Wireweed

Polygonum aviculare
Wireweed (Polygonum aviculare) is a widespread annual with wiry, trailing stems that form mats up to 1 m in width. Wireweed prefers to germinate in wet soils so it is problematic in winter and in spring sown crops as it can be very competitive and smother crops. Once larger than a seedling, is difficult to control, with selective herbicides in crops.
Wireweed