It has been another interesting week in Colquitt County agriculture. Topics this week include soil temperatures, corn weed control, cotton burndown. The corn crop ranges from just to planted to V6. The wheat crop is in the grain fill stage of development. Cotton growers are trying to burn down fields before planting.
Peanuts: According to the UGA peanut production guide, the recommended planting timeframe for peanuts in Georgia is the last week of April (if soil temperature is adequate) through late May. The soil temperature at the 4” depth needs to be greater than 68 Degrees F for 3 consecutive days without the risk of a cold front after planting. Below are the soil temperatures from the Sunbelt Ag Expo location of the UGA Weather Network for the last week.
UGA does not recommend that Valor be applied pre-plant incorporated (PPI) for weed control in peanut! Valor is not labeled for that type of application and pigweed control will be significantly reduced (PPI is 25-35% less effective than when applied PRE behind the planter).
A few questions and answers from Dr. Bob in reference infurrows, inoculants, and fungicides.
I got a grower wanting to put out an inoculant under his peanuts this year. Dr Monfort and Dr Tubbs say it is cheap insurance. Can the grower mix it with azoxystrobin? With Velum? With Proulse?” The answers to all of those questions are “Yes”.
“Bob, can the grower mix the inoculant with Vydate CLV and other oxamyl products?” I do not know the answer to that, but I would be cautious if I were you until we get an answer.
“Bob, my grower wants to put some fertilizer in the furrow at-plant. Can he mix the inoculant with the liquid fertilizer?” Answer: I think fertilizer in the peanut furrow is a no-go in the first place, but I defer to Harris, Monfort, Sintim, and Tubbs. HOWEVER, I would not mix inoculant with fertilizer.
Cotton: What are my plant back restrictions when using Valor in cotton burndown?
- In strip-till cotton where the strip till rig (including ripper shank) is run after application and before planting, Valor plant-back intervals are as follows:
1) >30% ground cover = 7 days
2) 10–30% ground cover = 14 days plus 0.5″ rain/irrigation
3) <10% ground cover or tillage = 21 days plus 1″ rain/irrigation - In no-tillage production or when the strip is implemented prior to
application. Valor plant-back interval should be 28 days. Additionally,
0.5″ (>10% ground cover) or 1″ (<10% ground cover) rainfall/irrigation is
needed. If Reflex (or generic) will be applied PRE, suggest adding an
additional 7 days to planting intervals. - Add a nonionic surfactant or crop oil concentrate (preferred), regardless of
glyphosate brand.
Dr. Camp Hand mentioned the NC State Cotton Planting conditions calculator the other day in the new cotton team pod cast. Cotton requires warmer temperatures for growth and development. Georgia’s planting window starts in April and runs through June. However, chilling temperatures below 50°F can still be observed at early planting dates. Favorable planting conditions are when the top 4-in soil temperatures reach 65°F for three days with predicted warm temperatures over the next several days. The accumulation of heat units needed for plant growth and development is referred to as DD-60s. DD-60s are calculated by the following formula: DD-60s = [(Tmax + Tmin)] -60°F. For optimal germination and development, an accumulation of 50 DD-60s are required within the first 5 days after planting. The Cotton Planting Conditions Calculator by North Carolina State is a great tool for estimating DD-60s and future weather conditions https://products.climate.ncsu.edu/ag/cotton- planting/. Similar resources can be found at http://www.georgiaweather.net/. Below is the relationship between 5-days predicted DD-60s and planting conditions.
I ran the model for Colquitt County assuming that cotton was planted today (4-20-24).
Corn weed control: I had a few questions about corn weed control this week. Below is an example of utilizing Prowl in corn from Dr. Eric Prostko, UGA Weed Scientist. According to Eric, Texas panicum/buffalograss/bullgrass is one of the most common annual grass weeds in Georgia field corn. Put very simply, Prowl provides the best residual control of Texas panicum. If growers are concerned about potential crop injury from Prowl, other residual annual grass control options include Anthem Maxx (pyroxasulfone + fluthiacet), Dual Magnum (s-metolachlor), Outlook (dimethenamid-P), Warrant (acetochlor), and Zidua (pyroxasulfone). Of these, Anthem Maxx and Zidua are slightly better on Texas panicum (but neither is as good as Prowl). FYI, Prowl should NEVER be applied PPI or PRE in Georgia field corn, only POST (labeled up to 30″ tall/V8).
Will Prowl injure my corn? According to Dr. Prostko, A long time ago in a galaxy far far away, Prowl was used as an EPOST (spiking) treatment in combination with atrazine. Back then, this was about the only way to get reasonable control of Texas panicum. In that scenario, root pruning was more likely to occur especially when corn was planted <1.5″ deep and furrow closure was incomplete. Delaying Prowl applications allows the corn plant to develop a deeper root system (but still a good idea to plant at least 1.5″ deep and have complete furrow closure though). For many years, I have been applying Prowl POST with various herbicides and have never observed any significant yield losses. http://If you want to see the original blog post it can be seen here.
Halex GT Mixing Problem in Corn Prostko.
A field corn grower in Macon Co. experienced a significant problem when Halex GT (mesotrione + S-metolachlor + glyphosate-K salt) was tank-mixed with a different type of glyphosate formulation (IPA salt) (Figure 1). This problem did not occur when other K salt formulations (Roundup PowerMax3 or Honcho K6) were used (Figure 2). Remember that all glyphosate formulations are not created equal. They have different concentrations of active ingredients, are formulated as different salts (K, IPA, DMA), and may/may not be formulated with adjuvants.
Mustang Max + NIS + Defoamer
Pecans: I got a few pecan questions this week. I received a picture or two of sawfly in pecan. Below is an example of this insect. If you review past information from the UGA pecan team, sawfly do not really cause much of a problem in most cases, not unless, they have caused considerable defoliation on young, small trees. Sawflies are gregarious feeders, which means they feed in groups. Two species of sawflies are common on pecans. The two species are Periclista marginicollis (Norton) and Megaxyela major (Creson). Larvae of P. marginicollis feed on the underside of leaflets during the spring, leaving small holes in the foliage. M. major larvae generally consume the entire leaflet. (Source: Texas A and M) A sawfly is actually the larvae of a wasp. If you decide to control sawflies, products for caterpillar control are effective against them, with the exception of Intrepid.
Below is an example irrigation schedule for young pecan trees.
When can I plant soybeans? Believe it or not, I had a question or two about soybeans. Research has indicated that the optimum soil temperature for soybean emergence is 82o to 85o F; however, there is a wide range of soil temperatures at which soybean will emerge. Soybeans can be planted in soils as cold as 42o F and as warm as 95o F. When planting in cold soils, between 42o and 59o F, emergence may take as long as 14 days after planting. As soils warm above 59o F soybean emergence can be as fast as 4 days after planting, depending on soil moisture status. When peak daily soil temperatures at the 2-inch depth exceed 100o F planting should be delayed until peak daily temperatures decrease. Soil surface temperatures can be reduced by utilizing conservation tillage methods that increase soil surface coverage.
How deep do I plant soybeans? Planters should be set so that seeds are placed 1.0 – 1.25 inches deep in moist soil. If surface soil moisture is limited, set planters to push aside dry soil and plant in a shallow seed furrow. When seed must be placed deeper than 1.25 inches to reach moisture delay planting until moisture returns.
Have a great week,
Jeremy M. Kichler
Colquitt County Extension Coordinator
The University of Georgia Cooperative Extension does not endorse or guarantee the performance of any products mentioned in this update.