By John Descary, Business Leader, MANA Crop Protection
When it comes to growing grapes, powdery mildew is one disease that can jeopardize a successful harvest. Reducing the potential for resistance to develop in your vineyard is imperative to ensure the effectiveness of your fungicide program.
Resistance occurs when a pathogen develops a genetic mutation that allows that pathogen to flourish despite being exposed to what should be a lethal dose of a fungicide. This typically occurs in one of two ways, the first of which is when a population is frequently treated and exposed to repeated applications of the same mode of action or FRAC (Fungicide Resistance Action Committee) Group. The second way is by using sub-lethal doses or below labeled rates of a product. Once resistance to a particular fungicide occurs, products or chemistries within the same FRAC Group ultimately suffer a similar outcome of non-effective control if applied within the same season.
The most effective strategy to combat resistance is to rotate chemistries. And, it is best to have a plan. The larger the vineyard or farm, the more detailed the plan needs to be. Clear communication with other members of the growing team about tasks and sprays that need to be made is necessary, as is understanding re-entry intervals and knowing when equipment and personnel are going to be available.
In addition to rotating chemistries, limit the number of individual mode of action applications per season and/or same mode of action sequential applications; avoid tank mixing or alternating fungicides within the same FRAC Group; and ensure that medium risk compounds such as Group 3 demethylation inhibitor (DMI) and Group 13 quinoline compounds are applied no more than three times per season and no more than twice in sequence.
When following these resistance management rules of the road, it’s also important to know which FRAC Groups hold the highest levels of risk. Group 11 fungicides, known as strobilurins, are viewed as high risk while other classes like DMI, quinolones, and benzophenones are considered a medium risk.
With increased levels of disease management now centered on resistance, growers are relying on products like Orius® 20 AQ fungicide as part of their defense strategy against powdery mildew. Orius 20AQ is a DMI FRAC Group 3 fungicide that is typically the foundation of a comprehensive disease management program that includes strobilurin and boscalid chemistries.
As a liquid formulation, Orius 20 AQ offers a unique and novel solvent system that delivers excellent efficacy and crop safety along with improved penetration of the cuticle when compared to dry formulations. With fast-acting absorption through the leaves and fruit blossoms, Orius 20 AQ delivers both curative and preventative disease protection. And, it features the less restrictive “Caution” signal word which is another advantage versus fungicides with “Warning” signal words.
A proven performer that helps grape growers avoid the pitfalls of resistance, Orius 20 AQ is a perfect fit for any season-long disease management protocol.
This season, be sure to include Orius 20 AQ as a critical component in your powdery mildew control program. It will help keep resistance at bay while expanding your options for continued use of other highly effective fungicide tools.
To learn more about Orius 20 AQ, go to the MANA Crop Protection website at www.manainc.com or call 866-406-6262.
MANA Crop Protection, 3120 Highwoods Blvd. #100, Raleigh, NC 27604. Always read and follow label instructions. Orius® is a registered trademark of a Makhteshim Agan Group Company.