Start Early, Stay Persistent on Apple Scab and Powdery Mildew Management

Apple growers know the headache that comes with managing scab or powdery mildew each season. Prevention is key to stay ahead of these diseases and now is the time to prepare your plan for next season.
 
Apple scab and powdery mildew overwinter in the orchard and become more severe based on in-season weather. Growers should not rely on previous pressure to predict the severity of the upcoming season. Growers must assume these diseases will be present and should manage them proactively to prevent primary and secondary infections.
 
These two diseases can affect apple growing areas differently depending on climate. Apple scab is a perennial problem in cool, wet, temperate production regions like the Northeast, Upper Midwest and west of the Cascade Mountains. Powdery mildew is most problematic in areas with mild, dry weather during spring and early summer like arid portions of the Pacific Northwest. Through cultural practices and chemical protection options, such as Excalia™ Fungicide, growers can manage these diseases effectively. Excalia is a tool that helps growers start clean by controlling early-season primary infections to minimize secondary spread of scab and powdery mildew.
 
Best Management Practices:
 
Apple Scab:

• Remove all fallen leaves and fruit in the fall to reduce infection potential next spring.
• Apply a preventive fungicide from green tip through petal fall, during the primary infection period.
• Continue to manage secondary spread with an appropriate fungicide program.

 
Powdery Mildew:

• In the fall, remove any primary sources of infection, including infected terminals by dormant pruning.
• Apply a preventive fungicide from green tip through petal fall.
• Inspect new growth in-season for early infections. The key is to control early infections beginning at the primary stage (bud break) through the period of active shoot growth.

 
Reducing Diseases
 
With careful scouting and removal of infested leaves and fruit, growers can help proactively manage scab and powdery mildew. Additionally, there are chemical solutions that can protect orchards from the start of the season. Excalia is a new succinate dehydrogenase inhibitor SDHI (Group 7) fungicide that offers fast, locally systemic movement into the plant tissue to quickly form a complete zone of protection on the leaves for powerful early-season disease protection.
 
Proactive Resistance Management
 
Being proactive with fungicide applications will help prevent resistance from developing. This is critical to ensure that tools continue to be effective against these hard to manage pathogens for future seasons. Fungicide Resistance Action Committee (FRAC) guidelines for managing SDHI resistance include:

• Use product preventively or early in outbreak.
• Limit the number of SDHI applications per season; use no more than 2 consecutive applications.
• SDHIs should be premixed or tank-mixed with other effective modes of action.
• Practice rotating SDHIs with other modes of action.

 
Excalia is most effective for early-season use for quick control, then rotate to other modes of action (FRAC numbers) after petal fall. To learn more about Excalia, visit Valent.com/Excalia or talk to your retailer.
 
Always read and follow label instructions.
 
* First published by the U.S. Apple Association as part of their Thought Leadership series. Republished on the permission of the U.S. Apple Association.