NDSU Crop and Pest Report

Entomology


ISSUE 8  June 19, 2003

KEEP BEES SAFE DURING INSECT OUTBREAKS

Grower Precautions:

Use Insecticides with Low Hazard to Bees

Farmers hiring an aerial applicator to spray their fields should alert beekeepers with hives in the intended spray area so they can take appropriate protective measures. Since the hives may have to be moved, the beekeeper should be given notice at least one to two days before spraying.

If hives cannot be adequately protected (moved or covered) before spraying begins, the aerial applicator should be alerted to the exact location of the hives so that they will not be contaminated by direct spraying or drift.

Applicator Precaution:

Use Insecticides That Have Low Hazard to Bees.

Timing of insecticide application: Never spray a crop in bloom unless it's absolutely necessary. If spraying a crop in bloom is necessary, spray when there will be minimal bee activity, preferably during the evening hours. Evening spraying also allows the insecticide to dry on the crop before bee activity begins the next morning.

Modify control programs according to weather. Cold temperatures prolong the residual of insecticide while warm temperatures break down insecticides more rapidly. Warm temperatures in late afternoon, early evening or early morning can "hold" bees in blooming fields for longer periods. Pay attention to wind direction and velocity in relation to nearby bee yard locations.

Applicators who are unsure of where beehives are located should find out by consulting with farmer-customers or contacting:

Judy Carlson, State Apiary Director

North Dakota Department of Agriculture

Phone: 800-242-7535 or 701-328-4997

email: jcarlson@state.nd.us

A document with bee yard locations, by county, is now available on the internet, as well. It can be found on the Pesticide Program Home Page under "What's

Hot".  The URL is:

http://www.ag.ndsu.nodak.edu/aginfo/pesticid/pesticid.htm

 

BEEKEEPER PRECAUTIONS

If an insecticide with high toxicity to bees is to be used in an area where your bees are foraging, be prepared to take steps to reduce the poisoning risk:

Andrew A. Thostenson
Pesticide Program Specialist
athosten@ndsuext.nodak.edu
Web: http://ndsupesticide.org

 

CEREAL APHIDS INCREASING RAPIDLY

Aphid infestations in wheat and barley continue to increase rapidly in the south and eastern counties of the state. Comments from Roger Ashley, Area Agronomist, Dickinson, indicates aphid numbers are increasing in the southwest, as well. The bird cherry-oat aphid has been the dominant aphid found. This aphid is a very dark green, almost black in appearance with a reddish band at the back.

Enclosed area represents locations where
aphid infestation have been reported at their highest.

Many of the fields in these areas are approaching heading very quickly. In general, the optimum results from applying an insecticide for aphid control in small grains occur when treatments are made at flag leaf to boot stage. Though a yield response often is associated with treatments at the fully headed stage, it is much lower, and often only equals the cost of the treatment. In Las Vegas they call that a "push". Growers, though, are interested in one application and currently the emphasis is on a fungicide for scab protection. Scab has a greater potential to reduce yield and quality than the aphids may have. Timing the application to optimize scab protection has a lot of merit. Just remember, the timing of fungicide treatments for scab and insecticide treatments for aphid really donít match up well.

If aphids are at the 85% infested stem level and the crop is at the flag leaf stage, the benefit from applying the insecticide has been demonstrated. The yield advantage from these treatments has exceeded the cost of control, demonstrating that two treatments, one for insecticide and another for a fungicide, can provide a favorable return for the investment.

 

WHEAT MIDGE UPDATE

The degree day accumulations for the start of wheat midge emergence are approaching. Wheat fields that are heading this week will be in good shape. Here are the key degree day accumulations:

DD (40EF)

Wheat Midge Biological Event

1300

10% of the females have emerged

1475

peak emergence with 50% of females

1600

90% of the females have emerged

Currently we are at 1000+ DD in many of the southern and eastern counties. In fact, the degree day accumulations across the region are very close. We are not going to see quite the spread of emergence times as we have seen in the past. Midge should be emerging in eastern and southern areas by next week. Remember, numbers have been low in these locations and pressure is not expected to be very high.

 

ALFALFA WEEVIL DECISION TIME

Reports from southwest North Dakota indicate the alfalfa weevil larvae are feeding and decision time has arrived. The choices are early cutting followed up by scouting windrow areas for surviving larvae later. Or, if infestations justify treatment, then apply an insecticide and wait until the post treatment interval has been reached.

Refer to Issue Number 1 of the Crop and Pest Report for specific thresholds and other recommendations.

 

CUTWORM CONCERNS CONTINUE

Concerns with cutworms continue from some central counties, particularly Emmons, Logan and Eddy, but are not restricted to these areas. The most severely impacted crop has been sunflower. In many cases, the cutworms are reported to be feeding on the seedlings before or as they emerge. The below ground feeding poses a serious problem and one that has no good solution. When cutworms feed above ground, the post emerge insecticides are effective. When the cutworms are feeding below ground, treating with an insecticide and hoping for movement down into the soil is not likely to provide control.

In these cases where feeding is on seedlings prior to their emergence, the best advice may be patience. The cutworms begin to pupate when they reach a size of 1ľ to 1Ĺ inches in length. At that time, evaluate the condition of the remaining stand and consider the need for replant or other options.

Phillip Glogoza
Extension Entomologist
pglogoza@ndsuext.nodak.edu


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