ROUNDUP AVAILABLE AS A FLAX HARVEST AID

A section 18 label has been approved for the use of Roundup Ultra or Roundup Ultra RT for pre-harvest application in flax. The label was granted to control weeds including Canada thistle, perennial sowthistle, and kochia. A single ground or aerial application of Roundup may be used at one quart/acre. Application must be made at least seven days before harvest and when the crop is physiologically mature. A rule-of-thumb to determine when flax is physiologically mature is when at least 75% of the bolls have turned brown. Applicators must read and follow label directions, and have the crisis label in their possession during Roundup application.

WHEAT DISEASE UPDATE

Jerry Schneider, surveying in Wells, Sheridan, Foster, Eddy, Benson, Griggs, Barnes, LaMoure, Dickey and Stutsman counties, found 100% of the 34 monitor spring and winter wheat fields to have some level of leaf rust. Severity of leaf rust on the flag leaf ranged from 1-25% but was difficult to see because of the ripeness of the crop. Septoria leaf blotch was observed on flag leaves in 96% of the spring and winter wheat fields and 100% of the durum fields surveyed, with severity ranging from 4-60% on the flag leaf. Glume blotch, the head infection phase, was observed in 93% of the fields surveyed. Head scab was detected in only 63% of the wheat fields surveyed but was again difficult to see due to the advanced stage of the crop. Field severity for head scab ranged from 8% to 32%. Black chaff was found in 37% of the spring fields at 4-28% incidence in the field. Other head diseases found in spring, winter, & durum wheat fields include: Ergot (19% of the fields, low severity), loose smut (15% of the fields), and Alternaria sooty mold (11% of the fields).

SUNFLOWER DEVELOPMENT

Most of the region’s sunflower fields are nearing or are in the flowering stage. The flowering stage (R5) can be divided into substages dependent upon the % of the head area (containing disk flowers) that are open or have completed pollen shed. As examples, R5.1 indicates 10% of the disk flowers have opened and R5.5 indicates 50% of the disk flowers have opened.

As sunflower are monitored for insects including banded sunflower moth and seed weevil, you may be interested in time required for sunflower development during the recommended insect scouting and treatment periods. The following table is a compilation of data from selected sunflower hybrids during 1994-96 at the Carrington Research Extension Center that provides an estimate of time required for sunflower to reach various development stages.

Sunflower stage and description	Average days accumulated from planting
VE - plant emergence	13
R4 - inflorescence begins to open (immature ray flowers visible when viewed from above)	71
R5.1 - beginning of flowering	73
R5.5 - 50% of disk flowers open	77
R6 - Flowering complete and ray flowers wilting	85
R9 - Physiological maturity (bracts yellow and brown)	117