Control of Ditylenchus dispsaci on Onion by Chemical Treatments with Cadusafos, Fenamiphos and Aldicarb

For controlling Ditylenchus dispsaci on onion, the effectiveness of cadusafos (rugby) at 3 and 5 g/m2 doses was tested and compared with fenamiphos (30 g/m2) and aldicarb (10 g/m2) in sandy soil at Zapponeta, Foggia province, Southern Italy. All the three nematicides significantly reduced the number of plants sjhowing symptoms of nematode damage as well as nematode population density in the soil. Cadusafos treatment at the above dosage was effective in reducing unmarketable bulb weight, but only fenamiphos gave significant increases of marketable bulb weight. Fenamiphos residues in marketable onion bulbs ranged between 0.085 and 0.140 mg/Kg; the tolerance limit of this chemical in onion bulbs in Italy is 0.1 mg/Kg.