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.”∆