INTERACTION BETWEEN ROOT-LESION NEMATODE, PRATYLENCHUS-NEGLECTUS (RENSCH 1924) CHITWOOD AND OTEIFA 1952, AND ROOT ROTTING FUNGI OF WHEAT

The most frequently isolated fungi from lesioned and non-lesioned segments of wheat roots collected from fields infested with Pratylenchus neglectus were Fusarium oxysporum (Fo), F. acuminatum (Fa), F. equiseti (Fe), Microdochium bolleyi (Mb), Gaeumannomyces graminis (Gg), Bipolaris sorokiniana (Bs), Pythium irregulare (Pi), Pyrenochaeta terrestris (Pt), Phoma sp., and Ulocladium atrum. In a glasshouse experiment, some of the above fungi plus Rhizoctonia solani (Rs) were tested singly and in selected combinations with and without P. neglectus. Number of nematodes per plant and per gram dry root and severity of root lesioning showed a positive interaction between some of these fungi and the nematode. Inoculation with Rs, Mb, Bs, Gg + Fe, or Pi resulted in significantly higher nematode populations per plant or per gram dry root. However, with Gg + Rs, nematode numbers were reduced. Pt, Pi, Fo, or Gg + Fe in combination with the nematode significantly increased severity of root lesioning.