Ground elder
Ground elder (Aegopodium podagraria) is a widespread, invasive garden weed. It is usually introduced into gardens as pieces of whitish, fleshy underground rhizome hidden in soil around roots of acquired plants. Or it creeps in from neighbouring gardens or waste land. Once established, it quickly spreads by underground stems. It can easily choke all but the most vigorous garden plants.
Cultural control
The majority of rhizomes are relatively close to the soil surface and can be removed by forking them out. Although unlikely to eradicate the weeds completely, growth can be brought down to acceptable levels as the roots are less capable of regenerating than the rhizomes.
Where ground elder is growing among the roots of garden plants the most practical control is to dig out the cultivated plants, carefully remove the weed roots and transfer the cultivated plants to clean ground until the infected areas have been cleared.
Mulches of black polythene or similar materials can be laid over uncultivated areas but may take several seasons to weaken growth sufficiently.
Chemical control
The most effective weedkillers contain glyphosate, a non-selective translocated herbicide applied in mid-summer when there is plenty of leaf growth. Check for regrowth later in the summer and re-treat. Glyphosate is inactivated on contact with the soil, so there is no risk of damage to the roots of nearby ornamentals. However it is essential to prevent the spray from coming into contact with the foliage of garden plants.
The residual herbicide dichlobenil (Casoron G4 Weed Barrier) can be used in early spring around certain established trees and shrubs (check the label for details).Tony Dickerson