Fungicide Management for Red Leaf Blotch in Almonds: Efficacy in Luna Sensation® and Adament® FLOW

Get answers on Red Leaf Blotch in California Almonds. See the latest fungicide efficacy research, management tips, and fungicide options. 
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What is Red Leaf Blotch? 

Red Leaf Blotch is a recently established foliar disease in California almonds, caused by Polystigma amygdalinum. Initial symptoms appear as small, pale yellow spots on leaves shortly after petal fall, progressing to orange-red blotches that can merge and lead to premature defoliation. Left untreated, this disease can cause significant canopy loss resulting in reduced photosynthesis, return bloom, and yield.

Promo Tools of What is Red Leaf Blotch? 

Quick Facts: Red Leaf Blotch in California Almonds

Key insights on disease spread, yield impact, and management strategies for California almond growers 

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Map of California highlighting specific counties, with some shaded red to indicate confirmed red leaf blotch infections in 2024 and others shaded yellow to indicate active monitoring. 

Where is Red Leaf Blotch in California?

Red Leaf Blotch was first confirmed in Merced County, California in May 2024 and was quickly detected in multiple California counties, including Yolo, Sutter, and Butte. By fall 2025, Red Leaf Blotch is now being monitored across all almond-growing regions in California. All commercial varieties are susceptible, and new detections are likely as scouting expands. 

Woman standing in a sunlit orchard, examining or reaching toward tree branches surrounded by dense green foliage. 

How to Manage Red Leaf Blotch in Almonds. The Preventative Management Recommendation.

Red Leaf Blotch requires a preventive management approach due to its delayed visible symptoms, which often appear 30–45 days after infection. The most effective strategy is a fungicide program beginning at petal fall, with follow-up applications 2–3 weeks later. Integrate orchard sanitation—removal or shredding of infected leaf litter and diligent equipment hygiene—to reduce inoculum pressure. Consider local coordination with neighboring orchards to help improve area-wide control.

Map of California highlighting specific counties, with some shaded red to indicate confirmed red leaf blotch infections in 2024 and others shaded yellow to indicate active monitoring. 

Where is Red Leaf Blotch in California?

Red Leaf Blotch was first confirmed in Merced County, California in May 2024 and was quickly detected in multiple California counties, including Yolo, Sutter, and Butte. By fall 2025, Red Leaf Blotch is now being monitored across all almond-growing regions in California. All commercial varieties are susceptible, and new detections are likely as scouting expands. 

Woman standing in a sunlit orchard, examining or reaching toward tree branches surrounded by dense green foliage. 

How to Manage Red Leaf Blotch in Almonds. The Preventative Management Recommendation.

Red Leaf Blotch requires a preventive management approach due to its delayed visible symptoms, which often appear 30–45 days after infection. The most effective strategy is a fungicide program beginning at petal fall, with follow-up applications 2–3 weeks later. Integrate orchard sanitation—removal or shredding of infected leaf litter and diligent equipment hygiene—to reduce inoculum pressure. Consider local coordination with neighboring orchards to help improve area-wide control.

Map of California highlighting specific counties, with some shaded red to indicate confirmed red leaf blotch infections in 2024 and others shaded yellow to indicate active monitoring. 

Where is Red Leaf Blotch in California?

Red Leaf Blotch was first confirmed in Merced County, California in May 2024 and was quickly detected in multiple California counties, including Yolo, Sutter, and Butte. By fall 2025, Red Leaf Blotch is now being monitored across all almond-growing regions in California. All commercial varieties are susceptible, and new detections are likely as scouting expands. 

Woman standing in a sunlit orchard, examining or reaching toward tree branches surrounded by dense green foliage. 

How to Manage Red Leaf Blotch in Almonds. The Preventative Management Recommendation.

Red Leaf Blotch requires a preventive management approach due to its delayed visible symptoms, which often appear 30–45 days after infection. The most effective strategy is a fungicide program beginning at petal fall, with follow-up applications 2–3 weeks later. Integrate orchard sanitation—removal or shredding of infected leaf litter and diligent equipment hygiene—to reduce inoculum pressure. Consider local coordination with neighboring orchards to help improve area-wide control.

Preventative Red Leaf Blotch Management | Bayer Fungicides 

For Red Leaf Blotch protection, apply Luna Sensation® once at petal fall and again 2 weeks later. For added protection, follow with Adament® FLOW Fungicide or Velum® One as a third spray. For resistance management, integrate multiple modes of action into your program. These recommendations reflect the latest data from the Troullis Lab at UC Davis and are supported by Bayer’s local technical experts. Always read and follow product labels and supplemental documents for instructions and restrictions on the use of these products.

Tractor driving between rows of trees in a sunlit orchard, with spray or dust visible behind it. 
Two people standing in an orchard examining something in their hands, with trees and farm equipment in the background.

How Bayer Products Performed in UC Davis Red Leaf Blotch Trials

FRAC #7-11 found in Luna Sensation and FRAC #3-11 found in Adament FLOW Fungicide both delivered top-tier Red Leaf Blotch control in 2025 UC Davis Trouillas Lab field trials, ranking among the most effective for disease reduction and canopy protection under California almond orchard conditions. Luna Sensation® achieves these results with just two preventative applications at petal fall and 2-3 weeks later, making it a great option for California almond orchards.

Recommended Resources  

Luna Sensation

Luna Sensation® has shown to deliver protection against Red Leaf Blotch and other key diseases in almonds. Learn how this proven fungicide can fit into your orchard program. 

Bayer Almond Protection Portfolio

Explore Bayer’s top-performing lineup of fungicides, insecticides, nematicides and more for almonds, including management options for Red Leaf Blotch, shot hole, scab, and more.

Adament FLOW Fungicide

Adament® FLOW Fungicide is based on two proven active ingredients that together provide broad, long-lasting disease control, a high-performance addition to Bayer's strong tree nut fungicide portfolio.

ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS.

Adament® FLOW Fungicide is only registered for use in California, Hawaii, Michigan, New York, Oregon and Washington. The distribution, sale, or use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. Check with your state department(s) of agriculture, local dealer or representative for the product registration status in your state. Not all products are registered for use in all states and may be subject to use restrictions. Adament® FLOW Fungicide, Bayer, Bayer Cross, Luna Sensation® and Velum® are registered trademarks of Bayer Group. For additional product information call toll-free 1-866-99-BAYER (1-866-992-2937) or visit our website at www.BayerCropScience.us. Bayer CropScience LLC, 800 North Lindbergh Boulevard, St. Louis, MO 63167. ©2026 Bayer Group. All rights reserved.

Disclaimer

Always read and follow pesticide label directions, insect resistance management requirements (where applicable), and grain marketing and all other stewardship practices.