Elder Tree
By Beetham
United Kingdom 
My neighbours elder tree is covered with black fly how can I get rid of them to stop them coming on my crops
Thanks.
10 May, 2009
Previous question
You can't except by spraying the whole tree with systemic insecticide - however, there is an advantage to their being on the elder. They love elder trees and english marigolds above all else, so all the time they're munching on the tree, they're not munching your crops! My dad used to grow marigolds deliberately to keep the blackfly off his crops.
13 May, 2009