Brambles such as raspberries and blackberries are particularly
susceptible to viruses. Always buy brambles that are certified virus-free.
The problem you mentioned only affected the berries and tips of the
stems which makes me think it was one of the gray molds which is a
fungus and one of the most common fungi here in western Massachusetts
Botrytis attacks the ripening berries. You might see the berries
covered with a white or gray moldy material. This causes the fruit to
rot and shrivel up. The fungus spreads quickly especially on overripe
or bruised berries.
Botrytis on raspberries and blackberries is pretty common. It is at
its worst during the hazy, hot, and humid weather we get in summer
which aids botrytis and other fungi, especially at the time the
plants bloom as well as at harvest time.
There are a few things you can do to prevent and control this common
problem. Spray Neem Oil once a week
starting when the raspberry plants bloom right up until harvest.
Don't water from above. Provide good air circulation by keeping the
plants apart and space the rows far enough apart.
Click here to read more about Neem Oil and
order it from Pernell Gerver's Online Store