Occurrence, Population Density and Biological Control of Root-Knot Nematode, Meloidogyne javanica Infecting Pomegranate Orchards in Assiut Governorate, Egypt

Abstract

The survey conducted to assess the incidence of root-knot nematode on pomegranate in five localities (El-Badary, Manfalout, Sedfa, Sahel-Selim and El-Fath) in Assiut governorate. Results showed that 490 out of 500 samples were infested with root-knot nematode showing 98% infestation. Maximum infestation was found in El-Badary, Manfalout and El-Fath (100%), while the minimum was observed in Sahel-Selim (94%) followed by Sedfa (96%). In growing season 2013, the highest occurrence of root-knot nematode second stage was in pomegranate orchards of Sahel-Selim locality (394 J2/100 g soil), but the lowest number was found in Sedfa county (88.8 J2/100 g soil). In 2014, the highest number of juveniles per 100 g soil was observed in El-Fath county (275.4), whereas Manfalout county was the lowest infection (134.2). Bioagents (fungi, bacteria, yeast and actinomycetes) were isolated from pomegranate rhizosphere and evaluated against root-knot nematode J2 mortality percent in vitro. Among 29 fungal culture filtrates, the highest effect was found in culture filtrate of 3 isolates (2, 3 and 10) with average mortality percent 8.33, 10.01 and 9.22, respectively with nonsignificant. The fungal isolate No. 3 was selected and identified as Fusarium verticilloids. From 17 isolates of bacteria, yeast and actinomycetes, the highest mortality was observed in case of isolates No. 8, 9, 10, 11, 12, 15 and 16 with average 24.22, 23.69, 25.59, 25.82, 26.52, 22.13 and 25.24 mortality percent respectively, with nonsignificantly difference. According to morphological and physiological characteristics, isolates No. 10, 11, 12 and 16 were identified as Xenorhabdus beddingii, Streptomyces halstedii, Pantoea agglomerans and Pichia guilliermondii.