CANOLA SWATHING TIME

The majority of canola fields in south-central North Dakota are nearing or are at the stage for swathing. A sign of canola being very near the swathing stage is the natural yellowing and senescence of leaves and leaf drop. When canola plants consist only of stems, stem branches and pods, the crop is probably very near the optimum time for swathing.

Canola swathing should be initiated when a minimum of 15-30 percent of seeds, contained in pods located on the main stem, have started to turn color. Seed color change is from green to light yellow, or reddish brown, brown, or black, depending on the cultivar. Seeds with only small patches of color should be counted as color changed. Seeds will begin maturing at the lower portion of the plant and will continue upward. Another rule-of-thumb for timing canola swathing is that the majority of seeds should have changed color in pods contained on the lower third of the main stem while seeds present in the upper third of the main stem will still be green but firm when pressed between your finger and thumb.

Plant and seed inspection should be performed throughout the field. Also, when scouting a canola field it is best to disregard plants infected with sclerotinia (white mold) and determine swathing time based on development of healthy (productive) plants.

Details on timing the swathing operation may be obtained from the NDSU Extension Service circular A-1171 ''.

WHEAT DISEASE UPDATE

The NDSU Extension Service small grain disease survey continues for south-central North Dakota. Thirty-four hard red spring and durum wheat fields in dough stages of growth were checked in Emmons, McIntosh, Dickey, Logan, LaMoure, Burleigh, Kidder, Stutsman, Barnes, and Foster counties during July 20-26. Tan spot, Septoria leaf blotch, and leaf rust were found on flag leaves in 94-97% of the fields surveyed. Septoria glume blotch was found on main stem heads in 65% of the fields. Scab (Fusarium head blight) was found in 94% of the fields surveyed with incidences of infected main stem heads ranging from 0 to 36%.

SEPTORIA LEAF SPOT IN SUNFLOWER

As you scout your early-bloom sunflower for seed weevils, banded sunflower moth, sunflower beetles, and rust you may detect another pest. Septoria leaf spot, a fungus disease, can be found in area sunflower fields. The disease first develops on the lower leaves and later may spread to the upper leaves. The spots begin as water-soaked areas (greasy green in appearance). The spots are somewhat diamond shaped, brown on the upper surface and a lighter grey-brown on the lower surface. A narrow yellow halo often surrounds newly-developed spots. Mature leaf spots may contain tiny, indistinct dark-brown specks called pycnidia, which are visible with a hand lens. Moderately high temperatures and abundant rainfall are required for rapid disease development. The disease develops more rapidly after flowering. Fortunately, this disease rarely is severe enough to cause economic loss and currently fungicide treatment is not recommended.