Secretions from the roots of Tagetes Patula have an insecticidal effect on the soil, effective against nematodes and to some extent against keeled slugs. These secretions are produced about 3 - 4 months after sowing.
- One of the most damaging groups of plant-parasitic nematodes are the root-knot nematodes (Meloidogyne spp.).
- These can attack a broad range of vegetable, fruit, and ornamental crops causing swellings or galls on the roots.
- If there is a severe infestation of root-knot nematodes, the plant may be stunted, wilt, or die. A plant that is already weakened can easily become infected with bacteria or fungi as well.
- Once a plant is infected by nematodes, treatment options are very limited. Therefore, most nematode management strategies are pre-plant treatments.
- Marigold patula produces a substance called alpha-terthienyl, which can aid in the reduction of root-knot nematodes and other disease promoting organisms, such as fungi, bacteria, insects, and some viruses
Allelopathy is the ability of an organism to produce chemicals that are toxic to other organisms. Marigold roots release the chemical alpha-terthienyl, one of the most toxic naturally occurring compounds found to date. This compound is nematicidal, insecticidal, antiviral, and cytotoxic. The presence of alpha-terthienyl inhibits the hatching of nematode eggs.