Cooperative Extension: Maine Wild Blueberries

5.25.17 Botrytis Risk from May 25 to May 26

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Mummy Berry

Mummy berry symptoms have appeared in many growers fields.  You may be finding both dead flowers and leaves on your plants.  If it looks like the flowers did not open before they died, the flowers were probably killed by mummy berry. You can see grey masses of spores at the base of the flowers or dead leaves.

Botrytis

Botrytis is another disease that may kill your flowers.  It is more likely to attack almost open and open flowers.  The flowers will die and have black hairs sticking out from them.  Botrytis typically spreads from dead flowers to other flowers and sometimes leaves The presence of Botrytis in a field has been highly variable over the years.  You need to scout to see if you have the disease before applying fungicides to control this disease. There has been enough wetness to cause Botrytis infection at some of our weather stations, but ONLY if the fungus was already present in the field.   If you are in early bloom and have confirmed you have flowers infected with Botrytis, you may want to consider protecting your plants from further Botrytis infection if it looks like we will have a substantial amount of rain in your area.  If you are already in late bloom, fungicide sprays are not going to be cost effective.

Botrytis kills almost open (pink stage)  and open flowers. There may be only a few flowers in a cluster or a few clusters of flowers on a stem that are infected.  The characteristic sign of the fungus is black hairs (often with gray spore masses at their tips) sticking out from the dead flowers. You may need to use a magnifying glass to the see the hairs on the flowers.

Please see the 2018 fungicide recommendations on the Fact Sheet 219 – Disease Control Guide for Wild Blueberries and the most current Maine Wild Blueberry Pesticide Chart (Fungicides) (PDF).

– Seanna Annis