ISU Extension
IA State Univ.
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June 2002

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In This Issue
   What are Degree Days & Phenology Models?
   Tuning Up Your Pasture Potential
   Livestock Producers—Stay Vigilant about Foreign Animal Diseases
   2002 Farm Program Basics

What are Degree Days & Phenology Models?
by Todd Vagts, ISU Extension Crops Field Specialist

We often hear in disease prediction, insect control and crop management strategies the use of Degree Days (heat units) and crop models used to predict the onset or phenology (particular physiological event) of a disease, an insect or plant organism.  So what do we really mean by degree-day and phenology and how are they calculated?

Temperature controls the developmental rate of plant and pest organisms.  The amount of heat required to complete a given organism’s development does not vary, in other words the combination of temperature and time will always be the same.  The end result is that physiological time is expressed and approximated in units called Degree-Days.  Degree-Days are the total amount of heat required for an organism to develop from one point to another in its life cycle.  We measure and accumulate degree-days to predict total physiological development of an organism, such as hatch, instar or emergence of insects, growth stages of plants, or disease onset.

To further complicate the equation, most organisms have a temperature range in which they are physiologically active.  These temperature limits are typically called lower and upper thresholds.  For example, corn’s developmental thresholds are between 50 and 86 degrees Fahrenheit.  The daily maximums greater than 86 degrees F are set equal to 86 in the calculation of the daily average temperature. Similarly, daily minimums less than 50 degrees F are set equal to 50 in the calculation.  Thresholds will vary with different organisms.

The degree-day (DD) formula calculates daily accumulation of (DD) as the average daily temperature minus the minimum threshold (50 degrees F for corn).

Formula:  (Temp Max + Temp Min) ¸2 - 50

Phenology models use current and local degree-days to predict time of events in an organism’s development.  Because of yearly variations in weather, measuring the amount of heat accumulated over time provides a physiological time scale that is biologically more accurate than calendar days.

So what does all this mean and what use is it to the producer?  The use of weather data to calculate degree-days in conjunction with crop phenology models may improve a crop manager’s ability to make more timely and educated in-season decisions.  We must recognize that yield is determined throughout the growing season and being able to predict in-season pest and crop phenology events may help to protect and manage final crop yield.

Now that you recognize the importance of degree-days for crop and pest management, you can put them to use.  To obtain degree-day accumulation and phenology events for corn and crop pests in NW Iowa, visit my web page at http://extension.iastate.edu/carroll/crops/

Tuning Up Your Pasture Potential
Beth Ellen Doran, ISU Extension Beef Field Specialist

Cow-calf producers who want to tune up their pasture potential are invited to attend an Iowa Beef Center program, Cyclone Beef Days, on Tuesday, June 25. The morning program will be at the Heritage Bank, 115 East Main Street, Anthon, IA.  The afternoon program will be at the Brian Weaver farm near Anthon.

Topics featured are:

Fertility Variation in Your Pasture - Tuning Up the Deficits will involve using producer data from host farms to evaluate the variations in pasture fertility as impacted by animal use and loafing areas.

The Forage Planner is a cutting edge software program that producers can use to extend the grazing season.  Participants will receive hands-on training and a free copy of the software.

Banking on Iowa's Streams is a tour of alternative stream access and crossing designs.  Designs that qualify for EQIP matching funds will be covered.

Watering Systems for Managed Riparian Areas focuses on protecting vulnerable riparian areas while still providing an adequate water source.

Summer Health Concerns will feature pinkeye and pasture management to reduce internal parasites.  An area veterinarian will present methods to keep the herd healthy and profitable.

Your Whole-Farm Grazing Strategy discusses how to utilize contour buffer strips and headlands in your crop and grazing systems.

Registrations ($25 if pre-paid or $35 at the door) may be made with Dennis DeWitt, ISU Extension Livestock Field Specialist, at 712-336-3488.  The fee includes the noon meal and meeting materials.  Registrations must be received by June 10.  Participants are encouraged to register early, as registration is limited to 25 participants per site.

Livestock Producers—Stay Vigilant About Foreign Animal Diseases

Chris Mondak, ISU Extension Dairy Field Specialist 

Although the Foot and Mouth Disease crisis is diminishing in Great Britain, the U.S. is still at risk for a FMD or other foreign animal disease (FAD) outbreak. In all the many discussions and publications on this topic recently, a common point is repeatedly stated: Early detection and response by producers and veterinarians will be key to gaining early control of an outbreak. Producers and veterinarians should be prepared to be the first persons to encounter a foreign animal disease.

What actions can livestock producers take at this point?
Dr. Patrick Webb, DVM, and FMD/FAD coordinator for the Iowa Dept. of Agriculture, strongly recommends these approaches:

1.      Request that your veterinarian do a biosecurity review of your operation to identify and correct deficiencies in your plan or biosecurity practices.

2.      Report all disease outbreaks to your veterinarian, especially for diseases that occur suddenly or cause unexplained mortality.

Specifically, what can a producer do to improve biosecurity?
Dr. Hamlen, DVM in the California Dept of Food and Agriculture describes some basic biosecurity strategies:

1.      Raise the level of health and disease resistance in your herd. Implement an internal parasite control program, vaccination program, treatment protocols, and minimize stress during handling, housing, and hauling.

2.      Control and monitor the movement of animals, people, equipment, and vehicles on and off your premises:

·        Quarantine and test herd additions

·        Restrict visitor access. Set up boot wash stations using correct disinfectant concentration.

·        Educate family and employees about potential for contaminated vehicles to transmit disease.

·        Educate family and employees about the importance of hand washing and the potential for dirty clothing to transmit disease.

 3.      Control disease spread on your farm by controlling rodents, insects, and stray animals. Restrict access and movement between groups of animals.

4.      Manage your facilities to reduce risks. Use gates to restrict access. Establish a remote site on the perimeter of your property for rendering truck pick-ups, keep ventilation systems cleaned, make written protocols for cleaning and disinfecting gear and housing.

The importance for good biosecurity to control the spread of livestock diseases cannot be over-emphasized.  Dr. Webb’s comment after working on state-wide disaster response plans to deal with a foreign animal disease outbreak is a good take-home message: “Biosecurity can make the difference between a herd being depopulated and a herd that gets quarantined.”

2002 Farm Program Basics
by Ron Hook, ISUE Farm Management Field Specialist

The Farm Security and Rural Investment Act (FSRIA) of 2002 recently signed by President Bush is a six-year farm bill with some new twists that need to be examined.  Along with the commodity title, FSRIA includes titles for conservation, trade, nutrition, credit, rural development, research, forestry, energy, and miscellaneous.  There will be lots of details to be filled in by the various agencies during the rule making process.

For grain producers FSRIA provides for three kinds of payments: Loan Deficiency Payments (LDP), Direct Payments (DP), and Counter Cyclical Payments (CCP).  It also makes soybeans a program crop with a base similar to corn to be established.

LDPs have not been changed except to lower the national average soybean loan rate by $.26 to $5.00 per bushel and to increase the national average corn loan rate by $.09 to $1.98 per bushel. 

Direct payments will be made using the corn acreage base and program yield that existed under the previous program, which was based on yields from 1981-85.  A soybean base can be added that will be equal to the average number of acres planted for the 1998-2001 crop years. The program yield for direct payments on soybeans will be the average yield in 1998-2001 crop years adjusted to yield levels experienced in 1981-85.  The direct payment will be equal to the payment rate times the program yield times 85% of the base acres.  The payment rate for corn is $.28 per bushel and for soybeans is $.44 per bushel. The total corn base acreage plus soybean base acreage cannot exceed the number of acres of farmland in the farm unit.   

CCPs have been added to help provide additional support when prices are low.  FSRIA sets the corn target price at $2.60 per bushel and the soybean target price at $5.80 per bushel.  The CCP rate per bushel will equal the target price minus the direct payment rate minus (higher of loan rate or national average market price).  The payment will equal the payment rate times program yield (old or new) times 85% of the base acres.

CCPs require a producer to make a decision to determine the program yield used.  The choices are: (1) use “old” acreage base plus “new” oilseed acreage and use “old” yields; (2) use “new” acreage base and use “old” yields; (3) use “new” acreage base and use partially updated yields based on 70 percent of difference between “old” and “new” yields, or (4) use “new” acreage base and use partially updated yields based on 93.5 percent of “new” yields.

The rules for implementing this new farm bill have not been completely written, so the information contained in this article is subject to the final interpretations of the Farm Service Agency.  For a look at how the various alternatives affect the payments available there is a spreadsheet at this website: http: www.extension.iastate.edu/feci

For additional information or help using the spreadsheet contact: Ron Hook, 712-754-3648 or Tom Olsen, 712-732-5056.

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