Powdery Mildew

[OaklandCityFarmer]

I am absolutely at my wits end with the powdery mildew this year! (I tested and was positively identified as Sphaerotheca pannosa and is not downey mildew).

I have tried a sodium bicarbonate and water mixture, diluted whole milk, sulfur, copper, and neem with little to no effect. I've pulled infected plants, and have replanted. I know we're having an extremely humid and warm summer this year.

Any other suggestions folks may have?

Thanks
Carlos

 

[stepstephens2]

I had a problem with it on some of my squash plants. I used the neem. What I noticed was that it didn't stop it from killing the leaves that it was already on, but it did stop its spread to other leaves. I think all of these things work more like a control than something that actually cures the plants. It wasn't until the second application that I felt like it may be helping. I had to pull out some of the plants, too. I've got a couple of plants that I've been misting down because of aphids near the squash... I think that is what caused the spread. Since then I've been very careful to not get any water on the leaves. I feel your frustration, though. At one point I had spider mites (that thrive in dry conditions) killing plants at one end of my garden and the powdery mildew (that thrives in damp conditions) killing plants at the other end.

 

[calypso985]

I feel your pain. Four years ago (the last time I had a garden), all of my squashes & cukes became infected with powdery mildew. I had no idea what to do about it, and just watched helplessly as it destroyed my plants, along with any hope of a harvest. I did know that even though my plants were long gone that the p.m. was still present in the soil, lurking there, waiting to latch onto anything else I planted there.

Fast forward to this spring. My neighbor has 4 splendid deep raised garden boxes. Since she had no plans to plant them this year, she most generously offered for my use. I was thrilled! I planted 3 kinds of summer squash and 2 kinds of cucumbers in one of the boxes. For many weeks, they flourished, and I was riding the crest of a bumper crop of zukes & cukes. That is, until I noticed a few pale dusty spots on some of the leaves. I didn't need anyone to tell me what it was. Crapola. It was back. Not just in MY yard, but hers too, after 4 years of basically laying fallow. This stuff spreads like CRAZY. Within a week, all of the plants in that box were infected. I tried the milk and baking soda to no avail. So I began cutting back the plants. HARD. The box looks like it has gone bald. I cut off every leaf and stem that even LOOKED like it might have mildew on it. MAYBE the milk/soda spray helped because the NEW growth -- which I retained -- is all clean. Now, the question is, will it STAY clean? Is there enough of the season left for the plants to recover and perhaps produce again? Or is it just a pipe dream? I can't afford some of the fancier "treatments". Should I hit what is left of the vines with milk/soda again? Has ANYONE out there ever had luck at controlling this stuff??

Help!

 

[VeggieNessa]

I'm new here, so I'm not totally sure of what's OK and what's not here. I need help regarding Powdery Mildew and I thought I would just join in with you all and see what happens.

I'm a container gardener and for the first time this year decided to try growing spaghetti squash. Everything was going great, lots of blossoms and even one squash! Then I started to notice the leaves yellowing and white "dust" on them. The vines were growing willy-nilly over some stakes and a hand truck and over the railings. I did some research and I think what I have is Powdery Mildew too. Today I decided to try the milk-dish liquid-water solution and trimming off all the infected and dead leaves. It took me about 2 hours to prune them and spray the solution. It's trying to spread to my Tomato plants and I just can't have that! : So my plan is to use the milk solution for a few days (3) and then move on to the Baking Soda solution and finally the Neem (I have the oil and the leaves and plan to make a tea of the leaves and add some oil and an emulsifier to hold it together) in order to give the squash a chance to pollinate. So, I will post back with the results and updates. I hope that helps and I hope I'm not offending or violating by not starting my own thread. BTW, I this forum! Peace

 

[April Manier]

I highly recommend either burning your soil this year with a torch or solarizing.

You will get it year after year because the stuff is crazy strong! Take steps at the end of your season by either throwing potted soil away or the aforementioned.

Whatever you do DO NOT OVERHEAD WATER! Stop watering immediately and try and force the fruits~!

 

[hoodat]

Unfortunately powdery mildew isn't restricted to hiding in the soil like some viruses. It blows around in the air so it is always with us. When conditions are right you will get a breakout. Toward the end of the gardening season I accept it as a part of the natural order in squash vines but it's a shame when it comes early in the year before the crop sets. I've tried all the remedies I can find and none of them really does the job. All I can do is try to have the leaves dry before sundown and prune off the earliest signs of it to slow the spread.

 

[VeggieNessa]

Just thought I would report back.

So far, I've sprayed the plants heavily with the milk solution, even the ones that did not seem to have any mildew. Everything "looks" better, but I think the squash vines are kaput. I will probably spray with the baking soda solution later this week and continue to watch all of the plants. Thanks for all of the advice.

Solarizing or "torching" the soil was mentioned. Do I solarize over the winter or just before I'm ready to plant out in the Spring? Is this the same as baking soil in a oven? I've also heard of pouring boiling water over the soil too to kill mildew and other problems. I do water from the top. Most of my containers are laundry baskets and have worked well. Actually, all summer until a couple of weeks ago, this was the BEST garden I've ever had. So many enemies in the garden.

Again, thanks for all of your support and advice. Back to the drawing board.

 

[April Manier]

Solarize when it's hot enough to cook things. you will need to spay or water your soil with a yeast solution when you are done. Try using drip hoses next year. You are sterilizing the soil.

You should cover with CLEAR plastic to solarize.