MELON THRIPS MANAGEMENT ON EGGPLANT, 1997:

R. F. L. Mau and L. R. Gusukuma-Minuto
University of Hawaii
Dept. of Entomology
3050 Maile Way, Rm. 310
Honolulu, HI 96822
Phone: (808) 956-7063

 

EGGPLANT: Solanum melogena L. ‘Molokai Nitta Hybrid’

Melon thrips (MT); Thrips palmi Karny

The study was conducted at the substation of the Kula Research Station, Maui Agricultural Park. The field was set up in a randomized complete block design with seven treatments and four replications (blocks). Each treatment plot consisted of a double row of eggplant planted at 30 in. between plant spacing. Each row consisted of 14 plants for a total length of approximately 35 ft. A spacing 8 ft. wide separated treatment plots. Blocks were separated by a 4 ft. spacing. Total field size was 0.35 acres. Treatments were applied at 60 psi with an output of 100 GPA using a compressed CO2 sprayer. One flat fan 6504 spray nozzle was used. Treatments were applied at 7-day intervals on 25 Jun, 2, 9, and 19 July.

Insect surveys were made on a weekly basis 5-days after the previous treatment application for a total of three post treatment surveys. At each survey, one-half of the third leaf from the apical growing tip was sampled and placed in separate plastic zip lock bags. Ten randomly selected leaves were sampled per treatment plot. Each sample was washed separately with a detergent solution and the thrips were collected on a 150 mesh sieve. Thrips were recorded by developmental stages first instar larvae (LI), second instar larvae (LII), and adults' (A). Percent MT feeding damage under the calyx of the fruit was also recorded on the mature fruit harvested from the treated plots.

Alert successfully controlled the melon thrips. All three rates of Alert effectively reduced MT on leaves during the study. AgriMek treatments gave moderate levels of control for leaf infestations of MT. The 16 oz./A rate was more effective than the 8 oz rate. Vydate L was not very effective at controlling MT leaf infestations.

Mature fruits harvested from the Alert treated plots exhibited less MT feeding damage under the calyx region of the fruit. Damage on fruits harvested from the Vydate treated plots exhibited the most amount of damage after that of the untreated check. This demonstrates that Vydate L is no longer effective in providing economic levels of MT control.

 

                                                                                              Seasonal number of thrips/10 leaves
                                                              ______________Larvae_____________
Treatment/formulation     Rate
amt/acre
    LI     LII     TOTAL     Adults     Total no. thrips
Alert 2 SC     0.1 lb. (AI)     5.48+0.91d     5.54+1.14c     11.02+1.88d     2.14+0.24bc     13.16+1.98d
Alert 2 SC     0.2 lb.. (AI)     3.96+0.75d     2.64+0.54c     6.60+1.13d     1.72+0.25c     8.32+1.12d
Alert 2 SC     0.3 lb. (AI)     3.40+0.75d     4.85+2.97c     8.25+3.53d     2.48+0.33bc     10.73+3.64d
Vydate L     4.0 pt.     16.71+1.72ab     19.40+3.48b     36.11+4.61b     3.08+0.38ab     39.19+4.75b
Agri-Mek 0.15 EC     8.0 oz.     16.34+2.35bc     17.88+2.15b     34.23+4.24bc     2.69+0.30bc     36.92+4.40bc
Agri-Mek 0.15 EC     16.0 oz.     10.31+1.41c     11.99+1.86b     22.30+2.81c     3.48+0.46ab     25.78+3.06c
Untreated check     ---     20.08+1.79a     51.91+6.53a     71.99+7.71a     4.45+0.49a     76.44+7.91a

Means in the same column followed by a different letter are significantly different (P<0.0001, SAS for Windows version 6.11). Data was transformed by square root (Y+0.5) prior to analysis. Untransformed means are presented.

 

 

                                                           

_% Fruits damaged under
calyx at harvest dates_

Treatment/formulation     Rate
amt/acre
    14 Jul     21 Jul
Alert 2 SC     0.1 lb. (AI)     67.5+1.7cd     35.0+0.8f
Alert 2 SC     0.2 lb.. (AI)     30.0+2.0f     45.0+0.8e
Alert 2 SC     0.3 lb. (AI)     47.5+3.0e     35.0+1.4f
Vydate L     4.0 pt.     76.0+0.7b     85.0+1.4b
Agri-Mek 0.15 EC     8.0 oz.     70.0+2.5bc     62.5+1.3c
Agri-Mek 0.15 EC     16.0 oz.     62.5+0.7d     55.0+0.2d
Untreated check     ---     92.5+1.3a     92.5+0.7a

Means in the same column followed by a different letter are significantly different (P<0.0001, SAS for Windows version 6.11). Data was transformed by arcsine transformation prior to analysis. Untransformed means are presented.

 

 

Trade Composition\
Common name
    Formulation         name     Source
Alert     SC         chlorfenpyr     American Cyanamid
                       
Agri-Mek     EC         abamectin     Merck & Co.
                       
Vydate     L         oxamyl     Du Pont