HPIPM:Southwestern Corn Borer FC
Author: Frank B. Peairs[1]
Identification (and life cycle/seasonal history)
Southwestern corn borer, Diatraea grandiosella Dyar, larvae are dull white with dark brown to black spots forming a regular pattern along the body. These spots generally disappear in over wintering larvae. Fully developed larvae are 25 to 32 millimeters (one to 1.2 inches) long. Moths are white to pale yellow in color and about 19 millimeters (0.75 inch) long. They have no dark markings. Adults are active primarily at night but can be found during the day under leaves.
Overwintering larvae pupate in the spring and emerge as adults about 10 days later. These moths lay eggs that produce the first generation of southwestern corn borers. There are two to three generations per year. Generally, eggs, which have distinctive red bands, are laid in groups of two to five, overlapping slightly on the upper surfaces of leaves.
Plant Response and Damage
Young larvae feed in the whorls of young corn plants. This feeding may result in "dead heart," the death of the growing tip. Half-grown larvae of the second or third generation crawl down from the whorl and burrow into the stalk and begin tunneling in preparation for over wintering. The larvae chew a groove around the inside of the stalk a few inches above the soil surface. This girdling weakens plants and makes them susceptible to lodging. The mature larva over winters in the underground part of the crown of the corn plant.
Management Approaches
Second brood larvae girdle stalks, which often results in lodging. Early planted corn may escape second brood damage. Early varieties and crop rotation may also reduce yield losses. Fall and winter stalk destruction, on an area wide basis, can reduce over wintering populations. If 25 percent of the plants have egg masses or newly hatched larvae, chemical control is justifiable.
Control can be expected with Bt corn hybrids, except those containing just events that target corn rootworms. See Managing Corn Pests with Bt Corn, [2], for details on the use of Bt corn hybrids to control corn pests. See [3] for an excellent summary of currently available traits.
Product list for southwestern corn borer
| Pesticide | Product/Acre (Fl oz. or oz. product) | Preharvest Interval, remarks |
|---|---|---|
| FastacR,1 | 2.7 - 3.8 | 30 days grain and stover, 60 days forage. 12 hr REI. Extremely Hazardous to Bees! No more than 11.4 fl oz per season. |
| Bacillus thuringiensis1,2 | See labels | 0 days. 4 hour REI. Use of a spreader-sticker is recommended. |
| beta-cyfluthrinR,1,2 | See labels. | 21 days. 12 hour REI. See labels. Extremely Hazardous to Bees! |
| Beauveria bassiana1,2 | See labels | 0 days. 4 hr REI. Potentially pathogenic to bees; avoid applying where bees are foraging or around hives. |
| bifenthrinR,1,2 | See labels | 30 days. 12 hour REI. Use rates below 0.08 lb a.i./acre only if spider mites are NOT a concern. Extremely Hazardous to Bees! |
| HeroR,1 | 4.0 - 10.3 | 30 days to harvest grain or fodder. 60 days to forage. 12 hour REI. See labels for additional restrictions for individual active ingredients. Do not apply more than 0.4 lb ai/acre/crop. Extremely Hazardous to Bees! |
| bifenthrin + chlorpyrifosR,1,2 | See labels | 30 days. 24 hour REI. Maximum 50.5 fl oz product/season. See labels for additional restrictions for individual active ingredients. Extremely Hazardous to Bees! |
| carbaryl1,2 | See labels | 48 days grain and stover, 14 days silage. 12 hour REI. Extremely Hazardous to Bees! |
| Prevathon | 14-20 | 14 days grain, 1 day fodder, forage, stover, silage. 4 hour REI. Do not apply more than 0.2 lb ai/acre/crop. |
| chlorpyrifos 4ER,1,2 | 16 - 32 | 21 days. 24 hour REI. Not for use on popcorn. Extremely Hazardous to Bees! |
| chlorpyrifos + gamma cyhalothrinR,1,2 | See labels | 21 days. 14 days to graze. 24 hour REI. Extremely Hazardous to Bees! See labels for additional restrictions for individual active ingredients. |
| Cobalt AdvancedR,1 | 16-38 | 21 days. 14 days to graze. 24 hour REI. See labels for additional restrictions for individual active ingredients. Extremely Hazardous to Bees! |
| Grandevo1 | 1-3 lbs | 0 days. 4 hour REI. May be repellent to bees. |
| cyfluthrinR,1,2 | See labels | 21 days. 12 hour REI. See labels. Extremely Hazardous to Bees! |
| deltamethrinR,1,2 | See labels | 21 days to harvest grain or fodder. 12 days to forage. 12 hour REI. Do not apply more than 0.095 lb ai/acre/crop. Extremely Hazardous to Bees! |
| esfenvalerateR,1,2 | See labels | 21 days. Apply as necessary to maintain control. Extremely Hazardous to Bees! |
| Belt1 | 2 - 3 | 28 days grain, 1 day forage and silage. 12 hour REI. |
| gamma cyhalothrinR,1,2 | See labels | 21 days. 24 hour REI. Do not apply more than 0.12 lb a.i./acre/season. Extremely Hazardous to Bees! |
| lambda cyhalothrinR,1,2 | See labels | 21 days. 24 hour REI. Do not apply more than 0.12 lb a.i./acre/season. Extremely Hazardous to Bees! |
| BesiegeR | 6 - 9 | 1 day for forage, 7 days for hay. 24 hr REI. Make applications when bees are not actively foraging by applying during early morning or evening hours. See labels for additional restrictions for individual active ingredients. Do not apply more than 31 fl oz product/season. |
| methoxyfenozide2 | See labels | 21 days. 4 hour REI. No more than 1.0 lb AI/A/season. See label for timing information and crop rotation restrictions. |
| methomylR,1,2 | See labels | 21 days to harvest grain or fodder. 3 days to forage. 48 hour REI. Do not apply more than 2.25 lb ai/acre/crop. Extremely Hazardous to Bees! |
| permethrinR,1,2 | See labels | 30 days grain or fodder. 0 days forage. 12 hour REI. Liquids are Extremely Hazardous to Bees! |
| Radiant SC1 | 3 - 6 | 28 days. 3 days forage or fodder. 4 hour REI. Highly toxic to bees! |
| spinosad1,2 | See labels | 28 days grain, 3 days fodder or forage. |
| ConseroR,1 | 2-3 | PHI 28 days, 1 day graze or fodder; REI 24 hrs. See labels for additional restrictions for individual active ingredients. |
| Mustang MaxxR,1 | 2.7 - 4.0 | 7 days. 12 hour REI. Extremely Hazardous to Bees! No more than 0.10 lb AI/A/season. |
| StallionR,1 | 9.25 - 11.75 | 30 days grain or stover, 60 days forage. 24 hr REI. Extremely Hazardous to Bees! See labels for additional restrictions for individual active ingredients. No more than 11.75 oz per application, 35.25 oz per season. |
| SteedR,1 | 3.5-4.7 | PHI 30 days grain, 60 days forage; REI 12 hrs. See labels for additional restrictions for individual active ingredients. No more than 18.7 fl oz product/season. |
| Triple CrownR,1 | 4.5 - 10.3 | PHI 30 days grain, 60 days forage; REI 12 hrs. See labels for additional restrictions for individual active ingredients. No more than 30.7 fl oz product/season. |
| RRestricted use pesticide. 1Labeled for chemigation. 2Generic active ingredient, several formulations. | ||
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.
