Can't get rid of powdery mildew

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father nature

Well-Known Member
Outdoor grow in the middle of my lawn. Plenty of airflow.its been humid but temps are dropping this week down to mid 70's during the day. I've tried 20% milk/water a week ago followed by another spray 4 days later. Didn't help. I Just tried potassium bicarbonate at 3/4 teaspoon per liter. It looks like it got worse overnight. Is it possible those are just stains from the Potassium Bicarbonate? It looks horrible. Should I up the dosage?
I Don't want to loose my plants this close to harvest which I think will be in 3 or 4 weeks.
 

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Hobbes

Hobbes

Well-Known Member
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Fr Manfredo:

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I'm surprised no one recommended Marrone Bio's Regalia...It's simply the best. My pm issues are long gone after trying a shit load of home recipes, and other products which only work temporarily. And Regalia is certified organic and can be used right up until harvest.


Cultivated Garden (CG) | Marrone Bio Innovations
We help customers around the globe control pests, improve plant health, and increase crop yields while reducing the environmental pesticide load, decreasing chemical residues and fighting the development of pest resistance. Our CG line for cannabis growers offers integrated pest management of...
marronebio.com
marronebio.com

It's not cheap to buy, but a quart will bring hundreds of plants to harvest powdery mildew free, without killing you (like a sulfur burn could). I also use their Venerate, as part of my IPM program.

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Only sold in the us.

.
 
Bosgrower

Bosgrower

Well-Known Member
Looks like you've got a while to go before harvest. I've always had good results with hydrogen peroxide. I'd start with about 1 1/2% solution (mix a container of 3% from CVS or Walmart with a container of water) and use a pump sprayer to thoroughly drench the plant top and bottom of all leaves and the stems.
If there's no breeze to help things dry out, try a leaf blower to get rid of excess moisture.
Repeat at least 3 times every 3-4 days.
You'll have some discoloration on the leaves, but that should stall the PM.
If it's still coming back after the 3rd treatment, try increasing the concentration.
 
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Bosgrower

Bosgrower

Well-Known Member
Hobbes said:
.

Fr Manfredo:

"
I'm surprised no one recommended Marrone Bio's Regalia...It's simply the best. My pm issues are long gone after trying a shit load of home recipes, and other products which only work temporarily. And Regalia is certified organic and can be used right up until harvest.


Cultivated Garden (CG) | Marrone Bio Innovations
We help customers around the globe control pests, improve plant health, and increase crop yields while reducing the environmental pesticide load, decreasing chemical residues and fighting the development of pest resistance. Our CG line for cannabis growers offers integrated pest management of...
marronebio.com
marronebio.com

It's not cheap to buy, but a quart will bring hundreds of plants to harvest powdery mildew free, without killing you (like a sulfur burn could). I also use their Venerate, as part of my IPM program.

.

Only sold in the us.

.
Click to expand...
Regalia's great stuff, but look at the buds ... that ship has sailed for these plants. Both as a foliar and a drench it's really only recommended until very early flower.
 
S

StonyMacPot

New Member
Hey whats up man, it sucks that your going through this with your plants. So here's something I did when I had some powdery mildew on my soil and fungus gnats. 1st I sprinkled around the base a decent amount of cinnamon, as wide as plant. The cinnamon is natural insecticide and fungicide. Then I watered it in with 1 gal of water mixed with 1 tblspn Dawn Dish Soap. I made sure it was bubbly. I let it sit and drain off like 10 mins. Then I flushed with another 5 gals of water clean. In the end it killed the gnats the fungus and the plant was revealed and is in flower now, ill post a pic. Oh yeah since you pretty much flushed and killed all bacteria and stuff in the soil. After the thorough flush to get soap out. Let dry for few days, then start resupplementing Nutes and Bacterias.
 

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father nature

Well-Known Member
I'm mid flower with nice big nugs, Branches are getting heavy and look great and are getting sticky
Don't want to lose this harvest and want to let it ride till the correct harvest time. I'm thinking another month.

How do I Kill this and save my buds?

Should I up Potassium Bicarbonate?
If so what ratio?
 
S

StonyMacPot

New Member
Look up cinnamon, and its plant benefits, its a natural insecticide as well as fungicide. Also you might be able to try a product that can flush out by the time you do your final flush, anyways hope you solve this plant riddle
 
Rivendell

Rivendell

Well-Known Member
Peroxide, 1 cup to a gallon of water, spray top to bottom. I have yet to find anything that works better. You can mix it stronger if needed, the worst side effect you will see is burned pistils.

I also spray sections with full strength if I have to cut out any bud rot.
 
F

father nature

Well-Known Member
Rivendell said:
Peroxide, 1 cup to a gallon of water, spray top to bottom. I have yet to find anything that works better. You can mix it stronger if needed, the worst side effect you will see is burned pistils.

I also spray sections with full strength if I have to cut out any bud rot.
Click to expand...
Pandemic paranoia means zero Peroxide anywhere from CVS to supermarkets and everything in between. I wanted to try Peroxide before anything else but its disappeared off the shelf worse than Toilet paper. That's why I tried the other options
 
Bosgrower

Bosgrower

Well-Known Member
father nature said:
The 3 amigos..... Their 8' tall trees I hope they make it I'm hoping to get at least a couple pounds. Would suck to lose them this late in the game so I really need to figure this out
Click to expand...
Step 1
Get yourself something like this

Step 2
Get some 3% or stronger hydrogen peroxide locally or online
www.walmart.com

hydrogen peroxide

www.walmart.com
bulkperoxide.com

Shop

Products Archive - Bulk Peroxide
bulkperoxide.com bulkperoxide.com

Step 3
Wash off any strong concentrations of PM with plain water (hose or sprayer) ... it won't kill the spores but it will clean off most of the growth. Be sure to wash the stems as well as the foliage. Let the plant dry thoroughly ... a leaf blower to get rid if most of the water after the washing will help.

Step 4
Once the plant is dry, fill the sprayer (2 gallons) with the 3% H₂O₂ and spray all surfaces of the plants thoroughly.
I suggest waiting until you know there will be several days of dry weather ... no sense trading PM for bud rot.

Step 5
Repeat the H₂O₂ treatment at least 3 times at 3-4 day intervals. You will see leaf burn from the treatment ... especially if it's very sunny right after the treatment but you should be able to beat the PM without destroying your crop.
 
F

father nature

Well-Known Member
Bosgrower said:
Step 1
Get yourself something like this

Step 2
Get some 3% or stronger hydrogen peroxide locally or online
www.walmart.com

hydrogen peroxide

www.walmart.com
bulkperoxide.com

Shop

Products Archive - Bulk Peroxide
bulkperoxide.com bulkperoxide.com

Step 3
Wash off any strong concentrations of PM with plain water (hose or sprayer) ... it won't kill the spores but it will clean off most of the growth. Be sure to wash the stems as well as the foliage. Let the plant dry thoroughly ... a leaf blower to get rid if most of the water after the washing will help.

Step 4
Once the plant is dry, fill the sprayer (2 gallons) with the 3% H₂O₂ and spray all surfaces of the plants thoroughly.
I suggest waiting until you know there will be several days of dry weather ... no sense trading PM for bud rot.

Step 5
Repeat the H₂O₂ treatment at least 3 times at 3-4 day intervals. You will see leaf burn from the treatment ... especially if it's very sunny right after the treatment but you should be able to beat the PM without destroying your crop.
Click to expand...
Walgreens had the 3%. Getting some today. What would the concentration be per gallon and I'll do the math with my sprayer.

I just went out and sprayed about 15% milk and 1 1/2 teaspoons of potassium Bicarbonate in a liter of water and the PM pretty much vanished. There is still very light white dots that look like the leaf is stained or its "in" the leaf. That happened before with just the milk but it just keeps coming back in a day or 2 so I'm not sure if its actually killing anything.. And when it comes back it comes back stronger each time. Temps and humidity are supposed to drop like a rock starting today (mid 70's with 50% humidity) so hopefully that helps. It's been oppressive humidity and mid 80's the last couple weeks. (over 70% humidity)


I'll add the H2o2 into the rotation.
 
Bosgrower

Bosgrower

Well-Known Member
father nature said:
Walgreens had the 3%. Getting some today. What would the concentration be per gallon and I'll do the math with my sprayer.

I just went out and sprayed about 15% milk and 1 1/2 teaspoons of potassium Bicarbonate in a liter of water and the PM pretty much vanished. There is still very light white dots that look like the leaf is stained or its "in" the leaf. That happened before with just the milk but it just keeps coming back in a day or 2 so I'm not sure if its actually killing anything.. And when it comes back it comes back stronger each time. Temps and humidity are supposed to drop like a rock starting today (mid 70's with 50% humidity) so hopefully that helps. It's been oppressive humidity and mid 80's the last couple weeks. (over 70% humidity)


I'll add the H2o2 into the rotation.
Click to expand...
If the infection is as heavy and persistent as you have described, I'd use it full strength. If you want to be more conservative, start with half strength as soon as the plants have dried from their "milk run" :). If the 3 applications of 1/2 strength don't work, go to full strength.
 
petert

petert

Well-Known Member
father nature said:
Outdoor grow in the middle of my lawn. Plenty of airflow.its been humid but temps are dropping this week down to mid 70's during the day. I've tried 20% milk/water a week ago followed by another spray 4 days later. Didn't help. I Just tried potassium bicarbonate at 3/4 teaspoon per liter. It looks like it got worse overnight. Is it possible those are just stains from the Potassium Bicarbonate? It looks horrible. Should I up the dosage?
I Don't want to loose my plants this close to harvest which I think will be in 3 or 4 weeks.
Click to expand...
Weird that what works for some doesn’t work for all. I had the beginnings of PM 10 days ago and did a foliar drench of 30/70 milk to water and it took care of the problem. I haven’t sprayed again because I haven’t seen it and it’s smoky as shit outside
 
thumper60

thumper60

Well-Known Member
father nature said:
Walgreens had the 3%. Getting some today. What would the concentration be per gallon and I'll do the math with my sprayer.

I just went out and sprayed about 15% milk and 1 1/2 teaspoons of potassium Bicarbonate in a liter of water and the PM pretty much vanished. There is still very light white dots that look like the leaf is stained or its "in" the leaf. That happened before with just the milk but it just keeps coming back in a day or 2 so I'm not sure if its actually killing anything.. And when it comes back it comes back stronger each time. Temps and humidity are supposed to drop like a rock starting today (mid 70's with 50% humidity) so hopefully that helps. It's been oppressive humidity and mid 80's the last couple weeks. (over 70% humidity)


I'll add the H2o2 into the rotation.
Click to expand...
Go straight 3% will not burn or harm any thing just dont spray in full sun.
 
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