Powdery Mildew - Can we talk sulfur?

[BuzzyB]

I live in a legal state...problem is, we've had a horrible summer for growing...mostly cold, wet and overcast. Guess you know that speeds up and encourages PM! Does or has anyone used a commercial grade vaporizer and sulfur prills? I currently have just 4 girls left to harvest, probably this weekend. I've used Serenade, H2O2 and water, potassium bicarbonate and dish soap, horticultural castile soap (Dr. Bronner's) baking soda...you name it, I've tried it! None has worked well. On to sulfur...can anyone tell me how often to use the system and how close to harvest is safe? I assume my window has closed for this year, but next year looms! This was my first outdoor grow, and I've learned a bunch! Decent setup all in all...frost free and lots of sun (when it comes out)! Able to push through to the harvest, but I cannot deal with this again. I would really appreciate comments from serious growers on this subject...I'm going to have to grow indoors this winter to make up for what I've lost to PM this year. Nothing drastic, but who wants PM in their smoke? Not I!! Thanks in advance for your help! Hope everyone had a great Crop-tober!!!!

 

[iwltfum]

A general rule for using sulfur is to not do it in bloom at all. I'm not sure how you would even do it with an outdoor grow. But as a last resort, and if you don't want to taste the sulfur, you could burn the sulfur as late as week 4 or 5 in bloom (for a 9 week flowering cycle). Sulfur dioxide is approved for use in organic agriculture even though it's not technically an organic pesticide so there is some controversy over it, but TECHNICALLY it's "safe" to use up to and after harvest.

 

[BuzzyB]

A general rule for using sulfur is to not do it in bloom at all. I'm not sure how you would even do it with an outdoor grow. But as a last resort, and if you don't want to taste the sulfur, you could burn the sulfur as late as week 4 or 5 in bloom (for a 9 week flowering cycle). Sulfur dioxide is approved for use in organic agriculture even though it's not technically an organic pesticide so there is some controversy over it, but TECHNICALLY it's "safe" to use up to and after harvest.

Pretty sure that window is now closed...but great info for next year! I plan on being proactive with the sulfur, using it from the beginning. My outdoor grow actually has a 'lid' on it to protect it from rain (our well water registers better than the rain) and from the wind that blows constantly in the country as well as late season frost. We are in the process of building something sturdier for the next season...we will be replacing the reinforced plastic 'roofing' and add poly roofing with venting on the peaked roof. Do you happen to know where can I find information on how much sulfur to use and how often? I know that once you see the white powder, it's already in the plant, being a systemic condition. I tried 'washing' the finished product with H2O2 and water but not much effect, plus that's a lot of added moisture to a moisture problem. I don't know where it started, other than possibly a lilac bush that is in the area and has that problem every year. The lilac bush has now been cut down! Circulation has not been an issue...the plants are constantly moving one way or the other. I also added a heavy duty farm/construction fan set on low and redirected away from the plants. The watering system is drip irrigation and has been flawless. Any thoughts on where it began? The only thing I could come up with was that lilac bush that is upwind from the garden. Like I said, we ALWAYS have a good breeze out here! Maybe the spores came from that? I really appreciate your input! Thanks for the help and reps to you!!

 

[iwltfum]

It was probably the cold, wet, and overcast conditions that you described in your first post that made it able for the PM to take hold. Maybe it's just a susceptible strain or maybe your plant was not happy about something in (or not in) the soil. Could be alot of different things. If the breeze is blowing all the time, but it's blowing humid air around from one place to another, then the breeze is not going to help with the PM problem. In fact, it probably made it worse by spreading all the spores around to the other plants/branches.