Ag Connection
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Volume 9, Number 10
October 2003


This Month in Ag Connection




Herbicide Carryover

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Herbicide Carryover

While recent rains have eased some concerns, producers still need to weigh the risks of herbicide carryover injury when considering planting options for wheat this fall, and for corn and soybeans next spring, University of Missouri weed scientists said. 

We've really experienced the worst of conditions to magnify carryover issues this year. Across much of the state, a wet spring delayed planting and subsequent herbicide applications, and a very dry summer has left residual herbicides active in the soil profile. 

For herbicides with soil activity, the primary method to be degraded in the soil is by microscopic organisms, which break down many chemicals in the soil and use them for food, he said. A lack of water minimizes the activity of microbes, leaving more herbicides in the soil profile that could be active into the next cropping system. 

Before planting, producers should review their weed management program, determine if issues might exist and plan accordingly. 

Drought conditions have increased the probability of injury, especially in wheat, but rainfall is just one factor that can contribute to carryover. The type of herbicide applied to the previous crop is one of the most important factors that will determine the likelihood of injury to wheat. 

In fields where corn was the previous crop, carryover may be a concern if herbicides such as atrazine, Princep, and prepackaged mixtures that contain atrazine such as Bicep II Magnum, Degree Xtra and Harness Extra, were applied. In fields where soybeans were the previous crop, carryover from an application of Command could cause injury to wheat. These products aren't labeled for rotation directly into wheat, so it's critical to always read, understand and follow all herbicide label information. 

Other factors that may influence the likelihood of carryover injury to wheat are the herbicide application rate and the timing of the application. In general, the higher the rate and the later the application, the greater the risk of injury. 

The pH of the soil and the yield in a drought-stricken field can play a contributing role to atrazine carryover. If the pH is higher and yield is low, carryover is more likely. Atrazine is degraded by the corn plant; if the corn stand and overall growth is poor, more of the herbicide remains. 

While the risks are lower, carryover injury in a corn and soybean rotation can occur in certain situations. When soybean follows corn in the rotation, ALS-inhibiting herbicides such as Steadfast and Accent, which are applied post-emergence for grass control, may be subject to carryover. 

Another product to watch is Callisto, a herbicide with broadleaf activity in corn. This relatively new herbicide hasn't been tested in Missouri under droughty conditions. When corn follows soybean in the rotation, Reflex, which is applied post-emergence for broadleaf control, can cause carryover injury if applied under droughty conditions. Reflex degrades under saturated soil moisture conditions, so if there isn't enough precipitation, temporary bleaching of some corn tissue in the spring might occur. 

If a producer suspects a carryover issue in a field, a bioassay can help gauge its severity. Collect soil from the field you suspect and from one you don't, plant some seed in it, and see what happens. A little experiment like this can help avoid a 1,000-acre mistake. 

Step-by-step instructions on an herbicide bioassay experiment can be found at: .

A warm, wet fall will continue to decrease the risks of carryover injury. If this doesn't occur, producers can still protect their crops. If you've already had mistakes with carryover, learn from them. Adapt your weed management program. Don't set yourself up for a rotation problem. 

Under normal environmental conditions, herbicide carryover is not an issue provided the grower follows label recommendations. However, given the fluctuation in Missouri weather it is difficult to determine what normal is. 

For more information on crop rotation restrictions for some common herbicides, see MU Extension Guide MP575, "Weed Control Guide for Missouri Field Crops". See it online at:

(Sources: Kevin Bradley (573) 882-4039; Reid Smeda (573) 882-1329, Agronomy Department, UMC.)

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Heifer Program is Way to Add Value

The Missouri Show-Me-Select (SMS) Heifer Program is the only statewide coordinated heifer development program in the nation. Along with regional livestock specialists and local veterinarians, Dave Paterson, PhD, State Extension Beef Specialist and Richard Randle, DVM, State Extension Veterinarian, are the major coordinators of the SMS Heifer Program.

Program Objectives

  • Improve existing developing programs through a Total Quality Management approach 
    • Reproductive success 
      • Reproductive tract score
      • Estrus synchronization
      • Artificial insemination 
    • Decrease the problems associated with first calf heifers 
      • Pelvic measurements 
      • Improved health programs 
      • Body condition score
  • Increase marketing opportunities for and add value to Missouri-raised heifers 
  • Provide a reliable source of quality replacements (genetics and management)

Missouri is the number two state in cow-calf numbers, with approximately 1 million beef heifers produced annually. Currently, only 15 percent of the heifers produced in Missouri are retained for breeding purposes with the remaining fed for market. The development phase of the replacement heifer production process impacts longevity and lifetime production. Heifer producers need to make decisions based on sound principles of animal breeding and genetics, reproductive biology, nutrition, animal health, and economics. This is the premise of the Show-Me-Select Heifer Program.

Enrollments for heifers calving in the spring of 2005 are due to your regional livestock specialist by February 1, 2004. Enrollment forms may be obtained from your regional livestock specialist. There are required health practices that must be completed prior to eleven months of age. Program requirements can be found at the SMS web site or can be requested from your local extension center: .

(For more information, contact either Central Missouri Regional Livestock Specialists, Wendy R. Flatt by phone (660) 248-2272 or email or Mark Stewart, Regional Livestock Specialist (573) 642-0755, .)

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Show-Me-Select Heifers Can Be A Value Added Enterprise 

The Show-Me-Select (SMS) Heifer Development Program has evolved into a value added enterprise for many participants. In the spring of 2003, 850 SMS heifers were sold in sales at four locations in Missouri. The average sale price for the 850 heifers was $987 per head. Individual heifer lots varied in price from a low of $725 to a high of $1375 per head. Info is on the web at: 

If sold as feeder cattle in May 2002, these same heifers could have brought $80 to $88 per hundredweight at auction. This equals a value of $462 per head, assuming an average price of $84.00 per hundred for a 550 pound heifer. Given the SMS sales average was $987, the difference is $525. 

Is the dollar gain resulting from the SMS program profitable? When SMS producers in Missouri were asked about the costs of producing a SMS heifer, responses ranged from $250 to $500 per head. Most producers estimate a cost of around $300 per head or about a dollar per day. These extra costs include increased veterinarian expenses, purchased feed, raised feed and forage costs and others. These cost estimates provide a picture of the value-added opportunity for the SMS program participant. On the average, SMS heifers sold in these sales realized an additional $225 of income to provide a return to capital, labor and management. 

Heifer producers who had 'average' expenses of around $300 per head would have lost money if their heifers sold for less than $800 per head. Controlling heifer development cost is also important. Producers whose health or feed costs were not managed carefully could lose money even if their heifers sold at or above the sale average price. 

The following management suggestions summarize what successful SMS producers are doing to increase the value of their heifers: 

  • Select only high quality heifers for the sale 
  • Develop the heifers on as much high quality forage as possible 
  • Supplement as needed with forage-friendly feeds (by-product feeds) 
  • Use known and source verified genetics on the heifers 
  • Use quality AI and Natural sires 
  • Have carcass data on siblings 
  • Proper conditioning at sale time (not too fat, not too thin) 
  • Select for good dispositions 

(Authors: Wendy Flatt, Livestock Specialist, Mark Stewart, Livestock Specialist)

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Taxation Tidbit: Increased Social Security Retirement Age

Do you know that if you were born after the year 1937 that you will not be entitled to your full Social Security benefit unless you retire sometime after your 65th birthday? The sometime is determined by the year of your birth. Actually, this is not “late breaking” news, but many people are unaware of the changes being implemented in the Social Security full-benefit age. In fact, Congress mandated this change back in 1983 with implementation to begin in 2003. Note: while the age for full retirement benefit is being increased, the age for Medicare benefits is not being changed from age 65. 

As revealed in the following table, the full-benefit age is being gradually increased to age 67.

Year of

Age to Collect

Reduction %
for Age 62


65 years, 2 months



65 years, 4 months



65 years, 6 months



65 years, 8 months



65 years, 10 months


1943 through 1954

66 years



66 years, 2 months



66 years, 4 months



66 years, 6 months



66 years, 8 months



66 years, 10 months


1960 and later

67 years


You will continue to have the option of electing reduced benefits as early as age 62. However, since there will be more months between the full-benefits age and 62 – the benefits reduction will be greater. It is important to note this benefits reduction factor is FOR LIFE, however, you will be receiving an increased number of payments during your LIFE. So if you can tell an economist when you will die – they can calculate whether you would be better off financially to take the reduced-benefit at age 62 or take the full-benefit payment at full-retirement age.

Additionally, if your full-benefit payment is not as great as you need for a comfortable retirement, you can elect to post-pone retirement past your full-retirement age. In fact, the full-benefit payment is permanently increased by 8% per year for the years you delay retiring up to age 70. For example, for someone born in 1947 who waits until age 70 to start collecting benefits – they will receive payments that are 32% greater than if they had started at their full-retirement age.

In summary, to put this information into monetary terms – say your earnings history would indicate you could collect $1,200 of Social Security a month at your full-retirement age of 66. If you elect to begin collecting your Social Security at age 62, your payments will only be $900 per month. On the other hand, if you wait until age 70 to begin collecting Social Security your monthly payments would be $1,584.

(Parman R. Green, University Extension Ag Business Management Specialist)

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University of Missouri ExtensionAg Connection - Ag Connection Newsletter,  October 2003 -- Revised: April 20, 2004