2017 has been another typical year of extreme weather in the Midwest.
We were generally cooler than normal and wet into late May, with SE Iowa having a drier than normal June and early July, although rains came to many areas July 9 and 10. Disease development was initially slow, but because of recent rains, conditions are now favorable for disease. Corn fields planted in April tended to be a little more erratic in emergence and often are 10% lower in population than normal. Corn planted early, generally rooted down and pollinated well, although the corn is often 20% smaller than usual. Corn planted in mid to late May, could struggle to pollinate well, due to the hot night time temperatures forecast for July 18 to 21.
Carefully monitor weed pressure and try to spray corn for weeds before they exceed 4” tall, as weed pressure can have a dramatic impact on potential corn yield.
If using Liberty herbicide, use drops if corn is above knee high. A good herbicide with residual control of waterhemp is recommended. If you used Glyphosate “GT or RR” tolerant corn last year which did not contain Liberty Tolerance and this year you have Liberty tolerance in your corn, spray Liberty now to remove volunteer corn (VC) as VC can significantly affect yield and rootworm control, even in corn carrying the RW gene.
Miller Hybrids is one of only a few companies that continue to carry elite Liberty Link corn.
Agrisure shared some great slides to help explain a few things about their products. Check it out...
The many windy days we have experienced may have brought disease spores from the South and although we are currently in a dry spell, disease spores are prevalent in decaying tissue. Be sure to continue to scout and monitor disease favoring conditions, once this dry spell breaks.
Fungicide costs are down significantly from a few years ago and most of our top producers have seen a nice return on investment by using fungicides. This is especially true in high yielding fields that are either corn-on-corn or which are planted to conventional corn.
Low lying fields are more vulnerable as well as fields planted to less disease susceptible varieties. Insecticides can be mixed with fungicides, but it is important to follow the correct protocol for fields near beehives.
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There are questions about the corn height this year being shorter than normal for corn planted in April. This appears to be the case due to at least 3 factors:
1) Corn planted early is normally shorter than corn planted late due to a reaction to day length being shorter, early in the growing period.
2) Corn height was reduced due to suboptimal growing conditions during early development due to excess water and cooler temperatures in late April and parts of May.
3) Periods of excessive heat in early to mid June correlated with drier conditions and the corn plants often were unable to maximize growth as significant leaf rolling occurred and limited photosynthesis and moisture reduced cell elongation.
It may be interesting to look at the height as an indicator of potential yield, but chances are that it's minor compared to the water relations and temperature during pollination. For those farmers who missed the rains recently, we need to be concerned that the plants recover overnight and silk timely and, for now, be relatively unconcerned about plant height.
Thoughts from Ph. D. Corn Breeder and Miller Hybrids Owner, Bob Miller.
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