From page 21
BIODIVERSITY
points out that a diversity of
plants also act as refuges and
permanent habitats for
insects.
She adds, “There are many
herbs that would act as
insectary plants such as
yarrow, tansy, African
wormwood, catnip, and
clovers.”
Where you have planted one
crop, she suggests that you
plant borders around the
crop and also use cover crops
of diverse plants that will be
available throughout the year
for insects to establish
permanently in the area.
A useful technique is the
“push-pull” form of pest
management. The principle is
based on the use of repellent
plants which are planted
within the crop field and the
use of “trap” plants which are
planted in the margins
around the crop field.
She further comments, “If
smallholders practice mixed
agriculture with animals
incorporated in the system , it
would be a good idea to let
the animals graze the fields
after harvesting the crop.
The manure left by these
animals will bring back the
decomposers (mainly the
dung beetle assemblage).
This will increase the soil
health by carrying nutrients
into the soil, making it
available for uptake by plant
roots and increase the yield
of the crop as a result.”
Having designed a beautiful
and naturally pest repellent
plot, you may still need to
spray the most persistent
pests.
A general purpose organic
pesticide is easy to make.
Simply brew a tea of
chopped onion, garlic and
chillies. Leave to flavour the
water for a few days in a
sealed container. Strain the
mixture and add 50 parts of
the mixture to one part liquid
paraffin.
Finally, make a lather in the
mixture by grating in Sunlight
bar soap. As you spray the
leaves, the lather helps the
mixture to stick.
Dr Jankielsohn concedes that
the size of the plot will have
an effect on the insect
biodiversity. “If it is a small
plot surrounded by areas
where these principles are
not practiced it would
basically be an island where
the insect assemblage would
be isolated.
“If there are similar plots in
an area this would not be a
problem as long as the plots
are connected by green
corridors.
“The proximity to towns and
industrial areas will have an
influence if chemicals are
used in the surrounding
areas.
The drift and runoff of
chemicals from these areas
may influence the insect
assemblages negatively.”
23
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