powdery mildew

[Michelle Silva]

Anyone ever have an issue with white powdery mildew on their plants?? I am noticing it on some of the lettuce, mostly the red variety. I'm planning to spray with milk/water (1:4 ratio) as I read that is supposed to help, but I want to learn what causes it.

[Michelle Silva]

This is interesting..I had problems as soon as I had put hoops with plastic up over my verticals and raft tanks. I was getting tired of all the covering and uncovering I was doing to protect from the mutiple times we got freezing temps at night here and by the third time it got cold I decided to put them up thinking I would eventually just leave some kind of protection up on the top.

After covering I had issues I never had. Most all the pac choy got aphids, after treating with Dr. Bronners it went away, but then it bolted. I think because I had waited until almost 9:30 or 10am then next day to remove and it just got too hot. I haven't bothered to put it back on just the top yet because I originally wanted to figure an easy inexpensive way to be able to lift the sides to secure and have yet to put in lengthwise braces (I think they're called perlins). It's warmed up and.we're not getting rain now so don't have to worry about it just yet..The other reason I hesitated to secure the plastic on the top is  because I was concerned that soon it will be too much sun and would need to be changed to shadecloth on the top!

[TCLynx]

Yea, shade cloth soon.  I've had far fewer pest problems since I took my "greenhouse" down.  Granted, I can't really protect very much from the cold anymore but the cold season is actually my fav growing season here in Florida because broccoli, kale, collards, kohlrabi, cabbage and some others actually like it quite cool and the best year for me with broccoli it was actually waking up with ice on it.

 

Here in FL we will experience problems with powdery mildew on squash and pumpkin even out from under cover just because it tends to be so humid here.  At first I kept spraying to combat it but now I normally just kinda ignore it since I've usually still gotten plenty of fruit from the plants.  I think most seaweed extracts would work as a potassium supplement spray to help combat powdery mildew though.  A spray of potassium bicarbonate might also work.

[Chris Smith]

Raychel, the kelp extract I have been using is Maxicrop. It is available at the local hydro store. I purchased the UV stabilized plastic from store called Greenhouse Specialists here on the Big Island. There is probably a greenhouse supply store on Oahu where you can get it.

Raychel A Watkins said:

Hey Chris

Where did you get your kelp extract and in what form is it.  Another thing where did you get the uv resistant plastic for your roof.  I have the same problem with the rain.

[Chris Smith]

Kobus, what are the bottles at the top of the frame?  Nice looking cuke.

Kobus Jooste said:

My system also still have the roof up for rain capture, and two of the four sides - I took two sides of the plastic off (the gables have always been shade netting) and the mildew went away.  I had pumpkin and tomato in the very same bed as the pic taken below, and they were constantly full of mildew.  Sides came off, and look now!

[Chris Smith]

I have been playing with feeding my fish bananas and feeding my worms the peels. I cut up the bananas into bits size chunks and let them dry out a little in the sun so they are a little lighter and won't sink as fast. I feed the chunks to the fish first feeding of the day when they are very hungry and will hit anything that goes into the water. The peels take up to a week for the worms to break down. These methods are slow at releasing potassium to the plants. Spraying Maxicrop has an effect within hours. Foliar spraying allows immediate intake of nutrients through the leaves for the plants use. The change of leaf surface pH seems to be helping too. Next time I mix a batch I plan to check the pH out of curiosity.

[Ryan Chatterson]

What kind of concentration are you mixing up Chris?

[AJ Grottke]

Chris, what time of the day are you spraying your plants, and are you adding any wetting agents or a surfactants to help lower the surface tension of the water? Such as this OMRI listed one or wetbetty.

[Kobus Jooste]

Chris: The smaller one was a mix of corn starch extract used for mildew, but now it is just clean water.  The large pump bottle is used to combat ants with a mix of garlic and canola oil.  Also wipes out soft-bodied pests but they are not plentiful now.  The drought is bringing heaps of ants in though. 

[Christian James]

I would be careful w Neem Oil - it is supposedly very bad for fish and will coat their gills.  Last summer I was watching a neighbor's dog who's owner used lots of neem oil to get rid of fleas.  While at our house he started drinking out of our little 40 gallon pond - sure enough I ended up loosing almost all of the fish within a week.  It's nothing scientific, and I'm sure it could've been a million other possibilities - but I also won't be using neem oil anywhere near my fish in the future.

 
Sylvia Bernstein said:

Chris, I've had good luck with neem oil spray and a fan to increase air movement.

[Christian James]

For the Powdery Mildew I'm trying two techniques to see which one works best on my papayas, beans, and Japanese eggplants that are all suffering. 

First is compost tea w some Maxicrop added in, nothing conclusive with the results so far.  I've sprayed it twice, once being only last night. 

And second is a mixture of 1 part Skim Milk, and 9 parts Water - which worked great, didn't wipe it all out, but quite noticeable results.  I want to run the coarse w the Compost Tea for awhile and see if that alone will take care of it, or if I also have to use the Milk spray.

[Chris Smith]

I mix according to the instructions on the bottle.  For some time I have been spraying Dipel every 7-10 days. I use a 2 gallon spray bottle that I got new for the purpose. I try to spray in the morning as the dew is drying up because I find that I can take advantage of the moisture on the leaf to help spread the spray. I have never tried any surfactants for surface tension. I never spray in heat or direct sunlight.

[RupertofOZ]

Use full milk... not skim milk..... the difference is substantial...

Christian James said:

For the Powdery Mildew I'm trying two techniques to see which one works best on my papayas, beans, and Japanese eggplants that are all suffering. 

First is compost tea w some Maxicrop added in, nothing conclusive with the results so far.  I've sprayed it twice, once being only last night. 

And second is a mixture of 1 part Skim Milk, and 9 parts Water - which worked great, didn't wipe it all out, but quite noticeable results.  I want to run the coarse w the Compost Tea for awhile and see if that alone will take care of it, or if I also have to use the Milk spray.