EVALUATION OF INSECTICIDES FOR ONION THRIPS CONTROL ON DRY ONION, 1996:
ONION: Allium cepa L. Grano 1015Y
Onion thrips (OT); Thrips tabaci Lindeman
The insecticides were evaluated at the Kula Research Station, Maui Agricultural Park, from June to September. The field was set up in a randomized complete block design with six treatments and four replications (blocks). Each treatment plot consisted of four rows of plants planted at 8 in. between plant spacing. Each row consisted of 45 plants. Seedlings were transplanted into the field on 17 Jun. Treatments were applied using a compressed carbon dioxide sprayer at 60 psi and 100 GPA. Two twin jet nozzles (TJ-6502) were used per two rows. Applications of Warrior @ 0.02 and 0.03 lb. ai/A, Lannate, and Ammo were made at 7-day intervals on 16, 23, 30 July, 6, 13, 20 Aug for a total of six applications. The second treatment of Warrior @ 0.03 lb. ai/A was made when thrips numbers exceeded 3 thrips/plant. Thrips monitoring via in-field monitoring on 10 randomly selected plants in each plot were made. If the thrips average for all four replicates exceeded 3 thrips/plant, a treatment was made on the following day. Treatments were made on 23 July, 6, 20 Aug.
A pre-treatment survey was made on 15 Jul. Subsequent surveys were made on a bi-weekly schedule. In surveying for thrips, ten plants were randomly selected and removed . The bulb and leaves were removed and the whorl of the onion was placed in separate plastic zip lock bags.
Each sample was washed in a detergent solution and the thrips were collected in a 150 mesh sieve. The thrips were transferred into plastic 20 ml vials, preserved with 70% ethyl alcohol, and counted at a later date. Thrips were recorded by developmental stages first instar larvae (LI), second instar larvae (LII), and adults (A).
Weekly Warrior and Ammo treatments were very effective in causing a ten- to 20-fold reduction in thrips numbers. There was no difference in the thrips control produced by either rate of Warrior. Both were equally effective. Treatment with Warrior using a 3-thrips threshold was as effective as weekly calendar sprays of the insecticide. A single application of Warrior using a treatment threshold was ostensibly as effective as the two weekly applications of Warrior. The Lannate LV treatment increased moderately, but not at the same rate as in the untreated check. At the final post-treatment survey, the same order of effectiveness was found. Warrior and Ammo treatments successfully regulated thrips numbers at low levels. Thrips density in the Lannate LV treatment equaled that of the untreated check.
__________Mean number of thrips/10 plants__________ |
_____________Pre-treatment (15 July)_____________ |
Treatment | Rate/Acre | LI | LII | A | Total | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) | 8.85+1.76b | 15.88+2.42a | 6.63+0.89a | 31.35+4.50a | ||||||||
Warrior II 1 EC | 0.02 lb. (AI) | 8.08+1.24b | 17.15+2.54a | 6.90+0.92a | 32.13+4.12a | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) (3 thrips/plant threshold) |
10.85+1.20ab | 16.58+2.13a | 4.98+0.53a | 32.40+3.19a | ||||||||
Lannate LV | 0.45 lb.(AI) | 8.85+1.69b | 19.25+2.47a | 7.65+0.96a | 35.75+4.22a | ||||||||
Ammo 2.5 EC | 0.08 lb. (AI) | 11.28+1.20ab | 13.25+1.54a | 6.60+0.75a | 31.13+2.81a | ||||||||
Untreated check | --- | 14.80+1.90a | 12.20+2.02a | 4.75+0.48a | 31.75+3.62a |
Means in the same column followed by a different letter are significantly different (P>0.001, SAS for Windows version 6.11). Data was transformed by square root (Y+0.5) prior to analysis. Untransformed means are presented.
__________Mean number of thrips/10 plants__________ |
_______________*6 DAT 2 (29 July)_______________ |
Treatment | Rate/Acre | LI | LII | A | Total | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) | 0.13+0.06c | 0.15+0.07d | 1.08+0.21bc | 1.35+0.24d | ||||||||
Warrior II 1 EC | 0.02 lb. (AI) | 0.30+0.10c | 1.25+0.36cd | 0.63+0.17cd | 2.18+0.50d | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) (3 thrips/plant threshold) |
1.13+0.28bc | 1.68+0.29cd | 0.23+0.08d | 3.03+0.52cd | ||||||||
Lannate LV | 0.45 lb.(AI) | 12.98+2.12a | 12.33+2.19b | 1.73+0.25ab | 27.03+4.20b | ||||||||
Ammo 2.5 EC | 0.08 lb. (AI) | 3.05+0.55b | 3.73+0.80c | 0.83+0.17bcd | 7.60+1.23c | ||||||||
Untreated check | --- | 12.35+1.30a | 26.38+5.18a | 2.93+0.60a | 41.65+5.89a |
__________Mean number of thrips/10 plants__________ |
_____________*6 DAT 4 (12 August)______________ |
Treatment | Rate/Acre | LI | LII | A | Total | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) | 0.40+0.16c | 2.18+0.78c | 2.48+0.36b | 5.05+1.14c | ||||||||
Warrior II 1 EC | 0.02 lb. (AI) | 0.43+0.19c | 1.35+0.30c | 1.18+0.25b | 2.95+0.60c | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) (3 thrips/plant threshold) |
2.25+0.50c | 4.05+0.68c | 1.93+0.33b | 8.23+1.28c | ||||||||
Lannate LV | 0.45 lb.(AI) | 9.68+1.14b | 31.75+4.04b | 7.38+1.98a | 48.80+5.57b | ||||||||
Ammo 2.5 EC | 0.08 lb. (AI) | 1.35+0.40c | 5.18+1.04c | 1.98+0.32b | 8.50+1.51c | ||||||||
Untreated check | --- | 17.20+2.19a | 63.05+8.25a | 5.53+1.00a | 85.78+9.96a |
__________Mean number of thrips/10 plants__________ |
_____________*6 DAT 6 (26 August)______________ |
Treatment | Rate/Acre | LI | LII | A | Total | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) | 0.33+0.12b | 1.58+0.40b | 0.80+0.21c | 2.70+0.53b | ||||||||
Warrior II 1 EC | 0.02 lb. (AI) | 0.65+0.24b | 1.63+0.30b | 1.43+0.23bc | 3.70+0.61b | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) (3 thrips/plant threshold) |
1.15+0.30b | 2.10+0.35b | 0.83+0.16c | 4.08+0.58b | ||||||||
Lannate LV | 0.45 lb.(AI) | 8.90+1.35a | 25.33+3.38a | 4.10+0.80a | 38.33+4.68a | ||||||||
Ammo 2.5 EC | 0.08 lb. (AI) | 0.83+0.18b | 3.53+0.40b | 0.98+0.18bc | 5.33+0.53b | ||||||||
Untreated check | --- | 8.45+1.37a | 28.48+3.78a | 2.08+0.37b | 39.00+5.11a |
______Seasonal Means (Number of thrips/10 plants______ |
Treatment | Rate/Acre | LI | LII | A | Total | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) | 2.43+0.53e | 4.94+0.81c | 2.74+0.31b | 10.11+1.52c | ||||||||
Warrior II 1 EC | 0.02 lb. (AI) | 2.36+0.41de | 5.34+0.84c | 2.53+0.31b | 10.24+1.45c | ||||||||
Warrior II 1 EC | 0.03 lb.(AI) (3 thrips/plant threshold) |
3.84+0.47cd | 6.10+0.74c | 1.99+0.22b | 11.93+1.29c | ||||||||
Lannate LV | 0.45 lb.(AI) | 10.10+0.81b | 22.16+1.64b | 5.21+0.62a | 37.48+2.41b | ||||||||
Ammo 2.5 EC | 0.08 lb. (AI) | 4.13+0.48c | 6.42+0.60c | 2.59+0.28b | 13.14+1.19c | ||||||||
Untreated check | --- | 13.20+0.89a | 32.53+3.02a | 3.82+0.34a | 49.53+3.67a |
Means in the same column followed by a different letter are significantly different (P>0.001, SAS for Windows version 6.11). Data was transformed by square root (Y+0.5) prior to analysis. Untransformed means are presented.
Trade Composition\Common name | Formulation | name | Source | ||||||||
Ammo | EC | cypermethrin | FMC Corp. | ||||||||
Lannate | EC | methomyl | DuPont | ||||||||
Warrior | EC | lambdacyhalothrin | Zeneca. |