Assessment of Some Onion Accessions for Their Resistance to Thrips in Arumeru District, Tanzania

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Onion thrips (Thrips tabaci Lindeman) are dual destructive as both pests and vectors of Tospo viruses. Thrips tabaci has impact on a wide range of crops. Thrips damage, thrips count, leaf parameters, tolerance, susceptibility and onion yield of thirteen onion genotypes and three commercial onion cultivars were tested. The results of TAUIPC (Total Area Under Infestation Pressure Curve) showed that the accessions having their average leaf damage below two namely VIO38552, VIO38512 and AVON 1067 were categorized as the most tolerant accessions among the tested genotypes. There was no significant difference in leaf angles among the tested genotypes. Accessions with tougher foliage showed less symptoms of thrips feeding and oviposition damage compared to accessions with softer foliage. The mean bulb yields from infested but insecticide sprayed group were significantly higher (17.9 tons. ha-1 ) compared to non sprayed control group (13.5 tons. ha-1 ). Three tested accessions namely VIO38552, VIO38512 and AVON 1067 were least affected by thrips and gave the highest yield hence were considered as the most promising tolerant accessions. Accessions VIO38552 and VIO38512 lead in yield production by 43tons . ha-1 and 28 tons . ha-1 respectively in sprayed onion accessions and 38 tons . ha-1 and 22.5 tons . ha-1 in non-sprayed onion accessions respectively. Chemical contr

Agnes M.S. Nyomora
International Journal of Horticulture and Ornamental Plants