Effect of Meloidogyne hapla on multi-purpose use of oilseed radish (Raphanus sativus)

Oilseed radish (OSR; Raphanus sativus), which can be used as a trap, cover or biofumigant when incorporated as a green manure crop, has potential for managing soil-borne biotic factors such as Meloidogyne hapla. However, exploiting the multi-purpose traits of OSR requires careful understanding of the biology of M. hapla and the prevailing soil conditions. When an OSR Line 'RO4S-PSOSR', and cv. Diakon grown in 300 cm(3) of sandy, loamy sand or muck soils were inoculated with 3000 eggs of M. hapla populations (collected from the three soil types) and maintained for approximately 500 degree days (DD, base 10 degrees C), all nematodes completed their life cycle in both hosts, with significantly more nematodes infecting OSR plants in the sandy soil. When cvs Diakon and Rutgers tomato (standard susceptible species) were grown under the same conditions with an inoculum of 2000 eggs per pot, infection was greatest in the sandy soils. Oilseed radish shoot growth was significantly lower in the sandy soil compared with muck or loamy sand soils. While the effect of soil type on OSR growth and M. hapla population densities is to be expected, the nematodes' completion of a life cycle at about 450-500 DD suggests that OSR hosts like cv. Diakon may be best used as a trap crop and plants should be terminated before the nematode completes a life cycle.