Efficiency of Humic Acid and Three Commercial Biocides Against Meloidogyne incognita and Tylenchulus semipenetrans Associated with Olive Plants

Abstract

In comparison to a chemical nematicide (Oxamyl), humic acid and three commercial bioagents namely Abamectin (Streptomyces avermitilis), Clean Root (Bacillus subtilis) and Nemastrol (chitinase, glycosynolates, Glucanase, cytokinins and flavonoids) were tested in a greenhouse and field to see how they affect the population density of root-knot and citrus nematodes and, as a result, the effects on plant growth parameters. In greenhouse test, humic acid gave the highest results in terms of increasing total plant fresh weight (403.8 %) and shoot dry weight (400%) compared to untreated plants. Regardless chemical nematicide used, Abamectin showed the best results in suppressing Meloidogyne incognita reproduction with a reduction percentage of (85.4%), while Nemastrol resulted the best reduction percentage of Tylenchulus semipenetrans population (84.4%). Six months after treatment, Nemastrol showed the highest decrease percentage of root-knot nematode (82.4%) and citrus nematode (75.6%) in a field experiment. On the other hand, Oxamyl and humic acid outperformed other treatments in terms of improving the percentage of fruit weight (166.84 and 145.87 %), respectively. Furthermore, all treatments had an impact on the fatty acid composition of olive oil. At the same time, compared to untreated trees, such treatments resulted in lower peroxidase and polyphenoloxidase activities. In terms of phenol content, it was clear that Nemastrol, followed by humic acid improved total phenol content. However, Clean Root gained the highest overall protein concentration. Furthermore, humic acid increased the total carbohydrate level.

Inducing Systemic Resistance against Root-knot Nematodes in Eggplant by Chemical and Organic Fertilizers and Antioxidant Substances

“…This outcome was consistent with Song et al (2022) who observed a negative association between nematode abundance and soil accessible Se as a decrease in nematode abundance caused by selenite. Additionally, Hammad et al (2021) demonstrated that humic acid had an intermediate impact on the populations of citrus and root knot nematodes infected olive trees.When Meloidogyne spp. infected eggplant under field settings, integrated management clarified that most applications with three components performed better than those with only two.…”

“…The required dose for getting significant nematode control ranged from 0.04 to 2.0% concentration (Nagachandrabose and Baidoo 2021). Humic acid caused intermediate effect against M. incognita and Tylenchulus semipenetrans on infected olive (Hammad et al, 2021).…”