Powdery Mildew Regimen
Hello EGC friends. Several years ago I found myself uber frustrated with powdery mildew. It created white patches on the leaves of my precious squash, pumpkins, cucumbers, monarda, phlox, and tomatoes, then proceeded to kill these once beautiful, luscious plants. Several years of this drove me close to madness. So, I sat down and googled solutions that were tough on powdery mildew but gentle to the environment. There are many homemade powdery mildew sprays out there. After much research this is the regimen I chose for my own garden and use at the Hubbell garden with good results. I hope it works for you!
I alternate between two spray mixtures, a milk solution and a potassium bicarbonate solution depending on the weather conditions:
1. The MILK solution is best used PREVENTATIVELY, applied in SUNSHINE (morning best) and WEEKLY. How does it work? Still a mystery! Some say the milk protein is antiseptic in the sun, obliterating the fungi causing the powdery mildew; others think the milk may increase the plant’s immunity. This is gentle and my choice in HOT, SUNNY weather as WON’T CAUSE LEAF SCALD.
Recipe:
3 cups milk (no specific fat content; though some say lower fat has more protein solids)
7 cups water
½ tsp Castile Soap (mine has a peppermint scent to discourage bugs)
Mix in a spray bottle or gallon sprayer. Saturate top and bottom of leaves; don’t forget the underside! Shake the bottle occasionally as you go. Apply weekly.
2. The POTASSIUM BICARBONATE solution KILLS mildew and spores on contact. However, can cause LEAF SCALD if applied in HOT WEATHER or BLAZING SUN. I usually apply on cooler days toward evening or cooler, overcast days. I have never had a leaf scald issue following these weather guidelines. However, if you want to be cautious, apply to a small portion of plant and wait for 24 hours to make sure your plant tolerates the potassium bicarbonate solution.
Recipe:
1Tbsp potassium bicarbonate (1# bag from Maltose Express in Monroe about $7.00)
1Tbsp vegetable oil ½ tsp Castile soap (mine has a peppermint scent to discourage bugs)
1 gallon water Mix in gallon sprayer.
Again, saturate BOTH sides of leaves, shaking sprayer container occasionally during application. If weather permits, I tend to alternate the potassium bicarbonate solution with the milk solution on a weekly rotation. If weather to hot or blistering sun, I opt to use the milk recipe over potassium bicarbonate and rotate the potassium bicarbonate into the weekly spray schedule when weather permits.
Final thoughts…don’t forget to keep up with weekly sprayings; remember it’s POTASSIUM bicarbonate NOT sodium bicarbonate(baking soda); consider removing affected leaves on your plants if you miss a few sprayings or start late in the season and powdery mildew rears its ugly head. Good Luck and happy gardening!
- Carla Fairfield