Is it worth the money to have wheat seed treated with an insecticide seed treatment? There’s no simple answer to this questions.

Our experience with wheat seed treatments suggests that they work well to protect the seed and seedling 21-28 days after planting from wireworms, white grubs, flea beetles, grasshoppers, and aphids. If used at the appropriate rate, they will also protect seedlings from Hessian fly if infestations occur within that time frame and densities are not too great. Remember, Hessian fly infestations can occur in the spring also. Greenbugs and bird cherry-oat aphids have been controlled into the spring when the highest labeled rate of an insecticide seed treatment is used.

2010 Bird Cherry-Oat Aphid Seed Treatment Efficacy Trial: Riley County

 

Bird cherry-oat aphid (no. of aphids/5 plants)

Treatment

Dec. 29

Jan. 5

Jan. 12

Untreated

20.3

59.2

69.8

Cruiser @ 2 fl oz/cwt

0.8

4.6

11.2

Gaucho XT @ 3.4 oz/cwt

0.4

9.5

11.9

Infestation date: Dec. 22, 2010. Source: Jeff Whitworth, Holly Davis, K-State Research and Extension Entomologists

 

2009 Greenbug Seed Treatment Efficacy Trial: Greenhouse

Treatment

No. of greenbugs/5 plants

7 days post infestation

No. of greenbugs/5 plants

14 days post infestation

Untreated

275

550

Vitaflo 280 @ 4.4 oz/cwt + Attendant 480 @ 3.3 oz/cwt

1

40

Dividend XL RTA @ 5.5 oz/cwt + Cruiser 5FS @ 0.9 oz/cwt

0

12

Gaucho XT @ 3.7 oz/cwt

1

3

Infested 14 days post-emergence. Source: Jeff Whitworth, Holly Davis, K-State Research and Extension Entomologists

 

2005 Hessian Fly Seed Treatment Efficacy Trial: Hesston

Treatment

No. of larvae/plant

Untreated

8.45

Cruiser 600 FS @ 0.75 fl oz/cwt

0.80

Gaucho 480 @ 1.0 fl oz/cwt

0.25

Wheat planting date: Sept. 30, 2005. Plants transplanted to 4-inch pots on 10/21/05 and brought to greenhouse. Infested with 10 female adults/pot on 10/21/05 for 4 days. Larvae counts made on 11/10/05. Source: Gerald Wilde, K-State Research and Extension Entomologist

 

These charts include only selected treatments with products labeled for wheat, and do not include the standard errors involved in each trial. For full details, see: http://www.entomology.ksu.edu/p.aspx?tabindex=233&tabid=366

On the other hand, insecticide seed treatments are not effective, again from our experience, against false wireworms, fall armyworms, or army cutworms even if infestations occur within 21-28 days after planting.

Insecticide seed treatments are most likely be needed in conditions under which wireworms, white grubs, flea beetles, grasshoppers, Hessian fly, or aphids are favored. In general, the following guidelines apply to those insects Kansas:

* Wireworms and white grubs are more likely to occur under no-till conditions.

* Flea beetles can occur under almost any conditions.

* Grasshoppers can also occur under many different conditions, but are a little more common where wheat is planted next to a field that has grass or grain sorghum under late-season stress.

* Hessian fly is most likely to be a problem when wheat is planted early and in continuous, no-till wheat.

* Aphids can be a problem under many different conditions, but are a little more likely to be a problem on earlier-planted wheat.

Where these conditions do not exist, we generally have found that insecticide seed treatments do not result in any wheat yield response. K-State has conducted some trials that demonstrate this. In these trials (see charts below), there was little or no aphid, greenbug, or Hessian fly pressure.

2005 Insecticide Seed Treatment Trial on Wheat: Riley County

Treatment

Yield (bu/acre)

Untreated

29.23a

Gaucho 480 @ 48 GA/100Kg

31.85a

Cruiser @ 39 GA/100Kg

30.25a

Wheat planting date: Sept. 14, 2004 (4 replications). Yields followed by the same letter indicate no significant difference. Source: Gerald Wilde, K-State Research and Extension Entomologist

 

2011 Insecticide Seed Treatment Trial on Wheat: Dickinson County #1

Treatment

Yield (bu/acre)

Untreated

61.56

Nitro Shield (48.7% imidacloprid) @ 2.4 oz/cwt

60.01

Wheat planting date: Oct. 16, 2010. Plot size = 30 acres. Source: Jeff Whitworth, K-State Research and Extension Entomologist

 

2011 Insecticide Seed Treatment Trial on Wheat: Dickinson County #2

Variety

Yield (bu/acre)

Armour

34.36

Armour

39.53

Armour Gaucho XT @ 3.4 oz/cwt

37.13

Everest

42.60

Everest Gaucho XT @ 3.4 oz/cwt

40.28

Wheat planting date: Oct. 21, 2010. Plot size = 0.4 acre. Source: Jeff Whitworth, K-State Research and Extension Entomologist

 

For more information on the insects mentioned above, see: http://www.entomology.ksu.edu/DesktopDefault.aspx?tabindex=195&tabid=405