It struck me…. again. Like a blind punch to the gut, I was taken a back as I noticed the dreaded white fuzzy layers of fungus spotted on some of my squash leaves.
“Gosh darn it!” I un-embarrassingly shouted out loud. Yup, it was powdery mildew.
To the beginning gardener these spots, few and mostly cosmetic, may go unnoticed, but all ye beware… if left to grow on its own will spread like wild fire, rampant and uncontrollable, until it’s too late. The entire plant will need to be pulled and your harvest will be lost.
Powdery mildew is the name for different species of fungi that can infect squash, cucumbers, melons, beans, and grapes. The downside to this disease is that once your plant is infected, it can’t be cured; however, it can be controlled and in my own experience, it needs to be as soon as you notice those dreadful white spots.
Although it can’t be cured, it can be prevented.
How to Prevent Powdery Mildew
The key to this dreadful disease is to prevent it, but no worries, every gardener will experience powdery mildew. We’ll get to controlling it right after this.
To prevent it, I like to mix a solution of baking soda and water, 1 tsp in 1 quart of water. I then spray this on my foliage of my zucchini and squash plants once per week. It needs to be done as soon as the leaves start growing. This solution raises the PH levels creating an inhospitable environment for the plants.
How to Control Powdery Mildew
Once infected, the key is to control it right away before it’s too late. Here is my 3 step process that I use to controlling powdery mildew.
Step 1. Cut off all infected leaves at the very bottom of the stem.
The powdery mildew will grow on the leaves and stems so it’s important to cut off each stem at the base of the plant. The stems of squash plants are hollow, making it a great environment to harbor bugs, so you don’t want to leave homes for an even bigger disaster. Always make sure to cut them down at the base – those squash bugs, let me tell ya, are not fun to deal with!
Also, make sure to look at both the top and bottom of each leaf. Some leaves may look fine on top, but once turned over will harbor a ton of powder mildew.
If you’re entire plant is covered in powdery mildew, well, you can’t cut off all of the leaves so use your best judgement. Cut off the leaves with the most powdery mildew.
Once your leaves are cut, dispose of the diseased plants. Do not put them into your compost pile since the fungus can live dormant over the winter and reinfect your plants the following year.
Step 2. Prune Your Plants to Encourage Air Flow
Take a good look at your plant and decide if it needs some pruning. If your plant is thick and condense, cut some of the stems off to encourage airflow which should help prevent the spread of powdery mildew.
Step 3: Spray Your Plants with a Milk and Dish Wash Solution Weekly
This is the key. Each week I spray my infected plants with a milk and organic dish soap solution.
I mix 1 part whole milk to 9 parts water plus 1 tbls of this dish soap. It works really well for me. I make sure to spray it over all of my infected foliage, both top and bottom, and then the rest of the leaves surrounding the plant. The milk doesn’t kill the mildew, instead, it slows the spread.
Just remember, spray the leaves weekly.
A combination of these 3 simple steps helps me control powdery mildew. Once infected, it’s so important to keep your eyes out on your plants and to continue maintaining it with the pruning and milk/dish soap solution throughout the entire growing year. Once it gets too out of control, just pull the plant and think about prevention next year 😉
Ugh, this happened last year to our squash plants and I didn’t have a clue what to do! I am so glad you shared this because I think I spotted it again on our zucchini—Diana you are a life saver. 🙂
Hope it helps, Margaret!
Can I use another kind of dish soap?
I don’t see why not, Sandra.
Thanks, Diana. When you say 1 part to 9 parts, what amount do you mean, especially since you specify 1tbp of dish soap?
Sorry, Sandra, 1 part milk to 9 parts water.
Diana, in your recipe, what is 1 part equal to? 1 cup? 1 tablespoon? Thank you for clarifying for me!
Elle, it depends how big your container is. So if you have a small bottle and decide to use 2 tbls of milk, then you’d need an additional 18 tbls of water. If you’re making a big batch and use 1/2 a cup of milk, then you’d need an additional 4 1/2 cups of water (or a 1/2 cup of water 9 times more). Does that make sense? 1 part milk, 9 parts water.
I am so sorry that I didn’t word my question clearly enough! So, do you use 1 tablespoon of dish soap with any amount of milk and water? That’s where I am confused! Thank you!
Oh, sorry, Elle. Yes, 1 tbls of dish soap but if you’re making a large batch, I would add a bit more. Not too much.
It has been my experience, that you need to have your soil tested. We found that our ph was off and that we were low on some essential nutrients. Fixing that helped a lot with most things.
That’s good to know, Aliyanna. I really need to have my soil tested. Thanks for sharing that with us!
I have the white powder mildew on 3 of my plants that are badly infected. You said the they need to be pulled out n consider your loss. Does this also mean that what is growing as the vegetable is bad that you can’t eat it? I have 2 whole plants is almost totally infected. I have pruned them down to the base n still have leaves left n some new coming in. My concern is mainly the plants that are mostly consumed in the powder is the vegetable ok to eat. It’s growing really good just the has the powder on the leaves.
The fruit will be just fine 😀
Oh thank goodness!
Powdery MIlder is several different fungus’s that iscan be spread by air, wind and motion. Where we live if we have a lot of moisture ts it spread like wild fire and basicall nos it down. You can try purchasing sees that are resistance to it and this helps some what. Proper spacing helps lot also. You can also try neem oil and pyola and they help in a limited way. Dont buy into the neem oil fixes everything mentality. It doesnt kill squash bugs or grasshoppers or many other bad bugs.
Thank you so much for this post. Not only did I not know about powdery mildew, but I didn’t know what to do about it. I have seen this on my zucchini plants before. Thanks so much for the information and the great pics. I sure appreciate it. Pinning this now!
Any suggestions….I live in Florida where the sky opens up and POURS almost everyday. I have fungus/mildew problems, but when it’s SO wet here, do you still spray everything when the rain will wash it away? Any other suggestions??
The wet and humidity can make it very difficult to control, Jennifer. Actually, watering falling on the leaves is actually a good thing as it tends to wipe away a lot of the mildew. But yes, after every rainfall, I would spray again.
Thanks so much for the advice. I found that mildew on my zucchini plants and had to rip them all out. I was so frustrated because now I don’t know if it is in the ground and will re-occur. I will spray the ground before I plant any more.
Hi Diana,
It’s good to know that you’re using milk as part of the mix in your ingredient. That is something new for me to know. For most I’ve read so far commonly uses dish wash soap and mix with this and that etc. I would like to share my own recipe which I use and it is quite famous here in the Tropics as I’m living in Asia.
What i do is, i use orange peelings or any other citrus fruit, pile it up together in a container (mine is 1.5L) mix with 1 cup of brown sugar and tblspn of liquid dish wash, then fill it up with warm water. Let it sit for a week or two and wait for the peelings to decompose. While in the process make sure to shake it a little perhaps once a day if you’re diligent. After a few days, if you’re a little too excited about it, you can try giving it smell as it gives a wonderful essence of the citrus and somewhat you may feel like wanting to drink it 🙂 trust me it smells nice. About those peelings, u can either buy it chew down those oranges or you could ask from a fruit store. I got mine on the weekly Sunday night market for free 🙂 It’s worth it to put away those shyness and ask for it. Heck they were going to throw it away anyways. With that much of peelings I’ve stocked up for a month of usage. They could last up to 2 months. I wouldn’t recommend any later than that.
After using this method i find that my butternut squash leaves are healthy green and shiny, yes shiny. So does the other plants as well, especially for my avocados and lemons. Oh and those cherry tomatoes and chillies, they look so clean as if they were in a market store. Goodbye aphids and ladybugs. So does those pesky black beetles. Anyways thanks for your time reading this.
Ps – i would love to try out those Homemade Natural Fermented Pickles recipe. thanks again 🙂
Thanks for sharing this, Roy!
Thanks for the milk tip. I found another remedy which has been quite successful for me this year=NO POWDERY MILDEW, YEA! It is a tsp of baking soda in quart of water sprayed on the leaves in the morning. Weekly too I think. I have just put about 1/4 t in a spray bottle of water
and it takes just a couple minutes. Whatever works, right?
Awesome, Kathy! Yes, next year, that’s what I’m doing for sure!!
Hi Diana, I saw it on my zucchini in the early part of the season. I keep colloidal silver in a spray bottle for many applications. It is anti bacterial, anti- viral and anti-FUNGAL !!! I sprayed all the mildew leaves and have had NO further problems with it the whole summer. I used it for many years and then discovered I could purchase a colloidal silver generator for home use. It is very easy to generate myself and far far more thrifty; about 36 cents a quart. Hope this helps because it is so simple.
Dianne
Dianne, I love this tip! I wouldn’t have thought to use collodial silver! Can you share with us exactly how you make it? Thanks so much!
Hi.
I have try with peroxide and it does kill the fungus. Still here in my country buy peroxide is quite expensive as it is only sold in little containers, but I know you can buy it by the galon in the US, you might want to experiment in with that. I use 50/50 on avocado trees, you might want to have a 1/4 to 3/4 for more tender leaves as squach.
I have also heard that using compost in the soil can kill the powdery mildew. but you need to put it on the soil real hot. and not use that spot in the garden for a year. You put manure on it and then cover with a clear plastic. The manure has good bacteria that will kill the bad bacteria. And the sun will heat it up and the heat helps sanitize the soil. the powdery mildew comes from a bad bacteria in the soil. I don’t have enough room to do this in my little garden but I can see how it would work.
Vicki, I’ve used compost and it does help prevent powdery mildew. Many experts say it helps boost the nutrient levels in soil so that microorganisms can keep the plant healthy (SOURCE: http://www.saferbrand.com/blog/treat-powdery-mildew-plants/)
I’ve used the milk method also. I’ve recently used just water that I ph to 8.0/low 8’s; this makes alkaline water and creates the higher ph that PM can’t grow in. I may try adding some dish soap or I’ve also read vegetable oil to help the solution “stick” better to the leaves.
I have a question, can we use the three step for watermelon plants?
Yes!
I sprayed my roses, pumpkins, strawberries and sunflower leaves which were covered in powdery mildew with 50/50 milk/water solution on a sunny morning, allowing it to dry in the sun all day. The powdery mildew was gone by that night and has not returned. That was a month ago. I have not sprayed it since, even though we have had rain twice since then.
I have read that milk is more effective in killing mildew once it is exposed to UV radiation. Have you seen any research or anything about that, and if it in fact works better in the sunlight than in the shade?
I haven’t, Lynda, but thank you for sharing what you did with milk. I’m going to try that next season!!
This was the first year I’ve ever grown squash – Delicata = 3 plants, Butternut = 2 plants. I have powdery mildew all over the Delicata, and none on the butternut and they are totally intermingled. I have harvested the Delicata already (we have had a very hot, dry summer) and I had around 45 squashes from 3 mildewed plants. I have lost one of the butternut plants – just died off, and the other, mildew-free, butternut has prduced only 2 fruits. Not sure what this means, but just thought I’d share. I didn’t treat the mildew because I just thought it was natural to the plant. For information also; my courgette plants have the mildew, and have produced so many fruits we gave up counting long ago. Is the mildew such a problem, as it hasn’t spread to anything else in the garden, and hasn’t affected harvest?
The mildew usually effects squash and cucumber plants. It doesn’t do harm to night shades, brassicas, lettuces, or root vegetables. It does spread quickly to what it does effect though!