spots on my broad beans
leaves of my broad beans have brown spots on them. What is this
and how can I treat it?
is likely to be the fungal disease Botrytis fabae. The fungus
causes brown spotting on leaves, pods and stems, and looks similar
in appearance to a dusting of chocolate powder, giving rise to its
common name, 'chocolate spot'.
Chocolate spot favours
acidic soils and is prevalent in damp or warm, humid spring weather.
Broad beans sown in winter are more susceptible.
The infection is likely
to reduce your crop; if severe, it will kill the plant. Apply a
fungal spray to prevent further spreading.
Burn infected plants
or place in the rubbish bin at the end of cropping. Clear away any
fallen leaves. You can still eat the beans, but the pods themselves
may be discoloured.
Broad beans should be
planted in well-draining soils neutral to alkaline soils
are ideal. If your soil is acidic, apply some lime. Space seeds
or plants well apart.
Chocolate spot spores
can survive in the soil for several years, so crop rotation is a
must. There should be a rotation of at least two years before broad
beans are grown in the same ground.
Broad beans do not need
large amounts of nitrogenous fertislisers being legumes,
they take in nitrogen from the atmosphere.
by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor
of Resource Management.
with permission from NZOOM Home and Garden content,
from the previous
The views expressed here are not necessarily those of the RNZIH