Algal Stem Blotch in Blueberries: Control Cane Infection Early
Algal stem blotch is becoming an increasingly common and damaging disease in blueberry production, especially in warm, humid regions like the Southeast. Caused by Cephaleuros virescens, this algal pathogen appears as reddish-orange lesions on blueberry canes and branches.
Unlike many common blueberry diseases, algal stem blotch is not caused by a typical fungal pathogen. That makes it more difficult to manage with standard fungicide programs, which are often designed to target fungal diseases rather than algal pathogens.
As infections develop, lesions can weaken canes, reduce plant vigor, and limit the plant’s ability to support healthy growth and consistent fruit production. Warm temperatures, high humidity, frequent rainfall, and dense canopy conditions can create an ideal environment for the disease to spread.
Because algal stem blotch can become difficult to manage after symptoms are established, early protection is critical. For stronger control, growers need a solution that can do more than remain on the plant surface. A systemic copper such as Magna-Bon CS 2005 helps protect canes externally while also moving within plant tissue to help suppress infection where it develops.
A Better Approach to Algal Stem Blotch Control
Magna-Bon CS 2005 delivers protection beyond conventional surface-only copper products by providing both contact and systemic activity.
On the plant surface, CS 2005 forms a protective copper barrier on canes and foliage to help prevent new infections from developing. Inside the plant, CS 2005 penetrates through stomata openings and moves within plant tissue to help suppress infection where it begins.
This dual-action protection is especially important in high-pressure environments where warm temperatures, frequent rainfall, high humidity, and dense canopy conditions can increase disease pressure. When infections are already developing within plant tissue, surface-only programs may fall short.
By protecting the plant both inside and out, Magna-Bon CS 2005 helps interrupt disease development early, reduce cane damage, preserve plant vigor, and support long-term blueberry production.
Application Timing for Effective Control
Effective algal stem blotch control starts with a preventative approach. Applications should be timed around key disease-risk windows, including post-harvest, active growth periods, and stretches of high humidity.
Post-Harvest Protection
Apply after harvest to protect exposed plant tissue and reduce the risk of new infections.
Active Growth Periods
Target new growth when blueberry plants are actively developing and more vulnerable to disease pressure.
High Humidity Conditions
Increase protection during periods of elevated humidity, frequent rainfall, and dense canopy conditions.
Applications may be repeated every 7 to 28 days depending on disease pressure, weather conditions, and label recommendations.
Take Control of Algal Stem Blotch Before It Impacts Yield
Waiting until symptoms are severe can put your crop at risk.
Magna-Bon CS 2005 delivers OMRI-listed, systemic and contact protection to help blueberry growers manage algal stem blotch before it weakens canes and reduces long-term yield potential.
👉 Protect your blueberries early with a preventative CS 2005 program.