in-crop-weather

State
Indiana Crop Weather

Week Ending Date  
July 8, 2007

Issue
IN-CW272007

                        Agricultural Summary

Cooler weather and scattered showers were offset by hot, dry 
conditions late in the week, according to the Indiana Field Office of
USDA's National Agricultural Statistics Service. Major crops were 
under stress in many areas as afternoon temperatures were above 90
degrees during the weekend. Many corn fields have now entered the 
critical stage of pollination, so farmers are hoping for cooler 
temperatures and precipitation. Wheat harvest along with cutting 
and baling of hay made good progress. Farmers are spraying to control
feeding of Japanese beetles on corn silks and soybean plants.

                                   
                         Field Crops Report 

There were 5.6 days suitable for field work. Corn condition is rated 
51 percent good to excellent compared with 60 percent last year at 
this time. Thirty-five percent of the corn acreage has silked compared 
with 12 percent last year and 19 percent for the 5-year average. 
Thirty-six percent of the soybean acreage is blooming compared with 11 
percent last year and 21 percent for the average. Soybean condition is 
rated 45 percent good to excellent compared to 59 percent last year at
this time.

Winter wheat harvest is 87 percent complete compared with 65 percent
last year and 71 percent for the 5-year average. By area, 80 percent 
of the winter wheat crop has been harvested in the north, 85 percent 
in the central region and 97 percent in the south. The second cutting
of alfalfa hay is 61 percent complete compared with 49 percent last 
year and 39 percent for the average. Major activities during the week
included: maintaining irrigation equipment, scouting fields, spraying,
cutting and baling hay, mowing roadsides and ditches and taking care 
of livestock.

                                   
                    Livestock, Pasture and Range Report 

Pasture condition is rated 0% excellent, 13% good, 33% fair, 34% poor,
and 20% very poor. Hot, dry conditions late in the week placed 
livestock under some stress. 

                 
                    Crop Progress Table
-------------------------------------------------------
                       : This : Last : Last : 5-Year
     Crop              : Week : Week : Year :  Avg
-------------------------------------------------------
                             Percent
Corn Silked               35     10     12     19
Soybeans Blooming         36     15     11     21
Winter Wheat Harvested    87     49     65     71
Alfalfa Second Cutting    61     38     49     39

                    Crop Condition Table
-----------------------------------------------------------
                    : Very :      :      :      : Excel-
     Crop           : Poor : Poor : Fair : Good :  lent
----------------------------------------------------------- 
                             Percent
Corn                    4     13     32     43      8
Soybean                 6     13     36     40      5
Winter Wheat            3     18     46     30      3
Pasture                20     34     33     13      0

        
        Soil Moisture & Days Suitable
             for Fieldwork Table
----------------------------------------
               : This  : Last  : Last :
               : Week  : Week  : Year :
----------------------------------------
                      Percent
Topsoil
  Very Short      26      18       4
  Short           38      34      19
  Adequate        34      46      70
  Surplus          2       2       7
Subsoil
  Very Short      25      23       3
  Short           40      38      15
  Adequate        34      39      74
  Surplus          1       0       8
Days Suitable    5.6     4.5     5.9
                                            
Contact information
--Greg Preston, Director
--Andy Higgins, Agricultural Statistician
  E-Mail Address: nass-in@nass.usda.gov
  http://www.nass.usda.gov/Statistics_by_State/Indiana        
---------------------------------------------------------------------
 Other Agricultural Comments And News

                   SEX IN THE CORN FIELD: SILK EMERGENCE

*  Corn produces individual male and female flowers on the same 
   plant. 
*  The ear represents the female flower of the corn plant. 
*  Severe soil moisture deficits can delay silk emergence and 
   disrupt the synchrony of pollen shed and silk availability,
   resulting in poor kernel set. 

Published 2001 (Rev. July 2007)

As important as the process of pollination is to the determination of
grain yield in corn, it is surprising how little some folks know 
about the details of cornfield sex. Rather than leaving you to learn
about such things "in the streets", take the time to read this article
and the accompanying one on tassels and anthers (Nielsen, 2007b) that 
describe the ins and outs of this critical period of the corn plant's
life cycle.

The corn plant produces individual male and female flowers (a 
flowering habit called monoecious for you corny trivia fans.) 
Interestingly, both flowers are initially bisexual (aka "perfect"),
but during the course of development the female components (gynoecia)
of the male flowers and the male components (stamens) of the female
flowers abort, resulting in tassel (male) and ear (female) 
development. 

The silks that emerge from the ear shoot are the functional stigmas 
of the female flowers of a corn plant. Each silk connects to an 
individual ovule (potential kernel). A given silk must be pollinated
in order for the ovule to be fertilized and develop into a kernel. Up
to 1000 ovules typically form per ear, even though we typically 
harvest only 400 to 600 actual kernels per ear.

Technically, growth stage R1 (Ritchie et al., 1993) for a given ear is
defined when a single silk strand is visible from the tip of the husk. A
field is defined as being at growth stage R1 when silks have emerged on
at least 50 % of the plants. 

Silk Elongation and Emergence

Silks begin to elongate from the ovules about 10 days prior to growth
stage R1. Silk elongation begins first from the basal ovules of the 
cob, then proceeds sequentially up the ear. Similarly, silks from the
basal (butt) portion of the ear typically emerge first from the husk,
while the tip silks generally emerge last. Complete silk emergence 
from an ear generally occurs within four to eight days after the 
first silks appear. 

As silks first emerge from the husk, they lengthen as much as 1.5 
inches per day for the first day or two, but gradually slow over the 
next several days. Silk elongation occurs by expansion of existing
cells, so elongation rate slows as more and more cells reach maximum 
size. Once pollinated, elongation of an individual silk will stop.
Silk elongation stops about 10 days after silk emergence, regardless
of whether pollination occurs, due to senescence of the silk tissue. 
Unusually long silks can be a diagnostic symptom that the ear was 
not successfully pollinated.

Silks remain receptive to pollen grain germination up to 10 days 
after silk emergence, but to an ever-decreasing degree. Natural 
senescence of silk tissue over time results in collapsed tissue that 
restricts continued growth of the pollen tube. Silk emergence usually 
occurs in close synchrony with pollen shed, so that duration of silk 
receptivity is normally not a concern. Failure of silks to emerge in
the first place, however, does not bode well for successful 
pollination. 

Pollination and Fertilization 

For those of you serious about semantics, let's review two definitions
relevant to sex in the cornfield. Pollination is the act of 
transferring the pollen grains to the silks by wind or insects.
Fertilization is the union of the male gametes from the pollen with 
the female gametes from the ovule. Technically, pollination is almost
always successful (i.e., the pollen reaches the silks), but
unsuccessful fertilization (i.e., pollen tube failure, silk failure,
pollen death) will fail to result in a kernel.

Pollen grain germination occurs within minutes after a pollen grain 
lands on a receptive silk. A pollen tube, containing the male genetic
material, develops and grows inside the silk, and fertilizes the 
ovule within 24 hours. Pollen grains can land and germinate anywhere 
along the length of an exposed receptive silk. Many pollen grains may
germinate on a receptive silk, but typically only one will 
successfully fertilize the ovule. 

Silk Emergence Failure 

SEVERE DROUGHT STRESS. The most common cause of incomplete silk 
emergence is severe drought stress. Silks have the greatest water 
content of any corn plant tissue and thus are most sensitive to 
moisture levels in the plant. 

Severe moisture deficits will slow silk elongation, causing a delay
or failure of silks to emerge from the ear shoot. If the delay is 
long enough, pollen shed may be almost or completely finished before
receptive silks are available; resulting in nearly blank or totally
blank cobs. Severe drought stress accompanied by low relative 
humidity can also desiccate exposed silks and render them 
non-receptive to pollen germination. 

The severity of drought stress required for significant silk emergence
delay or desiccation can probably be characterized by severe leaf 
rolling that begins early in the morning and continues into the early
evening hours. Such severe leaf rolling is often accompanied by a 
change in leaf color from "healthy" green to a grayish-tinged green
that may eventually die and bleach to a straw color. 

SILK CLIPPING BY INSECTS. Although technically not defined as silk 
emergence failure, severe silk clipping by insects such as corn 
rootworm beetle or Japanese beetle nonetheless can interfere with the 
success of pollination by decreasing or eliminating viable or 
receptive exposed silk tissue. Fortunately, unless the beetle 
activity is nonstop for days, continued elongation of silks from the
husk will expose undamaged and receptive silk tissue at the rate of 
about one inch or more per day. 

Related References

Kling, Jennifer G. and Gregory Edmeades. 1997. Morphology and
growth of maize. IITA/CIMMYT Research Guide 9. Int'l Institute of
Tropical Agriculture. [On-Line}. Available at http://www.iita.org/
cms/details/trn_mat/irg9/irg9.htm (URL verified 7/2/07).

Nielsen, R.L. (Bob). 2007a. A Fast & Accurate Pregnancy Test for Corn.
Corny News Network, Purdue Univ. [On-Line]. Available at http://www.
kingcorn.org/news/timeless/EarShake.html (URL verified 7/2/07). 

Nielsen, R.L. (Bob). 2007b. Tassel Emergence & Pollen Shed. Corny News
Network, Purdue Univ. [On-Line]. Available at http://www.kingcorn.org/
news/timeless/Tassels.html (URL verified 7/2/07). 

Ritchie, S.W., J.J. Hanway, and G.O. Benson. 1993. HOW A CORN PLANT 
DEVELOPS. Iowa State Univ. Sp. Rpt. No. 48. [On- Line] Available at 
http: //www.extension.iastate.edu/pages/hancock/agriculture/corn/
corn_develop/CornPlantStages.html. (URL verified 7/2/07). 

Russell, W.A. and A.R. Hallauer. 1980. Corn. (a chapter in) 
Hybridization of Crop Plants. American Soc. of Agronomy-Crop Science
Soc. of America. Madison, WI. Steffey, Kevin. 2005. Rootworm Adults 
and Silk Clipping. Pest & Crop Bulletin, Univ. of Illinois. [On-Line].
Available at http://www.ipm.uiuc.edu/bulletin/article.php?issueNumber
=15&issueYear=2005&articleNumber=2. (URL verified 7/4/07).

This "Silk Emergence" article was originally published in 2001, but
was revised July, 2007. The article also contains photos, which can 
be viewed at: http://www.kingcorn.org/news/timeless/silks.html, pages 
1-4. 

R.L. (Bob) Nielsen, Department of Agronomy, Purdue University, West
Lafayette, IN  47907-2054, Email address: rnielsen@purdue.edu
----------------------------------------------------------------
The INDIANA CROP & WEATHER REPORT (USPS 675-770), (ISSN 0442-817X) is
issued weekly April through November by the USDA, NASS, Indiana Field
Office, 1435 Win Hentschel Blvd, Suite 110, West Lafayette IN 
47906-4145. Second Class postage paid at Lafayette IN. For 
information on subscribing, send request to above address. POSTMASTER:
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---------------------------------------------------------------------------------

             Weather Information Table

           Week ending Sunday July 8, 2007
-----------------------------------------------------
                | Past Week Weather Summary Data   
                |---------------------------------
 Station        |      Air      |            | Avg  
                |  Temperature  |  Precip.   |4 in.  
                |---------------|------------|Soil 
                |Hi |Lo |Avg|DFN| Total|Days |Temp 
----------------------------------------------------- 
Northwest (1)                                    
Chalmers_5W      88  52   72  -3   0.91    2     
Francesville     85  54   70  -3   2.10    3     
Valparaiso_AP_I  87  50   72  +0   0.24    1     
Wanatah          88  52   71  -2   0.33    2   80
Winamac          87  54   71  -2   0.49    3   77
North Central(2)                                 
Plymouth         88  53   71  -3   0.27    2     
South_Bend       89  56   73  +1   0.30    1     
Young_America    87  52   71  -3   0.12    2     
Northeast (3)                                    
Columbia_City    88  51   71  -2   0.00    0   74
Fort_Wayne       90  51   72  -2   0.00    0     
West Central(4)                                  
Greencastle      86  52   71  -5   0.95    1     
Perrysville      89  51   73  -3   0.47    1   82
Spencer_Ag       88  53   72  -3   0.37    2     
Terre_Haute_AFB  88  53   72  -3   1.92    2     
W_Lafayette_6NW  88  52   71  -3   0.08    1   80
Central (5)                                      
Eagle_Creek_AP   88  57   74  -2   0.19    1     
Greenfield       87  54   72  -3   0.10    2     
Indianapolis_AP  89  60   75  -1   0.03    1     
Indianapolis_SE  88  55   72  -4   0.16    2     
Tipton_Ag        86  51   70  -4   0.19    1   78
East Central(6)                                  
Farmland         85  48   69  -4   0.48    2   74
New_Castle       86  51   69  -4   0.33    1     
Southwest (7)                                    
Evansville       91  58   76  -3   0.60    1     
Freelandville    88  58   74  -3   0.20    2     
Shoals           89  51   72  -3   0.85    2     
Stendal          91  57   76  -1   1.26    1     
Vincennes_5NE    89  54   74  -2   1.25    2   73
South Central(8)                                 
Leavenworth      89  57   75  -1   1.97    2     
Oolitic          88  53   72  -3   0.68    2   75
Tell_City        90  60   75  -3   1.24    2     
Southeast (9)                                    
Brookville       89  53   72  -3   0.98    2     
Greensburg       86  54   72  -3   0.46    2     
Scottsburg       91  51   74  -2   1.21    2       
----------------------------------------------------

      Weather Information Table (Continued)

         Week ending Sunday July 8, 2007
------------------------------------------------
                        Accumulation           
                --------------------------------
                      April 1, 2007 thru       
 Station                 July 8, 2007       
                 --------------------------------
                  Precipitation   |GDD Base 50oF
                 --------------------------------
                       |     |    |     |
                 Total | DFN |Days|Total|  DFN   
-------------------------------------------------
Northwest (1)   |
Chalmers_5W     |10.66  -1.57  32   1442  +118
Francesville    |11.47  -0.97  33   1371  +171
Valparaiso_AP_I | 5.77  -7.37  25   1415  +251
Wanatah         | 9.91  -2.61  31   1305  +199
Winamac         |10.36  -2.08  32   1379  +179
North Central(2)|
Plymouth        |10.87  -2.11  35   1313   +62
South_Bend      | 8.41  -3.78  26   1443  +296
Young_America   | 8.81  -3.13  32   1460  +243
Northeast (3)   |
Columbia_City   | 7.01  -5.27  33   1315  +227
Fort_Wayne      | 7.71  -3.62  34   1461  +254
West Central(4) | 
Greencastle     |10.54  -2.95  29   1431   +24
Perrysville     | 9.15  -4.14  28   1620  +313
Spencer_Ag      |15.61  +1.56  33   1467  +163
Terre_Haute_AFB |12.36  -0.79  32   1612  +211
W_Lafayette_6NW |11.83  -0.44  32   1492  +268
Central (5)     |
Eagle_Creek_AP  | 8.44  -3.85  32   1669  +281
Greenfield      | 9.23  -3.90  39   1513  +201
Indianapolis_AP | 7.75  -4.54  33   1697  +309
Indianapolis_SE |11.23  -1.33  36   1510  +147
Tipton_Ag       | 9.52  -2.73  37   1407  +228
East Central(6) |
Farmland        | 9.47  -3.03  37   1372  +234
New_Castle      | 9.49  -4.06  29   1412  +244
Southwest (7)   |
Evansville      | 9.66  -3.62  32   1862  +199
Freelandville   | 9.60  -4.09  35   1703  +243
Shoals          |12.10  -2.54  32   1577  +180
Stendal         |10.88  -3.99  32   1882  +336
Vincennes_5NE   |12.05  -1.64  36   1771  +311
South Central(8)|  
Leavenworth     |11.75  -3.06  36   1714  +316
Oolitic         |11.06  -2.84  30   1527  +205
Tell_City       |12.13  -2.77  24   1855  +293
Southeast (9)   |
Brookville      |10.13  -3.06  24   1580  +351
Greensburg      |11.81  -1.69  31   1630  +333
Scottsburg      |12.86  -0.72  32   1660  +212   
------------------------------------------------------------------
DFN = Departure From Normal (Using 1961-90 Normals Period).
GDD = Growing Degree Days.
Precipitation (Rainfall or melted snow/ice) in inches.
Precipitation Days = Days with precip of .01 inch or more.
Air Temperatures in Degrees Fahrenheit.

Copyright 2007:  Agricultural Weather Information Service, Inc.
                 All rights reserved.

       The above weather information is provided by AWIS, Inc.
For detailed ag weather forecasts and data visit the AWIS home page
                        at: www.awis.com