Tall growing vigorous weeds such as fat hen (Chenopodium album) can have the most pronounced effects on adjacent crops, although seedlings of fat hen that appear in late summer will only produce small plants.
Chickweed (Stellaria media), a low growing plant, can happily co-exist with a tall crop during the summer, but plants that have overwintered will grow rapidly in early spring and may swamp crops such as onions or spring greens.
The presence of weeds does not necessarily mean that they are competing with a crop, especially during the early stages of growth when each plant can find the resources it requires without interfering with the others.
A variety of herbal remedies, either applied topically or taken internally, may possibly assist in the treatment of contact dermatitis.
A poultice (crushed herbs applied directly to the affected area) made of jewelweed (Impatiens spp.) or chickweed (Stellaria media) may soothe the skin.
A cream or wash containing calendula (Calendula officinalis), a natural antiseptic and anti-inflammatory agent, may help heal the rash when applied topically.