Agronomy notes
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Permanent Link: http://ufdc.ufl.edu/UF00066352/00137
 Material Information
Title: Agronomy notes
Uniform Title: Agronomy notes (Gainesville, Fl.)
Physical Description: v. : ill. ; 28 cm.
Language: English
Creator: Florida Cooperative Extension Service
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.
Place of Publication: Gainesville
Publication Date: July 2011
Subjects / Keywords: Crops and soils -- Florida   ( lcsh )
Crop yields -- Florida   ( lcsh )
Agriculture -- Florida   ( lcsh )
Agronomy -- Florida   ( lcsh )
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government publication (state, provincial, terriorial, dependent)   ( marcgt )
periodical   ( marcgt )
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General Note: Description based on: January 1971; title from caption.
Statement of Responsibility: Florida Cooperative Extension Service, University of Florida, Institute of Food and Agricultural Sciences.
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Resource Identifier: aleph - 000956365
notis - AER9014
System ID: UF00066352:00137


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Agronomy Notes July 2011 Volume 35:7 Features: Forage: Budgets for Pasture Establishment ...........................Page 4 Y. Newman, Extension Forage Specialist ( ycnew@ufl.edu) ; J. Bennett, Crop Physiology (jmbt@ufl.edu); F. Fishel, Pesticide Information Officer (weeddr@ufl.edu); D.C. Odero, Extension Weed Specialist (dcodero@ufl .ed u); D. Wright, Extension Agronomist (wright@ufl.edu). The use of trade names does not constitute a guarantee or warrant of products named and does not signify approval to the exclusion of similar products. The Institute of Food and Agricultural Sciences (IFAS) is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to rac e, color, sex, age, handicap or national origin. For information on obtaining other extension publications, contact your county Cooperative Extension Offi ce. Florida Cooperative Extension Service/Institute of Food and Agricultural Sciences/University of Florida/Millie Ferrer Chancy, Interim Dean. Miscellaneous: Weeds and Pesticides: Registrants Request Voluntary Cancellation of Dicofol ................................................................Page 8 Effects of Drought on Sugarcane Production .............Page 9 Calendar ................................................................Page 10 Crops: Irrigating Corn with Limited Water Supplies ..............Page 2 Drought and Plating Date ..........................................Page 3 Cotton Stands .............................................................Page 3 Crop Varieties and Water Use ...................................Page 7


4 2 Crops Dr. David Wright, Extension Agronomist North Florida REC, Quincy wright@ufl.edu Irrigating Corn with Limited Water Supplies With corn prices at near all time highs growers planted more corn in 2011. Many fields are non irrigated while others have limited water supplies from ponds or wells that cannot keep up with demands. In general corn requires about 22 inches or water to make a crop from planting until harvest. The most critical period is during the 10 days of pollination. For those who have only 3 4 inches of water for the entire crops, water should be applied at the start of silk and tassel followed by an application in 4 5 days later followed by the 3rd application 5 6 days later. If there is adequate water for another application, it can be made about 7 days later. Corn needs about a third of an inch of water per day during the silk ear fill period if adequate water is available for top yields. Non irrigated corn that is past silking and tassel period under severe drought stress. Photo: David Wright


4 3 Crops Dr. David Wright, Extension Agronomist North Florida REC, Quincy wright@ufl.edu Cotton under severe drought stress with poor stands and weed control Photo by David Wright Drought and Planting Date Due to the drought that we have experienced this year many people have lost non irrigated corn crops and July is too late for peanut and cotton. However soybeans may still be planted in July if drilled and irrigated. Yields can be very satisfactory for MG V VIII for planting through the month of July into the first 10 days of August. Many of these corn fields will still have residual fertilizer from the corn. Corn may be planted as a second crop for grain or silage if a Bt hybrid is used that has good disease resistance. The latest planting date for corn should be July 15 20 to make satisfactory yields. Cotton Stands Growers have had a tough season to get a stand of cotton and had added weed control issues due to the drought. Many growers have had stand problems due to dry soil conditions and herbicides splashing on young cotton seedlings along with heavy thrips feeding. Most growers elected to go with the current cotton stands even if it were less than satisfactory due t o the uncertainty of getting any rains before it was too late to plant again. The last date that we recommend planting in Florida is the third week of June even though cotton can be planted in July in the Deep South and still grows and fruits well but will not open normally in most years due to cool weather and frosts. Up to this point growers have faced more weather challenges than in most years. Cotton is a southern crop and will withstand high levels of stress and still has the potential to produce good yields if we have good weather conditions in July and August. The new cotton varieties that have replaced DP&L 55 will be severely tested this year.


4 Forages Dr. Yoana Newman, Extension Forage Specialist ycnew @ufl.edu Les Harrison, Leon Co. Extension Agent harrisog @ufl.edu 4 Budgets for Pasture Establishment The budgets presented in the next two pages are offered to assist in the making of a rational decision when establishing a pasture or paddock in Florida. They should be used as a guide to assessing the expenses of establishing a seeded type pasture like bahiagrass or seeded bermudagrass versus vegetatively propagated hybrid bermudagrasses such as Tifton 85, Jiggs, or Tifton 44. For production, adaptation, and quality comparisons, the reader is referred to the Forages of Florida website where a description of the different grasses is provided ( http:// agronomy.ifas.ufl.edu/ForagesofFlorida/ index.php ) The use of the budgets presented is a starting point for the development of a value analysis. This application should lead the user to an economic conclusion and a business choice as it relates to his or her farming enterprise. After due diligence, the user may decide to pursue pasture establishment if the anticipated returns sufficiently outweigh the forecast expenses. Conversely, the user may decide it is not efficient to proceed, and either rent a pasture and/or purchase forage for their livestock. The Cost Presented Here : The user should recognize the input cost provided here are static statewide composite figures and may be different from what is encountered locally depending on a variety of factors. Those factors include time of year, location within Florida, market dynamics which can raise or lower cost by changing demand and\or supply, a weather event, modification of the regulatory environment, plus other variables, or some combination of any or all of the aforementioned. The prices in the following tables were representative data in February 2011 See next page for budget tables


4 5 Budgets for Pasture Establishment: ( continued from page 4) Forages Dr. Yoana Newman, Extension Forage Specialist ycnew @ufl.edu Les Harrison, Leon Co. Extension Agent harrisog @ufl.edu


4 6 Budgets for Pasture Establishment: ( continued from page 4) Forages Dr. Yoana Newman, Extension Forage Specialist ycnew @ufl.edu Les Harrison, Leon Co. Extension Agent harrisog @ufl.edu


4 7 Crop Varieties and Water Use less water? Stimulated by extended droughts like we have experienced this spring and early summer discussions sometime (transpiration). While many advances have been made in producing new crop varieties with improved characteristics, research has not been very successful in breeding new varieties of crops for high biomass production with significantly reduced water use. Many years of research have shown that, for a specific geographical location, water lost from a crop through transpiration is directly, and linearly, related to the amount of crop biomass produced, as shown below: The scientific literature is filled with examples showing this very tight linear relationship, at least for the highly productive crops, such as the agronomic crops. (Just a note: the slope of the line is significantly affected by dryness of the air and will be different in arid and humid environments.) So, why are water use and yield so tightly linked? The reasons are actually quite simple. Both the loss of water out of leaves (transpiration) and the movement of carbon dioxide (necessary for photosynthesis and yield) into leaves occur through the same microscopic pores (stomata) in leaves. These small pores can open or close depending on the level of water stress in the plant. If the stomata are open under well watered conditions, water is lost and carbon dioxide moves into the leaves, resulting in high water loss and high photosynthesis. However, under drought conditions when the stomata close to conserve water the movement of carbon dioxide into the leaves is also severely restricted which reduces photosynthesis (biomass or yield). Thus, the dilemma and the age old question is how can water loss from plants be reduced without also reducing photosynthesis. Indeed, breaking the tight linkage of water loss and photosynthesis will be a very difficult challenge to overcome simply because of the anatomy of plant leaves where stomata regulate both difficult to envision how high biomass can be produced without the loss of significant amounts of water from crops. One must always question claims that high yields will be achieved with low inputs (and that statement applies to many other inputs in addition to water). It simply takes requires significant amounts of water to proagriculture! Nevertheless, efficient crop management, and especially efficient irrigation management, ensures that water is used effectively for crop production. Proper irrigation management is a key to ensuring that applied water is used for transpiration rather than being lost to drainage below the root system, runoff, or evaporation as it moves from the irrigation system to the soil. As we look to the future, all segments of society will be under more and more scrutiny to justify use of our limited water resources and other natural resources Crop Physiology Dr. Jerry Bennett, Crop Physiology jmbt @ufl.edu


4 8 Registrants Request Voluntary Cancellation of Dicofol In a Memorandum of Agreement with EPA dated May 17, 2011, the registrants of dicofol requested voluntary cancellation of all their dicofol registrations. EPA is requesting comment for 30 days on the registrants' request, which would terminate the last dicofol products registered in the United States. EPA plans to grant the registrants' request at the close of the comment period unless substantive comments require further deliberation. Dicofol is the last organochlorine pesticide to go through a cancellation process to terminate all its remaining uses in the U.S. The registrants, Agan Chemical Manufacturing, Ltd. and Makhteshim Agan of North America, Inc., ceased all production of dicofol as of May 17, 2011, and have agreed to cease all sales and distribution of the pesticide by October 31, 2013. The companies also have agreed to amend product labels for existing stocks by August 31, 2011, to prohibit use of dicofol after October 31, 2016. EPA plans to revoke the tolerances associated with commodities treated with dicofol effective October 31, 2016. Dicofol is registered for use as a miticide on cotton and several other agricultural crops and on non residential lawns and ornamentals. Use of dicofol has significantly declined since the amended Reregistration Eligibility Decision (RED) in 2006. The 2006 amended RED significantly increased the re entry interval for most crops in order to protect workers harvesting the crops after application of dicofol. Submit comments by July 22, 2011 on the dicofol voluntary cancellation request through docket EPA HQ OPP 2005 0220 at Regulations.gov. The Memorandum of Agreement is also available in the dicofol reregistration docket; see EPA HQ OPP 2005 0220 0016 at Regulations.gov. Pesticides Dr. Fred Fishel, Pesticide Information Director weeddr @ufl.edu


9 Weed Science Dr. D. Calvin Odero, Extension Weed Specialist dcodero @ufl.edu Effects of Drought on Sugarcane Production Extreme and exceptional drought conditions have covered Palm Beach County, Florida in the last several months, according to the National Weather Service. Palm Beach sugarcane grown in the Everglades Agricultural Area (EAA). This is the fourth such extreme drought that the county has experienced in the past decade, according to the National Drought Mitigation Center. The protracted drought has negatively impacted water level in Lake Okeechobee which reached the lowest water elevation ever recorded in the month of April. Low water level in the lake has resulted in South Florida Water Management District cutting back 45% in water allocation to EAA growers. Of the over 500,000 acres cultivated in the EAA, less than 4% is under fallow implying that the entire EAA is in dire need of water for sugarcane and other crops. The effects of drought on sugarcane have been manifested by slowdown in production of new shoots and leaves, and accelerated shoot and leaf senescence. The growers are hoping that summer rainfall will be adequate to help sugarcane grow by at least an inch a day especially for fields that are scheduled for harvest in another 100 days. In addition, the drought has negatively impacted sugarcane management practices including weed control. Competition for water between sugarcane and weeds has increased as soil moisture becomes limited under drought conditions. Weed species that have been observed in sugarcane fields during this drought period have been mainly grasses, predominantly fall panicum. Weed control before sugarcane canopy closure is normally achieved by use of a combination of herbicides and cultivation between the rows. Many fields especially in shallow muck and transitional sandy soils have seen a reduction in cultivation to conserve available soil moisture. Therefore, some of these fields have relied entirely on herbicides for weed control. However, most herbicides become less effective when plants are under water stress. Thus, applications of grass herbicides such as asulam have exacerbated the effect of drought stress on sugarcane by causing phytotoxicity to the crop while providing poor grass control. While the vigor and size of these grasses have been reduced by herbicide application and drought conditions, they have still been able to produce a lot of viable seeds which will become sources of reinfestation in subsequent crops. Consequently, herbicide use during extreme drought needs to be reevaluated to minimize adverse effects that they may have on sugarcane. It is important to always read herbicide labels to see if they permit use of lower rates when the sugarcane and weeds are under dire water stress.


10 Calendar Jul. 3 9 Caribbean Food Crops Society meeting Two Mile Hill, St. Michael, Barbados,. http://www.cfcs2011barbados.org/ Jul. 15 17 Florida Small Farms and Alternative Enterprises Conference Kissimmee, FL. http://conference.ifas.ufl.edu/smallfarms/index.html Oct. 3 5 Southeast Herbicide Applicator Conference Panama City Beach, FL http://conference. ifas.ufl.edu/sehac/index.html Oct. 16 19 American Society of Agronoy Annual meeting, San Antonio, TX https://www.acsmeetings.org