Evaluation of fluopyram for the control of Ditylenchus dipsaci in sugar beet

Abstract

Fluopyram, a succinate dehydrogenase inhibitor fungicide, has shown potential in controlling Meloidogyne incognita and Rotylenchus reniformis in tomato. The effectiveness of this compound for the control of Ditylenchus dipsaci in sugar beet was evaluated. In this study, laboratory, growth chamber, glasshouse, and field experiments were conducted. In a motility bioassay, the EC 50 value was determined with 3.00 μ g/ml a.i. after 72 h exposure to fluopyram. The growth chamber experiment did not show any effects on D. dipsaci penetration rate; however, field experiments revealed a positive effect of fluopyram applied at planting in reducing D. dipsaci infectivity. The glasshouse experiment confirmed a limited effect of fluopyram on D. dipsaci population development. Under field conditions, despite a reduction of D. dipsaci penetration rates in spring, fluopyram was not effective in reducing the population development until harvest. Consequently, D. dipsaci densities in plant tissue and soil were high at harvest and not different among treatments. However, root-rot symptoms were significantly reduced at harvest. Fluopyram applied at planting showed good potential to reduce root-rot symptoms caused by D. dipsaci in sugar beet. However, for the long-term reduction of nematode populations in soil, further integrated control measures are needed to reduce the risks of substantial yield losses by D. dipsaci.

Virulence and pathogenicity of four Ditylenchus dipsaci populations on sugar beet

“…Its penetration on sugar beet seedlings leads to the dissolution of the middle lamellae and swelling of the hypocotyl (Duncan & Moens, 2013;Madani et al, 2015). Later in the growing season, bacterial and fungal pathogens introduced by D. dipsaci engender rotting of the sugar beet crown (Hillnhütter et al, 2011;Kühnhold, 2011;Storelli et al, 2020). To date, no resistant cultivars towards D. dipsaci are available to farmers (Storelli, Minder, et al, 2021b).…”

Screening of sugar beet pre-breeding populations and breeding lines for resistance to Ditylenchus dipsaci penetration and reproduction

“…Ditylenchus dipsaci proved to have a rapid population growth (Abolfazl et al 2017;Kühnhold et al 2006;Storelli et al 2020). The few nematodes that penetrated sugar beet 4.8 (± 3.4) 10.1 (± 0.8)** 50 (± 28.3) 'DIT_150' 8.7 (± 3.5) 10.3 (± 3.9) 75 (± 21.2) 'DIT_166' 9.5 (± 2.8) 12.5 (± 3.1)* 73.3 (± 9.4) 'DIT_207' 7.5 (± 3) 12.7 (± 3.5)** 75 (± 21.2) 'DIT_213' 9.6 (± 2.6) 9.3 (± 3.2) 25 (± 0)…”

“…The pre-breeding population 'DIT_207', with its particular low heterogeneity and low number of D. dipsaci per seedling, is a potential candidate for a source of resistance towards D. dipsaci penetration, despite the high incidence and reproduction rate of the nematode. The initial inoculum level used in the experiments was up to 1000-fold higher than an initial natural density occurring in the field at sowing (Storelli et al 2020). An initial density of 10 D. dipsaci individuals per 500 g soil may cause severe damage to onions.…”

“…The broad range of host plants of D. dipsaci hinders crop rotation strategies for successful management of this nematode (Jones et al 2013). The fungicide fluopyram, a succinate dehydrogenase inhibitor (SDHI), effectively reduced the fungal and bacterial infection introduced by the stem and bulb nematode (Storelli et al 2020). However, no long-term effect on D. dipsaci population development was observed.…”

Integrated Nematode Management

“…Yield losses can range between 10% and 60% in Germany and Switzerland, but under optimum conditions for the nematode (cool and moist), 90-100% is possible. However, next to the yield loss, if more than 10% beets show crown rot symptoms the complete harvest will be rejected by the sugar factory (Storelli et al, 2020). Germany and Switzerland consider D. dipsaci to be of high economic importance in their main sugar beet production areas.…”