ONION THRIPS MANAGEMENT ON DRY ONION, 1996:

 

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
 
R. S. Shimabuku
Cooperative Extension Service
310 Kaahumanu Ave., Bldg 214
Kahului, HI 96732

 

ONION: Allium cepa L. ‘Granex 33’

Onion thrips (OT); Thrips tabaci Lindeman

 

The insecticides were evaluated at the Kula Research Station, Maui Agricultural Park. The field was set up in a randomized complete block design with nine 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 26 Sept. Treatments were applied using a compressed carbon dioxide sprayer at 60 psi and 100 GPA. Silwet L-77 surfactant was used at a rate of 0.0625% v/v. One twin jet nozzle (TJ-6502) was used per row. Treatments were applied at 7-day intervals. The first treatment was made 5 weeks after transplanting. A total of five applications were made (2, 12, 19, 26 Nov, and 3 Dec).

A pre-treatment survey was made on 28 Oct. Subsequent surveys were made on a bi-weekly schedule using the following procedures. Ten plants were randomly selected. The roots and most of the leaves were removed. The remaining portions of the plant (stem, leaf axils, and 2 in. of leaves) were each bagged separately. In the laboratory, each sample was washed in a detergent solution. Thrips were collected in a 150-mesh sieve, 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).

Warrior II 1 EC and both rates of Fipronil 80 WDG provided excellent control throughout the test. Malathion and Alert provided moderate levels of control and could be valuable in an integrated resistance management program for onion thrips. Diazinon and Lannate were ineffective, as overall counts were not significantly different from the untreated check.

 

                                                                  __Number of thrips/10 plants (Pre-treatment: 28 Oct 96)__
Treatment/formulation     Rate
amt/acre
    LI     LII     Adults     Total
Alert 2 SC     0.2 lb. (AI)     1.93+0.38abc     1.58+0.30bcd     0.98+0.19ab     4.48+0.62bcd
Alert 2 SC     0.3 lb. (AI)     0.75+0.18bc     0.73+0.22d     0.78+0.18b     2.25+0.46b
Diazinon AG500     1.0 pt.     1.23+0.32abc     0.93+0.21bcd     0.73+0.12b     2.88+0.54cde
Fipronil 80 WDG     0.025 lb. (AI)     1.63+0.36abc     2.35+0.44abc     1.13+0.22ab     5.10+0.73abc
Fipronil 80 WDG     0.035 lb. (AI)     2.28+0.38a     3.70+0.59a     1.50+0.25ab     7.48+0.82a
Lannate LV     3.0 pt.     1.18+0.26abc     1.90+0.43bcd     1.75+0.29a     4.83+0.68abcd
Malathion 5 EC     2.5 pt.     0.55+0.14c     1.00+0.29cd     0.75+0.16b     2.30+0.37de
Warrior II 1 EC     0.02 lb. (AI)     1.70+0.30abc     1.80+0.34bcd     1.10+0.19ab     4.60+0.63abcd
Untreated check     ---     2.03+0.42ab     2.28+0.32ab     1.45+0.19ab     5.75+0.57ab

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.

 

 

                                                                  __Number of thrips/10 plants (6 DAT 2; 12 Nov 96)__
Treatment/formulation     Rate
amt/acre
    LI     LII     Adults     Total
Alert 2 SC     0.2 lb. (AI)     1.98+0.44cd     17.08+1.99bcd     2.73+0.32a     21.78+2.19bcd
Alert 2 SC     0.3 lb. (AI)     2.40+0.39c     15.38+1.79cd     3.15+0.54a     20.93+2.12cde
Diazinon AG500     1.0 pt.     4.55+0.77ab     25.30+3.07ab     3.30+0.41a     33.15+3.55ab
Fipronil 80 WDG     0.025 lb. (AI)     1.30+0.25cd     12.60+1.14de     3.65+0.51a     17.55+1.63def
Fipronil 80 WDG     0.035 lb. (AI)     0.98+0.20cd     8.45+1.10ef     3.60+0.48a     13.03+1.43fg
Lannate LV     3.0 pt.     1.25+0.23cd     8.08+1.04ef     3.75+0.58a     13.08+1.50efg
Malathion 5 EC     2.5 pt.     2.60+0.54bc     22.70+2.67abc     3.25+0.52a     28.55+2.54abc
Warrior II 1 EC     0.02 lb. (AI)     0.75+0.14d     4.53+0.60f     2.03+0.31a     7.30+0.82g
Untreated check     ---     5.68+0.54a     30.43+2.35a     2.10+0.32a     38.20+2.46a

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.

 

 

                                                                  __Number of thrips/10 plants (6 DAT 4; 25 Nov 96)a
Treatment/formulation     Rate
amt/acre
    LI     LII     Adults     Total
Alert 2 SC     0.2 lb. (AI)     3.98+0.61c     18.98+2.42     4.35+0.55ab     27.30+2.96c
Alert 2 SC     0.3 lb. (AI)     6.33+0.74bc     26.83+1.84b     4.98+0.54a     38.13+2.30b
Diazinon AG500     1.0 pt.     9.50+1.10b     38.83+3.96ab     3.05+0.40bc     51.38+4.38ab
Fipronil 80 WDG     0.025 lb. (AI)     0.98+0.25d     4.08+0.90d     1.23+0.21d     6.28+1.09d
Fipronil 80 WDG     0.035 lb. (AI)     0.35+0.11d     2.00+0.59d     1.13+0.17d     3.48+0.63d
Lannate LV     3.0 pt.     15.75+2.03a     28.73+2.93b     2.43+0.37cd     46.90+4.41ab
Malathion 5 EC     2.5 pt.     8.40+1.14b     10.48+0.99c     3.43+0.38abc     22.30+1.94c
Warrior II 1 EC     0.02 lb. (AI)     0.85+0.18d     4.15+0.36d     2.03+0.24cd     7.03+0.50d
Untreated check     ---     7.28+0.76b     46.60+3.52a     4.20+0.44ab     57.08+4.00a

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.
aLannate and Diazinon, 13 DAT 3. Maximum amount active ingredient allowed on crop reached at third application.

 

 

                                                                  __Number of thrips/10 plants (6 DAT 6; 9 Dec 96)a
Treatment/formulation     Rate
amt/acre
    LI     LII     Adults     Total
Alert 2 SC     0.2 lb. (AI)     3.97+0.61c     18.98+2.42c     4.35+0.55ab     27.30+2.96c
Alert 2 SC     0.3 lb. (AI)     6.33+0.74bc     26.83+1.84b     4.98+0.54a     38.13+2.39b
Diazinon AG500     1.0 pt.     9.50+1.10b     38.83+3.96ab     3.05+0.40bc     51.38+4.38ab
Fipronil 80 WDG     0.025 lb. (AI)     0.98+0.25d     4.08+0.90d     1.22+0.21d     6.28+1.09d
Fipronil 80 WDG     0.035 lb. (AI)     0.35+0.11d     2.00+0.59d     1.13+0.17d     3.48+0.63d
Lannate LV     3.0 pt.     15.75+2.03a     28.73+2.93b     2.43+0.37cd     46.90+4.41ab
Malathion 5 EC     2.5 pt.     8.40+1.14b     10.48+0.99c     3.43+0.38abc     22.30+1.94c
Warrior II 1 EC     0.02 lb. (AI)     0.85+0.18d     4.15+0.36d     2.03+0.24cd     7.03+0.50d
Untreated check     ---     7.28+0.76b     45.60+3.52a     4.20+0.44ab     57.08+4.00a

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.
aLannate and Diazinon, 27 DAT 3. Maximum amount active ingredient allowed on crop reached at third application.

 

Trade Composition\
Common name
    Formulation         name     Source
Alert     SC         chlorfenpyr     American Cyanamid
                       
Diazinon     EC         diazinon     Prentiss
                       
Fipronil     WDG         fipronil     Rhone-Polenc
                       
Lannate     LV         methomyl     DuPont
                       
Malathion     EC         malathion     Drexal

 

 

PART II (Continued) R. F. L. Mau

(808) 956-7063

Trade Composition\
Common name
    Formulation     Chemical name     name     Source
Warrior     EC     lambda-cyhalothrin[1a (S*),3a (Z)]-(+)-cyano -(3-phenoxyphenyl)methy l-3-(2-chloro-3,3,3- trifluoro-1-propenyl) -2,2-dimethylcyclopropanecarboxylate     lambdacyhalothrin     Zeneca