Effect of Plant Age on Resistance to Aphids (Aphis craccivora Koch) and Rosette Virus in Groundnut uri icon

abstract

  • In greenhouse trials at Chitedze, Malawi, long-duration Virginia-type groundnut cultivars Chalimbana and CG7 (susceptible to both virus and aphids) and RMP 12. EC 36892 and ICGV-SM 90704 (not resistant to rosette disease (caused by groundnut rosette umbravirus) but resistant to aphids) were infested with aphids at 14, 23 or 43 days after sowing (DAS). Three days after infestation, half of the plants were sprayed with pirimiphos-methyl (Actellic 50EC) and all plants were covered with perforated plastic sleeves. Aphid populations were largest on plants infested at 14 DAS, followed by those infested at 23 DAS. Rosette infection was significantly lower in plants infested at 43 DAS than in plant infested earlier. Aphid population growth was significantly lower on EC 36892 (an aphid-resistant line) than on the other cultivars. Rosette infection was highest on CG7 and Chalimbana. Rosette infection was higher when aphids were allowed to remain on the plant for an additional 25 days following the 3-day infestation period (54.4%) than when they were sprayed with pirimiphos-methyl. It is suggested that the optimum feeding period for aphids is longer than 3 days

publication date

  • 1997