Effect of Phorate 10G and Neem Cake on Tylenchulus semipenetrans in a Declining Nagpur Mandarin Orchard in Central India

A field experiment was conducted during the year 2008–10 to assess the effect of phorate 10G @ 1.0, 1.5 and 2.0 kg a.i. per ha and neem cake @ 10, 15, 20 kg/tree on population behavior of Tylenchulus semipenetrans in a declining Nagpur mandarin orchard in central India. Nematode population levels were assessed before treatment and after 4, 8 and 12 months following treatment. Application of phorate 10G and neem cake beneath the tree canopy resulted in significantly higher % reduction (44.2% in soil and 48.4% in roots in case of phorate 10G @ 2.0 kg/ha and 39.2% in soil and 32.8% in roots in case of neem cake @ 15 kg/tree) in nematode population compared to untreated control plants (22.6% in soil and 20.59% in roots) twelve months after treatment. The results indicated that in general the percent reduction over initial population was significantly more in trees treated with phorate 10G in comparison to trees treated with neem cake. Percentage reductions in population of females per gram fresh root weight were approximately double in plants receiving phorate 10G compared to untreated control plants. Plants receiving phorate 10G supported minimum nematode reproduction (Rf = 0.55) compared to all treatments and control plants. Maximum increase in canopy volume (9.54%) was observed in the treatments where phorate 10G was applied @ 2 kg per ha.