tomato

M

Mexican Marigold

Tagetes erecta

Tagetes erecta roots exude alpha-terthienyl and thiophene derivatives that suppress root-knot nematodes (Meloidogyne spp.), a verified, replicated companion planting benefit for solanaceous crops including tomato.

G

garden nasturtium

Tropaeolum majus

Nasturtium acts as a trap crop for aphids and repels whiteflies, reducing pest pressure on nearby tomato plants. The pungent volatile compounds deter thrips and spider mites.

Y

Yarrow

Achillea millefolium

Yarrow is reported to improve the essential oil content of aromatic neighbors and to attract predatory insects (ladybirds, lacewings) that reduce tomato aphid pressure.

B

Bronze Fennel

Foeniculum vulgare

Fennel produces allelopathic root exudates that inhibit growth of Solanaceae; tomato plants grown near fennel show stunted growth and reduced fruit set in replicated garden trials.

E

eastern black walnut

Juglans nigra

Juglans nigra exudes juglone (5-hydroxy-1,4-naphthoquinone), an allelopathic compound that causes wilt and death in solanaceous plants including tomato within a 50-80 ft radius.

P

Persian walnut

Juglans regia

Persian walnut also produces juglone compounds that inhibit growth in susceptible plants though typically in lower concentrations than black walnut.