Tank-Mixing Cobra or Ultra Blazer with Cadre in Peanuts (Prostko)

Over the last few days, I have had a few questions about tank-mixing Cobra or Ultra Blazer with Cadre + Dual Magnum + 2,4-DB.  Most are concerned about potential crop injury but this tank-mix has not been overly caustic in my research (Figures 1 and 2).  But, keep in mind that crop injury with tank-mixes can vary greatly depending upon many factors including time of application, GPA, air temperature, leaf wetness, and humidity.  Thus, I can provide no guarantees when 4-6 products are dumped in 1 spray tank.  

Peanut growers who suspect (or are not sure) that they have ALS-resistant Palmer amaranth and/or other weeds that Cadre is less effective on (i.e. tropic croton) would greatly benefit from this tank-mix.  In this scenario, Dual Magnum could be replaced by Outlook, Warrant, or Zidua (grower preference not mine).  Also, I would probably avoid Anthem Flex in this particular situation because of the Aim (carfentrazone) in the Anthem Flex.  When using Warrant or Zidua, a NIS should be included (0.25% v/v or 1 qt/100 gals).

Figure 1.  Cadre + Dual Magnum + 2,4-DB + Cobra.

Figure 2.  Cadre + Dual Magnum + 2,4-DB + Ultra Blazer.

Weed Control Update - June 16, 2021

Just a few things I thought you might be interested in seeing from my research plots over the last few days (a la Dr. Bob K., the E-Mail King of Georgia): 

1) The most effective weed control program (in any crop) happens by starting clean, using a strong residual program that gets activated by rainfall/moisture, and making timely POST applications.

2) Lots of folks interested in using Anthem Flex (pyroxasulfone + carfentrazone) on their peanut crop.  Anthem Flex is a very good herbicide but it will cause more peanut injury than the other WSSA Group 15's. Growers need not forget the other WSSA Group 15's that work equally as well in the UGA recommended peanut weed control programs including Dual Magnum (s-metolachlor), Outlook (dimethenamid-P), Warrant (acetochlor), and Zidua (pyroxasulfone). 

3) Preliminary herbicide/fungicide/peanut response tank-mix research with Provysol looks promising.  I have observed similar results positive results with Cobra and Ultra Blazer.

4) Check out this soybean injury from 2,4-DB (2 oz/A) applied in combo with Reflex (24 oz/A) + Classic (0.5 oz/A).  The use of 2 oz/A of 2,4-DB in just about every POST herbicide application in soybean was very common in the late 1980's/early 1990's before all of the technology explosions.  Looks worse than I remember.  Good weed control though!

Irrigating Peanut Fields Treated with Valor (Flumioxazin) During a Hot/Dry Period (Prostko)

The weather forecast for Tifton and many other areas of south Georgia over the next 10 days is not great (> 85 F and < 35% chance of rain).  Consequently, growers are wondering if it is a good or bad idea to irrigate cracking peanuts that received a PRE application of Valor.  Growers are very conscious of the fact that the potential for Valor injury significantly increases with moisture especially around the time of peanut emergence.  

I am of the opinion (based upon 20+ years of research/field experience with Valor) that if a grower needs to irrigate a Valor treated peanut field in order to get a good stand, he/she should do so.  What is worse?  A crappy peanut stand or Valor injury?  The impacts from a poor stand are more detrimental than Valor injury.  Production/history/research over the last 20 years has confirmed this.  Also, an irrigation event of 0.3"-0.5" over several hours is not the same as a 2" rain in 20 minutes!

I recently completed a 3 year study where the main goal was to try and injure the peanut crop by subjecting the field to as much irrigation/rainfall as possible,  In these studies, the peanuts received anywhere from 7.8 to 11.2 inches of rainfall/irrigation in the first 30 days after planting (Table 1).  Yes, the peanuts did suffer from Valor injury (as expected) but they recovered without yield loss even at a 2X rate (Table 2). UGA does not recommend the use of 6 oz/A of Valor (also not labeled) but this high rate was used to demonstrate peanut tolerance and simulate worse case scenarios.

I have addressed the Valor/peanut injury issue in numerous other blogs so check those out for more information/injury pictures/etc. (May 20, 2014; May 4 and 27, 2017; May 6, 2019; May 21, 2020).

Table 1. Rainfall/irrigation data (in) for first 30 days after planting for Valor/Dual Magnum high moisture peanut tests in Georgia (2017-2019).

Time (DAPa)	2017			2018			2019
	Rain	Irrigation	Total	Rain	Irrigation	Total	Rain	Irrigation	Total
0-7	0.5	3.7	4.2	0.0	5.3	5.3	0.2	3.0	3.2
8-14	0.4	0.0	0.4	1.1	0.0	1.1	1.2	2.3	3.5
15-21	1.2	0.5	1.7	1.5	0.0	1.5	0.6	0.5	1.1
22-30	0.5	1.0	1.5	3.3	0.0	3.3	0.0	0.5	0.5
Total	2.6	5.2	7.8	5.9	5.3	11.2	2.0	6.3	8.3

^aDAP = days after planting.

Table 2. The influence of Valor on peanut injury, J-rooting, and yield under high moisture conditions in Georgia (2017-2019)^a.

Valor Rate	Peanut  Injury (%)		Peanut J-Rooting	Yield
oz/A	10 DATb	50 DAT	%c	lbs/A
0	14 cd	8 b	46 a	5842 a
3	31 b	9 b	48 a	5870 a
6	51 a	16 a	50 a	5823 a

^aAveraged over three years (2017, 2018, and 2019) and four Dual Magnum rates (0, 16, 21, and 42 oz/A).

^bDAT = days after treatment.

^cData collected 21 days after planting.

^dMeans in the same column with the same letter are not significantly different according to Tukey-Kramer method (P<0.10).

 

Heat or Herbicides? (Culpepper)

Next week is shaping up to be a challenging week for cotton planting, similar to late May of 2019. Remember that soil temperatures greatly influence cotton emergence, Figure 1 includes a graph from a USDA manuscript sharing the relationship of lateral cotton root development as influenced by soil temperature (McMichael and Burke, Environmental and Experimental Botany, Vol 34, I added the F temperatures to their graph). Take special note the highest soil temperature that they studied was 104 F; next week we could easily exceed 115 F if predicted air temperature and lack of cloud predictions are accurate. Back in 2019, most blamed herbicides for the lack in cotton stand when in fact most issues were a result of high soil temperatures. Thus, Figure 1 also shares different levels of visual symptoms of cotton damage from hot soils (pictures from no-herbicide control plots). Any factor cooling soils may have a positive influence. For example, one of Dr. Camp Hand's graduate projects conducted during late May of 2019 noted 35% better stands with a rye cover crop compared to tilled systems; although stand was reduced in both systems. 

Herbicides and Dusting in Cotton Can Be a Mighty Challenge! (Culpepper)

The most effective approach to minimize cotton injury from preemergence (PRE) herbicides is to place the cotton seed in moist soil where it can imbibe (absorb) clean water free of herbicides (Figure 1). Next, we need our cotton roots to “out run” the herbicide as the herbicide is moving down into the soil with rainfall or irrigation. When placing cotton seed in dry soil and then applying a PRE herbicide, it is likely impossible for water to get to the seed without being contaminated with the herbicide causing much greater potential for injury.

Thus, dusting cotton in and applying PRE herbicides is far from ideal in regards to avoiding cotton injury. The next thought from every grower, is to hold off on the herbicides until the cotton emerges. This thought is extremely dangerous when considering the monumental challenges our family farms face with herbicide resistance in Palmer amaranth. However, it may be the only option in some environments. If one does follow the path of not using PRE herbicides and planting cotton into dry soils, there are several key points to consider.

First, there needs to be no weeds emerged (especially Palmer) when the cotton seed is placed in dry soil. If there is, get the backhoe out to dig the Palmer up later in the year. In theory, if the field is weed-free when dusting cotton in the soil then no additional weeds should emerge until it rains.

Second, the first postemergence herbicide application should occur as soon as the cotton is fully emerged; the treatment must kill emerged weeds and must include residual herbicides. The level of selection pressure placed on the postemergence herbicide in this situation is very high and not sustainable over time.

Third, a second postemergence herbicide application should be made 12 to 15 days later and again include a residual product, this timing assumes you were timely with the first postemergence application. If you were not timely, the interval needs to be tightened down following label recommendations.

And finally, the value of a layby application in fields without a PRE increases astronomically in regards to herbicide sustainability. Although it is very time consuming, it is still better than hand-pulling pigweed!

Why Does UGA Only Recommend Dual Magnum in Cantaloupe and Watermelon Row Middles? (Culpepper)

Agents, many of you have asked “What will happen to my melons if Dual Magnum is applied broadcast prior to transplanting or broadcast overtop after transplanting”?  Figures 1 and 2 will help you understand why we need to avoid these application methods and focus on using Dual Magnum only in our row middles!

Mixing Order of Pesticides is Important (Prostko)

This is a friendly reminder to all young and old extension agents that the tank-mixing order/sequence of pesticides is very important.  I discussed this topic in a previous UGA Weed Science Blog (Tank-Mixing - April 4, 2018) so check that one out so I do not have to reinvent the wheel.   

Got a call from a industry tech rep today about some mixing problems with Roundup PowerMax3 and Zidua SC.  You can see in the slide below that when the Roundup was put in the plastic bottle first followed by the Zidua, that some problems (i.e. the formation of precipitates that could gum up a sprayer) occurred immediately but did not do so when the Zidua was mixed in the bottle first.  This simple demonstration was conducted using 1500 mls of water (0.396 gallons) so just imagine the potential mess in an 800 gallon sprayer.  This problem could have been easily avoided by reading page 13 of the Zidua SC label (https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/ZiduaR_SC1t_herbicide_Label.pdf).