||This Month in Ag Connection|
Building Confidence in Variety Testing
Variety testing performance guides are now available at Outreach and Extension Centers and it is worth every crop farmers time to look over the yield data. These are some of the best sources for selecting varieties for next year.
Most agricultural experiments such as the variety trials will have Least Significant Differences (LSDs) listed in the tables. LSD's can greatly benefit your decision making ability if you understand how they work.
Lets say you step off 1/100th of an acre of each of three corn rows in a field and measure the yield in each row. Yield differences are expected to occur between rows. For example: one row will yield 130 bushels per acre, the second 135 and the third 138. It may be that when you average the entire field it yields 115 bushels. Variations can result from soil type, poor drainage, weed infestation, fertility, planting depth or a host of other things. LSD helps to remove the normal variations in an experiment and enhances unbiased results of field treatments.
A common phrase in performance guides is "LSD at the 5% confidence level". This is simply another way of saying there are 95 chances in 100 that this yield variation was due to a variety difference and there are 5 chances in 100 that this was due to unidentified factors.
If the top yielding soybean variety in a test is 50 bushels and the LSD at 5% equals 5 bushels, you can be 95% confident that varieties yielding 44 bushels or less were lower because of variety, not field variations. Top yielding varieties inside the LSD are the ones that deserve the most attention.
Side-by-side strip trials are very common when comparing varieties on farms. The drawback is that they dont accurately account for field variations unless a check variety is used. A check is simply a single variety planted in between each variety in the test or sometimes between every other variety in the test. Final yield results are adjusted across a field based on the variation in the check strips.
Strip trials have a major place in on-farm testing but consider their limitations before putting a great amount of stock in their results. Some seed companies put a lot of stock in strip trials with no replications or checks, but their confidence comes from having many locations to compare. The fewer strip trials there are, the greater the importance of having checks to remove field variability.
Variation is normal, so look for the LSD and the confidence level in small plot tests or the presence of checks within strip trials when you are comparing a new product or farming practice. These will give you greater confidence in variety selection.
(Author: Tim Schnakenberg, Agronomy Specialist)
Rotating Herbicides -- More Than a Name Change
Pesticide resistance was first detected with insect control. An early example was when the insecticide DDT become ineffective against several insects - most notably the housefly. Later, when synthetic pyrethroid insecticides were introduced it was expected that they would not have resistance problems for a long time since they were a different chemistry. Resistance began appearing relatively soon after pyrethroids were introduced. The reason was discovered to be that the mode of action was the same as DDT even though they were very different chemistries.
The same thing happens with herbicides. If the mode or site of action within the weed is the same, then resistance has a chance to build up more rapidly than with herbicides that attack different sites or have different modes of action.
The most common herbicide class involved with weed resistance is commonly known as ALS inhibitors. ALS inhibitors block the amino acid production of acetolactate synthase (ALS). Therefore, plant growth and development are stopped and the plant dies.
The ALS inhibitors come from the chemical groups, imidazolinones, sulfonylureas and sulfonamides. Using different products under these chemical groups is like using the same herbicide.
Herbicides By Mode of Action Include:
Common imidazolinones herbicides include Septer (imazaquin), Pursuit (imazethapyr), Raptor (imazamox), and Arsenal Lightning (imazapyr).
Sulfonylurea herbicides are Classic (chlorimuron), Accent (nicosulfuron), Beacon (primisulfuron), Pinnacle (thifensulfuron), Oust (sulfoneturon), Express (tribenuron), Permit (halosulfuron-methyl), Peak (prosulfuron), and Basis Basis Gold (rimsulfuron).
cides in the sulfonamides group are Broadstrike, Hornet, and Scorpion III (flumetsulam), and FirstRate (cloransulam). New products, mixtures, and formulations of ALS inhibitors continue to be introduced.
Since there are so many different products with the same mode of action, it is easy to repeatedly use ALS herbicides year after year. Farmers should rotate between herbicides based on modes of action rather than brand names. Choose herbicides that are not from the above list, a true herbicide rotation, to avoid weed resistance. As new products enter the market, be sure to identify mode of action.
Other herbicide modes of action include:
Source of modes of action, classes of herbicides, and herbicide names is from the Ohio Field Crops Weed Control Guide.
We may be inadvertently developing weed resistance by using the same herbicide year after year. Repeated plantings of Roundup-Ready soybeans and corn are recent examples of how this can occur. This year waterhemp tolerant to typical rates of Roundup (glyphosate) were detected in northeastern Missouri. This is the first sign that resistance is developing rapidly. Also, Touchdown (sulfosate) inhibits EPSP synthase just like Roundup. Switching between Roundup to Touchdown is not rotating herbicides. Even though tolerance to Roundup is not wide spread, it should be taken as a warning. Rotate herbicides voluntarily before it becomes a necessity.
(Author: Jim Jarman, Agronomy Specialist)
Long-Term Care Insurance -- Deductibility
Longer life expectancies and escalation of medical and health care expenses have increased interest in long-term care insurance. The deductibility of long-term care insurance premiums can substantially influence the decision to purchase this type of insurance.
For farmers and other self-employed taxpayers, the premiums for a qualified long-term care insurance contract for yourself, your spouse, or your dependents are to be included (subject to the limits listed below) in the "health insurance deduction of the self-employed". The current deductible percentage (1999-2001) for self-employed health insurance is 60%. The deductible percentage increases to 70% for tax years beginning in 2002 and to 100% after 2002.
Limits on the annual deduction for long-term care insurance premiums are the lesser of:
(Author: Parman R. Green, University Outreach & Extension Farm Business Management Specialist)
Electronic Crop Trail ResultsThe University of Missouri Crop Performance Testing (Variety Trial) results are on the MU Ag Electronic Bulletin Board at: http://agebb.missouri.edu/
Once at the site go to "Crop Performance Testing". Data is online for corn, soybean, grain sorghum, hard red winter wheat, soft red winter wheat and dry bean varieties. To reach the actual data, click on the crop of your choice, then another screen will appear giving you options on how to view the data.
Be sure the data represents the most current year. Information is updated upon completion of harvest and analysis of the data. Once the data is on the website, it stays until the next harvest. Typically, the data on the website is the first information available. The written reports are available about a week after the website is updated.
Although yield usually receives first consideration, other agronomic characteristics may be equally important when selecting a crop variety or hybrid.
Soybean Variety Selection
Corn Hybrid Selection
(Author: Tim Schnakenberg, Agronomy Specialist)
At a recent commercial agriculture meeting, Pat Guianan, UMC Department of Atmospheric Science, presented information on weather resources on the Internet. There is not room here for all the sites, but here are some weather sites you might find useful:
Missouri Weather Information on AgEbb: This site contains information on Missouri weather forecasts, national outlook, river stage forecasts, monthly weather summaries, and Missouri weather stations across the state.
Storm Event Data Base: All notable and severe weather events from 1993 to present including tornadoes, thunderstorms, and hail. This could be useful in negotiation with insurance companies on losses due to the weather.
Climate Prediction Center: Products at this site include 6-10 day forecasts, monthly and seasonal outlooks, soil moisture conditions, El Nino and La Nina advisories, hurricane forecasts, etc.
(Author: Don Day, Ag. Engineer/Information Technology Specialist)
Ag Connection - December 2000