Early to Mid-Season Irrigation for Peanuts
Wesley Porter, Extension Precision Ag and Irrigation Specialist, UGA
David Hall, Extension Water Educator, UGA
Jason Mallard, Extension Water Agent, UGA
Similar to May of 2021 which was very hot and dry, we had some very hot and dry weather during May
of 2022, dry enough that we have needed to apply some small irrigation events to our young peanut
crop. While we have received some sporadic rainfall across the state, this either was not enough to
adequately meet the water requirements or it was missed. Thus, even though we do not typically apply
irrigation to peanuts early in the season, years such as 2022 may require some applications to ensure it
has adequate moisture.
Keep track of irrigation using our irrigation guide https://secure.caes.uga.edu/extension/publications/files/pdf/C%201189_5.PDF in the field throughout the season, stay on top of your irrigation requirements. If you planted your peanuts during late April or early May, most of these earlier planted peanuts will be beginning to bloom, so expect water usage to gradually increase. Peanuts will begin flowering on average around 40 days after planting.
Remember the water requirement is IRRIGATION and RAINFALL. Also consider irrigation efficiency
especially on hot dry days. A typical pivot is 85% efficient, so don’t under-irrigate, but at the same time
don’t over-irrigate either as research has shown reductions in yield just as significant for over-irrigating
as for under-irrigating. Good record keeping and a sound irrigation scheduling strategy can aid
significantly in increasing profitability in multiple ways, including reductions in irrigation applications,
correlating to reductions in energy requirements, and potentially increases in yield.
A couple of quick reminders regarding irrigation of peanuts. Early irrigation applications can tell you very
valuable information regarding your water application uniformity. If a Mobile Irrigation test was not conducted, pay close attention to the way your soils dry out after an irrigation application. If your
peanuts were planted into conventional tillage, this will be easy to see especially prior to full canopy
closure. Visible bands drying out quickly or bands staying wet for longer periods are signs of poor
uniformity. Go to these areas of your pivot and address them now. As the peanut canopy develops and
laps, the obvious signs will not be visible. Hot dry weather makes it easy to see if your pivot was working
properly due to the extreme heat and drought. The under applying nozzles are easy to see by the
evidence presented as stressed crops in bands under the pivot. Doing the same thing twice expecting
different results is never good.
Lastly, if you are using soil moisture sensors and have “weighted” the sensors, now is the time to
reweight the sensors because of increased root development and crop progression. Consider using
other tools in conjunction with your moisture sensors. IrrigatorPro (https://irrigatorpro.org/) integrated
with a soil moisture sensor system through UGA trials has repeatedly shown higher yields than the
Checkbook method. For more assistance and information on IrrigatorPro usage, contact your local UGA
Extension ANR Agent, additionally, The IrrigatorPro website includes a step-by-step video tutorial on
how to download the app.
June 2022 Outlook
Pam Knox, Agricultural Climatologist, UGA
Over the past month, the temperature across the Southeast has been warmer than normal in almost all
locations. Rainfall has been variable, with bands of wet and dry conditions across the region due to the
impacts of slow-moving fronts that have concentrated precipitation in some places while leaving others
high and dry. The Drought Monitor has shown this with an increase in dry conditions depicted until late
May but some decrease since then as rain has become more frequent.
The outlook for June and July is for warmer than normal temperatures to continue for most of the next
six weeks, although it will not be as outrageously hot as the drought regions out west and will have
some breaks with cooler weather interspersed. Precipitation is expected to be fairly dry through early
June with some daily thunderstorm activity scattered around the region. Rainfall is expected to pick up
in mid-June for a week or two before dry weather returns to the region through mid-July. If you are
applying field treatments that depend on the absence or presence of rain, you will want to watch the
forecasts carefully to make sure you find the right timing. If the dry conditions in late June and early July
do occur, I expect to see an increase in drought conditions since the warm temperatures will also
increase water stress.
The first real tropical activity of the year was the Potential Tropical Cyclone #1 that just traveled through
southern Florida, dropping as much as 15 inches in some locations in Miami and surrounding areas. Just
a few areas in coastal Georgia received any rain from the outer bands of this storm, and most of us were
sunny and dry. PTC#1 did not develop a closed circulation and so was not given a name, but after it gets
back out over water and the warm Gulf Stream, it will likely be named Alex as it tracks off to the east
away from the US. Just shows that it does not need to be a named storm to cause a lot of damage if it
hits near you, and rain can be as much of a problem as high winds.
There is nothing else brewing in the tropics right now, but the Gulf of Mexico is warmer than normal and
that is the prime tropical development region in June and July, so we could see more action later in
June. The GFS model is hinting at another Gulf storm around the 3rd week of June, but it often does that
far in advance. Most of the time, those predicted storms do not come to fruition, so don’t get too
excited if people post dire maps of hurricanes at hour 360 on social media, since they are usually just a
single model without much support from other predictions. If a storm does develop, it will likely be in
plenty of time for you to react as long as you are watching the forecasts regularly.
La Nina is still hanging on in the Eastern Pacific Ocean and has gotten a little colder, which means it will
likely continue through the summer. That will enhance the storm activity in the Atlantic, making this
another active year, as predicted. But of course, it really only matters if it comes near you, so be
prepared but not worried at this point. The start of the season is a great time to make sure you are
ready so that if a storm does head for you, you have planned what to do and have all your
documentation in order.
Early Season Observations
Scott Monfort, UGA
Seed quality has been very good this season. I have received very few phone calls regarding poor stands
as it relates to seed quality. In conducting a few stand counts, we were getting 5 to 6 plants per foot of
row so we were getting very good emergence. The only calls I have received regarding planting have
been related to grower mistakes like: planting to fast, wrong chain sprocket setup, not using inoculants
in a field new to peanut. Luckily, the stands in the first two were adequate and did not need to be
replanted. The missing inoculant question would require 60 units of nitrogen. Thrips pressure seemed to
be pretty heavy for much of April and May. With this in mind we are already seeing TSWV, especially
where growers used imidacloprid.
A few things to remember regarding peanut cultivars:
• Georgia-06G
– Still the most flexible variety across state. Still highest overall yield. 140-150 day
maturity. Good peg strength.
• TifNV-High O/L – High Oleic
– Newest nematode variety, ~145 day maturity, better WM, TSWV and LS resistance than
06G which allows for earlier planting, some peg issues observed. Very good resistance
to root-knot. 500 to 1000 lbs yield lag vs. GA06g
• TiftNV HG – High Oleic
– 2-3 years before seed will be available. Very good resistance to root-knot and does not
have yield lag. Yielding just as good as ga-06G
• AUNPL-17 – High Oleic
– We are still learning about this variety but looks pretty good so far. The breeders say it
has a good level white mold, Leaf spot, and TSWV resistance. Maturity is 145 DAP.
Alabama group says it performs well across environments.
• Georgia-12Y
– Acreage is growing, 150-155-day Maturity, performs in most environments, High level of
TSWV resistance, good level of White Mold resistance. better level of LS resistance than
GA-06G, very susceptible to Rhizoctonia limb Rot. This variety needs to be managed for
vine growth (Apogee or Kudos) in irrigated fields. Needs to be planted before May
12th, it does not reach high yields after May 12th in most years. Grade is 1-2 points less
than GA06G.
• Georgia 16HO – High Oleic
– This variety has performed well compared to Ga-06G. One of the better high-oleic
varieties. It performs well in most environments. It had good TSWV resistance so it can
be planted early. It is slightly more susceptible to early leafspot than GA-06G. We
noticed some elevated pod loss (excessive moisture) this past year with this variety but
it still yielded very close to Ga-06G. 140-145 Day Maturity.
• Georgia-18RU
– This variety has performed well compared to Ga-06G. It is slightly more susceptible to
TSWV (I would be cautious about planting in April). Yield is similar to GA-06G with
grades being 1-2 points higher. 140-145 day maturity. Seem to do good across
environments.
• Georgia-20VHO – High Oleic
– This variety has performed (yield and Grade) well compared to Ga-06G in well drained
soils. 140-145 day maturity. We noticed some elevated pod loss (excessive moisture)
this past two years with this variety. You could observe significant yield loss in fields
with excessive moisture.
Late Planting
Just like most years there are several areas in the Georgia peanut belt that did not receive sufficient
rainfall in May to plant during our recommended time frame. There will be some fields planted in early
to mid-June, but hopefully only a few. The risk in planting after about June 5th is that it pushes maturity
well into October, which can start to get cold enough to stop normal maturation of the pods, thus
lowering yield and grade potential. If Georgia-06G, or any other similar maturity range cultivar, is
planted on June 15, then the “normal” maturation period of 140-145 days after planting would put
digging around November 2nd. The average minimum temperature at Tifton for November 2nd is
around 50. However, it is not unusual to have low temperatures in the lower 40’s in mid to late October
in some years. The bottom line is that planting as late as June 15 is very risky for reaching optimal yield
and grade.
Dates of upcoming events:
• Sunbelt Expo Field Day
– The annual Sunbelt Expo Field Day will be held July 21st at Spence Field near Moultrie.
• UGA Cotton Defoliation and Peanut Maturity Clinic (Locations may Change)
– Tuesday August 30th in East Georgia, Location – Midville REC Station
– Wednesday August 31st in West Georgia, Location in Tifton
• UGA Cotton and Peanut Research Field Day
– The annual field day will be on Wednesday September 6, 2022
Peanut Maturity Calendars (April, May & June)
April
May
June
Should I Use Gypsum on my Peanuts This Year? Or Maybe an Alternative Source of Calcium?
Glen Harris, UGA
There doesn’t seem to be as much talk about a gypsum shortage this year, but there are still ‘supply
chain” issues and price of input concerns to the point where there is plenty of talk about whether to
apply gypsum or maybe use an alternative.
To review, UGA Extension recommends using gypsum when you take a pegging zone soil sample (4
inches deep) soon after peanut emergence and when the results say you have either 1) less than 500 lb
Ca/a or 2) a Ca:K ratio of less than 3:1. If either of these criteria are not met then we recommend
applying 1000 lb/a gypsum m at early bloom (approximately 30-45 days after planting). All peanuts to be
saved for seed get 1000 lb/a gypsum automatically since calcium levels in the nut are critical to good
seed germination.
Can I use lime instead of gypsum? Yes, but lime needs to be applied before planting since the calcium in
lime is not as soluble as the calcium in gypsum. So timing is important. Also if you deep turn you need to
deep turn before applying lime so you don’t bury it. So placement is important. The calcium needs to be
in the “pegging zone” (top 4 inches). And technically, lime should only be used when you either need a
pH adjustment (below 6.0) or start around 6.0 so the lime will not raise the soil pH too high.
What about “liquid lime” ? There is a product currently available called “Topflow” that has been field
tested at a 12 gal per acre rate, surface applied at planting. This may not provide as much calcium to the
pegging zone as 1000 pound per acre of gypsum and won’t raise the soil test calcium as much but can be
considered an alternative if you cannot get gypsum. Even though it is a liquid, it is still lime so it needs
to be applied before or at planting.
What about other “Liquid Calcium’s” ? Well, it depends on which “liquid calcium: you are talking about.
For example, recent research has been conducted showing 10 gallons per acre of calcium chloride (or 20
gallons of calcium thiosulfate) through the pivot during peak pod fill (around 75 days after planting) can
have some benefit. Again, this is not as good as a timely gypsum application but can be viewed as an
‘emergency” or “insurance” application. The calcium in both of these products is basically 100 % soluble
and therefore can be applied during peak pod fill. Also, calcium chloride should be the more affordable
option but check on price and availability.
What if I get delayed getting gypsum? Or how late is too late to put out gypsum? Again, gypsum should
be applied at “early bloom” or approximately 30-45 days after planting. Since “peak pod fill” is around
60-90 days after planting you can still see benefit from gypsum applications made any time before 60
days after planting. It can also depend on water or irrigation since you need water to dissolve the
calcium and get it through the hull into the developing kernels.
Does every field of peanuts in Georgia need gypsum ? Probably not, so if supply is short or budgets are
tight how do you decide which fields get gypsum? First, any peanut being saved for seed should
automatically receive 1000 pound per acre of gypsum, regardless of soil test calcium levels. Second, any
field where results from a pegging zone test show you need gypsum should get it. Remember, if the soil
test calcium (Mehlich 1 Extractant) is 500 or higher and the calcium to potassium ratio is 3:1 or higher in
a pegging zone sample then the soil test calcium will be considered adequate and no gypsum will be
recommended. This is based on research field trials looking at yield and grade. Research also shows that
gypsum is even more important in dryland compared to under irrigation since water will be more
limiting in dryland and less soil test calcium will be available.
Can I base my gypsum or calcium needs on a Fall soil sample? You can, and this is better than nothing,
but it is still better to base your calcium needs on a pegging zone sample. Soil samples taken in the Fall
were likely taken at a deeper than the pegging zone. Also, calcium can leach out of the pegging zone
between a Fall sample and early bloom and give you a false sense of security. Finally, if you take a fall
soil sample and then deep turn before planting peanuts you can very possibly turn up soil into the
pegging zone that is low in calcium.
How important is gypsum for peanut production? This probably should have been the first question
answered. And the answer …. It is very or extremely important! Since peanuts as a deep tap-rooted
legume can fix nitrogen and scavenge residual soil phosphorous and potassium, calcium is the most
critical element. Lack of calcium in the pegging zone to be absorbed through the hull can result in
“pops” or no kernels which obviously reduces yield. Calcium deficiency on peanut can also lead to pod
rot. And again, calcium is critical to germination for peanuts saved for seed for next year.
Sprayer Considerations
Simerjeet Virk, UGA
Spray Considerations: As growers shift their focus from planting to crop management, it is important to
be timely and efficient with fungicide applications in peanut to stay on top of pest and disease control
throughout the season. Adequate spray coverage and penetration into the peanut canopy is important
for achieving desired efficacy and to protect peanut yield. Below are several considerations for effective
fungicide applications with boom sprayers:
Nozzle Selection: Nozzle type affects product rate and spray coverage. Make sure to check fungicide
labels for recommended application rate, droplet size, and conditions needed for safe application.
Consult the manufacturer’s nozzle catalog for selecting the nozzle that provides the desired rate and
best coverage. Nozzle selection will also depend on the ground speed and pressure required to achieve
the rate in gallons per acre.
Spray Pressure: Spray pattern and droplet size changes with pressure. Lower pressures result in larger
droplets whereas higher pressures produce smaller droplets for a given nozzle size. For most fungicide
applications, consider selecting a nozzle that provides the medium to coarse droplet size in 30 – 50 PSI
pressure range.
Ground Speed: Application speed plays an important role in achieving the desired application rate. A
higher travel speed will require a higher nozzle flow rate to achieve the given application rate and viceversa. It is recommended to reduce the sprayer speed (less than 10 mph) to obtain a consistent and
more uniform coverage.
Boom Height: Boom height influences overlap and uniformity of spray application at a selected nozzle
spacing and spray angle. Lower boom height (20 – 30 inches from the target) is highly recommended for
maintaining a proper spray pattern and overlap to achieve satisfactory coverage while reducing spray
particle drift.
Environment: Weather conditions such as wind speed and temperature also play a role in making ontarget application while also achieving the desired spray coverage. High wind speed results in greater
drift and less product being applied onto the crop. Wind direction should be also considered to avoid
spraying towards sensitive crops, homes, etc. Warmer temperatures also increase drift especially at
higher boom heights.
Sprayer Calibration: Proper sprayer calibration is important to verify the nozzle output (gallons per
minute) and consequently application rate (gallons per acre) based on the selected ground speed and
nozzle spacing. During calibration, make sure to check all the nozzles for application uniformity across
the whole boom, and for any leaks or uneven spray patterns.
Spray Technology: Spray technologies such as rate controller and section or individual nozzle control
can be utilized to minimize variations in application rate and coverage. Advanced technologies such as
PWM (pulse width modulation) and automatic boom height control systems are also available for use on
boom sprayers for improving application accuracy – both rate and droplet size.
June, 2022 Peanut Pointers
Bob Kemerait, UGA
White mold could easily become one of the greatest threats to peanut production in 2022.
Temperatures in southern Georgia are expected to be in the mid-to-upper 90s for the remainder of
June. Rainfall is anticipated to be sparse and scattered. Sclerotium rolfsii, the fungal pathogen that
causes white mold (more properly referred to as “southern stem rot”) thrives in hot weather. Lack of
rainfall, especially in non-irrigated fields, can make it more difficult to control white mold as rainfall or
irrigation within 24 hours after a fungicide application is important to move the fungicide from the
foliage to the crown of the plant. Protecting the crown of the plant is an important “target” for
management of white mold.
Sclerotium rolfsii can infect peanut plants at any growth stage, but causes the greatest damage when
the limbs and foliage along a row have closed. This allows the fungus to easily spread from one plant to
the next when conditions are warm and humid. Smaller plants can be affected by white mold early in
the season; however spread from one plant to the next is much more restricted.
Recommendation: Though “white mold programs” typically begin at about 60 days after planting when
the peanut canopy is larger and more at risk for disease spread, growers should consider putting
something out at 45 days after planting. I believe a more aggressive white mold program is justified this
season because of early-season conditions. Growers could initiate a “white mold” program by one of
three ways.
- Mix 7.2 fl oz of tebuconazole with a leaf spot material, for example chlorothalonil.
- Use products like Priaxor or Lucento that have fair white mold activity in addition to strob leaf spot control.
- Initiate the 3-spray Elatus (7.3 oz) or Excalia (2.0-3.0 fl oz/A) programs.
For several reasons beyond those mentioned above, June is a critically important month for disease management and, sometimes, for nematode management as well. Based on planting date, most of the peanut crop will be between 30 and 45 days after planting at some point in June. Some of the below is “recycled” from last season. I hesitate to do this, but it fits again this year, so here goes….
- Fungicide programs for management of leaf spot diseases (except for the earliest and latest planted peanuts) are typically initiated during the month of June. Leaf spot programs should
begin closer to 30 DAP when A) the field is at higher risk to leaf spot based upon results from
Peanut Rx, and/or when B) fungicides to include chlorothalonil, Mazinga, chlorothalonil +
Domark, and chlorothalonil + Alto are used as the first fungicide application. - Fungicide programs for leaf spot management can safely begin closer to 45 days after planting when A) the field is low-risk to leaf spot diseases as determined with Peanut X, B) fungicides such as Priaxor, Lucento, or Aproach Prima are used in the opening fungicide application, or C) Velum or Velum Total is used in-furrow at planting.
- Growers should avoid, if at all, possible initiating a peanut fungicide program later than 45 days after planting.
- The “backbone” of most fungicide programs for control of white mold does not begin until approximately 60 days after planting; however growers often start earlier, especially when short rotation increases risk to disease. Effective ways to begin a white mold program within the first 45 days after plantings are to A) apply Proline (5.7 fl oz/A) in a narrow band over the peanuts, B) include tebuconazole or azoxystrobin with your first leaf spot applications, or C) adopt Elatus or Excalia programs that begin as early as 30 days after planting.
- Applications of Propulse can be made as early as 45 days after planting to fight leaf spot, white mold, and to supplement earlier nematicide applications for control of nematodes.
The “Good”: Timely fungicide applications (before disease is established) are a critically important tactic for controlling disease. Starting your leaf spot program on-time, often in June, sets the stage for a successful disease management program and best yields.
The “Bad”: Getting behind in a fungicide program early in the season may allow disease to become established that is difficult (if not impossible) to manage later in the season. While I know some growers wait until 50-55 days after planting to begin their program, I strongly advise you to not wait later than 45 days after planting and to begin as early as 30 days after planting in a number of situations.