...
 
2Dog said:
I dont know I have never had mildew but I keep my airflow up and my room is in the 70's...
Do you filter the intake? What kind of filter? Passive/Active?
 
lol no its called an open window and fans...for shame I know...hanging head... my room feels dry unlike a lot of grow rooms.
 
2Dog said:
lol no its called an open window and fans...for shame I know...hanging head... my room feels dry unlike a lot of grow rooms.
"feels Dry"????

Only way to tell is with a hygrometer!!!

Go to home depot and get one.

I really like using silicon ALL the time, from day one add a bit to the resevoirs and maybe you can avoid catching it in the first place. Its really easy, cheap, and is a nutrient anyways.


The challenge is killing the asexual spores called conidia. These are the white "mildew" that is seen. PM also has sexual spores that it releases when it gets cold and it thinks winter is approaching. I think these are called cleistotheca and are little brown sap looking things on leaves that look like thrip turds. The conidia I read can live up to 21 days, the Cleistotheca live months. I think if you have mildew it is better to up the cold nights so that u only have conidia to fight against. These conida are asexual spores that need to live on another plant. They are obligate parasites. In nature they might get blown by the wind into atmosphere when conditions good and land far away and start to grow. In a room they might land on walls or any surface like edges of tables, under tables etc. I have yet to find out if conidia or cleistos can rest in medium and grow onto root for example. But so the spores are on the walls. How to kill them? You can turn off everything for 3 weeks which hopefully the spores will have died. But u do not want to have everything down that long so how can we accelerate this shut down? I think the variables and products might include Sulfur Burners, Ozone Gnerators, high temps and maybe other stuff too.

I just read a book called Hemp Diseases and Pests by MacPArtland, Clarke and Watson. It is very comprehensive and one guy is a college professor. Serious people should but it, it costs ~175 but worth it. On page 11 they mention PM. There are TWO species that infect cannabis; Sphaerotheca macularis and Leveillula taurica. Knowing these two names means interested people can research google these names and get lots of SPECIFIC information. One tidbit of interest is that the relative humidity for each for germination is different. L taurica conidia can germinate with 0% RH and optimal growth is 25C (77F). In contrast, S. macularis conidia germinate best at 100%RH with optimal growth at 15-20C (59-68). So perhaps the experience and advice that one might have could depend on the species you r experienced with and that is hard to know. L taurica likes it warm and dry whereas S macularis likes cool and wet. I supose there are some conditions that are bad for both. S macularis infects hops which is similar to cannabis.

Here is a brutal story; Hops used to be grown around New York, about 70 years ago PM infected the field and annihilated them. Not sure which strain, perhaps s macularis. The whole hops industry shut down and all hops growing moved to Washington state where this PM strain did not exist until about 2002 when it started showing up Outdoors, throught the last 100 years, PM often is so hartd to fight the whole industry will just move when possible. Now all the hops is fumigated and grown like grapes with lots of sulfur. The entire wine grape industry in USA uses Fumigants like Supher. Without them there would literally be no wine industry!

Pro-Tekt Silicon might be able to help against PM
Fighting this Borg is tough. I read some articles by greehouse people about silicon being used to toughen up plants. Dyna Gro makes it and lots of people use it, i think more for heat tolerance but it might be good for PM. Barricade also is Silicon. It will not eradicate it, it might control or mitigate it. It might makes leaf cells thinker. Below is an article from a recent legit journal. Any thoughts? Anybody use this? I recommend using it proactively as a normal fertilizer element BEFORE getting exposed to PM. Then u may never get PM!


hXXp://www.springerlink.com/content/j6r7153t37233522/


Abstract Foliar and root applications of different silicon (Si)-based formulations were evaluated for their effects in reducing powdery mildew and promoting growth of wheat plants. X-ray microanalyses of treated plants revealed that root applications resulted in consistent deposition of Si in the leaves. In terms of powdery mildew control, root applications at 1.7 mM Si gave consistently the best results, reducing disease severity by as much as 80%, regardless of the product used. Although less effective than root applications, foliar treatments with both Si and nutrient salt solutions led to a significant reduction of powdery mildew on wheat plants. This suggests a direct effect of the products on powdery mildew rather than one mediated by the plant as in the case of root amendments. In our experiments, Si amendment, either through the roots or the leaves, did not increase plant growth. These results lead to the conclusion that Si is primarily, if not exclusively, absorbed by the root system and that such absorption by the roots is necessary for an optimal prophylactic effect.


I came up with a concept of infection that I will delineate now so that we can have a baseline for what infection is.

Level 0 (zero) infection: is actually NO infection. There are absolutely NO PM fungal bodies, mycellium, hyphae living anywhere in the system. This is primarily in a greenhouse or closed environment.

Level 1 infection: Low level infection. Under control. Rarely see patches but they do not really progress. Control might be natural immunity, resistance, neem oil, serenade. This is the natural state outdoors where spores might land on plants and not progress or might only get bad if weather changes. This is the state that many growers are in. They say they do not have mildew but really have a latent infection. If they give away clone that look ok the giftee gets PM. If they change the temp/humidity/environment then it shows up leading these people to say PM is always there and only conditions prevent it.

Level 2 infection: Full blown infection. Everything is being annihilated by PM. Trillions of spores. Might be using sulfur burner every week or two here to keep down infection, but stop and soon - WHAM.

I will try to use this nomenclature from here on sincce I think many people are in level 1 infection and think they are in level 0. An analogy is Herpes. Some people have cold sores all the time (level 2), many people have occasional outbreaks or even almost never (level 1), while some people do not have it and this can be proved by a negative antibody test (level 0).

I like to be at Level 0. Level 2 is unacceptable. Level 1 is an interesting place. Might plants that are really treated wtih proper control regimen and fresh vegeative plants revert to level 1????

The person I spoke with today said that Serenade applied weekly to level 1 plants might eradicate PM. The way that I have gone from Level 1 or 2 to level 0 is by shutting down as I mention above.


Link to article on greenhouse L taurica
http://www.agf.gov.bc.ca/cropprot/peppermildew.htm
Of note is that in peppers here they take 21 days to grow and seem to have spores on underside of leaves.

Link to S macularis on hops
hXXp://www.plantmanagementnetwork.o...ead.php?t=129670 So now I am more confused!
 
Im chillin here with my buddy and he just enlightened me on some new info.


My friend recently put his a/c on a timer 12/12. He said it was to save energy. Only problem is that his room's night is our day. So, when the problem began, during the light off (night in his room) he tells me the temps are 80 degrees and 65 degrees when the lights come on(day in the room)!

LOL


I think this might be the source problem! Anyone else?

Now he just has to contain it and get it out!@
 
oh wow...

good info here to. Considering not much research on Bud Plants has been published, I think other types of unseen infection may be happening.

Check this out:

Pepper powdery mildew grows unseen, within the leaf tissue for a latency period of up to 21 days. Unlike tomato and cucumber powdery mildew which is easily seen on the top side of the leaves, pepper powdery mildew grows on the under side of leaves (Figure 1). Disease monitoring, early detection and prevention of pepper powdery mildew is critical. By the time pepper powdery mildew is detected in a greenhouse many more leaves are already infected but do not show any disease symptoms or signs. In addition, pepper plants can become defoliated and do not recover as quickly as other greenhouse crops when infected with powdery mildew. Pepper powdery mildew does not infect the fruit or stems but can quickly destroy unprotected leaves and eventually the entire pepper crop.
hXXp://www.agf.gov.bc.ca/cropprot/peppermildew.htm


This is the Leveillula taurica strain, 1 of 2, that only affects Marijuana.

Send samples of pepper powdery mildew for lab confirmation to the BC Ministry of Agriculture and Lands provincial Plant Diagnostic Lab. Send a representative sample of infected leaves showing mild to severe symptoms and include some healthy appearing leaves.

Provincial Plant Diagnostic Lab
BC Ministry of Agriculture and Lands
Abbotsford Agriculture Centre,
1767 Angus Campbell Road,
Abbotsford, BC, V3G 2M3

Tel: 604.556.3126 (directly) or 1.800.661.9903 (main office)
Fax: 604.556.3154

WTH...IS this free^^^?
 
4u2sm0ke said:
Bring that heat up....Thats too cold to grow in...I bet they aint even growing...sounds as though he has more issues then just Mildew ....Tell him 4u2sm0ke said bring his arse and his pictures to us here...its best help without middleman...not that your doing anything bad...just he would get Much help..as you all ready know...Take care and be safe

I'm so sorry but your avatar is just so...... distracting...


Been running into all morning... read: looking for it all morning :)
 
OGKushman said:
So my buddy is having bad issues with mildew. It is growing on all parts of the leaves and even the buds. He ripped his entire grow down and started over with some advice from me. He started a new grow in a new room, from the Black and White poly down to the drywall was replaced!

He is now seeing some lower areas with mildew spots starting again.


His humidity is 20% during day, 40% at night, and get this...his temps are 60-66 degrees MAX. It is freezing in there.

But the mildew is still showing up. What can he do? I am out of ideas. :holysheep:


I find ozone is something that is largely overlooked. Might read about ozone generator uses, it will kill viruses and bacteria and mold, so probably PM too???
 
SkunkPatronus said:
I find ozone is something that is largely overlooked. Might read about ozone generator uses, it will kill viruses and bacteria and mold, so probably PM too???

Ozone gererators also have the ability to damage plants, research is a wonderful thing.

:peace:
 
2Dog said:
Don’t fertilized until the problem is corrected. Powdery mildew favors young, succulent growth

This comment is wrong.

PM will come and attack any growth.

A growth space is like a petri dish, give it ideal situations and it will flourish.

Young, established, old, they will all get its vigour.

Its the dish that attracts it, remove the dish.

:peace:
 
OGKushman said:
Im chillin here with my buddy and he just enlightened me on some new info.
My friend recently put his a/c on a timer 12/12. He said it was to save energy. Only problem is that his room's night is our day. So, when the problem began, during the light off (night in his room) he tells me the temps are 80 degrees and 65 degrees when the lights come on(day in the room)!
LOL
I think this might be the source problem! Anyone else?
Now he just has to contain it and get it out!@

You mean that he runs the lamps at night and has them off during the day? That's what I do. For the reason that day temps can go as high as 30C even at this time of year, but night temps are dropping as low as 12C. The lamps keep the grow room at about 25C at night which the plants love, and during the day they rest, the grow room would be as high as 38C if I ran the lamps in the day. Now, what you said last made little sense related to the first post about the grow room being so cold. :confused:
 
i bought clones in sacramento ... have had them since the middle of september. when i got them i learned what PM was. at first it was only on one or two plants. i quickly got rid of them. but now it is STILL here and i have been spraying with Garden Safe Fungicide3 since the beginning. i spray daily and am contemplating tearing out my girls after reading this.

is there ANY way to get from LEVEL 1 to LEVEL 0 ?? i am definitely at level 1 because it is only on a few leaves so far everyday. but i am going to have to do something within a few days as i am worried of getting sick..
 

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