I have stressed more often than not that in Minnesota you
ought to seed your small grains as early as possible. The very late starts in the past two years and
the disappointing wheat and barley yields that followed in especially the southern
half of the state are a testament to my position on planting dates.
I try to practice what I preach and so I seeded
trials last Thursday and Friday near Rochester, New Ulm, LeCenter, and Becker.
I was happy to see that some of you were also seeding your first small
grains. And then it snowed again and the
thermometer will be stuck near or below the freezing point much of this week.
Should you and I be worried about these early seeded small grains?
Spring wheat (and spring barley and oats) will start
germinating in earnest when soil temperatures reach 36⁰F to 40⁰F. Once the imbibition phase starts there is no
return to dormancy and the germination/emergence should be as quick as possible
to establish a healthy, vigorous seedling.
Protracted emergence will predispose the seeding to attacks of soil-borne fungi like Pythium damping-off or common root rot, ultimately reducing
stands. During this whole germination
and seedling emergence and up to the 5-leaf stage, the growing point will be at
~1-inch depth. At this depth, it is
protected from the ambient temperatures.
The crown can sustain temperatures down to 28⁰F and probably even handle
short periods of temperatures as low as 22⁰F.
Even if above ground leaves freezes, the plant will survive and continue
its development as long as the crown does not suffer any freezing injury.
The seed is most prone to freezing during the imbibition
phase as the cells have not started actively growing and dividing yet. With air temperatures expected to drop down
into the high teens overnight, I have fielded a number of calls already this
morning with the question whether the earlier seeded wheat, barley, oats (or
any crop for that matter) will make it.
Know that the blanket of snow you received over the weekend will help insulate the seed
from the predicted lows. This morning
the recorded minimum temperatures at 2” soil depth at the SWROC and the SROC in
Lamberton and Waseca were 35⁰F and 36⁰F, respectively. The soil temperatures will likely not drop
below 28⁰F in the next few mornings and before the weather is forecasted to warm
up later this week.
The fastest way to tell whether the seed is still viable is to dig up some seed or seedlings
and place them on a wetted down paper towel at room temperature. Within 24 hours you should see elongation of
the coleoptile or radicle of the seedling. With
seed that had not germinated yet, you may have to wait a few days before you
see a radicle and coleoptile appear. If
the seed and the germ are damaged by frost they will turn to mush within 24
hours at room temperature.
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