Powdery mildew is something I battle each year. At first, it looks like white, powdery spots on my squash, but gradually it turns leaves yellow, then dry and brown. Unfortunately, powdery mildew also drastically reduces the productivity of plants, so you'll have less food (or flowers) from them. Fortunately, there are easy organic ways to treat powdery mildew:

 * Choose plants that are resistant to powdery mildew.

* Water at the base of plants. Moisture on leaves encourages powdery mildew to appear. You can't control rain or humidity, but you can keep irrigation water off leaves.

* Consider preventative measures. If your plants get powdery mildew each year, consider treating them before you actually see signs of the disease.

* Treat at the first sign of powdery mildew. The quicker you respond, the more you'll be able to control powdery mildew.

A squash plant with powdery mildew. The leaf center front is badly affected. The leaves just above and to the side show classic beginning symptoms of powdery mildew. Courtesy Wikimedia Commons.

* Choose an organic form of control. I've blogged before about how ordinary milk does a great job of treating powdery mildew, but this year, I found vinegar works even better.

To use Vinegar to Treat Powdery Mildew:

1. Fill a clean spray bottle with 32 oz. of warm water.

2. Add 1 tablespoon of vinegar.* I've used both organic apple cider vinegar with the "mother" (like Braggs) and white distilled vinegar. I can't see a difference between them; both work equally well treating powder mildew on my plants.

3. Close the bottle and shake it.

4. Spray directly on plant leaves (both the tops and bottoms). Although I've never had any trouble with the vinegar mixture burning plants, some sensitive plants may react badly to the spray; therefore test first on one leaf, and check for damage the next day. After this initial test, spray affected plants every day for one week, then every other day from thereon.

Incidentally, vinegar is also the best aphid killer I've ever used.

* To mix a larger quantity, use 1 gallon of water with 2 - 3 tablespoons of vinegar.