Rain in the Forcast

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Image from: Biochemical, Physiological and Molecular Avenues for Combating Abiotic Stress Tolerance in Plants. 2018: 297-316

Thomas County has not seen a significant rainfall event in the past 30 days.   Low humidity is also leading to high evapotranspiration.  Recently we have been losing up to .30 in. from evaporation each day.  All shallow soil moisture has basically been depleted at this point.  Shallow soil temperatures are also very high – 88 degrees yesterday.  Small tender plants are really suffering in this heat – the best solution for many growers is to irrigate at night (which is very difficult logistically because it takes up to 12 hours or more for a pivot to make a full rotation).  Cotton and peanuts are in the early stages of production so all that has mainly been affected is emergence – many have had to replant.  Those with irrigation systems can manage this issue, but those without need only pray for rain and manage weed and insect issues which have been made worse by the dry heat.  Weeds are more competitive in this environment and insects have moved off of other drought stressed plants onto more tender, newly emerged crops.  Good news – once cotton and peanut crops have emerged water demand is low (about a half in per week).  In an average year – we have no average years – this would be taken care of by rainfall.  By late June cotton and peanuts will be in peak water demand.  Approaching or in tasseling stage corn so yields are also being severely affected due to water requirements being about 2.5 in per week.  Pecans are also in need of irrigation with the onset of nut sizing coming up.   With temperatures up around 100 degrees for several days growers will be tempted to increase the irrigation further, but this is not necessary.  Pecan can still function normally at temps of 106 degrees as long as they have the water they need. Temperatures are much cooler at night though, which allows for some recovery for our crops.  Rain is also in the forecast for this weekend so hopefully we can all get some relief soon.  If not, good record-keeping and sound irrigation strategies can increase profitability in several different ways – reducing irrigation costs through reducing energy costs, and increasing yield.

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Pecan Water Requirements and Heat

We have some very high temperatures in the forecast for the next several days. With this in mind, I wanted to provide some irrigation suggestions. The irrigation schedule below is the recommended schedule for drip and microsprinkler on pecan in Georgia. As you can see you should move up to 35-40% of the maximum amount in June. It is probably a good idea to go ahead and move to that June rate at this point with the high temps and the onset of nut sizing coming up. With temperatures up around 100 degrees for several days growers will be tempted to increase the irrigation further. However, this is not necessary. Pecans are adapted to heat, and in fact, need it. Photosynthesis begins to shut down in many plants once temps get above 94 degrees. Pecan, however, can still function normally at temps of 106 degrees as long as they have the water they need. The June rate of 35-40% of maximum is adequate for mature pecan trees on drip or micro-sprinkler at this time. For solid set systems you should be at 1″ per week.

For non-bearing trees, I would go up to as much as 170 gallons/week during the heat wave and dry weather on sandy soils.

 

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Peanut Weed Control Update for May 23 (Prostko)

A few things to think about in regards to peanut weed control given the current weather conditions:

1)  Rainfall events on Mother’s Day Weekend (May 9-13) caused some Valor related peanut problems in many areas of south Georgia (Figure 1).  Since I have addressed this issue numerous times in other blogs, I feel no need to bloviate any further.  But, this problem should not be a surprise to anyone who has ever used Valor in the past.  Valor injury will almost always happen when rainfall events occur from cracking up until about 2-3 weeks later.  Historically, this injury has been cosmetic only and not resulted in reduced peanut yields.

Figure 1.  Valor injury at UGA Ponder Farm, May 14, 2019.

2) Cracking/EPOST applications of paraquat mixtures or solo applied Storm or Ultra Blazer should be delayed as late as possible in peanut fields suffering from Valor injury.  I would argue that if Valor injury has occurred, then good weed control has also occurred and a cracking treatment might not really be needed.  Paraquat treatments can safely be applied in peanuts up to 28 days after cracking.

3) Common paraquat mixtures include paraquat + Storm or Basagran + Dual Magnum or Warrant or Zidua.   I have no preference between Dual Magnum, Warrant or Zidua.   There is no need for additional adjuvants with Dual Magnum mixes but a NIS (0.25% v/v) should be used in Warrant or Zidua + paraquat tank-mixes.  FYI, I am not a huge fan of paraquat + Dual Magnum or Warrant or Zidua without any Basagran/Storm due to greater injury potential that might reduce yields (especially under these lava-like weather conditions). Also, paraquat without Basagran/Storm is not very effective on smallflower mg (Figure 2).

Figure 2.  Smallflower morninglory

3) With paraquat mixes, I prefer Storm (bentazon + acifluorfen) over Basagran (bentazon) due to the variety of weeds that can occur in any given peanut field in Georgia.  My typical recommended use rate of Storm in EPOST paraquat tank-mixes is 16 oz/A.  If need be, growers can make their own “Georgia” Storm by mixing 16 oz/A of Ultra Blazer 2SL + 8 oz/A of Basagran 4SL (yesthis is a slightly hotter mix than 16 oz/A of Storm).

4) It is very hot and very dry right now.  Non-irrigated growers who were planning on using paraquat tank-mixes after peanut emergence might want to re-considering their options.  Why?  Rainfall/irrigation is critical in helping peanut plants recover from paraquat injury.  I do not think that irrigated growers need to worry about this issue since they can help the peanut plants recover from paraquat injury with well-timed irrigation events.

5) When paraquat + Storm/Basagran + Dual/Warrant/Zidua mixtures are applied in peanut, there is no need to be a great ID’er of weeds since these mixes control just about everything (small grasses and small broadleaf weeds).  But, if a non-irrigated grower decides to go with something other than paraquat mixtures (which is fine), such as Ultra Blazer or Strongarm or Cadre or 2,4-DB, they better know what is in the field since these herbicides are not as broad spectrum.  I am not comfortable with very early applications of Cobra unless the peanut plants have reached the 6 true leaf stage.

6) No matter what I say or do, if it don’t rain, it don’t matter! (That’s a famous quote from former UGA Extension Peanut Specialist, Dr. John Baldwin)

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Two Remaining UPW Trainings

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April 11, 2019 · 8:22 PM

Paraquat Certified Applicator Training Required Before Applying Paraquat After March 8, 2019. (Culpepper/Prostko).

Below is a new requirement for anyone that applies paraquat (Firestorm, Gramoxone, Helmquat, Parazone, etc.) from this point forward. Sarah Grayce Culpepper (my daughter) and I took the test this morning. It was actually fairly interesting, especially to her, and even kept her entertained for the entire training module…..I was very surprised. We then took the test where she got 14 of the 15 questions correct; I changed the one she had wrong so we would get a 100 which is required to get the certificate for me to be able to apply paraquat.

All in all, this is an excellent course about stewarding pesticides and continues to support UGA’s overall mission. I believe (but not completely sure) that one of the very sad case studies with paraquat poisoning discussed in the training occurred in GA.

Couple of thoughts:
As a first time user, I did have to create an account with eXtension by clicking on the link in the information below. It took about 10 minutes to get it set up for me to be able to get to the module.
It took 29 minutes for us to take the course…….our internet is rather slow.
Sarah Grayce and I took the test together which took 11 minutes. (if you do not make 100, you have to keep taking test until you get 100 so that would add a little more time).
Took 4 minutes to figure out how to print certificate; make sure to print certificate.
The issue that many of us (growers/applicators) throughout Georgia either do not have access to the on-line training or do not know to make the technology work is real. Please consider ways to help; even though we know each of you are way too overwhelmed.
We will add a very brief statement at the end of our UPW trainings and any remaining weed meetings to help share the information.
Paraquat is an IMPORTANT part of nearly every single sound management program UGA weed science recommends in agronomic crops.
Critical points to remember include: a) paraquat can only be applied by a certified pesticide applicator and b) an EPA-approved paraquat training is required every 3 years.
For complete information about this new required training program please refer to the following web-site:
https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators

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Citrus Red Mite

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On a site visit this week I saw some trees that had mite populations that were higher than what I would expect this time of year.  They turned out to be citrus red mites and luckily they are pretty easily controlled.  At one time the citrus red mite was a serious pest in Florida, but now it is less of an issue.  These mites are less than five tenths of a centimeter in length with the females being larger than the males.  Females lay up to 37 eggs in two weeks and live about 23 days.  However, high temperatures and high humidity reduce the growth of populations.  When populations are higher, from November to June, they cause a stippled look on leaves.  This can cause heavy leaf drop and limb dieback in the most severe infestations.  When trees are dormant mites can be controlled with a dormant oil and once this is no longer an option there are several other insecticides that are.

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Peanut Update Reminder

2019PeanutMeetingReminder

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February 14, 2019 · 5:44 PM