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 😉