Integrated Crop Management

Wireworms Part 2: Insecticides evaluated in Iowa

Wireworms are occasionally a concern to farmers planting corn. Stand loss occurs in a very small percentage of Iowa cornfields, but where the problem does exist, it may persist for several years. Prevention of stand loss caused by wireworms can only be accomplished with the use of an insecticide. In the March 20 ICM newsletter, data from Missouri [1] were presented that measured the percentage of healthy plants in several insecticide treatments. In this article, Iowa data are presented but the numbers measure the percentage stand increase over the untreated check. The Missouri and Iowa data cannot be compared because each is using a different method of evaluation.

[2] Wireworm and damage to a corn seed.

Data from several Iowa experiments are shown in Table 1, below. Only those tests in which the wireworm population caused substantial injury (injury rating scale rated 2.0 or higher) to the untreated check plots are included. The wireworm injury scale is

  1. seed or seedling undamaged;
  2. seed or seedling damaged, but plant established;
  3. seed or seedling damaged, plant showing some signs of stress; and
  4. seed or seedling damaged, no plant or questionable establishment

Selecting the "best" product may be difficult because of the small number of times a product was evaluated or because of variability in performance over the years. A ranking of the products based upon their performance may be a convenient way of judging which products are most likely to provide the best seed and seedling protection.

Table 1. Comparison of efficacy of registered insecticides for control of wireworms in corn measured as percentage stand increase over the untreated check.

Insecticide Formulation Rate* Placement 1998

Linden
1997

Lacona
1996

Garner
1992

Onslow
1986

Decatur
1986

Hedrick
1985

Murray
Agrox D-L Plus ST 3.6 oz mat/cwt ST -- -- -7 48 48 9 20
Agrox Premiere ST 1.8 oz mat/cwt ST -- 24 -- 42 -- -- --
Aztec 2.1G 0.07 Furrow 26 20 6 -- -- -- --
Aztec 2.1G 0.14 Furrow 27 10 8 -- -- -- --
Counter 20CR 0.6 Furrow 26 8 7 -- -- -- --
Counter 20CR 1.2 Furrow 29 14 -2 12 46 28 7
Force 3G 0.15 Furrow 22 14 6 55 -- -- --
Force 3G 0.15 T-band 35 32 3 44 -- -- --
Fortress 5G 0.15 Furrow 23 20 -1 -- -- -- --
Germate Plus ST 3.6 oz mat/cwt ST 30 10 -3 -- -- -- --
Kernel Guard ST 3.6 oz mat/cwt ST 30 24 11 63 -- -- --
Lorsban 15G 1.2 Furrow 16 20 -- -- 37 9 6
Regent** 4SC 0.12 Furrow-M 25 -- -3 -- -- -- --
Thimet 20G 1.2 T-band 23 22 -- 55 34 14 9
CHECK Stand Count 19.25 19.67 24.63 15.50 16.75 19.75 16.50
CHECK Damage Rating*** 2.36 2.46 2.06 2.31 2.80 2.02 2.64

* Granular insecticides listed as oz(AI)/1,000 row-ft.

** 1 GPA water carrier.

*** Rating scale as described in text.

This article originally appeared on pages 28-29 of the IC-484 (4) -- April 10, 2000 issue.


Source URL:
http://www.ipm.iastate.edu/ipm/icm//ipm/icm/2000/4-10-2000/wireworms2.html