sulfur powder

[nunya]

on the package of sulfer powder it says not to use on curcubine plants. as i want to put out pumpkin plants next year is it safe to put it down now and then plant in spring. what effeect would it have on a pumpkin plant? sherm

[Pat Kiewicz]

Sulfur is not safe to use for mildew control on cucurbits (especially during summer when temperatures are high). If you are putting the sulfur on the soil in the fall (presumably to lower the pH) or on a current crop that needs treatment, well, that's an entirely different thing, and, unless you apply so much that you swing the soil pH into acidic territory, the pumpkins next year will be fine.

[nunya]

my pumpkins get what i assume is a fungus as the older leaves get a white covering like powdery mildew and then they brown out. the rest of the plant seems to continue growing but i assume it takes some strentght away from the plant. what is something i should use to control this? i was hoping to use the sulphur now so as to kill off the overwintering bacteria.

sherm

[Pat Kiewicz]

Two remedies that can be used to control powdery mildew quite safely are baking soda and milk.

"Some of the work at Cornell has focused on controlling fungal diseases on cucurbits.(4) A single spray application (to runoff) of 0.5% (wt./vol. of water) baking soda, plus 0.5% (vol./vol. of water) SunSpray UFP® horticultural oil almost completely inhibited PM on heavily infected pumpkin foliage. Baking soda without spray oil was ineffective, and a 2% (wt./vol. of water) solution of baking soda damaged the leaves. Baking soda/oil sprays also provided good control of urocladium leaf spot in cucumber, alternaria leaf blight in muskmelon, and gummy stem blight in muskmelon. ...

"On-farm observations on melon acreage in Virginia resulted in one farm operation switching from synthetic fungicides to a baking soda/oil spray. These growers incorporated a liquid fertilizer into the mix."

"For decades, organic gardeners had to rely on making a spray from baking soda to control the disease. Now, instead of measuring out the baking soda and combining it with a surfactant (a "sticking" substance) of either oil or soap, gardeners need only head for their refrigerators.

"In his experiments with zucchini plants, Bettiol found that a weekly spray of milk at a concentration of at least 10% (1 part milk to 9 parts water) significantly reduced the severity of powdery mildew infection on the plants by 90%. While some gardeners may be tempted to increase the concentration of milk for more control, Bettiol found that once concentrations rose above 30%, an innoccuous fungus began to grow on the plants."

[Steve]

It's a fungus, not a bacteria and don't bother trying to kill it off at this season. Even if you could eliminate it from your garden, it would just blow in on the breeze next summer when your squash (etc.) are growing again.

Steve

[nunya]