Effects of elemental sulfur and some chemical fertilizers on activity of the sugar beet cyst nematode Heterodera schachtii under microplot conditions

Reducing the damage of the cyst nematode Heterodera schachtii is one of the research fields in sugar beet producing countries. Using chemical fertilizers can improve soil fertility and reduce damages of plant parasitic nematodes. In this study, the effects of ammonium sulfate, calcium sulfate, zinc sulfate, potassium sulfate, potassium nitrate, sodium silicate, triple superphosphate, iron sequesterine and sulfur on H. schachtii and growth parameters of susceptible sugar beet cultivar (cv Sharif) were investigated in two experiments. The first experiment was performed in plastic pots containing 6 kg of pasteurized field soil and river sand (1:1), and the second one in pots filled with 9 kg of field soil for four and five months, respectively, both under microplot conditions. Fertilizers were mixed with pots soils before sowing and the nematode was inoculated by adding 200 g of infested soil containing 18 cysts with 4200 eggs. The results showed that chemical fertilizers and sulfur did not have significant effects on growth of the infected sugar beet plants in pasteurized mixed or field soils, and some of them reduced it. In the pasteurized soil, zinc sulfate 50 kg/ha, iron sequestrene 5 kg/ha, sodium silicate 10 kg/ha and triple superphosphate 100 kg/ha caused a relative decrease of more than 67% in the nematode final population and reproduction factor. In the field soil, these indices in triple superphosphate 100 kg/ha and sulfur 100 and 200 kg/ha were lower than other treatments, but were at the same statistical level with the control. The third experiment was performed in small containers filled with infested soil to investigate the effects of treatments on nematode egg hatching in greenhouse. The results showed that the highest hatching was happened in the treatment of ammonium sulfate 200 kg/ha, which was statistically at the same level with triple superphosphate 100 kg/ha.