Efficiency of commercial products of antagonistic fungi for controlling root–knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood of cassava

Abstract

The efficiency 4 commercial products of antagonistic fungi, Product 1 (Beauveria bassiana), Product 2 (Paecilomyces lilacinus), Product 3 (Metarhizium anisopliae) and Product 4 (Trichoderma harzianum) on control root–knot nematode (RKN, Meloidogyne incognita) of cassava variety Rayong 9 was investigated under greenhouse condition in comparison to using nematicide (carbosulfan) and no use of the products or nematicide but inoculation with RKN egg suspension (control 1) and untreated cassava (control 2). Two experiments were conducted in the rainy season (June 27^th – August 12^th 2018, 21–35.5 ˚C, 88–96 % R.H.) and cool season (November 23^rd 2018 – January 7^th 2019, 17–35.7 ˚C, 80–96 % R.H.). The commercial products of antagonistic fungi were applied using recommendation rates to the cassava plants in pots, 1 plant/pot. After 7, 5, 3 and 0 days of fungal application, the RKN egg suspension was infested in the potting soil. The experiments were carried out in a greenhouse for 2 seasons, each experiment comprised 19 treatments, 4 replications (pots). After 45 days of RKN inoculation, cassava plants were determined and evaluated on nematode parameter, the number of eggs per root system (main criteria for assessing severity) number of eggs per gram root and number of female adults per gram root, including growth parameter, (plant height, shoot and root fresh weight and root fresh weight).  The result from 2 seasons, rainy season (June 27^th –  August12^th 2018, 21–35.5 ˚C, 88–96% R.H.) and cool season (November 23^rd 2018-January7^th 2019,17–35.7 ˚C, 80–96% R.H.) showed that the use of T. harzianum 7 days before inoculation, gave the best result, compared to other antagonistic fungi used for control root-knot nematodes with the number of egg masses per root system of 21.05 and 116.64 egg masses, respectively, which were not significantly different to the use of carbosulfan with the lowest value (20.87 and 97.14 egg masses, respectively). It also reduced number of eggs per root system  89.67 and 93.92, respectively. The results on growth evaluation of cassava plants, shoot height, shoot and root fresh weight, and root fresh weight obtained from 2 seasons showed that shoot height of control 1 was the minimum height, while more – the most of shoot height, and shoot and root fresh weight were obtained from the application of M. anisopliae in different treatments, whereas the control 1 was in the group of low – the lowest values of shoot and root fresh weight. The result of this study indicated that the antagonistic fungus of commercial product T. harzianum can be applied efficiently comparable with carbosulfan to control RKN in cassava under this greenhouse condition.