Cabbage

Brassica root exudates can damage grapevines

Brassicas stunt strawberry growth

Walnut trees produce juglone which is toxic to many vegetables including cabbage, causing stunted growth and yellowing.

Heartnut releases juglone which inhibits brassica family plants

Big sagebrush produces allelopathic compounds that can inhibit germination and growth of brassicas

Large rubber plant trees create extensive shade and root competition that inhibits cabbage growth

Japanese plum yew, like other conifers, may produce allelopathic compounds affecting brassica growth

Rutabaga and cabbage are both heavy feeders that compete for soil nutrients, especially nitrogen