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Ask the Master Gardeners: Prune apricot trees before rainy season to avoid fungal infection

By: Elaine Applebaum, Placer County Master Gardener
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Question: Whole branches of my apricot tree have suddenly wilted and appear to be dying. They are getting the same amount of water I’ve always given them and there doesn’t appear to be any insects attacking them. What is going wrong? Answer: In areas like ours where winters are wet, apricot trees are susceptible to a condition called Eutypa dieback. This fungal infection causes twigs or whole limbs to suddenly wilt and die in late spring or summer. The fungal spores are spread by rain and enter the tree through pruned areas that haven’t fully healed. Infected limbs may be darker in color and exude an amber-colored gum. Pruning should be done in July or August, after harvest. Remove any infected limbs at least one foot below signs of the infection. By pruning at least six weeks before the start of winter rains, the tree will have a chance to close the wounds and prevent entry of the fungal spores. In addition to removing diseased limbs, thin out about 20 percent of the older branches each year to allow light to reach the center of the tree. Avoid cutting into the branch bark ridge, the swollen area where the branch attaches to the trunk or larger branch. This is the area that will produce the new tissue to close the pruning cut. If you have gardening questions or need more information, call the master gardener hotline at (530) 889-7388.