|Pheromone traps monitor bugs|
|Written by Assefa Gebre-Amlak, Regional Pest Management Specialist, CSU Extensio|
The northern region pest alert program has officially begun for the 2009 growing season. This program monitors economic pests using pheromone traps and field scouting between now and the end of August 2009.
Pheromone traps are located in Akron, Burlington, Eckley, Haxtun, Kirk, Sterling, Wauneta, Neb. and Yuma.
There will be a weekly pest alert newsletter covering information on trap catches, timing of scouting, field biology, economic threshold and management strategies for major pest problems in the area.
Western corn rootworm: The western corn rootworm larvae feed on the underground root systems of corn plants. Peak feeding usually occurs from late June to mid-July. Lodging (goose necking) of corn plants due to larval root feeding is a typical symptom of damage.
Damage from corn rootworm larvae is most likely in continuous corn. However, chemical applications to first year corn are not recommended. Incorporation of soil insecticides into the soil protects wildlife. If corn is planted prior to May 15, post emergent treatments are preferable.
Post-emergent treatments: The granular formulations can be applied at the same rates, as a band on either side of the row, by cultivator shoes and disc hillers at cultivation. For details of product formulation and application rates go to the High Plains IPM Guide www.highplainsipm.org. Check the label for dosage and application details.
Bt corn hybrids containing the Agrisure RW, YieldGuard Rootworm and Herculex RW events are expected to provide good rootworm control. See “Managing Corn Pests with Bt Corn,” www.ext.colostate.edu/pubs/crops/00708.html, for details on the use of Bt corn hybrids to control corn pests.
European corn borer moths began flying in most of the pheromone trap locations in northeastern Colorado. Corn borer larval damage is not expected in corn plants that are below 16 inches long (with extended leaves) due to presence of a chemical substance called DIMBOA.
However, as corn develops most varieties lose their resistance to larval feeding and should be scouted. More detail information regarding its field biology and management will be provided in the subsequent pest alert press release.
Alfalfa weevil: First cutting of alfalfa is underway in northern Colorado. A non-insecticide control measure for alfalfa weevil is an early first harvest if an economic infestation is not detected until late in the growth of the first cutting. Harvesting alfalfa in an immature stage provides good control of larvae for the first crop. Rapid removal of hay will accelerate larval mortality due to desiccation by direct sunlight.
An early first cutting tends to cure more rapidly because lighter windrows dry quickly, and forage quality is enhanced by higher crude protein and lower fiber content. Additional steps should be taken to ensure that surviving larvae do not cause economic damage to the regrowth.
Alfalfa weevil can also be problematic after first cutting. The failure to green up in about seven days may be due to weevil and/or variegated cutworm infestations. It is important to scout for these and other pests in your alfalfa. Among the insecticides labeled for alfalfa weevil some are also effective against variegated cutworm.
Grasshoppers: Grasshoppers have started hatching and hoppers/nymphs (immature stage) are seen along field margins and road sides in Yuma County. They are commonly seen in the Eckley area as well as north of Wray.
Grasshoppers can be a serious pest of many crops including corn, alfalfa and dry beans. They can also damage grass in rangeland. Keep an eye on grasshopper populations in your crop as well rangeland.
If small hoppers reach 20 per square yard in field margin, a chemical control may be justified. Once they disperse through the field, 8 hoppers per square yard are considered to be economical. Use of higher rates of effective insecticides is recommended when adults are present.
Those who are in northeastern Colorado, may contact Yuma Pest District at 970-848-2509 to sign up for a special program developed for grasshopper management in rangeland.