Preventing Powdery Mildew For Next Year

[PGB1]

Hi All!
We have two areas with acorn squash. They are about 60 feet apart. Unfortunately, both got powdery mildew (white dusty looking stuff on leaves) which killed all the leaves. I'm sure it was my fault, as the plants ended up being too close together (the leaves got huge and overlapped). They stayed wet after a rain for a long time. Both areas also have limited sunlight.

When the powder first showed up, I tried the milk spray treatment and later the baking soda spray. Neither saved the plants.

I read that the mildew will live over the winter, even though it often gets below zero degrees-F in Detroit. So, I searched on line and asked in gardening centers for advice how to kill this stuff before next year.

A gardening center person told me to salt the ground. This advice does not sound quite correct.

Doesn't salt prevent things from growing in the future? I use salt & vinegar mix on the weeds in pavement cracks and they stay gone for years. If I skip the salt & use just vinegar, they die, but come back in a month or two, so I am guessing the salt is a long term plant preventer. I remember from school that, in the way-back days, armies would pour salt on the fields to prevent crops from growing in the enemy turf.

Another gardening center person told me to spray chlorine bleach on the ground this fall. I can see how this will kill the spores, but I'd like to avoid releasing
ozone-wrecking chlorine into the atmosphere. And, I have no idea what it will do to the creatures living in the dirt (worms, bacteria, insects, etc.).

Jut to complicate things, some of the wide leaf weeds in the adjacent lawn have the powder, too. So the problem isn't contained in the garden.

Do any of you know an earth-pet-people friendly way to prep the soil this fall so the mildew spores die?

Thanks for sharing your expertise! I sure appreciate your advice.
Enjoy This Day!
Paul

 

[Chuck]

Hi All!
We have two areas with acorn squash. They are about 60 feet apart. Unfortunately, both got powdery mildew (white dusty looking stuff on leaves) which killed all the leaves. I'm sure it was my fault, as the plants ended up being too close together (the leaves got huge and overlapped). They stayed wet after a rain for a long time. Both areas also have limited sunlight.

When the powder first showed up, I tried the milk spray treatment and later the baking soda spray. Neither saved the plants.

I read that the mildew will live over the winter, even though it often gets below zero degrees-F in Detroit. So, I searched on line and asked in gardening centers for advice how to kill this stuff before next year.

A gardening center person told me to salt the ground. This advice does not sound quite correct.

Doesn't salt prevent things from growing in the future? I use salt & vinegar mix on the weeds in pavement cracks and they stay gone for years. If I skip the salt & use just vinegar, they die, but come back in a month or two, so I am guessing the salt is a long term plant preventer. I remember from school that, in the way-back days, armies would pour salt on the fields to prevent crops from growing in the enemy turf.

Another gardening center person told me to spray chlorine bleach on the ground this fall. I can see how this will kill the spores, but I'd like to avoid releasing
ozone-wrecking chlorine into the atmosphere. And, I have no idea what it will do to the creatures living in the dirt (worms, bacteria, insects, etc.).

Jut to complicate things, some of the wide leaf weeds in the adjacent lawn have the powder, too. So the problem isn't contained in the garden.

Do any of you know an earth-pet-people friendly way to prep the soil this fall so the mildew spores die?

Thanks for sharing your expertise! I sure appreciate your advice.
Enjoy This Day!
Paul

Powdery mildew is basically a weather related problem although the mildew spores do overwinter in the soil and are transmitted by wind and splashing rain. I have found prevention is the best cure. In my experience if you will start a spray regimine using Neem Oil you will find the mildew not much of a problem. Powdery mildew thrives in humid conditions so if you start spraying before it becomes hot and humid you can stop it from becoming a serious problem. I spray every couple of weeks throughout the growing season. Sometimes I still get the stuff but by trying to keep ahead of it, it does not affect my production. At the end of the season I burn all tomato, cucumber and squash plants and I heavily mulch all of the plants which are susceptible to mildews and blight.

 

[PGB1]

Thank You Chuck for your helpful reply and advice. I appreciate it.
That is a helpful reminder to get rid of the tomato, cucumber & squash plants rather than composting them with the others. I'll be sure they go out in the yard waste for collection. (We can't burn here.)

Thanks Again!
Paul

 

[skinyea]

if you spray the squash before PM shows, you very seldom get it.

 

[PGB1]

if you spray the squash before PM shows, you very seldom get it.
Thanks Skinyea for that tip. I'll be sure to do this next growing season!
Paul

 

[Lorri]

Powdery mildew is basically a weather related problem although the mildew spores do overwinter in the soil and are transmitted by wind and splashing rain. I have found prevention is the best cure. In my experience if you will start a spray regimine using Neem Oil you will find the mildew not much of a problem. Powdery mildew thrives in humid conditions so if you start spraying before it becomes hot and humid you can stop it from becoming a serious problem. I spray every couple of weeks throughout the growing season. Sometimes I still get the stuff but by trying to keep ahead of it, it does not affect my production. At the end of the season I burn all tomato, cucumber and squash plants and I heavily mulch all of the plants which are susceptible to mildews and blight.

New member here with a question. Why do you burn the tomato, cucumber and squash plants as opposed to composting? Thanks!

 

[Chuck]

New member here with a question. Why do you burn the tomato, cucumber and squash plants as opposed to composting? Thanks!

Because almost invariably these plants will have contracted a fungal disease of some sort, with tomatoes it's usually blight and with cucumber and squash it is usually either downy mildew, powdery mildew or brown spot fungus. All of the diseases are spread by spores and putting these plants into your compost will just give the spores a place to live until the compost is used. Better to burn the plants and make sure than to compost a seemingly healthy plant which unbeknown to you has a disease.

 

[AuntRose53]

You need to only use unpasteurized home grown milk otherwise it will contaminate plants more. Good luck dear.

 

[PGB1]

Thank You AuntRose53 for your mention of using unpasteurized, home grown milk. I never even thought about this & used regular grocery store milk. No wonder I had few good results.

I'm curious; what is is about the grocery store milk that contaminates the plants? Is it the hormones that are in the cattle feed (and probably the many pesticides used on the feed)?

Thanks Again!
Paul
PS: I apologize for my delayed reply. I thought I replied, but something must have gone wonky while posting, as things often do when I try to use a computer!

 

[DirtMechanic]

She referred to more fungus. With milk, the proteins are the effective agent, and are best used in the midday sun, where their stickiness can best form a defensive layer between the the plant and the spore and even around the spore. Fungi use chemicals (enzymes) that are quite specific and easily defeated - if you can seperate them from their target. This is why the various oils, silicones, clays and so forth are found useful. If the layer gan breathe, it is useful. Beeswax would work as well.

 

[PGB1]

Thanks DirtMechanic for the very good explanation you gave.

From reading it, we're not trying to kill the attackers, rather we're trying to form a barrier between the fungus and the leaf. (Did I understand this correctly?)

I never heard of beeswax for this purpose. It sounds like a more earth-friendly approach than a chemical spray, which I won't use. Wax might be tricky to apply, unless I can get it to be liquid.
I may try it next year- or perhaps neem oil if I can find one without pesticides added.

Thanks Again!
Paul

 

[Chuck]

Thanks DirtMechanic for the very good explanation you gave.

From reading it, we're not trying to kill the attackers, rather we're trying to form a barrier between the fungus and the leaf. (Did I understand this correctly?)

I never heard of beeswax for this purpose. It sounds like a more earth-friendly approach than a chemical spray, which I won't use. Wax might be tricky to apply, unless I can get it to be liquid.
I may try it next year- or perhaps neem oil if I can find one without pesticides added.

Thanks Again!
Paul

Neem oil is Neem oil and is derived from the Neem tree. There are no added pesticides or fungicides or miticides. These are natural products of the tree.

 

[PGB1]

Thanks Chuck for the explanation.
I saw one brand with several long chemical names in the EPA sheet attached to the bottle, so that's what cautioned me. (I guess I should have thought to look further.)
After reading your post, I looked on line and saw pure ones with no junk added. That will be my plan for spring!