Impact of different spraying techniques on chemical control of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) on cowpea at Sharqia Governorate, Egypt

Abstract

In the current study, three equipment were used to control fall armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) on cowpea (Vigna unguiculata). This equipment was a knapsack motor sprayer (Armitsu) (120 L/fed.), knapsack sprayer (Sunflower) fitted hollow cone nozzle (Tx-6) (40 L/fed.), and even a flat fan nozzle (80 L/fed.), and conventional motor sprayer (300 L/fed.), at Facous, Sharqia Governorate. The present study aimed to determine the effects of application technique with different equipment on initial and late biological efficacy using two recommended insecticides, methomyl (Top cromic SP 90% w/w) 300g/fed [Carbamate group] and indoxacarb (Dronz EC 15% w/v) 25cm3/100L [Oxadiazine]. Regarding the efficacy of the two used insecticides results showed that indoxacarb and methomyl on the larval populations of S. frugiperda on cowpea were insignificant ("F" value = 14.75), whereas indoxacarb produced reduction percent with the used equipment (95.6%, 93.3%, 89.53% and 74.0%) and methomyl recorded (91.83%, 85.13%, 84.00%, and 69.97%). Also, comparative between the equipment, showed that the most effective equipment was the knapsack motor sprayer which recorded (95.6% for indoxacarb and 91.83% for methomyl) percent reduction, then the knapsack sprayer with Tx-6 recorded (93.27% for indoxacarb and 84.0% for methomyl), subsequent with knapsack fitted with an even flat fan recorded (89.53% for indoxacarb and 85.13% for methomyl), and followed by conventional motor sprayer which recorded (74.0% for indoxacarb and 69.97% for methomyl), respectively "F" value was 14.75 and LSD was 1.73. Also, the sprayer recorded 13 and 20 droplets with methomyl and indoxacarb, respectively. In the case of the knapsack motor sprayer, the loss was 10 and 7 droplets with methomyl and indoxacarb respectively, the knapsack sprayer with Tx-6 went down the lowest as 5 and 2 droplets with methomyl and indoxacarb respectively, whereas the same equipment with even flat fan gave lost 5 droplets with both two insecticides.