The potential of Brassica green manure crops for controlling root-knot nematode (Meloidogyne javanica) on horticultural crops in a subtropical environment

Abstract

In glasshouse experiments, Meloidogyne javanica reproduced on Brassica juncea, B. napus and BQMulch, a commercial biofumigant crop consisting of both B. napus and B. campestris. Although nematode multiplication rates were only 3–23% of the rate on a highly susceptible crop (tomato), they were high enough to suggest that Brassica rotation crops will increase root-knot nematode populations to potentially damaging levels in situations where temperatures do not limit nematode reproduction. A field study showed that this problem could be prevented in subtropical climates by restricting the growth of Brassica crops to June, July and August, when low temperatures limit nematode development and eggs are not produced until about 10 weeks after planting. Field and pot experiments in which M. javanica was introduced into soil following incorporation of Brassica residues failed to demonstrate a 'biofumigation' effect, possibly because the soil was too dry or the degree of tissue disruption was insufficient to maximise isothiocyanate release. Numbers of root-knot nematodes were reduced when Brassica roots, leaves and stems were incorporated into soil at 17 t DM/ha, but it is unlikely that this was due to the production of nematoxic chemicals, as large numbers of free-living nematodes multiplied during the decomposition process. From a practical perspective, these results suggest that green-manured Brassica rotation crops are unlikely to be useful for controlling root-knot nematodes on some subtropical horticultural crops that are currently fumigated for nematode control. The susceptibility of brassicas to M. javanica and the need to grow them during winter limits their potential in the vegetable industry, while difficulties in obtaining a biofumigation effect in dry soil will reduce effectiveness in non-irrigated pineapple soils. Brassicas are likely to be most useful in the ginger industry, as they can be grown during the winter break between ginger crops and fields can be irrigated before the Brassica crop is incorporated into soil.

Control Potential of Brassicaceae Cover Crops as Green Manure and their Host Status for Meloidogyne javanica and Criconemoides xenoplax

“…The vines in the pots that received the green manure also experienced a growth response, indicating the secondary effect of the green manure applications. Stirling and Stirling (2003) sowed brassicas in field soil and incorporated the green material into the soil at a depth of 180 mm after 10 weeks. A root gall index indicated a significant reduction in the M. javanica root galls where brassicas were incorporated at an earlier stage.…”

“…The reproduction of M. javanica on certain brassica crops was compared to that on other crops that were not known to have biofumigation properties (Stirling & Stirling, 2003). The crops that were included in these trials were B. juncea cv.…”

The Effect of Cover Crops and their Management on Plant-parasitic Nematodes in Vineyards

“…The importance of DMP is also stressed in work done by Rahman and Somers (2005), who found that the suppression of M. javanica in vineyards was better with higher biomass being applied to the infested soil. Stirling and Potter (1998) also found that at least 2 t/ha of Brassica biomass are needed for a significant biocidal impact, while Stirling and Stirling (2003) indicated a reduction of M. javanica after the application of 17 ton DMP/ha in comparison to the impact of lower DMP, but could not determine whether the reduction was specifically due to the ITC release or perhaps due to other, secondary aspects. The DMP of Nemat (MC) was below 2 tons/ha for all three seasons and, bearing in mind the work by Stirling and Potter (1998), this treatment is not expected to have a dramatic impact on the M. javanica numbers, as the amount of biomass produced and therefore the potential to form ITC was very low.…”

Glucosinolates in Some Brassica Species as Sources of Bioactive Compounds Against Root Knot Nematodes.

“…Therefore, radishes in this study may have a more biofumigation potential than other brassica plants if utilized as a green manure amendment. In order to increase the success of biofumigation, non-host or poor host species for target nematode species or population should be grown especially when soil temperature is suitable for nematode activity (Stirling and Stirling 2003;Pattison et al, 2006;Avato et al, 2013). Otherwise, nematode population increases in the soil during cultivation before the incorporation of biofumigant plants into the soil.…”