Colquitt Ag Update
The Cotton Marketing News
Below is the link to the cotton marketing news from Dr. Don Shurley for July 6, 2017. He discusses the USDA acreage report and its effect on the cotton market.
Cotton Layby Options…
This time of year growers often ask about layby options for cotton. Factors such as cotton size and weed species can influence these decisions. Below is information on layby or directed applications in cotton from Stanley Culpepper. If you have questions please feel free to contact the Colquitt County Extension office.
DIRECTED APPLICATIONS – ROUNDUP AND/OR LIBERTY SYSTEMS
Liberty should not be applied as a layby treatment as a means of sound resistant management, regardless of cotton technology. It is critical that it is preserved for topical applications; other options exist and are more effective. Thus, the discussion below will focus on Roundup or MSMA layby applications. If cotton is not tolerant to Roundup, apply only MSMA mixes.
Palmer amaranth is the dominant species present across the state and an application of diuron (Direx, other) + MSMA or Suprend + MSMA is suggested as these are the most effective options; only Gramoxone + diuron (under hoods, no crop contact) is more effective.
Diuron + MSMA has many strengths with only two weed control weaknesses. First, it lacks control of larger (>3”) morningglory. When both Palmer amaranth and morningglory need to be controlled then one should include 1) Aim, 2) Envoke, or 3) ET with diuron + MSMA; make certain cotton is large enough for the selected product. Second, Diuron + MSMA lacks grass control. If Palmer amaranth is not problematic but grasses larger than 0.5” are an issue, Roundup mixtures will be more effective.
Potential partners with Roundup to post-direct include Aim, Caparol, diuron, Dual Magnum (generics), Envoke, ET, Fierce, Staple, Pyrimax, Suprend, Valor (generics), Warrant, and Zidua. Each of these mixtures will be discussed below.
Aim and ET mixed with Roundup will improve control of larger morningglory. Additionally, Aim will provide excellent control of emerged tropical spiderwort that is 4” or less. Cotton should be at least 20” tall, and the spray must be directed precisely to the woody portion of the stem. Spray contact with green stem tissue will cause injury. Neither product provides residual control.
Caparol or Diuron mixed with Roundup will improve control of morningglory and pigweed. Caparol at 2 pints or diuron (Direx 4 L, other) at 1.5 pints will provide some residual control of small-seeded broadleaf weeds, such as pigweed, if activated. Diuron is usually more effective on Palmer amaranth than Caparol. Cotton should be at least 12” tall before directing Caparol or diuron at these rates. Occasionally, mixing Caparol or diuron will reduce grass control by Roundup. This is most likely to occur under dry growing conditions with large grasses. Do not reduce the Roundup rate when applying these mixtures.
Dual Magnum, Warrant, or Zidua mixed with Roundup will not improve control of emerged weeds but, if activated, will provide residual control of annual grasses, (Texas millet is only suppressed), pigweeds, and some other broadleaf species. Dual Magnum and Warrant will provide doveweed and tropical spiderwort control; data is not available with Zidua. Warrant can be directed anytime up to first bloom; Zidua can be directed from 5-leaf state to first bloom, and Dual Magnum can be directed to cotton from 3” tall until 80 days prior to harvest.
Envoke mixed with Roundup will improve control of nutsedge, hemp sesbania, and larger Ipomoea morningglory (not smallflower morningglory). Cotton should be at least 6” tall. Preliminary research indicates Envoke has more residual activity on broadleaf weeds than originally thought but residual activity is not effective in controlling Palmer amaranth. Palmer amaranth resistant to Envoke and other ALS inhibitors is present in many Georgia fields.
Fierce is a mixture of the active ingredients in Valor and Zidua and can be used in the same manner as Valor discussed just below. When mixed with Roundup, it is a very effective herbicide providing control of emerged weeds and residual control once activated. Notable escapes from the residual component of the program include Texas panicum and nutsedge. Compared to Valor, greater grass control and longer residual control can be observed with Fierce.
Staple LX or Pyrimax mixed with Roundup will improve control of hemp sesbania, morningglory (except tall morningglory), spreading dayflower, tropical spiderwort, and glyphosate-resistant Palmer amaranth that is non-ALS resistant. Excellent residual control of susceptible weeds will also be observed once Staple is activated.
Suprend is a mixture of the active ingredients in Caparol and Envoke. Suprend mixed with Roundup will improve control of larger morningglory, nutsedge, and pigweeds. It provides excellent residual control of susceptible weeds. Cotton should be at least 8” tall when directing.
Valor SX mixed with Roundup will improve control of doveweed, larger morningglory, Florida pusley, tropical spiderwort and glyphosate-resistant Palmer amaranth. Outflank, Panther, and Rowell have the same active ingredient as Valor, as well as several other generics. Cotton should be at least 18” tall with a completely “woody” stem before this combination is precisely directed to the bottom 1- to 2-inches of the cotton stem. Add nonionic surfactant at 1 qt per 100 gal spray solution if Roundup brand requires adjuvant. DO NOT use crop oil concentrate, methylated seed oil, organo-silicone adjuvants, or any adjuvant product containing these. Valor, once activated, will provide excellent residual control of pigweed species including Palmer amaranth, Florida pusley, and many other broadleaf weeds. Valor has a very favorable rotational package, see label.
Peanut:
Peanut crop injury and tank mixtures: I have received a few comments from growers about peanut crop response and tankmixes on peanut. Below are comments from Dr. Eric Prostko, UGA Peanut Weed Scientist, on this subject.
There are too many variables to consider including the number of products in the spray tank, GPA, air temperature, humidity, leaf wetness, overall peanut plant health, and time of day. I think part of the problem last week was our higher than normal temperatures. A few tips for growers considering spraying untested tank-mixes:
a) Limit the number of products that are put in a spray tank. Bite the bullet and make separate applications when practical.
b) Spray early in the morning when air temperatures are lower and the peanut plants have not been baking in the sun all day.
c) Increase water volumes from 10 GPA to 15 GPA (less concentrated spray droplets).
The following is a good publication to keep handy at this time: Tank-Mixing Chemicals Applied to Peanut Crops: Are the Chemicals Compatible?. This publication can be accessed from the web at the following location:
http://www.peanut.ncsu.edu/pdffiles/004993/tank_mixing_chemicals_applied_to_peanut_crops.pdf
Irrigation Termination in Corn
Last week I received a few questions about corn irrigation termination. We have received a few showers this weekend and Monday and this might have answered those questions. For top yields, continue to irrigate as needed until the kernels are physiologically mature. This is when a black layer has formed at the base of the kernel. When a corn ear has approximately 85 percent of the kernels showing black layer formation then it is considered physiologically mature. Physiologically mature means that the ear has reached its maximum dry weight. The black layer keeps water or dry matter from transferring into the kernel. This usually happens about 60 days after silking.
Producers can also look for the milk line to determine how long you have until black layer. The milk line separates the solid from the liquid portion of the kernel. It takes about 11 days for the milk line to move from early dent stage to half milk line. Then it will take approximately 6 days for the milk line to get from half milk line to 3/4 milk line. When the kernel has reached 3/4 milk line it will take another 7 days to reach black layer.