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Ask Tom: New Organic Sprays

April 23, 2012

Dear Tom –

I have heard talk about new organic sprays for flea beetle and downy mildew. Can you tell me more about those products?

– Anxious in Asheville

 

 

Downy mildew damage

Dear Anxious –

Downy mildew is a problem on our farm most years in squash and cucumbers. It is not bad enough to kill the plant right away but it seems to slow down the production after about a month and eventually the plant looses enough leaves to stop producing.

I heard about a new product called Regalia.  Kelly Ivors, a plant pathologist at the NCSU Mountain Horticultural Crops Center in Mills River says that according to her tests Regalia works better on downy mildew than either copper or Serenade. Its active ingredient is an extract from giant knotweed.

According to the label, Regalia works by inducing the plant to increase its own defenses – up to five times the normal amount of internal phenol compounds, for example. It is a protectant and takes two days to reach full effectiveness. The company suggests a 10-14 day spray schedule. Since it is a protectant, Regalia needs to be on the plant prior to the arrival of the disease or any symptoms. I have seen it listed for $74 per gallon from web sources. It is OMRI listed.

I have not used this product but I intend to try it this year. One problem that we have with on-farm testing is that we usually do not keep a control for comparison purposes. The best I usually do is an assessment that “it seems to work” or “I didn’t notice any benefit.” Since NCSU has tested this product in the mountains and found it effective, I am even more confident that it will work on our farm. The product website indicates that it is also effective in tomatoes and peppers on late blight, early blight, target spot, powdery mildew, and botrytis.

Flea beetle

Flea beetle damage

Flea beetles are a persistent pest in our region and, until recently, without a good product for control as long as I can remember. Row cover and mulches have been used with varying success. At an Organic Growers School CRAFT meeting last year Meredith McKissick mentioned Molt-X as a product that is effective against flea beetles in her flower crops. At our latest CRAFT tour, a related product called AzaSol came up when Ben McCann described his interest in this product because it is stronger at 6% compared to 3% for Molt-X and because it is a dry formulation with a longer shelf life.

Also plant extracts, these products are broad spectrum insecticides which affect the pest’s ability to molt or change from one of their early life stages to the next. For that reason, it is likely to be less effective on adults but has the potential to reduce or eliminate the next generation and subsequent generations of the pest.

The active ingredient, azadirachtin, is also found in neem oil, which is made from a tree native to India.  It is reported by manufacturers to be a “anti-feedant, growth regulator, anti-ovipository, and insect repellent. It is toxic to soft bodied insect larvae.” The maker of Molt-X reports effective treatment of whitefly, mealybug, scale, thrips, aphid, psyllids, leafhoppers, flies, true bugs, sawflies, caterpillars, beetles, weevils, borers, mole crickets, and nematodes.

Molt-X is OMRI (Organic Materials Research Institute) listed and Azasol is pending OMRI approval. From the manufacturer AzaSol is $51 for 0.75 oz which makes 5 to 25 gallons of spray or $379 (6 oz.) to treat 1-3 acres. A pint of Molt-X at about $150 makes about 160 gallons of spray according to one source on the web (Quart for $194.) These prices are probably plus shipping, handling, and taxes.

The Molt-X brochure says that it is generally safe for beneficials but, as with all broad spectrum materials, I recommend cautious application.

Let me know if you try any of these products and how they work for you. Thanks

~Tom

More information from the makers of Molt-X and AzaSol:

Commercial farmers: got a question for Tom? Email us! 

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One Comment leave one →
  1. Mark Ogilvie permalink
    May 2, 2012 10:42 pm

    Tom,
    Margaret Tuttle McGrath at Cornell published a paper online* in 2004 in which she compared several fungicides, including several organics. I would love to see more recent field trial reports from her, since she did not have the opportunity back then to look at Regalia. I would love to try Regalia, but am hoping for more modestly-priced comparable organic fungicides.
    I am a former Serenade user and like her, I did not have good results. Microthiol Disperss,JMS Stylet-oil, and Bravo Ultrex came out on top in that year’s trials.

    * Protectant Fungicides for Managing Powdery Mildew in Cucurbits: How Do They Stack Up? http://vegetablemdonline.ppath.cornell.edu/NewsArticles/Cuc_Cntct_Fcides.htm

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