POSTEMERGENCE HERBICIDE OPTIONS FOR FLAX

POST herbicides applied soon after weed emergence to small weeds and flax usually give better control and allow more time for flax recovery from possible herbicide injury than to larger weeds and flax. The following is a listing of postemergence herbicide options for flax that includes information on application rates and timing, weeds controlled, approximate costs, and comments.

 

*Bromoxynil (various trade names):

Application rate = 1 pt/acre. Weeds controlled = wild buckwheat, volunteer sunflower and most broadleaf weeds. Flax stage = 2- to 8-inches tall. Some flax leaf burn may occur if high air temperatures follow application. Mixtures of bromoxynil plus MCPA may cause flax injury if applied during hot, humid conditions. Cost =$7/acre.

*Curtail M:

Section 18 label. Application rate and weeds controlled = 1.33 to 1.75 pt/acre for Canada thistle control and 1.75 pt/A for perennial sowthistle control. Apply when thistles are 4- to 6-inches tall. Also controls numerous annual broadleaf weeds. Apply when weeds are actively growing. Extreme growing conditions prior to, at, and following application may reduce weed control and increase risk of flax injury. Flax stage = 2- to 6-inches tall. Cost =$7-9/acre.

 

*MCPA (various trade names):

Application rate = 0.5 pt/acre (4 lb/gal concentrate). Weeds controlled = numerous annual broadleaves. MCPA amine rates higher than 0.5 pt/A or MCPA ester should be used in flax for improved kochia and Russian thistle control. Flax stage = 2- to 8-inches tall. Early application less injurious to the crop. Cost =$1/acre.

 

*Bromoxynil + MCPA:

Application rate = 0.9 pt/acre. Weeds controlled = most annual broadleaves. Apply to small weeds prior to crop canopy. Flax stage = 2- to 8-inches tall. Risk of crop injury. Cost = $5/acre.

 

*Poast:

Application rate = 0.5 to 1.5 pt/acre. Apply with oil additive at 1 qt/acre. 28% UAN at 2 to 4 qt/A or 2.5 lb/A of AMS with the oil additive may increase control of volunteer corn and small  grain, and quackgrass. Grass weeds = 2- to 8-inches tall. Poast is less effective when applied to grasses under stress. Poast provides only suppression of quackgrass. Quackgrass initially should be treated with 1.5 pt/A and regrowth 6- to 8- inches tall should be treated with 1 pt/A. Flax stage = prior to bloom. Allow a 75 day preharvest interval. Tank mixtures = Poast plus oil additive can be tank-mixed with bromoxynil at 1 pt/A or MCPA ester at 0.5 pt/A for broad-spectrum weed control. Bromoxynil or MCPA ester applied with Poast may cause leaf burn, retarded growth, and delayed maturity of flax. Grass control from Poast may be reduced when applied as a tank-mixture with bromoxynil. Cost = 4 to 12$/acre.

 

Refer to herbicide labels and NDSU Extension Service circular W-253 "2000 North Dakota Weed Control Guide" for required information on use.

WARM-SEASON ANNUAL FORAGE CROP PERFORMANCE

 Currently, average soil temperatures are in the 60's which is suitable for planting warm-season annual forage crops. Numerous forage choices exist for hay. As a reference for selecting forage species for hay production this season, the following are average yields (tons per acre at 15 percent moisture) for warm-season forage hay crops from the NDSU Carrington Research Extension Center trials during 1995-99: Siberian millet = 2.4, sudangrass = 2.4, pearl millet = 2.5, sorghum-sudan = 2.6, proso millet (red) = 2.7, and German millet = 3.5. The following is a 3-year (1995-96, 1999) average crude protein (percent) from the Carrington Center forage trials: German millet = 6.5, proso millet (red) = 8.2, pearl millet = 8.5, Siberian millet = 9.3, sudangrass = 9.7, and sorghum-sudan = 9.8. Other factors to consider when selecting forage crop types include seed availability and costs, prussic acid potential, harvest method, regrowth potential, etc. Additional forage crop performance data and production recommendations may be obtained from NDSU Extension Service or Research Extension Center offices.

 

SUNFLOWER SEED SPACING BASED ON PLANT POPULATION AND ROW WIDTH

 

The following table lists sunflower seed spacing required for selected plant populations and row spacing (assume 90% seed germination and 10% stand loss).

 

 

Row Width

Plants per acre

---------inches between seeds in the row------------

 

30

18

12

6

16,000

11.8

19.6

29.5

59.0

18,000

10.5

17.4

26.2

54.4

20,000

9.4

15.7

23.6

47.2

22,000

8.6

14.2

21.3

42.6

24,000

7.8

13.0

19.6

39.2