Disease Alert: Watch for Sycamore Anthracnose and Apple Scab!

Sycamore Anthracnose Apple Scab

Now that spring is beginning, tree diseases are starting to crop up across the country. For many of these cases, now is the time to consider treatment, especially if you’re an arborist in charge of recommending solutions to homeowners.

Two issues that are sure to be prevalent this year are Sycamore Anthracnose and Apple Scab. Here’s what you should know.


Sycamore Anthracnose

Sycamore Anthracnose is a fungus that winters on twig tissue and causes leaf spots. Considerable defoliation, sometimes with complete leaf loss, occurs on many trees by late spring in cool, wet years. Symptoms include tan to red-brown lesions extending along the veins and edges of the leaf.


Apple Scab

Apple Scab is a fungal disease that affects leaves, fruits, and twigs. Outbreaks are most severe following particularly wet and cool spring conditions. Symptoms include brownish-green spots on young leaves or fruit that become darker as the infection progresses.



For both diseases, we recommend preventative treatment with a trunk injection and a systemic fungicide, such as PHOSPHO-jet or Propizol.

For Sycamore Anthracnose, PHOSPHO-jet may be applied in the fall following leaf coloration or early spring prior to twig infection. Propizol applied in the fall will slow the spread of infection the following spring and help the tree to grow leaves more normally.

For Apple Scab, the best results will be achieved when PHOSPHO-jet or Propizol are applied prior to infection. Applying PHOSPHO-jet or Propizol in the fall will minimize or prevent infection the following spring. If applying in the spring, it should be applied as early in the spring as possible, before or at bud break. If treating an established infection, Propizol is recommended as a first treatment, with subsequent treatments of PHOSPHO-jet as necessary. Arborists should assess tree health prior to treatment.

PHOSPHO-jet inhibits fungal cells while eliciting a plant health response from the tree. It promotes stronger, tree cells, root development, and triggers the tree’s natural defense mechanisms, making it more resistant to infection with quicker recovery time.

Propizol will have more direct and aggressive activity against the fungus itself and is recommended if infection is chronic or particularly severe.

Arborists, if you have further questions, please contact an Arborjet technical manager in your area today. Now is the time to consider treatment and to let your customers know that you have the solution!