PM Prevention Program (BEFORE INFECTION)

[SpicySativa]

What's up, IC?

I'm hoping we can get a little discussion going about different methods of preventing powdery mildew infection BEFORE it happens. Where I live (in a fog bank) powdery mildew is ubiquitous. Despite having covered all the environmental factors:

*(beyond) sufficient airflow and circulation
*low humidity (less than 45%)
*healthy plants pruned for airflow, and
*Silica supplementation (Pro-Tekt)

I deal with a few minor spots of powdery mildew, usually showing up during or just after the stretch phase. This thread IS NOT concerned with how to treat these spots. When an infection happens, I'm able to treat it effectivly and prevent any new spots from showing up. But, at the same time I am then locked into a weekly spray schedule through bloom (not ideal, but hasn't caused any issues).

What I want to discuss is a preventative spraying program to hopefully ward off that initial infection and avoid spraying my plants during bloom.

So... What have you found to be the most effective spray BEFORE infection?

Cheers,

SpicySativa

 

[VerdantGreen]

PM spores have a high water content so they can still infect a plant in low humidity.

avoid water stress (plants getting too dry)
avoid root binding - up-pot in a timely fashion.
avoid excess N as this causes soft sappy growth that will get infected more easily.

VG

 

[SpicySativa]

Good tips, VG. I think excess N may be a factor for me. I'm still trying to fine tune my soil s they don't fade too early. I often end up needing to supplement a little N (alfalfa tea or top dress, or fish hydrolysate) during the stretch and early bloom.

Next round they will have 10 gal of soil instead of 7, so hopefully that will see them through.

 

[Eighths-n-Aces]

say NO to clones!

 

[SpicySativa]

say NO to clones!

Thanks for the tip. Unfortunately, with the concentration of PM spores in this area seed plants seem just as vulnerable. Either way, I'll be doing a couple rounds of seeds next anyway.

 

[Microbeman]

Do not use any forms of soluble phosphorus (IMO; IME) zero, none, zilch, nada.

After infection noticed;
Experiment 1/ Make ACT using very minor amounts of soft rock phosphate + pyrophyllite clay powder; If possible use fresh vermicompost; If you have a microscope look for the development of <5 micron sized peanut shaped (one stage) and round (another stage) fast moving well organized organisms (bonus if you see them feeding on yeast cells or fungi); when you see, these spray (using pump up sprayer) on foliage; I've seen a 90% reduction overnight.

Experiment #2
Get some Trichoderma harzianum, strain T-22 spores. Place a heaping tablespoon into a 5 gallon pail of dechlorinated water at room temperature; Stir in a tablespoon or so of black strap molasses; Let sit at least overnight or up to 24 hours; If you have a microscope observe that the spores have germinated; Then spray on foliage. I have no experience with the efficacy, having had no PM to apply to since getting the T22 and developing this idea. Hypothetically the T22 should dissolve the PM as a food source.

Spicy: Have you found the potassium silicate effective as a preventative? (Protekt)

 

[SpicySativa]

Microbeman- Thanks for the reply. I have not been foliar spraying my AACTs, but I like the idea of fostering a defensive "community" on my leaves. I will definitely give that a try as well. Do you think I'd be shooting myself in the foot if I rotated the AACT sprays with neem oil? I have read that the oil residue helps prevent the PM fungi from germinating/infecting.

As far as the Pro-Tekt, I can't honestly tell if it's making a difference in PM severity. I do notice I get less branch sagging at the end of bloom, which is nice. I read a research paper which seemed to conclude potassium silicate (supplied to roots) was only effective against PM for about 24 hours after application, but this was a hydroponic study (meanings when potassium silicate was not actively being fed, it wasn't there at all (in soil, I'm sure there is residual). I'll see if I can dig up that study. Either way, I don't add Pro-Tekt with every watering. More like every other, or less. Now with my drip system that will be EVEN less, because I'll have to do it by hand.

 

[30years]

hi,
you ever try potassium bicarbonate? i use it and it works well. omri listed for vine crops in green houses. once a week as prevention. careful of silica sprays if you make bho out of your waste. silica strips out in the process and you end up smoking it.
best.
30y

 

[DARC MIND]

choose to grow resistant varieties, lots of shitty genetics when it comes to resistance
if you can, remove infected foliage
FWIW
in socal, certain powder mildew species seem to enjoy warm dry conditions
foliar spraying helps replenish phyllosphere, specially with fresh DIY botanicals

several alternating bacillus subtilis, neem and other oils, lactic acid bacteria culture & coffee ground fed worm casting ACT misting works here on all PM

spraying garam masala spice, turmeric and or ginger/garlic extracts diluted with water are also much more holistic alternatives

 

[SpicySativa]

Microbeman - What are your thoughts on Actinovate (Streptomyces lydicus WYEC 108)? Do you suppose this bacteria can survive before powdery mildew is present (would it colonize the leaf surface)? Might this be helpful in conjunction with compost tea sprays (possibly mixed in after the brew cycle, prior to spaying?

Another bio-based treatment would of course be Serenade, but I don't think it's actually alive; more of a microbial "byproduct", if I'm correct. Probably wouldn't actually colonize or provide any residual benefit if there weren't an existing PM infection.

 

[SpicySativa]

hi,
you ever try potassium bicarbonate? i use it and it works well. omri listed for vine crops in green houses. once a week as prevention. careful of silica sprays if you make bho out of your waste. silica strips out in the process and you end up smoking it.
best.
30y

What's up 30years? Welcome. I absolutely have tried potassium bicarbonate. Green Cure is my go-to PM treatment as soon as I've noticed the slightest bit of visible PM. It does work wonders on an existing PM infection, but it's also pretty harsh on the tender shoots and flowers. I'm hoping to find something a little more mild that my plants will enjoy more than Green Cure since they will likely get hit with it once a week until about week 3-4 of bloom.

Another option I'd like to bring to the table is Hosetail (equisetum) tea. This is a big one in the "biodynamic" scene, and one of the popular posters in the organic section of Rollitup now swears by the stuff. I bought some powdered horsetail to try it out but have not had the chance just yet.

 

[gekolite]

keep n levels to bare minimum

 

[SpicySativa]

choose to grow resistant varieties, lots of shitty genetics when it comes to resistance
if you can, remove infected foliage
FWIW
in socal, certain powder mildew species seem to enjoy warm dry conditions
foliar spraying helps replenish phyllosphere, specially with fresh DIY botanicals

several alternating bacillus subtilis, neem and other oils, lactic acid bacteria culture & coffee ground fed worm casting ACT misting works here on all PM

spraying garam masala spice, turmeric and or ginger/garlic extracts diluted with water are also much more holistic alternatives

Thanks for the suggestions, DARC MIND. Without getting into too much of a strain selection tangent (although this is relevant...), can you recommend one or two you've found to be resistant?

Great ideas, guys. Keep em coming!

 

[Microbeman]

Do you think I'd be shooting myself in the foot if I rotated the AACT sprays with neem oil? I have read that the oil residue helps prevent the PM fungi from germinating/infecting.

My only experience with neem oil was years upon years ago and it was negative. I believe there are vastly improved sources and techniques. I'd check with KIS in Redmond as I believe they have the current skinny.

Microbeman - What are your thoughts on Actinovate (Streptomyces lydicus WYEC 108)? Do you suppose this bacteria can survive before powdery mildew is present (would it colonize the leaf surface)? Might this be helpful in conjunction with compost tea sprays (possibly mixed in after the brew cycle, prior to spaying?

I have read some encouraging studies on Streptomyces for fungal pathogens. If I were to try it, I would put the spores in at the beginning of the brew to grow it out so it hits the leaf surface in an active form.

 

[vapor]

Milk more fat better. 9 parts water to 1 part milk. spray every 10-14 daze, i add some calcium{lithovit} and some plant soap{biowash}. I also add ASA once and awhile. Stop at week 4-6 depending on flower size/thickness. I do not see pm very much now.....

 

[lostenspace]

I have great success with Serenade in early veg as the plant is growing as prophylaxis. I live in the PNW and was getting outbreaks every grow from seed. Started the serenade in veg and haven't seen it since. Also, i use the vent filters at home depot, link below, for my passive intake openings. I know its not hepa but it probably restricts a little. Also eliminate flyers with neem seed meal in your soil mix. they can carry spores from plant to plant.

http://www.homedepot.com/p/Web-Plus...-4-Air-Filter-WPLUSFPR/100351661#.UhzpDxtwp8E

 

[SpicySativa]

Lostenspace- Thanks for sharing your experience with Serenade. I have tried it as a treatment (after minor PM is visible), and found it to be marginally effective for about 5 days. I'll definitely give it a try as a preventative, too.

I think my approach is going to involve spraying at about 5-7 day intervals, probably alternating between Serenade, Actinovate, and horsetail tea.

I'd still love to hear of any other experiences.

Thanks again, guys.