Integrated management of Meloidogyne incognita and Fusarium oxysporum in cucumber by combined application of abamectin and fludioxonil

Abstract

The southern root-knot nematode (Meloidogyne incognita) and Fusarium wilt (Fusarium oxysporum) are major constraints in cucumber production worldwide. Co-infection of these pathogens results in a disease complex which is difficult to control. In China, growers apply nematicides and fungicides separately to control M. incognita and F. oxysporum, respectively, which requires a great amount of labor thus increasing production costs. We hypothesized that the combined application of nematicides and fungicides would significantly reduce the labor cost, and control M. incognita and F. oxysporum. In this study, toxicity of abamectin and fludioxonil was determined against M. incognita and F. oxysporum, respectively, in the laboratory, and the efficacy of a combination of abamectin and fludioxonil (abamectin + fludioxonil) for control of M. incognita and F. oxysporum simultaneously was evaluated under field conditions. In the laboratory, abamectin was highly toxic to second-stage juveniles (J2) of M. incognita with the median lethal concentration (LC50) of 2.60 mg L−1 and fludioxonil inhibited colony growth of F. oxysporum on potato dextrose agar (PDA) with the median effective concentration (EC50) of 0.34 mg L−1. In the field trials, abamectin + fludioxonil at 300 and 375 g ha−1 was effective in reducing population levels of M. incognita and incidence of Fusarium wilt in two consecutive years. Moreover, abamectin + fludioxonil at 375 g ha−1 significantly (P < 0.05) increased cucumber fruit yield by 45.23% and 40.85% in two years, respectively, compared to the untreated control. The yield increasing effect by the combined treatment was significantly greater than either treatment alone. Results from this study indicated the simultaneous application of abamectin + fludioxonil was effective for the control of the M. incognita and F. oxysporum disease complex in cucumber production, while enhancing cucumber fruit yield.