Grabs Fungi Right by the Chitin but Plays Well with Others

By The Certis Team

OSO® fungicide may not be what you think biological fungicides are all about.
It acts directly on disease; it acts fast and it can stand shoulder to shoulder with
(and sometimes above) conventional fungicides.

Direct and Fast
 The active ingredient in OSO, Polyoxin D zinc salt, works on contact to break down and stop the formation of chitin-based cell walls in fungal cells. It also inhibits hyphal growth, blocking nutrient absorption, and prevents spore germination to help stop future infections. These modes of action contrast with many biological fungicides that rely on slower, indirect methods to control disease: competitive exclusion for space and nutrients, triggering a plant’s induced reaction or producing secondary metabolites for antifungal action against the pathogen.

The direct, fast acting attack of OSO against pathogens is a critical benefit in preventing disease when a sudden change in environmental conditions sparks an outbreak, with no time for in-direct acting biological fungicides to become active.

Key in a Season-long Program
 Polyoxin D is the only active ingredient in FRAC Group 19. For growers running a resistance management program. OSO gives them a completely unique active ingredient that is easy to incorporate into their spray schedule with a broad label for use in many crops including berries, tree fruit, and vegetables. It has no cross resistance issues with other widely used fungicide groups: DMI’s (FRAC 3), Qol’s (FRAC 11) and SDHI’s (FRAC 7), all of which face high resistance potential.

OSO is effective enough to be a stand-alone component, needing no tank-mix partner, to be an integral component in a season long spray program while giving growers added flexibility in managing fungicide resistance.

Protects A Season’s Work and Investment:
A late season disease outbreak can destroy a season’s hard work if not controlled. Treatment with conventional fungicides is often not possible because of long PHI’s.
OSO carries a 0-day PHI so it’s control of Botrytis, Alternaria, Powdery Mildew and other diseases can be used until day of harvest. It is labeled for prevention of post-harvest diseases in pome fruits and stone fruits. Dr. Adaskaveg, UC Riverside, conducted numerous trials showing the effectiveness of a preharvest application of OSO in controlling Alternaria and Botrytis on apples being placed in storage.

The value of OSO fungicide doesn’t stop in-season. It’s effective, fast-acting disease prevention can protect a grower’s investment and hard work up to harvest and beyond. 

Application Tip
Because OSO attacks the pathogen cell walls directly it is crucial to have complete, uniform coverage on leaf and fruit surfaces for control.
Always use a high-quality, non-ionic surfactant in the tank to maximize the efficacy
of OSO fungicide.

“Grape growers who are waiting for Brix levels to hit their end-of-season target should have OSO ready to go for late season disease outbreaks. At that time of the season, conventional fungicides with long PHI’s might not be an option, but OSO with a 0-day PHI and quick MOA can help maintain grape quality until harvest.”

- Jeremy Wagnitz, Certis Western Region Senior Field Development Manager 

Interested in learning more?

Additional Product Resources:
For additional information on OSO® 5% SC, including technical specifications and labeled use directions, please refer to the resources below. 

• OSO® 5% SC: Tech Sheet | Product Label
  
  

Always read and follow label directions. For a full list of protected crops and controlled diseases, visit the product pages and refer to the product labels.