Observations on host range, vertical movement and soil pH on spores of Pasteuria Penetrans infecting Heterodera Cajani

Sixteen nematode species belonging to 14 different genera of the order Tylenchida, Dorylaimida and Mononchida were tested for encumbrance of Pasteuria penetrans spores obtained from Heterodera cajani cysts. Spores were found to encumber on the second-stage juveniles and males of Heterodera avenue; juveniles, males and females of Hoplolaimus indicus; and juveniles and females of Helicotylenchus delhiensis in the range of 10–20, 5–10 and 1–5, respectively while the number of spores on H. cajani were in the range of 20–45 at 2.8 x 10⁵ spores/g sand, on incubation at 2S°C for 48 h. Observations on the vertical movement of spores in different soil types using spore encumbrance as bioassay showed that the spores reached to a depth of 12 cm after a single application of water from the top. Their further movement and distribution in soil increased with greaterpore size and decreased with an increase in the silt and clay contents of the soils. Soil pH had a significant effect on spore encumbrance. At a pH of 8.0 and 10.0, the average number of spores encumbered on the second-stage juveniles of H. cajani was 36.45 and 26.32 compared to 7.0 and 10.35 at a pH of 4.0 and 6.0, respectively.