AgWatch

Manage Nitrogen To Prevent Lodging

LAMAR, MO.
   On March 26, Jill Scheidt, an agronomist with University of Missouri Extension, checked normal and late planted wheat north of Lamar.
   “A little septoria is still being seen on leaves. Septoria is usually not a problem this early, but if most of the leaf surface is covered, a fungicide should be applied,” said Scheidt.
   Septoria is identified by yellow lesions that later turn brown, small black specs of picnidia can be seen in the center of the lesion.
   Aphids were not seen this week; temperatures are below 60 degrees Fahrenheit and aphids are not active until temperatures reach 60 degrees or more. Bird Cherry Oat aphids will vector barley yellow dwarf virus, which causes stunting and sometimes severe yield loss in wheat.
   “The best way to protect against barley yellow dwarf virus is to spray an insecticide, like Warrior II or Hero, when bird cherry oat aphids reach threshold levels of 12 to15 aphids/foot of row,” said Scheidt.
   The best time to apply nitrogen is before jointing, usually in mid-March (but it will be later this year). During this time, the highest amount of nitrogen is used by the wheat plant to promote rapid growth and grain fill.
   If wheat was planted late, nitrogen is likely to be needed at green-up to stimulate tiller development. According to Virginia research, if you have greater than 90 tillers/square foot there is no need to apply nitrogen at green-up.
   “Applying excessive nitrogen can lead to lodging from plants growing too lush too quickly,” said Scheidt. “When looking at a soil test, phosphorus target levels should be at 45 pounds/acre. If soil does not contain this much phosphorus, more needs to be added to assist in grow of the wheat plant.”∆


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