ndsucpr_L_sm.jpg (11690 bytes)

ent_Logo_Lg.jpg (12173 bytes)


ISSUE 2  May 14, 1998

 

GRASSHOPPER THREAT FOR 1998 IN NORTH DAKOTA

    Grasshoppers have been hatching around the state for two weeks plus, now. Localized hot spots, where populations will exceed threatening levels are expected all around the state. So far, the hatch has not resulted in the need for significant insecticide treatments to protect seedling crops. There are reports from the Red River Valley of spraying borders to protect sugar beet seedlings. With the warm spring, hatching has begun about two weeks earlier than observed the past three years. Now, with the temporary change in weather to cool rainy conditions, hatch should slow briefly and may cause some mortality of the young hoppers.

    At this time, vigilance is the best recommendation. Scout areas where adult grasshoppers were present last fall. The open fall in 1997 was favorable for egg laying. Inspect infested areas once a week. Newly hatched grasshoppers are small (about the size of a kernel of wheat) and sites require more than a casual inspection. Field crop management decisions are based on the number of grasshoppers per square yard. Estimate populations by moving through an infested area and counting the number of grasshoppers that jump or move within a square foot area. Keep a record of your square foot counts. Divide the total number of grasshoppers counted by the total number of samples taken, then multiply by nine to calculate the number of grasshoppers per square yard. Refer to the table to evaluate damage risk.

Grasshoppers per Square Yard =

Infestation rating

Nymphs

Adults

Margin Field Margin Field
Light 25 - 35 15 - 23 10 - 20 3 - 7
Threatening 50 - 75 30 - 45 21 - 40 8 - 14
Severe 100-150 60 - 90 41 - 80 15 - 28
Very Severe 200+ 120+ 80+ 28+

 

Rainfall Effects on Grasshoppers
  • Cloudy, wet weather for 1+ weeks
    Promotes fungal pathogens, prolonged period of wet weather important
  • Heavy rains during emergence
    Kills young grasshoppers by trapping them in the soil or physically washing them away
  • Drought or lack of rain
    Poor egg hatc, hoppers starve from lack of food, and low egg production by adults   

 

Insecticides Available for Use Against Grasshopper

Field Corn and Sweet corn
   
Asana XL, Cythion, Diazinon, Penncap-M, Sevin, and Warrior.
Field Corn Only
   
Dimethoate, Furadan 4F, Lorsban 4E, methyl parathion.
Soybean
   
Asana XL, Dimethoate, Furadan 4F, Lorsban 4E, Penncap-M, Scout X-Tra, Sevin, Warrior.
Sunflower
   
Asana XL, Baythroid, Furadan 4F, Lorsban 4E, Scout X-Tra, Sevin, Warrior.
Dry Bean
   
Asana XL, Dimethoate, Orthene 75S, Sevin.
Potato
   
Asana XL, Dimethoate, Penncap-M, Sevin.
Sugarbeet
   
Asana XL, Cythion, Diazinon, Lorsban 4E, Malathion 57EC, methyl parathion, Sevin.
Wheat
   
Cythion, Dimethoate, Furadan 4F, Malathion 57EC, methyl parathion, Penncap-M, Sevin, Warrior.
Barley
   
Cythion, Furadan 4F, Malathion 57EC, methyl parathion, Penncap-M.
Oat
   
Furadan 4F, Malathion 57EC, methyl parathion, Penncap-M.
Alfalfa
   
Baythroid, Cythion, Dimethoate, Furadan 4F, Lorsban 4E, Malathion 57EC, methyl parathion, Penncap-M, Sevin,Warrior.
Clover
   
Cythion, methyl parathion, Sevin.
Grass and Grass hay
   
Cythion, Penncap-M.
Pasture and Range
   
Cythion, Orthene 75S, Penncap-M, Sevin,.
Non-Crop areas with grass cut for hay
   Cythion, Malathion 57EC, Sevin.
Non-Crop areas NOT cut for hay
   Asana XL, Diazinon, Orthene 75S.
Grain Sorghum
   
Dimethoate, Lorsban 4E, Sevin, Warrior.
Proso Millet, Lentils, and Flax
  
Sevin.
Canola
   
methyl parathion (This product is labeled for use on canola, however grasshoppers do not appear on the label. It should          provide control at labeled rates.)
Field Peas
   
Sevin ( in addition, Cythion and methyl parathion are labeled for field peas, however grasshoppers do not appear on the          label.)

    On a final note, there is a state label for the use of reduced rates of Asana XL to control first and second instar grasshoppers on many of the above labeled crops.

 

CUTWORMS AROUND THE STATE

    One of the first insect pests we encounter in a season are cutworms. Reports from the valley, north central counties and western sugar beet areas indicate significant activity has been present for one to two weeks. As reported last week from the north central areas, cutworms are feeding on volunteer plants before new crop has been seeded. Last season, significant cutworm injury to later seeded crops (example, sunflower) was reported in many eastern counties.

    Of the cutworms that pose problems in North Dakota, the army cutworm and dingy cutworms overwinter as partially grown larvae and are usually the first to cause damage. The pale western, dark sided, and red-backed cutworms, overwinter as eggs. Many cutworm infestations are associated with weedy, wet and reduced tillage areas. Here are brief descriptions and notes on the habits of the key cutworms (size is for full grown larva):

Army cutworm: 1 1/2 to 2 inches; pale greenish-gray to brown with pale stripes and mottled pattern. Larvae hatch in fall, resume feeding in early spring. Important in western North Dakota grain and alfalfa fields. There were reports from South Dakota in April of significant infestations by army cutworm in winter wheat and alfalfa; a few reports from SW ND.

Pale Western cutworm: 1 1/2 inches; generally gray in appearance. Larvae hatch in spring. They feed underground, sometimes damaging plants before they emerge; cut plants are pulled underground. Important in western North Dakota small grain fields.

Dingy cutworm: 1 1/4 inches. Dull, dingy brown color mottled with pale white spotting. Larvae hatch in fall, resume feeding in the spring when soils warm. Damage usually consists of chewed foliage and/or cut stems. Injure corn, sunflower, sugarbeet, and potatoes.

Darksided cutworm: 1 1/4 to 1 1/2 inches. Pale brown on top, lighter on the bottom. Sides have faint stripes. Larvae hatch in spring (mid to late May). Plant feeding same as above.

Red-backed cutworm: 1 to 1/4 inches. Dull gray to brown with dull reddish stripe down back. Larvae hatch in spring (mid to late May). Plant feeding same as above, same hosts.

 

1998 NORTH DAKOTA INSECT MANAGEMENT GUIDE AVAILABLE ON WORLD WIDE WEB

    For your reference, the insect management guide, published annually by NDSU, is available on the internet. You can find it at the following address:

http://www.ext.nodak.edu/extpubs/plantsci/pests/e1143w1.htm

Phillip Glogoza
Extension Entomologist


cprhome.jpg (3929 bytes)topofpage.jpg (3455 bytes)tableofcontents.jpg (4563 bytes)previous.jpg (2814 bytes)next.jpg (1962 bytes)