he lyrics of that well-known
Irving Berlin hit song have been a favorite selection on the
well-worn jukebox down at the Chat ‘n Chew Café these days as
farmers yearn for a return to sunshine and warmth to rejuvenate the appearance
of their corn fields. Uneven growth, pathetic leaf colors (yellow, silver,
purple, orange, red, transparent, straw-bleached), herbicide injury, nematode
injury, slug injury, insect injury, disease injury, UAN fertilizer leaf burn,
death by drowning, twisted whorls………you name the problem, it is
probably out there somewhere this year.
In addition to these cornfield problems, some are wondering whether the seemingly high number of cool, cloudy days these past four weeks or so will cause lingering yield-depressing effects on the corn crop. The answer is, as you might expect, not clearcut.
The effect of the cool cloudy weather itself on the corn crop to date has been a reduction in the rate of photosynthesis by the young corn plants (Nafziger, 2003). The immediate impact of this on grain yield has been negligible at worst simply because most of the state’s corn crop is only now entering the ear size determination period (post-V6). Growing conditions from here on will have a much greater effect on potential ear size.
Indirectly, though, the cool cloudy (and often excessively wet) weather has impacted yield due to the increased vulnerability of the lethargic young plants to other stresses; including those listed earlier. Where significant stand loss or plant stunting has occurred from these other stresses, the yield potential has undoubtedly been reduced. The ultimate extent of the yield loss, however, is very much dependent on growing conditions the remainder of the growing season.
“Blue skies smiling at me, Nothing but blue skies do I see …” (Irving Berlin, 1927).
Nafziger, Emerson. 2003. Thinking About Crop Stress. Illinois Pest & Crop Bulletin (6 June). Univ. of Illinois. Available online at http://www.ag.uiuc.edu/cespubs/pest/articles/200311i.html [URL verified 6/6/03].