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: Send address change to the USDA, NASS, Indiana Field Office, 1435 Win Hentschel Blvd, Suite 110, West Lafayette IN 47906-4145. --------------------------------------------------------------------------------- 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