Management of the stem and bulb nematode (Ditylenchus spp.) in winter beans (Vicia faba L) using biofumigant Brassica spp. and other allelopathic cover crops
Musa, N. (2022) Management of the stem and bulb nematode (Ditylenchus spp.) in winter beans (Vicia faba L) using biofumigant Brassica spp. and other allelopathic cover crops. Doctoral thesis, Harper Adams University.
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Abstract
Stem nematodes, Ditylenchus gigas and D. dipsaci, are major pests in field bean (Vicia faba L.) production in the UK. Currently, there are no recommended management measures for their control in V. faba production. A potential sustainable solution that has been used successfully for other plant parasitic nematodes is biofumigation using brassica cover crops. The active ingredient in biofumigant brassicas are isothiocyanates (ITC), which are produced from glucosinolates after disruption of brassica tissues. ITC have an affinity for proteins and can therefore cause mass disruption of the functional systems within target pests including nematodes. It is believed that concentrations of 50 μg/ml ITC are achievable in biofumigated soils. In vitro studies with allyl ITC identified that 50-100 μg/ml of 2-phenethyl ITC and benzyl ITC caused up to 100% mortality against the two stem nematodes after 24 h exposure whilst sulforaphane had no effect. Experiments to understand the effect of sub-lethal ITC concentrations were developed by exposing stem nematodes to doses of 3-100 μg/ml. In a 23% pluronic gel, stem nematodes were examined for their ability to move to the roots of their host, V. faba. The ITC affected the stem nematodes form by stimulating them to coil while limiting their foraging activities at sub-lethal (12.5-25 μg/ml) concentrations. At 25 μg/ml, 2-phenethyl ITC and benzyl ITC reduced migration towards the host by over 90% while sulforaphane had no effect on the stem nematodes’ ability to find their host even at 100 μg/ml. Brassica species were investigated under controlled conditions to determine whether they are non-hosts or hosts of stem nematodes. Three separate experiments were conducted for five brassica plants. The results showed that all brassica plants tested were poor hosts for D. gigas while certain brassica plant such as Sinapis alba and Eruca sativa can support the reproduction of D. dipsaci. Brassica plants that are associated with nematotoxic isothiocyanates were investigated for their suppressive effect in two field experiments. Brassica-legume mixtures and brassica grown alone were considered in field experiment 1, while field experiment 2 investigated the effect of three brassica species. The biomass of these brassicas was low in field experiment 1 because of a delayed sowing date and absence of N and S fertilizers although brassica plants grown in a mixture with legumes produced significantly greater biomass than brassicas sown alone. Field experiment 2 showed that brassica plants such as Brassica juncea, B. carinata and Sinapis alba could suppress Ditylenchus gigas compared to a fallow control. In conclusion, this study has demonstrated the potential of using brassica cover crops against Ditylenchus spp. in V. faba production.
| Item Type: | Thesis (Doctoral) |
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| Divisions: | Agriculture and Environment (from 1.08.20) |
| Depositing User: | Ms Kath Osborn |
| Date Deposited: | 09 Aug 2022 10:39 |
| Last Modified: | 09 Aug 2022 10:39 |
| URI: | https://hau.repository.guildhe.ac.uk/id/eprint/17872 |
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