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Cold Start for 2013 Corn Crop

It sure seems that the weather pattern is stuck in winter instead of spring over the last couple weeks.  Much of the corn that has been planted in Southeast and Southwest Arkansas has not emerged, even though some has been planted 3+weeks.  The cold weather this week will also slow emergence and growth even more.   Cool weather combined with heavy rains in some areas is causing considerable stress on corn that is trying to emerge and time will tell what kind stands have been obtained and whether replanting will be needed.   The weather experienced so far in March for 2013 has been vastly different than 2012.

In comparing growing degree days (GDDs), ie – heat units, in Southeast Arkansas at Rohwer, AR over the last 30 years, it was very obvious how abnormally warm March of 2012 was, which was the warmest March during the 30-year period (Table 1).  However it is interesting to see that the perceived very cold March 2013 is not all that far below normal.  In the 30 year period, there were 8 years that were cooler than 2013.  GDDs for March 26-March 31, 2013 were estimated using current weather forecast highs and lows.   In past research conducted in Arkansas, the number of GDDs required for corn to emerge has been approximately 150.  A considerable amount of corn was planted during the week of March 11 in Southeast and Southwest Arkansas.  Corn planted during this week has only had approximately 90 GDDs since planting, far below the estimated 150 needed for emergence.  So it is not unrealistic for corn planted in early March to take 3+ weeks to emerge this year.  Typically March planted corn takes somewhere near 10-14 days to emerge under “normal” conditions and decent soil temperatures.

 

Table 1.  30 Year Summary of GDDs accumulated at Rohwer, AR during March.

Year

GDDs

Year

GDDs

Year

GDDs

Year

GDDs

March 2012

472

March 1997

230

March 1992

192

March 2008

149

March 2007

415

March 1990

224

March 1987

192

March 1993

137

March 1995

279

March 2006

220

March 1994

185

March 2002

135

March 2004

249

March 1989

211

March 2003

180

March 1996

130

March 1985

244

March 1991

210

March 1988

169

March 2005

128

March 2009

232

March 1998

202

March 2013

168*

March 2010

122

March 2000

232

30 Yr Avg

201

March 1984

154

March 1999

100

March 1986

231

March 2011

201

March 1983

153

March 2001

64

 

 

 

 

 

 

 

 

 

 

 

 

*Estimated

Currently only counties in Southeast and Southwest Arkansas have a significant amount of corn planted.  Areas to the north have a limited amount of corn planted.

Am I going to get a stand of corn ?

This is the question that is arising right now.  There are really two issues going on here for stand establishment.  First we have had cool temperatures since planting and freezing temperatures the last two mornings and one more morning of freezing temperatures predicted.  Soils were cold at planting (below the 55+ degrees needed for quick emergence) and we have not had the warm weather since to increase soil temperatures much.  Soil temperatures in South Arkansas this morning have been near 40 degrees.   So corn has been slow to develop to say the least.    In addition to cold stress, many fields have had substantial rainfall events this past weekend, which adds another stress.    Saturated/sealed over soils may limit oxygen supply, potentially resulting in poor stands.

No decisions about replanting or destroying an existing stand should be made until we have given the crop ample time to emerge and fully evaluate stands.  The earliest planted corn in the state is still too early to make a call on what kind of final stand we will end up with.    It is hard to do, but being patient is the best thing we can do right now.  Next week with warmer weather hopefully we will be able to better evaluate where we are.

I will have more information on minimum plant stands and planting dates coming soon.

 

 

 

 

 

 

 

 

 

 

 

 

 


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