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nanaimo,B.C,Canada

Out of my 4 plants the 1173 Macari has a lot of powdery mildew on the leaves. Should I remove infected leaves or should i spray them with baking soda and horticultural oil?
This is the most I have seen this early on one specific plant. Could this be caused by too much fertilizer? I purchased a product called Floritect fungicide-insecticide- folpet,carbaryl and pirimicarbe. Would this eracticate the mildew?

Dave

Dave

8/9/2006 8:40:09 PM

Ctpumpkin@optonline.net

That Floritect is a strange product. The pirimicarb is a selective aphid killer. The Sevin would do us some good...but not for Powdery Mildew. Folpet is a contact-only protective fungicide so now that PM is started it won't help either. Save the Floritect for next year & use it before PM starts.

The Oil + baking soda will work fine. But make sure to coat the leaf bottoms & spray only in late afternoon when it is cool.

8/9/2006 9:58:45 PM

Wood River, IL (kennyw_49@yahoo.com)

Steve,

What is Horticultural oil,and where do you find it? How do you mix it?

Thanks

Kenny

8/10/2006 6:37:22 AM

Montoursville, PA

My two cents are close to Steve's comment. I use Neem Oil which controlls powdery just fine. I add the baking soda at the rate of two tablespoons per gallon....and spray under the leaves more carefully than on the top surfaces. Repeat...when using any oil base always spray late evening or early AM to avoid the hot sun. Once dried on the leaves the sun will not hurt the plant. Repeat....carefully follow the cotton picking instructions.

8/10/2006 10:40:34 AM

Northern Cambria, Pa.

Horticultural oil is highly refined mineral oil. Stylet oil and a newer product called Purespray Green are hort. oils. I believe they are both OMRI listed. Oil is much more effective for PM when mixed with baking soda. Use 2 tablespoons per gal. of each. You can get hort. oil from Fertrell and many other companies. I have used Stylet oil with baking soda and Immunox (Myclobutanil) all together for a real knock out punch. Again,
do not spray when hot and sunny.

8/10/2006 11:51:06 AM

Ontario, Canada.

I agree with Steve, Doc and Larry on this topic. I have used baking soda for the past couple of years with great success too. There are many documented studies to read....."Cornell University researcher Dr. R. Kenneth Horst observed suppression of PM and blackspot".............

http://attra.ncat.org/attra-pub/bakingsoda.html

Russ

8/10/2006 2:04:38 PM

Ontario, Canada.

"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,............ Other diseases against which baking soda may prove effective include anthracnose in cucurbits (6); rust, dollar spot, and pythium blight in turf; late blight in potato; rust in wheat; and diseases affecting peanuts, banana, and alfalfa.(7)"

8/10/2006 2:06:59 PM

Ontario, Canada.

I would like to make one observation on Doc's comment. last year I focused nearly 95% of my spraying to the top side of the leaf. It did not seam reduce the control of PM using Baking Soda. It was very effective.

Although I have not yet any signs of the disease in my patch, I have started a spraying program in the past few days. The Dog Days of August bring with them cooling night dews that PM thrives in.

One of the two components in dormant oil spray is HC oil. you maybe able to find this type of spray as a consumer product easier than a greenhouse type of product.

8/10/2006 2:15:05 PM

nanaimo,B.C,Canada

thanks to everyone for the valuable info. i will go with the oil and baking soda

dave

8/10/2006 7:33:00 PM

Ctpumpkin@optonline.net

Dave,

All great information here.

One item of caution. Be sure to specify that you want a "summer" oil. Many different companies purchase & repackage the same "Sunoco Sun Spray Superior 6E" oil. This is the good stuff but the companies that repackage it aren't going to tell you so.

Some others oils are not as highly refined & can be a problem in the summer. Generally speaking, if summer rates of 1-2% appear on the label then you have found the good stuff.

Do NOT use anything labeled only as "Dormant Oil".

Neem Oil & Stylet Oil are never in question but the same high temperature advisory applies to them.

8/10/2006 11:11:48 PM