Every growing season comes with its own unique challenges for apple growers and 2023 is no different. With new regulations around standard apple scab chemistries, managing this perennial disease can seem daunting. But with some preparation, it’s not impossible.
Careful planning will set you up for success so you can sell your beautiful fruit at full price or improve storage life, resulting in a higher packout.
Management practices to consider for apple scab in 2023
Apple scab activity can occur from the emergence of green tip until leaf drop in the fall, with the primary infection period in the early spring when spores are present and temperatures and moisture are ideal for infection.
The best method to protect the crop is to take a preventative approach.
One way to reduce inoculum is to shred old, infected leaves under trees. This will encourage quicker decay, reducing the risk of infection to new leaves in the spring.
Use a degree-day model to determine the risk of infection. This model helps to predict the percentage of ascospores that have matured so you know when it’s time to employ crop protection technology.
Consider the variety susceptibility to apple scab. Some varieties are more likely to be infected by apple scab than others.
Best practices for fungicide application
Preventative fungicide applications are preferred to protect foliage and fruit from apple scab. It’s important to understand the type of product you are applying. Does it move into the leaf and protect from the inside, or stay on the outside of the plant and stop spores as they encounter the product? Knowing how the product works helps to determine how it should be used.
If an unexpected infection occurs, certain fungicides may be applied within 48 to 72 hours after the occurrence, before symptoms are visible. Doing so allows for a lighter summer cover spray schedule.
As symptoms become visible 9 to 21 days after infection, leaves and fruit should be monitored from green tip to harvest to understand control success.
When employing crop protection technology, it’s imperative to rotate chemicals to avoid resistance. There are a few strategies available to you such as layering different groups of products, or tank mixing various groups of chemistries together.
Get the help you need to be successful
Planning for successful apple scab control this season may seem like a daunting task, but it doesn’t need to be. To make sure you have the best plan in place for your crop, talk to your local retailer or agronomist.