Mummy berry is a fairly common disease that affects blueberry plants. It can be a pretty devastating disease to your blueberry harvest. By the time that you see the affects of it, the opportunity to treat has passed. Let’s talk about mummy berry, how it works, and what you can do to manage it.
Mummy berry is a fungal disease on blueberry bushes. It causes the blueberries to rot and fall off just as they are ripening to be ready to harvest. This can be very frustrating to you as it looks like you’re going to have a lot of blueberries and then one by one the they fall off the bush. Mummy berry is not too difficult to manage, but you have to follow a couple of steps to make sure that you get the best control of the disease possible.
Mummy berry infects the blueberry bush when it is in bloom. Those blooms will turn into fruit over the course of the season. Blooms that were infected carry the mummy berry pathogen with them, which causes them to rot and fall off. When they rot and hit the ground, the pathogen stays there over winter. In the early spring it forms apothecia, or tiny mushrooms. These release spores that infect the leaves of the plant. The infected leaves produce spores that are transmitted to the flowers by bees or wind, and thus the mummy berry life cycle continues on and on.
Because the infection of the fruit occurs at bloom it is most important to treat plants at that stage each year. Captan is a fungicide that is very effective at making sure that making sure that the blooms do not become infected. It’s best to spray Captan every 7-10 days while plants are in bloom. There is an organic fungicide called Serenade that can be somewhat effective at controlling mummy berry if it is sprayed every 7 days. With Captan or Serenade it is important to get good coverage on the blooms of the plant. With any pesticide it is always important to read the label and follow it, as the label is the law.
A couple of other practices that can help to reduce the amount of mummy berry that you have are to remove dead berries after they fall. This will reduce the amount of pathogen that overwinters in the soil. To remove berries simply rake them out or use a leaf blower and then throw them into the trash or compost pile. Another practice is to mulch. Placing mulch 3-4 inches deep around the bush creates a physical barrier that is difficult for the mummy berry spores to move through. You don’t want to place the mulch all the way up to the trunk of the bush. Pine straw, pine bark, or wood chips all work well for mulch.
The best control of mummy berry is to use a combination of spraying, removing, and mulching. If your blueberry bushes are in a secluded place, not close to any other bushes, it might be that you don’t get mummy berry, or you have very little of it. Mummy berry is simple to control, if you get the timing right.
If you have questions about mummy berry contact your County Extension Office or email me at Jacob.Williams@uga.edu.