If you didn't already prune your apricots at the end of last summer, please hold off a little longer.

Our area has a fungus called Eutypa that infects fresh pruning wounds when rainfall occurs 2 to 6 weeks after pruning. Eutypa causes limbs or twigs to die suddenly in late spring or summer, with their wilted leaves still attached.  Infected bark has a dark discoloration with amber-colored gumming.  A cross section of a twig or branch will reveal an irregular discolored brown where the fungus has invaded.

If your apricot shows symptoms of Eutypa, remove the infected limbs at least 1 foot below any internal symptoms of the disease. The preferred control method is to prune during July and August after harvest, and, ideally, before the first fall rains.  At that time, there will be less regrowth from pruning cuts.   Treating wounds with paints or sealants is not satisfactory because it is difficult to treat all of the pruning wounds immediately after pruning is completed and many sealants frequently crack after application, letting in moisture and trapping it under the sealant.

If pruning wounds are made outside of the preferred pruning period of July/August, cauterizing freshly pruned branch wounds with a hand-held propane burner may prevent infection.  Boron, (B-Lock) is the only recommended water-resistant elastic coating for treating tree wounds that home gardeners should use as a sealant on their apricot trees. 

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area, visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at (530) 538-7201. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.