Never had much in the way of luck with swedes, but this year have 2 lovely half rows of swede seedlings, on their 3 true leaves, however, the new tender leaves are SMOTHERED in greenfly! What to do? Spray? Derris?? Pull them up and give up???
Squash 'em
Garlic spray - they hate it:
blend a few cloves of garlic with 2 pts of water. let it sit for several hours. strain and spray.
diluted wahing up liquid sprayed on should do the trick-weedgrower