Bob Nielsen put together an article yesterday on his Chat 'n Chew Cafe website with a bit more information on the impact of hot and dry weather on early corn. This adds a bit to my earlier post on dry weather and corn which looked at dryness in and of itself without considering heat impacts.
In essence, Bob is concerned about the impact of the dry weather and in particular some of the heat we've had on the root development of young corn. Not sure there's a lot that can be done unless you have irrigation.
One article I haven't seen is on the accumulative stress of quickly transitioning from periods with nights in the 40's to ones with days in the 90's. If I come across something on this I'll post it.
Showing posts with label Dry. Show all posts
Showing posts with label Dry. Show all posts
Wednesday, May 23, 2012
Monday, May 21, 2012
Impact of Dry Weather on Early Corn
Since the rain last night missed us for the most part, I think it's worth taking a look at how early season dryness impacts corn development. Some years ago (unfortunately this now translates to a few decades ago) when I worked in Nebraska folks didn't worry much about the early season dryness and there was plenty of 7-ft corn which made pretty good yields (this being relative as 150 bu was pretty good). In any case, they generally didn't turn the irrigation on until June, whatever the weather.
Chad Lee and John Grove from the University of Kentucky posted an interesting article a couple of weeks ago on this. In essence, until V6, so long as the plants don't actually burn up, there's little impact from early season dryness. From that point on it starts to become a problem.
Aspects not covered in this article include things like outgrowing potential cutworm damage. Fortunately, while it seems like it would be an ideal year for cutworm damage, I haven't heard of any problems in Clinton County.
Chad Lee and John Grove from the University of Kentucky posted an interesting article a couple of weeks ago on this. In essence, until V6, so long as the plants don't actually burn up, there's little impact from early season dryness. From that point on it starts to become a problem.
Aspects not covered in this article include things like outgrowing potential cutworm damage. Fortunately, while it seems like it would be an ideal year for cutworm damage, I haven't heard of any problems in Clinton County.
Thursday, August 4, 2011
Weather Impacts on Corn
Everybody who grows corn knows that the recent hot, dry weather during pollination isn't ideal. The question then becomes how to assess what the impact has been.
The most accurate way is to simply go out and do yield checks by counting ears and kernels. Rather than spell this out here, I'll refer people to Bob Nielsen's article from last October, Estimating Corn Grain Yield Prior to Harvest. In talking to people who've done this already, the general response I'm getting is, "It's not as bad as I was afraid it might be." I know that's not terribly specific but it appears that the corn has been weathering this surprisingly well.
From "drive-by windshielding" there has been remarkably little visible signs of stress in corn, in particular leaf rolling. This has recently started to change a bit in areas of the county which have not received much rain. If you're wondering how leaf rolling equates to yield loss, I'll refer you to an article from July 15 by Roger Elmore and Elwynn Taylor from Iowa State, Corn and “a Big Long Heat Wave on the Way”. In particular, these passages in the final section are interesting:
"By rule-of-thumb, the yield is diminished by 1 percent for every 12 hours of leaf rolling - except during the week of silking when the yield is cut 1 percent per 4 hours of leaf rolling."
and
"The second impact is less obvious initially. When soil moisture is sufficient, as it is for the most part this July, the crop does not have a measurable yield response to one day of temperatures between 93F to 98 F. However, the fourth consecutive day with a maximum temperature of 93 F or above results in a 1 percent yield loss in addition to that computed from the leaf rolling. The fifth day there is an additional 2 percent loss; the sixth day an additional 4 percent loss. Data are not sufficient to make generalizations for a heat wave of more than six days, however firing of leaves then becomes likely and very large yield losses are incurred."
Unfortunately, just in the past few days there has been some lower-leaf firing in corn. As a caution, this goes back to my "drive-by windshielding" sampling method which tends to include quite a bit of end-rows which are generally more compacted and will show more of this.
The most accurate way is to simply go out and do yield checks by counting ears and kernels. Rather than spell this out here, I'll refer people to Bob Nielsen's article from last October, Estimating Corn Grain Yield Prior to Harvest. In talking to people who've done this already, the general response I'm getting is, "It's not as bad as I was afraid it might be." I know that's not terribly specific but it appears that the corn has been weathering this surprisingly well.
From "drive-by windshielding" there has been remarkably little visible signs of stress in corn, in particular leaf rolling. This has recently started to change a bit in areas of the county which have not received much rain. If you're wondering how leaf rolling equates to yield loss, I'll refer you to an article from July 15 by Roger Elmore and Elwynn Taylor from Iowa State, Corn and “a Big Long Heat Wave on the Way”. In particular, these passages in the final section are interesting:
"By rule-of-thumb, the yield is diminished by 1 percent for every 12 hours of leaf rolling - except during the week of silking when the yield is cut 1 percent per 4 hours of leaf rolling."
and
"The second impact is less obvious initially. When soil moisture is sufficient, as it is for the most part this July, the crop does not have a measurable yield response to one day of temperatures between 93F to 98 F. However, the fourth consecutive day with a maximum temperature of 93 F or above results in a 1 percent yield loss in addition to that computed from the leaf rolling. The fifth day there is an additional 2 percent loss; the sixth day an additional 4 percent loss. Data are not sufficient to make generalizations for a heat wave of more than six days, however firing of leaves then becomes likely and very large yield losses are incurred."
Unfortunately, just in the past few days there has been some lower-leaf firing in corn. As a caution, this goes back to my "drive-by windshielding" sampling method which tends to include quite a bit of end-rows which are generally more compacted and will show more of this.
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