On 20/06/19 08:24, Janet G wrote:
A week ago I planted out a lot of young module-grown brassica plants in a new bed created out of long-standing meadow land. Three days later a large number of quite big black shiny flea beetles had landed on several of the weaker plants and were fast reducing them to lacy thinness. I tried a soapy spray and diatomaceous earth but to no avail. I read that talcum powder can deter flea beetle so I liberally dusted the plants with Johnson's Baby Powder. Having hopped away, the beetles regrouped within an hour or so of my treatments and moved on to slightly stronger plants. A day or so later I resorted to a pyrethrum based spray which advertised itself as killing beetles. The attack remains unabated and it look as though within a few days the whole planting of about 70 or so plants will have been finished off.
I've never encountered flea beetle on this scale before and wondered whether there's any explanation for this sudden onslaught and whether anyone else has had similar experience

Welcome to the future.

There are no effective chemical insecticides, because they've all been
removed from the market (at least for amateur use). I'm not advocating
wholesale, unlimited use of chemicals - I have had many unopened or
little-used bottles of insecticides over the years as I find many
attacks are self-limiting. However, I don't grow food crops, so it
doesn't matter if an ornamental gets a bit unsightly for a time, or I
just give up on it and grow something else. But food crops are another
matter; sure there are bioinsecticides coming one (you might find a bit
of googling on Beauvaria bassiana of interest), but they aren't cheap,
sometimes don't work well at low temperatures, and resistance is on the way:
https://www.frontiersin.org/articles/10.3389/fpls.2015.00381/full

I find a certain irony - at least with what you have been trying to grow
- that the Greens policies are ensuring there won't be any greens for
you to eat.

--

Jeff