Blueberry season has arrived!
This means you should be outside berry-picking intead of on the computer. Before you go, I'll introduce you to the fungus that causes mummyberry.
Have you ever seen a shriveled, pinkish berry like this? If you have, there's a good chance it was infected with the fungus Monilinia vaccinii-corymbosi , commonly called mummyberry. It is one of the biggest blueberry diseases and can cause yield losses of up to 50%.
Understanding the lifecycle of agricultural pests, insects and fungi alike, is key for proper management and the life cycle of this fungus is pretty cool. There are spores involved, and it is called mummyberry after all.
We'll start from the shriveled berry pictured above. The berry falls to the ground and waits until the next spring to wreck havoc. Mummied- berries look kind of like tiny black pumpkins.
In the spring when it is cold and wet the mummied berries 'sprout' small cup shaped mushrooms called apothecia. They produce millions of spores that travel travel all over fields via wind. Spores land on blueberry bushes and in just a few hours infect leaf buds and young shoots. These spores don't actually infect new berries - there's a second spore that does that!
Blueberry shoots and leaves infected by apothecia suddenly have a blighted appearance. They turn brown, and when humidity is high a second spore, called conidia, forms on grey-green tufts. The conidia infect nearby blossoms either by rain washing the spores into flowers, or by pollinators attracted by their sugary scent. Infection from healthy looking berry to shriveled, pink mummy is a slow process which makes it difficult to detect until late in fruit development.
So, what to do?
No one wants mummyberry in their blueberries. For growers it decreases yields and for eaters it's pretty gross to think of fungi lurking in your fruit. Happily there are a number of things farmers do to control the fungus, and they start thinking about mummyberry management way back in the winter. (Can you remember when it was actually cold out?)
Apothecia begin appearing after the snow melts in the spring. Once they appear, the ground surrounding the bushes can be cultivated to destroy them, or fungicide can be applied. Some fungicides are approved for organic use. Alternatively, adding two or more inches of mulch around blueberry bushes will bury the apothecia and they won't be able to release spores. This is only really feasible for small scale blueberry plantings - like home gardens.
Am I going to worry about mummyberry when blueberry picking this weekend?
Nope! Although I may be on the lookout for blueberry maggots.