INSECTICIDE TRIALS FOR ONION THRIPS (THRIPS TABACI) CONTROL – 2002^††

Lynn Jensen

Malheur County Extension Office

Oregon State University

Ontario, OR, 2002

Introduction

Onion thrips are the major insect pest of onions in the Idaho-Eastern Oregon production area. Many growers are making four to six insecticide applications during the growing season in order to keep the pest suppressed enough to maintain economic yields. Thrips control with Warrior, the most commonly used insecticide treatment, has gone from over 90 percent control in 1995 to less than 60 percent in 2002. New insecticides or new methods of using currently registered products are needed in order to keep onion thrips under control.

Materials and Methods

Two trials were established on the edge of a commercial furrow-irrigated onion field near Nyssa, Oregon. The onion variety was 'Vaquero'. One trial consisted of screening foliar-applied insecticides to identify new compounds or new ways to apply registered materials. The other trial evaluated insecticides that could be soil applied.

Foliar treatments were applied with a CO₂ pressurized sprayer calibrated to apply 38.8 gal/acre water at 30 psi with 8004 flat fan spray nozzles except for one treatment that was applied with a three-nozzle row banding sprayer. This sprayer consisted of three 8001 nozzles/row and was calibrated to apply water at a rate of 37.85 gal/acre. Foliar treatments were applied on June 11 and a second time on June 21. The treatments are listed in Table 1.

On June 6, the soil-applied treatments were shanked into the soil 2 inches to the side and 2 inches deep on the irrigation furrow side of the row. The gallonage was 56.5 gal/acre.

Thrips counts were made on June 13, 21, and 29 in the efficacy trial and on June 13, 21, 29, and July 5 in the sidedress trial.

Results and Discussion

The efficacy trial data are reported in Table 3. Except for the first evaluation date, none of the treatments was significantly different. There was a trend for Warrior (Fig. 2) applied with the three nozzle/row spray boom to result in fewer thrips than Warrior sprayed with the regular boom, except after the second application, but that trend was not significant. There was also a slight advantage to the Warrior-Sugar Solution (Fig. 2) over Warrior alone on the first application but this was not significant. Warrior gave the overall best performance, but it provided less than 60 percent thrips control. Actara, Platinum, and F0570 all performed similarly to Warrior (Fig. 3).

The soil-applied trial results are shown in Table 4. Furadan as a soil-applied insecticide was very effective for the first 2 weeks following application, but control declined after that. Vydate gave some control at the high rate but it was not economical. These data are illustrated in Fig. 4.

Conclusion

Furadan resulted in good early season thrips control as a soil-applied insecticide; however it is not registered for use on onions. None of the foliar-applied materials performed very well. The new chemistries of insecticides such as Actara, Platinum, and F1785 did not perform any better than Warrior.

Table 1. Insecticides and rates evaluated as foliar applications for thrips control in onions. Nyssa, OR, 2002.

*Untreated check.

Table 2. Insecticide treatments and rates for thrips control in onions, Nyssa, OR, 2002.

Treatments – soil applied	Rate lb a.i./acre	Formulated rate
Platinum	0.125	8 oz/acre
Platinum	0.25	12 oz/acre
Vydate	2.0	2.0 qt/acre
Vydate	4.0	4.0 qt/acre
Furadan	1.0	1.0 qt/acre

Table 3. Results of foliar-applied insecticides on onion thrips control in dry bulb onions from applications made on June 11 and 21, Nyssa, OR, 2002.

Treatment	Formulated rate	6/13/2002	6/21/2002	6/27/2002
		----------Average thrips/plant----------
F1785 50DF	1.15 oz/acre	11.9	8.3	10.4
F1785 50DF	2.27 oz/acre	13.0	9.3	19.9
F1785 50DF	4.6 oz/acre	8.8	8.8	13.0
F1785 10WP F0570 15WP	0.36 oz/acre 0.134 oz/acre	8.7	7.9	12.8
F1785 10WP F0570 15WP	0.53 oz/acre 0.134 oz/acre	9.0	6.9	16.7
F1785 10WP F0570 15WP	0.71 oz/acre 0.134 oz/acre	7.9	7.2	14.2
F0570 15WP	0.134 oz/acre	10.9	8.3	12.2
F0570 15WP	0.167 oz/acre	8.9	6.5	13.4
Actara	3.0 oz/acre	8.6	7.0	11.5
UTC*	-------	12.7	11.5	17.6
Platinum	8.0 oz/acre	8.4	6.0	14.9
Warrior	3.84 oz/acre	7.7	6.6	13.9
Warrior (Spray boom)	3.84 oz/acre	5.5	4.8	19.1
Warrior MSR	3.84 oz/acre 24.0 oz/acre	6.1	6.6	12.5
Warrior Sugar Solution	3.84 oz/acre 5.0 lb/100 gal	6.8	6.2	16.0
LSD (0.05)		3.7	ns	ns

*Untreated check.

Table 4. Results of soil-applied insecticides on onion thrips in dry bulb onions, Nyssa, OR, 2002.

Treatment	6/13/2002	6/21/2002	6/27/2002	7/5/2002
	-----------------------Average thrips/plant-----------------------
Platinum 8 oz	18.7	9.5	18.0	37.8
Platinum 12 oz	11.7	10.3	14.7	36.8
Vydate 2.0 qt	13.2	7. 5	14.3	32.1
Furadan	4.1	2.0	11.0	28.3
Vydate 4.0 qt	10.1	4.8	13.5	34.5
LSD (0.05)	5.5	5.1	ns	ns

Figure 1. Comparison of thrips control using Warrior insecticide with a standard spray nozzle configuration versus a three-nozzle/row band, Nyssa, OR, 2002.

Figure 2. Comparison of Warrior and a sugar-solution applied with Warrior for thrips control in dry bulb onions, Nyssa, OR, 2002.

Figure 3. Comparison of new insecticides to Warrior for thrips control in dry bulb onions, Nyssa, OR, 2002.

Figure 4. Results of soil-applied insecticides on onion thrips in dry bulb onions, Nyssa, OR, 2002.

^††The information in this report is for the purpose of informing cooperators in industry, colleagues at other universities, and others of the results of research in field crops. Reference to products and companies in this publication is for the specific information only and does not endorse or recommend that product or company to the exclusion of others that may be suitable. Nor should any information and interpretation thereof be considered as recommendations for the application of any pesticide. Pesticide labels should always be consulted before any pesticide use.

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Last updated  Tuesday September 12, 2006 .