Control of Globodera pallida Using Sinapis alba or 4-Hydroxybenzyl Alcohol with the Trap Crop Solanum sisymbriifolium or the Biofumigant Brassica juncea Seed Meal Extract

The pale cyst nematode Globodera pallida is a highly specialized, economically important pest for potato production. The specialized hatching requirements, ability to adapt, and the loss of effective control strategies such as methyl bromide fumigation increase the challenge to eradicate G. pallida in Idaho. Without a suitable host, this nematode can remain dormant as encysted eggs in soil for up to 20 years. In this study, we first demonstrated that Sinapis alba seed meal extract (SME) or 4-hydroxybenzyl alcohol (HBA), under laboratory and greenhouse conditions, enhances G. pallida egg hatch rate when exposed to potato root diffusate (PRD). This hatch rate enhancement in the presence of PRD is speculated to be due to an increase in egg-shell permeability. We then tested the efficacy of (i) Solanum sisymbriifolium following prior treatment with S. alba SME (0 and 4.48 t/ha) or HBA (0 and 0.12 t/ha) and (ii) Brassica juncea SME (0, 0.14, 0.56, and 1.12 t/ha) following HBA treatment (0 and 4.48 t/ha) on egg viability, hatch rate, and reproduction of G. pallida encysted eggs. S. sisymbriifolium alone reduced the number of encysted eggs compared to the nontreated control by up to 67%, indicating that this trap crop triggered G. pallida eggs to hatch. When combined with S. alba SME or HBA, S. sisymbriifolium significantly reduced egg count, hatch rate, and viability more than S. sisymbriifolium alone. The combination of S. sisymbriifolium with HBA or S. alba SME eliminated G. pallida reproduction on the susceptible potato. All the tested rates of B. juncea SME alone or with HBA reduced egg hatch rate, viability, and reproduction compared to the nontreated control. Combining HBA and B. juncea SME further significantly reduced egg hatch rate, viability, and reproduction than those rates of B. juncea SME alone.

Automated summary

In this study, it was demonstrated that Sinapis alba seed meal extract or 4-hydroxybenzyl alcohol can enhance the hatch rate of Globodera pallida eggs when exposed to potato root diffusate. Combining Solanum sisymbriifolium with HBA or Sinapis alba SME significantly reduced the egg count, hatch rate, and viability of G. pallida. B. juncea SME alone or with HBA also reduced egg hatch rate, viability, and reproduction of G. pallida.