By The Certis Team
A Q&A with Wilbur-Ellis’ Paolo Sanguankeo on Disease Management in Pome and Stone Fruits
To gain a deeper understanding of how OSO® fungicide from Certis Biologicals is being utilized in the field, we spoke with Paolo Sanguankeo, R&D specialist at Wilbur-Ellis.
Paolo shares his experience using OSO® to manage Botrytis, fruit rots, and Powdery Mildew in pome and stone fruits. He highlights its performance, benefits, and strategic use in pre-harvest applications based on his extensive trials and research.
Q: How has OSO® fungicide performed in managing Botrytis and fruit rots in pome and stone fruits?
Paolo: OSO® offers a unique mode of action for controlling plant pathogens in organic farming systems. It’s an organic counterpart of a conventional fungicide called Ph-D, which has been used extensively for many years. To have an organic fungicide that provides a level of disease control on par with conventional systems is both very unique and exciting.
I first tested OSO® in crop research trials before it was registered for use in tree fruit here in Washington State. My initial trials in the lab, followed by field trials on apples and cherries, showed that OSO® performed just as well as Ph-D in controlling diseases like Botrytis cinerea and various fruit rots. In terms of efficacy against other organic fungicides (except for sulfur), OSO® performed the best. Our growers have enjoyed better disease control both in the orchards and in the warehouse where the fruit is stored and processed.
Q: What has been the feedback from growers using OSO® for Powdery Mildew control in tree fruits?
Paolo: OSO® has been very well received by growers dealing with Powdery Mildew in pome and stone fruits. In my trials across Washington state, OSO® has consistently proven to be one of the best materials for managing Powdery Mildew and certain fruit rot diseases when used at the maximum labeled rate.
What sets OSO® apart is its flexibility. It can be tank-mixed with sulfur or other organic materials, or it can be used as a standalone material applied in rotation with other fungicides. This flexibility has made OSO® an essential part of many growers’ integrated pest management (IPM) strategies, particularly in organic production systems.
Q: How do you position OSO® within your organic crop protection program for pome and stone fruit growers?
Paolo: OSO® has quickly become the leading choice for managing Botrytis, fruit rots, and Powdery Mildew in organic tree fruit production. It provides disease control on par with conventional fungicides, which is a major advantage for organic growers.
At Wilbur-Ellis, we’ve positioned OSO® as a key component in our organic crop protection program, and it has been a great addition ever since. Our growers have seen improved disease control, and OSO®’s performance has set the stage for its continued use in our portfolio.
Q: How do you recommend OSO® as part of an integrated pest management (IPM) strategy, particularly with pre-harvest applications?
Paolo: While I usually leave crop recommendations to our crop consultants, if I were to suggest a good way to control Powdery Mildew and fruit rot diseases to organic growers, I would certainly recommend OSO® in their pest control program. There’s a maximum of six applications that can be made with OSO® per season at the full rate of 13 fl oz/acre*. This provides great flexibility to use OSO® either in a tank mix or in rotation with other fungicides during the tree fruit growing season, which can last between three to six months depending on the crop.
I would recommend that at least one application at the highest rate be saved for pre-harvest timing to control post-harvest fruit rot diseases. OSO® has been safe to use in a wide variety of tank mixes, which is a great way to provide an additional mode of action for controlling certain challenging diseases in tree fruit.
Q: How does OSO® compare to other fungicides in controlling Botrytis and Powdery Mildew based on your trials?
Paolo: When it comes to Powdery Mildew diseases in organic pome and stone fruit, there’s probably nothing that achieves as good efficacy as a high rate of sulfur application. However, we can safely use high rates of sulfur only early in the season. When the weather gets warmer, we either reduce the sulfur rate or switch to other organic materials altogether. This is where OSO® comes into play.
OSO® can be tank-mixed with sulfur or other organic materials or used as a standalone material in rotation with other fungicides. In my years of testing across Washington state, OSO® has consistently shown to be one of the best materials for Powdery Mildew and certain fruit rot diseases when used at the maximum labeled rate. Additionally, the efficacy of OSO® can be improved when tank-mixed with Systemic Acquired Resistance (SAR) materials like Romeo (Cerevisane). I’m unaware of any reports of resistance to OSO®’s active ingredient, so it should be a valuable tool for organic farmers for years to come.
*While OSO® fungicide can be effectively used at a rate of 13 fl oz/acre as highlighted by Paolo Sanguankeo, many growers achieve commercial control at a lower rate of 6.5 fl oz/acre when a surfactant is added. Application rates should be selected based on specific crop conditions and in consultation with a crop advisor. Always read and follow label instructions.
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To learn more about OSO® fungicide, visit Certis Biological/OSO.
