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ISSUE 7  June 15, 2000

 

SUNFLOWER BEETLES

    Sunflower beetle adults have been active for a couple of weeks now. Egg laying is underway. Though we have not had reports of large numbers of adults feeding on seedlings like recent years, it is time to intensify scouting to determine population levels in your fields.

    Scouting Method: Sampling should be 75 to 100 feet from the field’s edges. Adults and/or larvae should be counted on 20 plants at each of 5 sites along an X pattern for a total of 100 plants. The average number of adults and/or larvae per plant should be determined.

    Economic Threshold: Adult - one to two per seedling. Larvae - 10 to 15 per plant will cause approximately 25 to 30% defoliation if allowed to continue feeding. Control is advised if average defoliation reaches the 25 to 30% level.

Insecticides Approved for Sunflower Beetle

Trade Name

Product/Acre

Dosage (lb AI/acre)

Asana XL*

1.45 - 5.8 fl oz**

0.0075 - 0.03

Baythroid*

0.5 - 1.6 fl oz

0.0125 - 0.025

Sevin

(varies)

1.5 - 2

Furadan 4F*

0.25 - 0.5 pts

0.125 - 0.25

Lorsban 4E

1 - 1.5 pts

0.5 - 0.75

Scout X-tra*

0.71 - 1.42 fl oz

0.005 - 0.01

Warrior*

1.28 - 2.56 fl oz

0.01 - 0.02

* RUP - restricted use insecticide
** reduced rates are for SF beetle larvae

 

WHEAT MIDGE . . . EMERGENCE IN SOUTHEAST ND

    It’s that time of year for wheat midge emergence to get underway in southern ND counties. We will reach 1200 DD in Richland, Sargent, Ransom, Dickey, LaMoure, and Cass counties around June 17 - 19. These counties have not had significant numbers of midge found during fall surveys. However, there have been isolated fields where populations have come close or slightly exceeded the treatment threshold of 1 adult midge per 4 to 5 wheat heads in previous seasons.

    Since a large number of fields will be heading soon, some evening scouting would be recommended to assess adult populations in the region.

    To see when your production area reaches 1200 DD, the point when wheat midge emergence gets underway, visit the NDSU Entomology Updates web site at:

http://www.ag.ndsu.nodak.edu/aginfo/entomology/entupdates/index.htm

    Of greater concern in these parts of the state will still be the Cereal Aphids. Surveys indicate populations of aphids are still low. The recent rains and abundant predators are going to help delay aphid population increases. Grain growers and consultants in South Dakota are reporting larger populations of aphids this week. Their wheat is a little farther along than ours and fully headed fields are present in that area.

 

DIMILIN 2L, SPECIAL LOCAL NEEDS LABEL FOR RANGELAND GRASSHOPPER CONTROL

    A label for Dimilin 2L was issued this week in North Dakota for the use of this insecticide, an insect growth regulator, to control grasshoppers in rangeland. The manufacturer is Uniroyal Chemical. The active ingredient in Dimilin is called diflubenzuron. It controls immature stages of insects by inhibiting their ability to synthesize chitin, a polysaccharide which binds with proteins to form the hard outer covering, or exoskeleton, of insects.

    The product is used against the nymphs. For optimum results, treatments are recommended when the majority of grasshopper nymphs are 2nd and 3rd instar. This product is not effective against adult grasshoppers since they no longer will molt, or shed their exoskeleton.

    The label rate is o.5 to 1.0 fl oz per acre. Aerial application requires 1 to 5 gallons of water plus crop oil; ground application requires 5 to 20 gallons of water plus crop oil. The label does include a recommendation for using Reduced Area and Agent Treatment (RAATs). RAATs is a strategy where treated and non-treated strips are alternated, capitalizing on movement of grasshoppers between the two areas. RAATs may involve treating as low as 50% of the total area while achieving satisfactory control of young grasshoppers.

    If interested, a copy of the label will be available through the North Dakota Pesticide Training and Certification web page which can be found at:

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

 

NORTH DAKOTA BIOLOGICAL CONTROL FIELD DAYS AND EVENTS

    Collection dates for obtaining Leafy Spurge Flea Beetles have been set for around the state. There are 32 sites on the schedule. Counties with dates scheduled include: Ransom, LaMoure, Dickey, Cass. Barnes, Stutsman, Foster, Eddy, Nelson, Pembina, Burleigh, Morton, Grant, Stark, Billings, Ward, and Burke.

    For dates, schedules, collection specifics, and contacts, visit the North Dakota Department of Agriculture web page at:

http://www.state.nd.us/agr/

If you do not have access to the internet, you can contact the Department of Agriculture at 1.800.242.7535.

 

EPA ACTION REGARDING CHLORPYRIFOS

    On Thursday, June 8, EPA and DowAgrosciences announced new restrictions on the insecticide, chlorpyrifos. This insecticide is found in Lorsban, Dursban, and many other brand name products.

    The primary action involves the uses of chlorpyrifos in structural and lawn/ornamental applications. These uses will be eliminated as of December 2001.

    Agricultural use changes include the reclassification of Lorsban 4E and Lorsban 50W and other chlorpyrifos products to a Restricted Use Pesticide (RUP) effective with the 2001 growing season. North Dakota growers who have used Lorsban 4E-SG for controlling wheat midge, aphids, and grasshoppers in wheat should be aware that this formulation was already classified as an RUP. The Lorsban 15G , Chlorfos 15G (Griffin LLC) and other chlorpyrifos granular formulations for
agriculture will remain as a non-restricted use pesticide. Registered use patterns of these agricultural products will not change except for the following uses.

    Effective Dec. 31, 2000, applications of chlorpyrifos insecticide on apples will be allowed pre-bloom only. EPA also intends to reduce the tolerance for chlorpyrifos in apples.

    The EPA intends to reduce the residue tolerance on grapes, and to revoke the tolerance for tomatoes. This change will not impact product use patterns for U.S. producers of these crops. However, the tolerance reduction may impact the use of chlorpyrifos on grapes and tomatoes grown elsewhere for export to the United States, because residues on imported fruits and vegetables must conform to U.S. standards.

 

EUROPEAN CORN BORER UPDATE

    ECB moths have been captured in a few of our blacklight traps located in North Dakota. The numbers are still small. We also have emergence cages containing last years stalks at several of these sights. No emergence from stalks has occurred. The moths we are catching in the traps are most likely migrants from areas to the south. Significant numbers of moths have been captured in some blacklights traps in southern Minnesota and South Dakota.

    ECB require corn that is 17 inches tall before they are likely to survive on the plant. Corn plants less than 17 inches tall contain high enough concentration of the plant chemical DIMBOA to act as an antifeedant and disrupt normal behavior of the larvae, resulting in high mortality.

    To stay current on ECB moth activity in ND and neighboring states, visit the NDSU Entomology Updates web page and go to the European Corn Borer link:

http://www.ag.ndsu.nodak.edu/aginfo/entomology/entupdates/index.htm

 

Phillip Glogoza
Extension Entomologist
pglogoza@ndsuext.nodak.edu


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