Efficacy of some algal species, azolla and compost extract in controlling root knot nematode and its replection on cucumber growth

This study aimed to use nine culture filtrates of algal strains (Nostoc muscorum, Anabaena flos aquae, Anabaena oryzae, Chlorella vulgaris, Wollea saccata, Phormedium fragile, Oscillatoria sp., Nostoc humifusum and Spirulina platensis), Azolla pinnata aqueous extract filtrate (1:2 w/v) and compost watery extract filtrate (1:5 w/v) in controlling the population of the root knot nematode, Meloidogyne incognita in cucumber under both laboratory and greenhouse conditions. Laboratory experiment revealed that high juvenile mortality percentage occurred during all the exposure periods of all treatments, the best results were after 72 hr exposure. Only five cyanobacterial strains, namely, Spirulina platensis, Oscillatoria sp., Anabaena oryzae, Nostoc muscorum and Phormedium fragile, followed by compost watery extract, significantly increased juveniles mortality over 70% at the highest concentration of 1:10 (84.3, 80.4, 78.9, 75.4, 72.5 and 70.1%, respectively). Azolla pinnata aqueous extract filtrate achieved 69.8% at the same concentration while, Anabaena fins aquae and Chlorella vulgaris recorded the lowest effect on mortality percentage C 2.1 and 40.1%, respectively) at the concentration of 1:10. In the greenhouse experiment, the combination of mixing five algal culture filtrates of S. platensis, Oscillatoria sp., A. oryzae, N. muscorum and P. fragi. with A. pinnata aqueous extract filtrate and compost extract achieved the highest reduction in the number the 2nd stage juveniles in soil, the numbers of galls, developmental stages, females, egg masses, egg numbers/egg mass in roots of cucumber plants comparing with the individual treatment and the non treated control. In addition; all. combinations significantly improved fresh weight of roots and shoots and increased the yield of cucumber plants. The combined treatment of mixed algal culture filtrates + A. pinnata aqueous extract filtrate + compost extract significantly enhanced the soil biological activity in terms of total bacterial count, total cyanobacterial count, CO2 evolution, dehydrogenase and nitrogenase activities as well as the soil available nitrogen forms (NH4+, NO3' and NO2), available phosphorus and potassium over the control and resulting in soil electrical conductivity (EC) and soil pH reduction. It could be recommended that application of bioorganic agents as nematicidal against root knot nematode in cucumber is preferable in order to reduce the soil and plant polluting chemical nematicides.