Issue # 8, July 23, 2004

• Corn Growing Degree Days Comparison

• Wheat Stem Maggot

• Soybean Aphid

• Corn Borer

• North Dakota Noxious and Troublesome Weeds Guide

Corn Growing Degree Days Comparison

    This is a comparison of growing degree days over the last five years starting at May 1st of each year up to July 22 of each year.  The cool weather of May and June of 2004 has caused a lot of interest in how we compare to previous growing seasons.  The following table is for corn growing degree days.

Wheat Stem Maggot

    This insect is usually a minor problem but can be found every year in our area.  The Wheat Stem Maggot causes heads be turn bright white while the rest of the plant remains green.  To determine if the head was damaged by wheat stem maggot, pull on head and remove it from the leaf sheath.  Look at the lower part of the stem for any chewing or tunneling.  This is the type of damage done to the plant.

.Note the white head and damaged bottom of the stem.  (click on photo to enlarge)

    The insect overwinters in the larval stage.  The maggot being hidden away inside the lower part of the stem of plants.  The adults appear in June, lay their eggs on the leaves of plants.  Upon hatching the young maggots crawl down behind the leaf sheaths to the tender part of the stems and tunnel into them, reach maturity about mid-summer, pupate and the adults emerge.  This time the adults lay their eggs on grasses or volunteer grain.  These maggots mature although they do not pupate and emerge as adults until the following season.  The adult flies are yellowish-white in color and about 1/5 inch long.  The maggots are slender, pale green in color and about 1/4 inch long.

Soybean Aphid    

    Scouting reports from the NDSU Extension Entomolgist (Phil Glogoza), are finding very low levels of soybean aphids up to this point.  There is still a lot of time left in the season, so don't forget to scout fields.  But at this time, the outlook is optimistic that this insect might not be a problem in 2004.

Corn Borer

    Adult corn borer moths are starting to emerge and lay eggs.  Now is the time to start scouting for egg masses to determine possible thresholds that warrant control strategies.  For more information, click on the following publication "European Corn Borer Management in North Dakota".

North Dakota Noxious and Troublesome Weed Guide

    Rod Lym, NDSU professor of weed science, has updated a pocket guide for weed identification.  This is 4" by 5 3/4" color photo guide that illustrates mature weeds that are common in CRP, crops and pastures in ND.  To obtain a copy, contact any NDSU County Extension office.  The cost is $4.00. 

Please Contact Our Office For Additional Information
E-mail: john.swenson@ndsu.edu
Go to the 2003 AgAlert Index Page