FIELD EVALUATION OF BIO-RATIONAL INSECTICIDES AND COMBINATIONS FOR CONTROLLING DBM, 1993:
CHINESE CABBAGE: Brassica campestris L. 'Takii WR55'
Diamondback moth (DBM); Plutella xylostella (Linnaeus)
DBM parasite (DBMP); Cotesia plutella (Kurdijumov)
Aphid parasite (APA); Lysiphlebus testaceipes (Cresson)
Aphid predator (APR); Allograpta obliqua (Say)
Green lacewing (GLW); Chrysopa sp.
Insecticides were evaluated at the substation of the Kula Research Station, Maui Agricultural Park from October to December. The field was set up in a randomized block design with five treatments and four replications (blocks). Each treatment plot measured 70 ft. by 7.5 ft. It consisted of six rows of cabbage in 3 beds on 36 inch centers and 18 inch in-row spacing. Adjacent rows were offset to allow equidistant plant spacing between rows. Treatment plots in each block were separated by a 3 ft. border. Blocks were separated by a 10 ft. border that allowed sprayer access. Total field size was 150 ft. by 109 ft.
Treatments were applied using a tractor mounted with a PTO driven spray pump equipped with a 30 ft. boom. The boom was set with three banks of twin jet (TJ 8006, Spraying Systems) nozzles that coincided with row spacing. Each group of nozzles had its own line from the main tank, therefore, spray output to specific treatment plot could be easily controlled. Sprays were applied at 150 GPA (40 psi) for the first three applications and increased to 200 GPA (60 psi) for the last three.
Post treatment surveys were conducted on a weekly basis six days after treatment. Ten plants were randomly selected from the two center rows and removed for examination of insects. DBM immatures were counted in separate age groups: early larvae, late larvae, and pupae. Early larvae were those in the first two larval instars. They were identified by their small size and the occurrence of black colored head capsules. Late larvae were those in the last two larval instars. They were identified by their larger size and the occurrence of green or brown head capsules. Pupae were easily identified by their net like cocoons.
Treatment differences were detected after the fifth spray. The best treatment tested was the Align-MVP combination. Treated plots exhibited less feeding damage, the lowest number of caterpillars, and the highest percentage of marketable produce. Parasitoids and predators of the cabbage insect pests were not observed in the field until after the fourth spray application. However, for the remaining period of the trial, beneficial insects (DBMP, APA, APR, GLW) occurred throughout the field. The treatments did not appear to affect their distribution.
Mean number of DBM immatures after 0, 1, 2, 3 or 4 spray applications (date of survey) |
0 & 1 (11 & 16 Nov) | ___2 (23 Nov)___ | ___3 (30 Nov)___ | ____4 (7 Dec)___ |
Treatment | Rate/Acre | Early Larvae |
Late Larvae |
Pupae | Early Larvae |
Late Larvae |
Pupae | Early Larvae |
Late Larvae |
Pupae | Early Larvae |
Late Larvae |
Pupae | |||||
Align | 21 oz | 0.00 | 0.00 | 0.00 | 0.18a | 0.00 | 0.00a | 0.33a | 0.05a | 0.05a | 0.67ab | 0.45b | 0.00a | |||||
MVP | 3 qt | 0.00 | 0.00 | 0.00 | 0.13a | 0.00 | 0.03a | 0.33a | 0.05a | 0.08a | 0.28b | 0.25b | 0.00a | |||||
Align + MVP | 21 oz + 3 qt | 0.00 | 0.00 | 0.00 | 0.03a | 0.00 | 0.00a | 0.10a | 0.03a | 0.00a | 0.18b | 0.08b | 0.00a | |||||
Align + Pyrenone | 21 oz + 2 oz | 0.00 | 0.00 | 0.00 | 0.03a | 0.00 | 0.00a | 0.08a | 0.10a | 0.00a | 0.28b | 0.10b | 0.00a | |||||
Untreated check | --- | 0.00 | 0.00 | 0.00 | 0.10a | 0.00 | 0.00a | 0.13a | 0.10a | 0.00a | 1.33a | 1.70a | 0.03a |
Means in each column followed by a different letter are significantly different (Tukey's studentized range test P<0.001 SAS Institute, version 6.04). Data was transformed by square root (X+0.5) prior to analysis. Untransformed means are presented.
Mean number of DBM immatures after 5, 6, or 7spray applications (date of survey) |
___5 (14 Dec)___ | ___6 (21 Dec)___ | ___7 (27 Dec)___ |
Treatment | Rate/Acre | Early Larvae |
Late Larvae |
Pupae | Early Larvae |
Late Larvae |
Pupae | Early Larvae |
Late Larvae |
Pupae | % Marketable at Harvest |
||||||||||
Align | 21 oz | 1.03a | 1.98a | 0.00a | 0.65a | 3.05b | 0.13b | 2.10a | 2.13b | 0.28b | 12.5b | ||||||||||
MVP | 3 qt | 0.58ab | 0.55bc | 0.03a | 0.20a | 0.75cd | 0.05b | 0.90bc | 1.40b | 0.15b | 35.0ab | ||||||||||
Align + MVP | 21 oz + 3 qt | 0.15b | 0.05c | 0.03a | 0.15a | 0.45d | 0.00b | 0.28c | 0.38c | 0.08b | 62.5a | ||||||||||
Align + Pyrenone | 21 oz + 2 oz | 1.15a | 1.08b | 0.00a | 0.53a | 1.43c | 0.03b | 1.18b | 2.33b | 0.28b | 17.5ab | ||||||||||
Untreated check | --- | 1.20a | 2.10a | 0.13a | 0.60a | 5.48a | 0.48a | 0.95b | 5.68a | 1.03a | 0.0b |
Means in each column followed by a different letter are significantly different (Tukey's studentized range test P<0.001 SAS Institute , version 6.04). Data was transformed by square root (X+0.5) (insect counts) and arcsine (percent marketability) before analysis. Untransformed means are presented.
Trade Composition\Common name | Formulation | name | Source | ||||||||
Align | EC | azadiractin | AgriDyne | ||||||||
MVP | ME | B. thuringiensis | Mycogen | ||||||||
Pyrenone | EC | pyrethrins | Fairfield |