FROM AROUND THE STATE
ISSUE 3 May 17, 2001
Canola Insect Pest Update
Crucifer Flea Beetle: Flight activity has begun with the hot temperatures, average of 72 degree F from May 7-13 with a maximum temperature of 90 degrees F. Trap counts from the NCREC in Minot have increased to an average of 50 beetles per trap from the last two weeks average of 1-2 beetles per trap. Fields treated with a seed treatment (Gaucho or Helix) should be protected up 21 days after planting. Untreated fields should be scouted for flea beetle feeding activity during the seedling stage to 4-6 leaf stage. The current economic threshold is 25% of the plant leaf area damaged. Capture is registered in ND as a foliar insecticide for flea beetle control on canola at the rate 1.3 fl. oz. per acre, minimum of 10 gal per acre. It is compatible with Roundup herbicide and other herbicides for tank mixing.
Diamondback moths (DBM) were trapped in low numbers at the NCREC in Minot during May 3-10. With the strong northernly winds from the south, DBMs have migrated into ND early. In Colorado, entomologists are reporting larger numbers and more activity from DBMs than usual. DBM have also been sighted in Yorkton and Saskatoon, Saskatchewan near May 10 (source: L. Harris, L. Kaminski and O. Olfert). Wind trajectories from May 6 show winds from Texas north into southwest ND up to northwest ND into eastern SK and all parts of MB. Backward trajectories originating from Yorkton, SK on May 6 indicate flight into north central ND and angling down to southeast corner of ND (Source: L. Kaminski). The numbers of early migrants and success of the larval population will determine if DBMs become an economic situation in 2001. We also had an early arrival in 1998, but the larval population was drowned out during a heavy thunder storm in June 1998.
Other Insect Pests Reports:
Wireworms have been observed in high numbers in no-till or minimum till crops, especially sunflower and small grains in the north central region of ND. Wireworms start to become active when soil temperature reach 50-55 degree F and continue until the soils become too warm at >80 degree F. Maximum feeding activity in the upper six inchdes of soil occurs at about 65-75 degree F. Wireworms can live in the same field for 1-5 years to complete its life cycle. Due to the overlapping generations, a field can be infested for several years. It is recommended to use a seed treatment (lindane for small grains, sunflower) if you know your field has a wireworm problem. Wireworms can survive for 12-13 months without food, so crop rotations does not adversely affect the survival of wireworms.
Early season cutworms like the Dingy cutworm can also be found now. Check your field for clipped seedlings and dig for the worms(larvae) 2-4 inches underneath the soil. In small grains the economic threshold is four or more worms per square foot, or 25-30% stand loss as a general rule. It is best to kill the worms when they are small <¾ inch long. Otherwise, it is a waste of your time and money to spray mature worms that have finished feeding.
Wheat Midge Degree Day Window for Planting HRSW: The entire northwest and north central region is in the HIGH RISK PLANTING PERIOD (200-600 Degree Days). The following is a listing of total Degree Day accumulations from weather sites located in the northwest and north central region as of May 13th: Rolla = 298; Columbus = 341; Bottineau = 343; Baker = 344; Cando = 345; Mohall = 349; Hofflund = 363; Turtle Lake = 378; Minot = 387; Watford City = 417; Williston = 417; and Towner = 425.
Diseases: The fruiting bodies that produce the spores of leaf spots, like tan spot, are easy to find on straw residue.
Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center
Rainfall recorded at NDAWN sites in southwest North Dakota this past week ranged from 0.06 to 0.16 inches. However at many farm locations no measurable precipitation was received. Between above average temperatures and limited rainfall, soils have dried. Many producers have found that topsoil has dried to the depth of tillage resulting in dry seedbeds, and poor or incomplete germination and emergence of crops. Most producers would appreciate a good rain.
Early seeded hard red spring wheat is in the 4th leaf stage. Peas and lentils have emerged with some peas in the 4th node stage. Alfalfa at the Dickinson Research Extension Center is about 14 inches tall.
A few grasshopper nymphs have been found along field margins in Stark County but not at economically damaging levels. However it is still early in the season and producers should continue to monitor field margins and other known grasshopper hatching sites. Wireworm damage has been found in a few fields.
Roger O. Ashley
Area Extension Specialist/Cropping Systems
Dickinson Research Extension Center
During the past week (May 9-15), no rainfall was received in south-central North Dakota. Black soil temperatures recorded on May 15 at the 4-inch depth ranged from 58 to 70 F.
South of I-94, estimated small grain acreage seeded ranges from 50 to 100%. Corn planting is nearing completion and soybean planting is underway. North of I-94, small-grain seeding ranges from about 10 to 50% complete. Canola seeding should be completed soon. Soybean planting also is beginning. Across the region, the growth rate of alfalfa and pastures is rapidly increasing.
The high-risk period for wheat being susceptible to wheat midge (at heading time) is when wheat is planted during the period of 200 to 600 midge degree day accumulation.
On May 15, accumulated midge degree days ranged from 394 to 500 for this region. Newly-emerged canola should be frequently monitored for flea beetle presence and feeding injury. The economic threshold for POST insecticide treatment is about 25% of the plant leaf area damaged and flea beetles are present. POST herbicide application is starting in early-seeded small grain.
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center