Daconil for Cypress Trees With Cankers

Daconil

• Daconil is the trade name for the fungicide chlorothalonil. The broad-spectrum organochlorine fungicide is also sold under various other trade names. The product is used to control a number of fungi that are likely to infect small fruit trees, vegetables, turf and ornamental plants. The fungicide is ineffective for the control of cankers on cypress trees, according to the Alabama Cooperative Extension.

Disease Identification

• Cypress trees are prone to the seridium canker caused by Seridium cardinale and botryosphaeria canker or bot caused by Botryosphaeria dothidea. Both fungi also have other host plants besides cypress. Seridium canker is prevalent in the southeast regions of the United States. Bot is considered more of a destructive disorder on cypress than seridium canker.

Disease Symptoms

• Seridium canker produces lens-shaped cankers on various tree areas including twigs, branches and trunk. The cankers girdle the main trunk and scaffold branches, killing all plant areas above. Over time, resin starts to ooze from the cankers. Symptoms of bot are quite similar to seridium canker. Bot cankers have a more elongated shape and are sunken in appearance. Tree tissues above and below the cankers gradually start to turn brown. Bot cankers do not produce any resin.

Management

• Both canker-causing fungi are more likely to infect trees that are suffering from drought stress and frequently enter trees through bark wounds. There are no fungicides that can cure the disease once a tree in infected. The best management strategy focuses on preventive measures such as making sure that trees are well watered. Prune out and remove all infected areas as soon as cankers appear. This helps to minimize the spread of infection. In case the tree trunk is heavily infected, it is best to remove the tree entirely.