The effects of Seaweed (Ascophyllum nodosum) and Pagoda tree (Sophora alopecuroides) extracts on tomato root-knot nematode (Meloidogyne incognita)

Abstract

Background and Objective Root-knot nematodes (Meloidogyne spp.) are among the most important pathogens which cause great damage to the agricultural products. However, only a few methods such as crop rotation, resistant cultivars, and chemical compounds were approved for their control so far. Considering their environmental hazards and the relatively high price of chemical compounds, using non-chemical methods such as the application of plants and plant extracts for the nematode management increased. This study aimed to investigate the inhibitory effects of seaweed (Ascophyllum nodosum), and pagoda tree (Sophora alopecuroides) extracts on the activity of root-knot nematode (Meloidogyne incognita), including eggs hatching inhibition and second-stage juveniles (J2) mortality through the laboratory and greenhouse conditions. Materials and Methods After the sampling, the morphological properties of isolated nematodes were characterized and the species determined. Three different concentrations of each extract were used in three replications in laboratory tests. Egg hatching and second juvenile mortality (M. incognita) were evaluated after 24, 48, and 72 hours. In the greenhouse tests, two months after the inoculation, some plant growth traits (fresh shoot weight, fresh root weight, stem length) and nematode-related characteristics (number of galls, egg mass, and reproduction factor) were measured. The experiments were repeated twice, and the mean of two-step data was used for the statistical analysis. The analysis was performed using SAS software, and the comparison of means was achieved by the Tukey test. Results The laboratory results showed that the rate of egg hatching inhibition and mortality of J2 were directly related to the concentrations of applied extracts. Moreover, the results indicated that there was a significant difference among the treatments. The highest assessed percentage of larval mortality and hatching inhibition was observed in the seaweed extract application with 4/1000 concentration and pagoda tree extract with 1.5/1000 concentration, respectively. According to greenhouse results, the mean mortality of nematodes (J2) in seaweed, pagoda tree, and cadusafos nematicide was 66.80%, 35.81%, and 85.31%, respectively. Furthermore, the addition of plant extracts reduced the reproduction of root-knot nematodes in the infected tomato plants. The highest growth factors were observed on the nematode-free plant when seaweed extract was inoculated to the plant. In the nematode-infected tomato plants, all treatments which were applied to potting soil caused a significant increase in fresh shoot weight. Discussion The results indicated the positive effects of the studied treatments of Seaweed and Pagoda tree extracts and are promising for using plant extracts to control tomato root-knot nematode in greenhouses, the point that can be considered in the management of this nematode in greenhouse crops and combination with other control methods.