Does marigold have an effect on plant-parasitic nematodes when grown in an intercropping setting?
Probably not. Some research (El-Hamawi et al., 2004) suggests that interplanting marigolds with susceptible crops may reduce nematode numbers, but results are often complicated by soil dilution and other factors. No successful research on this topic has been done in Florida. Powers et al. (1993) showed that intercropping with marigold did not reduce plant-parasitic nematodes in Honduras. Typically root-knot nematodes will find and reproduce on roots of a susceptible crop or weed. So interplanting marigold and susceptible crops is very risky and may result in damage to the susceptible crops (Figure 3). Figure 3. Marigold interplanted with coleus. Coleus will not be protected by marigold even though marigold is planted in close proximity.
