[siandc]

 We noticed heavy damage to brassica seedlings over the weekend and having looked around today, and popped back down the plot now know we've got flea beetles. 
 I've read a few threads where people have been affected and gone on to use garlic/ onion/ mint infusions as sprays but none of them have had success or failure reports.

Did any of them work?

[mumofstig]

In my experience most brassicas recover from flea beetle attack anyway. Give the leaves a good soaking with the hosepipe, if you can..assuming they are big enough it seems to help.

Rhs advice

Control
Ensure rapid germination and development of seedlings so that they grow through this vulnerable stage quickly. Keep plants watered during dry spells and avoid sowing in to cold soil.

Chemical controls that can be applied include rotenone/derris* (Doff Derris Dust*, Vitax Derris Dust*), or pyrethrum (Py Spray Garden Pest Killer, Py Powder, Scotts Bug Clear Gun for Fruit & Veg). Seedling leafy brassicas, but not mature ones, can be sprayed with the systemic insecticide thiacloprid (Provado Ultimate Bug Killer Ready To Use).

* Rotenone/derris-based insecticides are being withdrawn from sale. Gardeners who have this pesticide may continue using it until 10 October 2009. Any unused products after that date should be disposed of safely by handing them to the staff at a local authority manned waste disposal facility.
Disposing of old chemicals

Pyrethrum spray is organic