Preventing and treating powdery mildew

White spots-powdery mildew on squash leaves

Sunday, September 3, 2017

You can tell it is late summer by the emergence of powdery mildew and other fungal diseases on your veggies and some flowers like roses and peonies.  There are things you can do to treat or minimize powdery mildew.

Powdery mildew loves squash!  It shows up during hot and high humidity conditions.  It can also be encouraged by overhead watering.  The best watering method is some type of slow drip at the roots of your veggies.  This gets the most actually in the ground to the plant and minimizes evaporation (reducing your water bill).  Summer garden tips

Also important is good space between plants that are susceptible to fungal diseases.  This allows good air flow which reduces conducive fungal conditions.

Overhead watering, besides encouraging mildew and other fungal diseases, can also remove the insects that pollinate the veggie flowers and even the pollen itself, leading to low harvests.

Powdery mildew can be treated by spraying the top and underneath of all leaves with a baking soda solution, copper or fresh whey.  An easy to make, low cost spray is as follows:  2 tbl of baking soda, 1/2 teas of gentle dish soap, 1 gallon of water.  Wet top and bottom of leaves thoroughly.  Reapply after a rain.

You can also purchase organic mildew sprays, like Safer.  For info on organic pest control, Natural, organic pest strategies and how to make your own bug sprays

Be careful in using sprays; they may be too harsh for some vegetable plants and some areas of the country where it gets scorching hot.  Test them on a small area of your plant, wait for a sunny, hot day to pass before spraying the whole plant.  Copper based sprays work great on my peonies, but not so well on my squash.

Many recommend if you cannot get rid of the mildew with a spray, you should remove any diseased leaves and throw away so it doesn't spread to other plants.  Do not compost because if you do not get internal temps in your compost at 140 or greater, it will not kill the spores and you will be spreading the fungus wherever you spread the compost.

A boost of potassium is good this time of year for your veggies.  Nitrogen supports the greenery of your plants while potassium supports the blooms.  Keeping your plants well fed helps them stay healthy and producing well into fall.  I fertilize monthly.  You can even make your own fertilizer inexpensively.  Make your own fertilizer, it's all natural and inexpensive

I have begun to start a second batch of zucchini and tomatoes around the 4th of July and replant into the garden in late July.  As the early planted succumb to fungal diseases or just plain get tired, the new plants come on to take up the slack.  Summer squash come on quick.  This won't work for winter squash as they require a much longer growing time to produce their fruits.