I have eggplant borer (Leucinodes orbonalis) in my eggplants for the third
year running. I have tried spraying regularly with pyrethrum this year
which has reduced the rate of infestation but not eliminated it. Without
spraying I get about 10% edible fruit, with spraying about 50%. I have
searched the internet and it seems there is no cut and dried solution. One
of the problems is that the eggs are layed by moths continuously through the
growing season and the grubs are only vulnerable for a short time to contact
toxins before they burrow into the fruit and vanish. I prefer not to use
systemic insecticides and it isn't clear that they are completely effective
either. I don't need 100% effectiveness but only 50% is too much waste for
my liking.

My next method of control (next year) is to grow my eggplants in net cages
to keep the moths off them. Before I go to this trouble does anybody have
experience of the problem who can offer a practical solution that is better
than 50%.

David

David Hare-Scott wrote:

I have eggplant borer (Leucinodes orbonalis) in my eggplants for the
third year running. I have tried spraying regularly with pyrethrum
this year which has reduced the rate of infestation but not eliminated
it. Without spraying I get about 10% edible fruit, with spraying
about 50%. I have searched the internet and it seems there is no cut
and dried solution. One of the problems is that the eggs are layed by
moths continuously through the growing season and the grubs are only
vulnerable for a short time to contact toxins before they burrow into
the fruit and vanish. I prefer not to use systemic insecticides and
it isn't clear that they are completely effective either. I don't
need 100% effectiveness but only 50% is too much waste for my liking.

My next method of control (next year) is to grow my eggplants in net
cages to keep the moths off them. Before I go to this trouble does
anybody have experience of the problem who can offer a practical
solution that is better than 50%.

Maybe exclusion bags. You can buy exclusion bags, or maybe use paper bags
(or make some bags from nylon fabric).

e.g. http://www.greenharvest.com.au/pestc...sion_prod.html

Do the plants continue to flower while other fruit are growing? If so, you
will presumably need bees to fertilise the flowers. Exclusion bags would
allow this - net cages wouldn't.

Tom N wrote:
David Hare-Scott wrote:

I have eggplant borer (Leucinodes orbonalis) in my eggplants for the
third year running. I have tried spraying regularly with pyrethrum
this year which has reduced the rate of infestation but not
eliminated it. Without spraying I get about 10% edible fruit, with
spraying about 50%. I have searched the internet and it seems there
is no cut and dried solution. One of the problems is that the eggs
are layed by moths continuously through the growing season and the
grubs are only vulnerable for a short time to contact toxins before
they burrow into the fruit and vanish. I prefer not to use systemic
insecticides and it isn't clear that they are completely effective
either. I don't need 100% effectiveness but only 50% is too much
waste for my liking.

My next method of control (next year) is to grow my eggplants in net
cages to keep the moths off them. Before I go to this trouble does
anybody have experience of the problem who can offer a practical
solution that is better than 50%.

Maybe exclusion bags. You can buy exclusion bags, or maybe use paper
bags (or make some bags from nylon fabric).


That's a good idea to follow up. It is unclear to me exactly when in the
cycle of flowering and fruiting the grubs enter. They seem to go into a
hole they drill in the formed fruit but some sources say to look for them on
wilted flowers and stalks as they attack the young flowers. I haven't seen
any flower damage. So maybe once fruit sets a quick squirt of pyrethrum
before bagging would do the trick.

e.g. http://www.greenharvest.com.au/pestc...sion_prod.html

Do the plants continue to flower while other fruit are growing?

Yes.

If
so, you will presumably need bees to fertilise the flowers.
Exclusion bags would allow this - net cages wouldn't.

I had thought that I would have to hand pollinate, we are talking about 50
flowers not 500. But the bags are worth a go. I might do some of each and
see how it turns out.

David