The Last 60 Days

The Last 60 Days from Central Valley Ag on Vimeo.

by Mike Zwingman

by Mike Zwingman

Finishing a crop isn’t all together different from landing an airplane: both are a process of decent, and both present a very fine line between success and failure.

That landing an airp

no longer create.  We hit the end of the process of gaining—the biomass of our crop peaks as our plants reach full stature and furnish the most green tissue of the season.  Now we can only control our decent from that high, which is a rapid change in where and how dry matter accumulates.

Our job in this equates to three things: 1) managing kernel depth, 2) preventing kernel abortion, and 3) maximizing kernel density, or test weight.   Until tassel, our job is all roots and shoots.  After tassel,  it’s filling the ear.

In order to do this job well, it helps to understand a bit about what is happening in your plants, which are truly dying a little everyday as they essentially sacrifice themselves for their ears.

To put it simply, your plants are split into two hemispheres: one above the ear, and one below.  The half above the ear is where all the plant’s photosynthetic capability lies.  As photosynthesis is the process in which plants create sugars, any damage to this portion of the plant at this time of the season will lead to yield loss, which is a strong argument for a fungicide application.  Though we are in a process of decent, even after we hit full dent, harm to this part of the plant can make for a 40% loss in ear mass as large amounts of dry matter continue to accumulate in the ear in the last 15 days.

The half of the plant below the ear contributes to ear development as your plants pull sugars from the stalks to contribute to the ear.  As root activity slows, the cheapest way to build starch in the ear is to pull from the stalk and leaves, so good stalk girth now is good for ear development.  You may have heard people speak of the “cannibalization” of the corn plant—this is usually the activity that they’re referring to.  I prefer to call it “reallocation” instead, as this process isn’t a bad thing at all.  (Though if it begins to happen too early, it can lead to stalk issues at harvest.  So long as you have enough nutrients left in your soil to stimulate some root activity, too-early reallocation shouldn’t be a problem, however.)

The importance of photosynthetic activity can’t be understated though.  Final kernel density is definitively impacted by photosynthesis, or lack thereof.  Once again, friends, fungicide!  And wish, hope, pray, whatever, for hot, sunny days.  It is a simple reality that weather plays a role here.  Cloudy and cool days slow photosynthetic activity, whereas sunny and hot days drive it.  The phenomenal yields we saw in 2013 were partially a product of the classic July and August weather we had that year—while it was uncomfortable for us, our plants ate it up, kind of literally.  2014 brought more clouds and rain in those same months, and a 20 bushel difference from the year before.  The reduced photosynthetic activity alone affected test weight by about 9% between those two years.

Which is an extreme example, but makes the point: do all you can do to land this plane.  Perhaps not all will line up perfectly in your favor, but your careful management of your plants and efforts to protect their photosynthetic capabilities will pay off in bigger, fatter, heavier ears.