While scientists debate over the Latin name of this little fungi (depending on which plant it attacks and who you talk to), Eutypa dieback is no joke. Also known as dead arm disease, Cytosporina, and gummosis, you often won’t see symptoms until it’s too late.
Symptoms of Eutypa dieback
In apricot trees, all of the leaves on an infected branch will wither and die, but remain attached to the tree. This is called flagging. Oozing cankers are found along the lower branch and the bark turns darker than normal. Two years after grape vines are infected with Eutypa dieback, they will begin to display leaf cupping and distortion, chlorosis, and stunted new growth. If you take a cross section of the wood, you will discover V-shaped cankers.
This insidious microorganism works its way toward the trunk, killing the entire tree or vine. Also, the fungus responsible for Eutypa dieback seems to be broadening its dietary preferences to include almond, apple, blueberry, citrus, fig, kiwifruit, nectarine, olive, peach, pear, plum, and walnut, as well as Ceanothus spp., chokeberry, crab apple, oak. oleander, poplar, and native California buckeye, big leaf maple, and willow. It is critical that infected trees and vines be completely removed as soon as they are identified, to avoid spreading to healthy plants.
Preventing Eutypa dieback
Like most fungi, moisture is a key component to its development. These little buggers are opportunists, so best practices must be implemented to avoid infection. While most pruning is done in winter, plants susceptible to Eutypa dieback are best pruned in summer. All pruning cuts are wounds. While trees and vines can develop a protective barrier, called a callus, these cuts need time to dry and heal. Never apply sealants to these wounds. Sealants have been found to hold moisture in, creating the perfect habitat for disease. If it rains 2-6 weeks after a cut is made, the Eutypa dieback fungus can take hold and kill you tree. Improperly aimed sprinklers can cause similar risks.
Eutypa dieback controls
If you discover an infected branch, you may be able to save the plant by removing infected limbs at least 12” below any internal symptoms. This means making a cut where you think the disease has not reached and examining the cross-section for signs of infection. If chaotic, oozing wood is found, pruning tools must be dipped in a household cleaner, such as Lysol, before making another cut, or you will become the infector! Keep cutting down the branch until healthy wood is seen. This does not guarantee the life of your plant - it is only marginally successful.
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