Alfalfa Weevil Information
Alfalfa weevil larva
Univ. of Illinois Ext.)
Alfalfa weevils have become more common in the area the past few years. During the past week, Golden Valley County has reached the point where hatch will occur, which means that it is time to begin scouting for weevils. Here are some tips for scouting and treating your alfalfa stands from NDSU Entomologist Janet Knodel.
Scout the south-facing slope or sandy knoll areas which warm up rapidly first. These areas will have early development of alfalfa weevil larvae. Scout fields by sampling 10 plants in 5 random locations (50 total plants)and walking in a M-shaped or similar pattern throughout the field. Small alfalfa weevil larvae are slate-colored. As larvae mature, their color changes to bright green with a white line running down their back and a black head capsule, and about 3/8th of an inch long (see photo). Alfalfa weevil larvae can be confused with the clover leaf weevil larvae. However, the clover leaf weevil is two times larger (5/16th inch long), with a brown head capsule, and the white stripe is usually bordered with smudges of pink. In alfalfa, the clover leaf weevil rarely causes economic yield loss. Management of weevil infested alfalfa stands depends on when the infestation occurs. If the infestation occurs relatively late, when the alfalfa has reached 20 to 25 inches in height, consider taking an early harvest. Small alfalfa weevil, those less than ¼ inch in length, will drop to the soil and generally die if the soil is dry. If the infestation occurs early, when alfalfa is 10 to 15 inches in height, chemical treatment may be necessary. Insecticide treatment is recommended if two live larvae per stem occur at this stage and/or 35 to 40% of the plants are showing tip feeding. In general, if alfalfa is 7-10 days out from harvest and 35-40% tip feeding is present, an insecticide treatment is recommended. ND insecticide recommendations for alfalfa are listed at: http://www.ag.ndsu.edu/pubs/plantsci/pests/e1143w1.htm Remember to check the preharvest interval as these restrictions vary according to the insecticide used and the rate applied. Other factors to consider when selecting an insecticide are its price, potential hazards to honey bees and whether or not it is a restricted use insecticide. If weevils infest an alfalfa field, be sure to scout the field following harvest for re-infestation of the second harvest. Major feeding by the alfalfa weevil will occur from 430 to 595 growing degree days (2nd - 4th instar). At greater than 600 growing degree days feeding normally stops and adult emerge. This will occur usually during the second harvest unless the first is taken late. If following the first harvest, your scouting shows 8 or more larvae per square foot or larvae are suppressing regrowth, chemical treatment is recommended.
Tan Spot on Wheat
The recent wet weather has created favorable conditions for Tan Spot. Cases of Tan Spot in both Winter Wheat and Spring Wheat have been reported in the SW part of the state. If tan spot is present and timing is right herbicide and fungicide applications maybe done together. The following is a table provided by Marcia McMullen NDSU plant pathologist on products available for early season control of tan spot.
Note: In the rate column for mancozeb products, the rate should have been: 1-1.5 lbs/acre (1-11/2 lbs/acre), not 1-1/12 lbs/acre.
Supplemental Herbicide Labels Issued.
A supplemental Select Max label has been issued for use in field pea, chickpea, lentil, safflower, and many other crops. The rates are similar to use in other broadleaf crops. For field pea, tank mixes with Basagran and Raptor are also labeled.
Also a supplemental label has been issued updating the crop rotation restrictions for WideMatch. The biggest change you will see here is that all references to rainfall and soil organic matter have been removed and the restrictions are now based only on time. The special directions for rotation to field pea have stayed the same however.
Project Safe Send Date Announced
Project Safe Send has again been funded through the ND Legislature, and will be hosting 16 collection sites during the month of July. Following is the closest locations.
Wed, July 18 Williston - 605 Dakota Parkway W.
Thurs, July 19 Dickinson - 700 Third Ave. W STE 101.
Fri, July 20 Mott - 9108 71st R St SW.
Mon, July 23 Beulah - 205 Highway 49 S.
Tues, July 24 Garrison - 515 Highway 37 SE.
No pre-registration is required to take part in project safe send. However it is asked that you call ahead if bringing in more than 5,000 lbs of unusable chemicals. More information on Project Safe Send can be found at www.agdepartment.com
ND Soil Summit to be held in Carrington
On Wednesday June 13th a soil summit will be held in Carrington at the Research Center. The major topics for the day include Salinity and Sodicity in North Dakota Soils and Soil Management for Sustainable Biofuel production. For more information please contact the office.