Granular Insecticide Rates for Narrow Rows in Corn

Keith Jarvi,
UNL Department of Entomology,
Northeast Research & Extension Center

February 20, 1997

More people are experimenting with rows of less than 30 inches for corn. If you are planting in continuous corn and are using a soil insecticide at planting for corn rootworm control, be aware that some insecticides have a maximum amount of total pounds that can be applied per acre. Soil insecticides are applied as a specific amount per 1,000 feet of row. In other words, the narrower your row spacing, the more total insecticide you apply per acre.

While some labels are specific on maximum amounts allowed, other labels are not quite as clear. The table below shows different amounts of some soil insecticides to apply in pounds per acre for various row spacings:

Amount of Product in Pounds per Acre for Various Row Spacings
Insecticide	Ounces/1000 row-ft)	38-inch Row	36-inch Row	30-inch Row	20-inch Row
Aztec 2.1G	6.7	5.8 lb	6.1 lb	7.3 lb*	11.0 lb**
Counter 15G	8.0	6.9 lb	7.3 lb	8.7 lb*	13.1 lb**
Counter CR	6.0	5.2 lb	5.4 lb	6.5 lb*	9.8 lb**
Dyfonate 15G	8.0	6.9 lb	7.3 lb	8.7 lb	13.1 lb
Force 3G	4.0	3.4 lb	3.6 lb	4.4 lb	6.6 lb
Fortress 5G	3.0	2.6 lb	2.8 lb	3.3 lb	5.0 lb
Lorsban 15G	8.0	6.9 lb	7.3 lb	8.7 lb	13.1 lb
Thimet 20G	6.0	5.2 lb	5.4 lb	6.5 lb*	9.8 lb**

Notes:

* Maximum allowable per acre.

** This rate is above the labeled rate.

Force 3G can be applied at 5 oz per 1000 ft of row.

Fortress label says 3 oz per 1000 row ft for any row spacing.

Only Dyfonate 15G and Lorsban 15G are clearly labeled for 20-inch row spacing at the "full" rate. Although there is no upper limit listed on the Force 3G label, the label recommends no more than 5 oz per 1000 ft of row. The Fortress label states, "apply Fortress 5G at 3 oz per 1000 ft of row for any row spacing". There is no upper limit on the Fortress label. Rates that are "maxed out" on the 30-inch row spacing would amount to a 2/3 rate if applied to 20-inch rows.