Texas Agri-Life Extension
Foundation For Weed Control
Since first being identified in 2011, the incidence of glyphosate-resistant Palmer amaranth or pigweed in the High Plains of Texas has steadily increased. Weed management in peanut affords producers the opportunity to use additional herbicide modes of action to manage herbicide-resistant weeds.
In general, dinotroaniline or “yellow” herbicides, such as Prowl H2O, Sonalan and Treflan, provide a good foundation for weed control and effective control of annual grasses and small-seeded broadleaf weeds. It is important to use proper application rates and incorporation techniques to maximize efficiency.
Pre-plant burndown applications of herbicides, such as Gramoxone Inteon and Roundup, can be used to provide a clean, weed-free seedbed.
Use of at-plant herbicides, such as Valor, Dual Magnum or Parallel, serves to extend the level of control by lengthening the level of residual activity well into the growing season and eliminating weed competition.
Additional products are registered for use in peanut and can be used in-season as the need arises to manage broadleaf weeds or grasses. Remember to read and follow all label recommendations when using herbicides. Replacing worn nozzles, properly calibrating equipment and paying attention to environmental conditions during applications will help improve efficacy.
North Carolina State University
Grower Meeting Points
During the past few weeks, we have been conducting our traditional grower meetings in North Carolina and Virginia. I always discuss the relationship of realistic yield potential, cost of production and price in order to determine net return. Growers are making these comparisons, especially in relation to net returns for other crops, and planting decisions. A yield of two tons with a production cost of $900 per acre and a price of $535 per ton will result in a profit of $170 per acre. How does that compare to other crops and the risks associated with growing other crops?
With the widespread presence of Palmer amaranth, using an intensive soil-applied herbicide program at planting and timely sprays of contact and residual herbicides within the first few weeks of the season can be the most effective approach. Limitations exist with postemergence herbicides when forced to rely on them early in the season and a great deal of the season remains until harvest.
Several insecticides are available as in-furrow options to control thrips, including acephate, imidacloprid and phorate. Each can be successful but in many instances will require a timely follow-up application of acephate. Apogee effectively controls vegetative growth of our rankest varieties. But this improvement in row visibility does not always translate into increases in yield. While we can spread out our planting dates and use different varieties, it is amazing how often peanuts reach optimum maturity at about the same time when it comes to digging. Ensure that your digging and harvesting capacities are in line with acreage and focus on the need to dig as precisely as possible. This is the short version of my presentation to growers during the past few weeks. I’ll touch on Dr. Barbara Shew’s key points relative to disease management as we move toward that part of the season.
University of Georgia
The impact of the Farm Bill on peanut acres in Georgia will soon be determined. In all likelihood, Georgia will increase acreage up to 20 percent compared to 2014. With contract prices continuing to decline as a result of the carryover from 2014 and a predicted increase in 2015, growers will need to minimize costs while maintaining yield potential. This is not an easy task. One suggestion is to invest in a crop consultant or scout to assist in making production decisions.
Growers also need to take soil samples and correct any fertility and pH issues prior to planting. Appropriately adjusting soil fertility, based on soil sample analysis recommendations, will provide a solid start for your crop and ensure maximum yield potential. Take advantage of this downtime to perform needed maintenance and calibration to planters and application equipment.
As you prepare to plant, consider these points:
- Soil temperature in the top four inches of soil should be at least 68 degrees Fahrenheit for three consecutive days with no predicted cold snaps within five days after planting. Check the average soil temperatures for your area online at the Georgia Automated Environmental Monitoring Network at www.griffin.uga.edu/aemn .
- Use high-quality seed. Seed is one of your largest investments. Take time to visibly inspect your seed. Your seed is alive! Protect your seed by storing it in a cool, dry place until ready to plant.
- Use appropriate seeding rates. Recommended rates for runner-type peanuts are five to six seed per foot for single row and three to four seed per row for twin rows. At these rates, you should average four to five plants per foot.
A Case For Conservation Tillage
Most growers are skeptical when it comes to conservation tillage. However, it is becoming more popular with many producers. Research has shown a yield drag due to conservation tillage when compared to the moldboard plow.
Resistant weeds, such as Marestail and Palmer amaranth (pigweed), have brought on new challenges. Deep tillage is not the answer to those troublesome weeds. The continuous tillage stirs the soil and allows for the weed seed to germinate and emerge. Disk harrows are like putting gasoline on a fire to stirring the soil for weeds to germinate.
Conservation tillage with a thick cover helps block sunlight to the soil and prevents some of the weeds from germinating. It also helps keep the soil cooler. Preparing only a narrow strip of soil for the seedbed so you are not disturbing much soil and leaving a good thick mat of cover in the middles is important and will help block the sunlight, increase water infiltration and help with erosion control.
Even if you have grazed the land early, you could still remove the cows and fertilize again as we recommend for cover crops, allowing the cover time to grow some size before you terminate it. Our test last year showed a 730- pound yield increase for peanuts where we had a cover crop versus no cover.