- Clemson Precision Agriculture Peanut Research & Extension
Browse abstracts, calculators and web apps, guides, research articles, intellectual property, news articles, presentations, and theses related to peanut from the Clemson Precision Ag program. Opens in new tab.Read More
- Green Peanut Production Factsheet
Green peanut production can be a profitable venture for many growers in South Carolina from the small hobby farmer to large commercial growers. Like commercial peanut production, one of the most important decisions a grower can make is “which variety to grow?” Green peanut markets can be locally specialized. That is, consumer acceptance and marketability is influenced by factors such as pod size, shape, kernel skin color, multi-kernel pods, and flavor. Despite this influence of tradition, a bright-hulled peanut with good flavor usually sells well and develops a market. Valencia, Virginia, and Runner type peanuts are commonly grown in South Carolina for the green peanut market. Below is a description of each of the peanut types and some of the recommended varieties for each type.Read More
- Clemson Precision Agriculture Peanut Research & Extension
Clemson Peanut Email Updates
- June 10, 2019 - Wet Weather Following Dry Weather
The last several days have been bringing much needed rain to the state, and we may yet see more before the first half of this week is done.
The dry and hot weather earlier is showing Aspergillus Crown Rot in some fields. This disease kills the plant, and evidence of the fungus shows up as black sooty spores at the crown of the dead plant. This disease is difficult to treat once it is seen in a field. The best thing we can do is plant good quality seed that has been treated. In-furrow Abound (azoxystrobin) can also help, but once we see dead plants it is too late to add an in-furrow product. The hot and dry conditions that encourage Aspergillus crown rot also promote lesser cornstalk borer, and feeding injury from lesser can make an opening for Aspergillus to enter the plant. While damage from Aspergillus can be visible from above ground, hot and dry conditions can also encourage white mold, which can be active and subterranean where the damage may not be visible until peanuts are inverted. Tebuconazole with the 40-45 day application will help.
Early leaf spot and late leaf spot can be found in a few places but are not out of control. The dry weather earlier gave us some latitude with starting fungicide programs maybe a little later, but maintaining protection and making sure we don’t get behind now will keep things manageable as we get further into the season.
Thimet injury can show up as a variety of symptoms, but they generally all start at the tip of a leaf and can be chlorotic/yellow. Several small round brown/black lesions at the tip of leaves are common. Injury from Thimet can look a little like hopperburn or leaf scorch. All 3 symptoms can appear near the tips of leaves and can also have wedge or V-shaped appearances. Hopperburn is the result of the potato leafhopper feeding on the leaf; it looks yellow (no brown) and does not by itself have lesions inside the chlorotic portion of the injury. Leaf scorch is caused by the same fungus that causes pepper spot and commonly has a small black lesion inside of the larger necrotic area on a leaf. This larger brown/necrotic spot of killed leaf tissue can take on a wedge shape. Thimet injury is more symmetrical and different leaflets are commonly affected at the same time, with symptoms common across fields. The symmetry is caused by the different plants and leaflets being exposed to the same compound (phorate) in the furrow at the same time. Hopperburn can occur on all or most leaflets when there are lots of leafhoppers in a field, but it is only yellow. Of the 3, only hopperburn potentially requires treatment, with the threshold for action being 15-20% of leaflets affected. Hopperburn usually pops up around June-July and typically starts on field edges, I have not yet seen it this year. Leaf scorch is overall not economically damaging and most fungicides we regularly use for leaf spot control are likely effective against it. Thimet injury can at times look alarming, but it is nothing to worry about and is more of a sign that “the Thimet is doing its job”.
- June 4, 2019 - Dry Weather and Residual Herbicides
Impact of Dry Weather on Soil Residual Herbicide Effectiveness
Mike Marshall, Extension Weed Scientist
With the challenging weather conditions since early May (i.e., early record high temperatures, lack of rainfall, and other stress factors have reduced the overall effectiveness of previous soil residual applications in peanuts. In most parts of the state, dryland peanut production is challenged by the lack of rain. Soil residual herbicides, such as Valor, Prowl, and Strongarm (preemergence after planting) and Dual Magnum, Warrant, Outlook, and Zidua (early postemergence residual) require some amount of precipitation soon after application for effective weed control. Prolonged dryness after application reduces the amount of herbicide that is moved into the soil profile and activated to control weed seedlings once rainfall returns. As a reminder, soil residual herbicides are a cornerstone in our weed resistance management program, especially with our limited portfolio of postemergence herbicide options in peanut. With a good chance of rain in our forecast this week, it is important to keep them in your herbicide program. Remember, if you applied a soil residual herbicide more than 10 to 14 days ago, be ready for another shot of a soil residual product (along with the proper postemergence product(s) to control any existing weeds) this week to take advantage of the upcoming precipitation events. Overlapping residuals also provide good insurance against weed resistance.
- June 4, 2019 - Land Plaster, Paraquat, Leaf Spot
Looks like we may get some needed rain this week. This will be a good opportunity to activate residual herbicides applied this week. Peanuts in the state are 97% planted, with 40% of the crop in good condition and 51% in fair condition, ahead of the crop insurance planting deadline of June 5 for most of the state. Current crop age mostly ranges between 14 days to 40 days old, with earlier planted peanuts at first bloom. Land plaster is being applied right around the 35 – 45 DAP mark to be in place for developing pegs. Rates for Virginia types are 1500 to 2000 lb/ac. Runners overall can benefit from 1000 lb/ac if soil test levels are between 400 – 600 lb/ac. With larger runners (TUFRunner 297 and 511) I would put out 1000 lb/ac as additional insurance with soil levels above 600 lb/ac, especially if grown for seed. Making sure the soil levels of Ca to K is at least a 3:1 ratio in the pegging zone (top 3”) helps protect Ca absorption.
Another question that has come up is whether it is beneficial to apply paraquat when it has been as dry as it is. Dusty fields may see some reduced activity of paraquat, but it is still helpful to slow the weeds down while we can. In addition to Basagran acting as a safener, some products such as foliar nutrient products can help the peanuts recover a little quicker from paraquat injury. Along these lines, there is not an indication currently that these “rebound” products would lower the effectiveness of herbicides applied at the same time on weeds.
Not much to speak of as far as leaf spot activity to date. Have seen the beginnings of lesions on a few volunteers in areas heavily infected last year, but even those were very few and far between. On the other hand, as hot and dry as it has been it would be good to add a little tebuconazole (7.2 oz) in with the 40 - 45 DAP fungicide spray to add an economical buffer against white mold. Insect issues besides thrips have currently been quiet as well. Mites haven’t started becoming an issue yet but if things stay hot and dry long enough this could change.
- May 25, 2019 - After Planting
As hot and dry as it’s been all week, it is good that most of the peanut planting is complete. Any dryland peanut acres still needing to be planted should wait until a good rain brings moisture back to the field. The forecast ahead looks like it may be a bit before we see that rain. Irrigated land not yet planted should receive 0.5” before planting, especially if peanuts have not been planted there before to avoid cooking the inoculant. If water is instead applied after planting it still helps but applying before is better.
Mike has more to say about weed control but here are a few quick notes. Paraquat is typically our standard for an early postemergence application less than 28 days after cracking, and should be safened (Basagran) to reduce peanut injury. Dry weather over the coming week will delay recovery, but they will perk back up after some rain. Dual/Warrant/Zidua/Outlook will help add residual activity. Cadre/Impose mid-post is commonly put out in the application following paraquat and has good broad spectrum activity and is one of our most effective nutgrass options but will not affect ALS-resistant pigweed and is not as strong on goosegrass as Select/Arrow (clethodim) + COC. If we are putting out Select Max/Arrow it works best when not mixed with a contact product (paraquat/Storm/Ultra Blazer…) so it has a chance to be absorbed. Some contact mixes can get effective control if the clethodim rate is increase 25-50%, but check labels.
Aproach Prima is newly labeled for peanuts this year and is attractively priced. Overall, the 6.8 oz rate has the same amount of cyproconazole as a 5.5 oz rate of Alto but also has strobilurin (picoxystrobin). In recent years, strobilurins as a group have decreased considerably in effectiveness against late leaf spot. More on this to come in a separate note. We will be looking at it more this year, but for now the safest route would be to mix Aproach Prima with 1 pt Bravo. Alto also benefits from Bravo, with another effective early combination being Alto + 5 lb Microthiol Disperss. These early applications do not have substantial white mold activity that is more important later in the season.
- May 20, 2019 - Early Peanut Injury
Drier weather and making use of remaining soil moisture over the past week has allowed planting to continue at a rapid pace. Peanut acres in the state are about 70% planted. Many growers are applying preemergence herbicides and at-crack/early-post applications. Peanuts that have emerged are overall looking good, but we need a good rain.
Thrips feeding is showing up on peanuts, with the most damage seen on peanuts planted without an in-furrow insecticide (attached). Even for peanuts planted with insecticide, our work has shown a yield benefit to an acephate application 14 to 21 days after planting when thrips feeding pops up on emerged plants.
Fields with Thimet have started to show classic phytotoxic leaf margins near 9 days after planting, which can expand in the following weeks but doesn’t tend to negatively affect the crop. Similarly, Valor injury can look alarming but peanuts generally grow out of it pretty quick without much of a problem. Damage from Valor occurs when rain splashes it onto peanut tissue. Keeping applications within the label target 2 days after planting and before emergence greatly helps limit injury. Every now and then peanuts can be seen coming up root first, j rooting. This has previously been thought to be related to certain herbicide application (Dual) but in most cases is instead linked to generally non-ideal growing conditions and lower seed vigor.
Diseases have been quiet so far, without any reports of leaf spot on crop peanuts or volunteers. We have a lot of good eyes throughout the state keeping on the lookout.
- May 3, 2019 - Seeding Rates, In-Furrow Insecticides
Peanuts in the state have begun to be planted this week, with some acres having been planted a little earlier as well. Soil temperatures have warmed nicely and have been hovering near 70F. After having a wet start to April, moisture has since been coming and going. Rain is spotty in the forecast, and some rain would help with washing in and activating preemergence herbicides that are going out, including Valor, Prowl and Strongarm.
As a few reminders, we like to shoot for 6 seed/row ft during planting to establish a strong stand, set the base for productive yield potential, and protect against increased thrips. Two ways we can do this is to count out how many seed are actually going into the furrow after planting a test strip, or by monitoring the lb/A going out. Seed size can change slightly, but listed in the table below are approximate seed sizes for common varieties for reference. Due to their larger size and price tag that comes along with it, Virginia types sometimes are planted at 5 seed/row ft to moderate the seed cost.
Peanut seeding rates (lb of seed/A)*
Peanut seeding rates per acre
Variety (approx. seed/lb)
Seed size (seed/lb)
Bailey, Sullivan (510)
TUFRunner 297 (600)
Georgia 16HO (625), TifNV-High O/L (620), TUFRunner 511 (615)
Georgia 06G (650)
FloRun 331 (675)
Georgia 09B, Georgia 12Y (700)
Georgia 14N (800)
Georgia 13M (830)
For in-furrow thrips/TSW/leaf spot management, the choice of Admire Pro vs. AgLogic vs. Thimet vs. Velum Total is ultimately up to each grower. Liquid formulations of Admire and Velum Total are hard to argue with, though Thimet and AgLogic have a long history of successful use. Based off our data, I am partial to Thimet, though productive and healthy peanuts can be grown without it. If nematodes are a documented problem in your field, Velum Total or AgLogic can help. If Propulse is also going out early, imidacloprid can be more readily substituted in place of Thimet while still preserving yield potential, particularly with green peanut production.
- April 11, 2019 - Preplant Herbicides
Early-Season Preplant Herbicide Recommendations for Peanut - 2019
Mike Marshall, Extension Weed Specialist
As preparation for peanut planting commence in the next few weeks, ensuring a clean start in your fields is very important. Planting into green weeds will result in stand emergence issues and early season competition. Several herbicide options are available for burndown in peanut (See 2019 South Carolina Pest Management Handbook for addition details on the products mentioned in this article). These include glyphosate, 2,4-D, paraquat, Liberty depending on your weed spectrum present at the time of application. Typically, difficult to control weeds, such as cutleaf evening-primrose, wild radish, and wild mustard (especially large flowering plants), require 2,4-D for satisfactory control. As a reminder, the preplant intervals for 2,4-D is dependent on the rate applied with 1 pt/A or less requiring 14 days, 1.5 pts/A requiring 21 days, and 2 pts/A requiring 30 days before planting. Tank mixing glyphosate with 2,4-D is typically the most cost effective and efficient burndown program in South Carolina row crops. A soil residual herbicide may be tank mixed with glyphosate and 2,4-D program for enhanced early season residual control of summer weeds including Palmer amaranth. Leadoff, Valor SX, and Warrant are some options for tank mix partners for glyphosate and 2,4-D. If late planting decisions do not allow the use of 2,4-D, then paraquat is another non-selective option for controlling weeds prior to planting. In general, the larger the weed, the higher the paraquat rate is needed for control (see label for details). In addition, spray volume is critical for effective control (i.e., at least 15 gallons per acre is recommended when applying paraquat). If planting is less than 7 days from application, delay the use of a soil residual herbicide until after planting at the preemergence timing. Finally, if volunteer peanuts are present at the time of preplant herbicide application, Liberty is an excellent choice for managing any early season volunteers. Tank mixing 2,4-D is an option with Liberty for enhance broadleaf weed control but follow the planting intervals mentioned above.
- February 22, 2019 - New Fungicides
Here are a few fungicides that have recently received (or may soon receive) their labels for use on peanut in the state.
Aproach Prima – Corteva fungicide labeled for foliar diseases of peanut, 6.8 fl oz/A rate contains the same amount of cyproconazole as Alto, but Aproach Prima also contains the strobilurin picoxystrobin. Has shown competitive early season leaf spot management activity (FRAC 3 + 11), not labeled for soil diseases.
Lucento (EPA registration approved, SC label pending, anticipated for 2019 growing season) – FMC fungicide made up of flutriafol + bixafen (FRAC 3 + 7), labeled for foliar and soil diseases of peanut, based on our trials appears to provide competitive leaf spot and white mold control without tank mixing, however, current data is still limited.
Provost Silver – Bayer, next generation version of Provost Opti, (prothioconazole + tebuconazole, FRAC 3 + 3), labeled for foliar and soil diseases of peanut (11 – 13 fl oz/A), 13 fl oz rate contains about 1.8 times the amount of prothioconazole contained in a 10.7 fl oz application of Provost Opti and about 0.8 times the amount of tebuconazole (0.165 lb/ac/application compared to 0.2 lb/ac/application for Provost Opti or generic Folicur).
Umbra – Nichino, flutriafol + flutolanil (FRAC 3 + 7), next generation version of Artisan that does not contain propiconazole, making it compliant with EU regulations, requires tank mix to provide adequate leaf spot control (e.g., Bravo, Miravis…)
- October 20, 2018 - Lows in the upper 30s
Sunday night into Monday AM is forecast to drop to near 37 to 40°F. For most situations this is warm enough to not cause frost damage. Fields with low areas can become cooler and may have more risk for lower temperatures. If there is enough of it, frost can cause recently dug pods to go Seg II through damage from freezing the moisture in the kernels. Peanuts that are dug and have dried for three days before a frost have a low risk of injury. For fields waiting to be inverted, if a frost does come through, digging can continue once it has past. The coming nights should for the most part be in good shape, but always good to keep on the radar as we move further out of October and into November.
- October 9, 2018 - Hurricane Michael
Hurricane Michael is on a track to make its way through the southeast and VC regions this week, with most of the rain for SC looking to come on Thursday. It looks like the storm should come and go, bringing somewhere between 2 and 4 inches depending on location. If this ends up being the case with a quick pass through, it would be more forgiving for peanuts that are still on top of the ground than if we were to get several days of cloudy misty rain. If the vines are healthy and the pods are not over mature, they would overall be safer left in the ground and dug once the storm passes and the field is accessible. On another note, for runners that may still have some time to go until harvest, keep an eye out for velvetbean caterpillar infestations. As temperatures in the coming week and beyond start to cool down, maturity development begins to slow. Thinking a bit further down the line (but not that much further) frost advisory dates for stations throughout SC can be found at the following link:
- September 29, 2018 - Peanut Digger Conveyor Speed Calculator
As impacted S.C. and N.C. farm land dries out from Hurricane Florence, some peanut growers are faced with the challenge of digging peanuts with weakened pegs due to over-maturity and other factors. Our studies show that above ground digging losses can be significantly impacted by conveyor speed. We believe that conveyor speed is even more important when the peg is weak. We've provided the calculator at the link below to help you set your conveyor speed.
- September 18, 2018 - Peanut items following Hurricane Florence
Airplane fungicide application can help provide coverage where fields are too wet to drive the sprayer. Bravo helps provide some protection, but for thicker canopies a systemic product like prothioconazole (Provost Opti) will help provide better coverage and protection. If earlier Virginia type fields are too wet to be dug on time and get delayed about a week, there may still be peanuts worth digging, but this also depends on how healthy the vines are and how advanced or tight the maturity was. Runner peg strength provides more leeway than Virginia types that can drop off quicker once they pass the black pod stage. Once the ground dries enough to prevent bogging and ruts, digging a few passes in a field where digging was delayed can help provide a visual on what the potential crop looks like. Peanuts can usually survive three days of being under water. Several rivers are anticipated to continue to rise over the coming days, including the Waccamaw and Pee Dee Rivers.
- September 10, 2018 - Hurricane Florence digging or harvest decisions and drying costs
- September 10, 2018 - Combine field capacity and executive order transportation of agricultural crops
Below is related combining capacity information from Kendall as well as the recent executive order increasing transport limits:
We've put together some tables to help you estimate your harvest capacity; to be conservative, figure on no more than 9 suitable harvest hours per day this time of year. Peanut Combine Field Capacity: http://precisionag.sites.clemson.edu/Extension_Guides/Peanut_Combine_Field_Capacity.pdf
Executive Order 2018-27 by SC Governor McMaster temporarily lifts weight limits to 90,000 lbs for transport of agricultural crops in anticipation of the potential impact of Hurricane Florence. Restrictions apply.
- August 24, 2018 - Velvetbean caterpillar and chlorpyrifos
Eye witnesses have identified velvetbean caterpillar at the scene of the crime munching on peanut leaves in a few fields south of the lakes. Damage was not yet outrageous, but they were described as “being up to no good”. One of the most important things in dealing with VBC is knowing if it is there, since they can eat leaves quickly. Fortunately VBC is easy to control, and we have two main options at our disposal: knockdown chemistries (including inexpensive pyrethroids) for current populations or 2 fl oz/A of the insect growth regulator Dimilin as a preventative treatment. Dimilin has a PHI of 28 days, and fields in Jasper, Hampton, Allendale or Colleton Counties can consider adding Dimilin in with a fungicide application if VBC are not yet present in the field for protection.
Chlorpyrifos (active ingredient in Lorsban) has been in the news recently, not so much for its activity against lesser cornstalk borer or burrower bug, but this time in a notice for a possible federal ban. The jury is still out on whether the EPA will appeal the court order, and until further notice it is still okay to use (though typically we don’t use much Lorsban this late in the season). Chlorpyrifos can also be an effective treatment for southern corn rootworm, but so far this pest has been a relatively minor concern under SC conditions (thankfully). Additional information about use of other insecticides for managing lesser cornstalk borer can be found at this link http://nwdistrict.ifas.ufl.edu/phag/2018/06/22/lesser-cornstalk-borer-damage-reported-in-florida-and-georgia-peanut-fields/ from Dr. Mark Abney of UGA. While Lorsban also has some activity against white mold, current fungicide options overall are more effective.
In addition to the coming Field Day on September 6, it is never too early to put the 40th South Carolina Peanut Growers’ Meeting on the calendar for January 24, 2019 in Santee.View Related Images
- August 10, 2018 - Aerial applications and delayed field access
In some cases, frequent rains have created fields that are too wet to bring spray equipment into. As spray intervals become due or past due, aerial applications are another tool that can help deliver fungicide to a field that is too wet for ground sprayers. Generally speaking, an aerial application does not provide as good of coverage as a ground sprayer would and costs more, but when wet weather persists and we are not sure when we could stand up in a field next, it is important to maintain protection, particularly with susceptible varieties and fields with a history of disease pressure. If we do get behind on timely applications, it helps to apply a leaf spot material that has systemic activity and be ready to tighten the following interval. Systemic fungicides often have limited curative activity (a few days at most), whereas a protectant like Bravo has no curative activity.
Fleming McMaster, consultant near Allendale and Barnwell Counties, says things are pretty quiet in peanuts currently. Late leaf spot lesions can be found in small amounts in some fields but for the most part is being well controlled. Insect numbers have also been low, in part due to frequent rains. Peanut leaves are looking very good and healthy.
- August 3, 2018 - Potato leafhopper, corn earworm / tobacco budworm, rainfastness
It feels like it hasn't taken long for it to be August. In addition to keeping an eye out for diseases, some fields have started having insects come in. Potato leafhopper can cause hopper burn, which looks like a yellow V at the tip of the peanut leaf. Typically leafhoppers start on field borders and work their way inward. Rule of thumb for deciding if we need to treat is if 20% or more of the leaves are affected and leafhoppers are still present in the canopy. Symptoms can be delayed in showing up after the initial feeding is done. Corn earworm/tobacco budworm has been found as well, for the most part at lower amounts. Healthy growing vines can tolerate some feeding damage (up to about 30% canopy damage) and about 8 worms per foot. If a worm problem is present, cheap pyrethroids can sometimes be effective, but they risk killing beneficials and flaring spider mites during dry years. Safer worm options include prevathon and intrepid edge, as well as additional products on page 57 of the money maker.
Rain shortly after a fungicide application can sometimes washoff the product from the leaves. This is in general a good thing for white mold control, since it helps the active ingredient get to where it can be effective. On the flipside, too quick of rain off can sometimes smell a bit like that Travis Tritt song Trouble, since we need good leaf coverage for good leaf spot control. Talking with Malone Rosemund from Bayer and Tony Hamlett from Syngenta provides the following estimates for rainfastness: Provost Opti rainfast at 2 hours after application if leaves were dry when sprayed and 3 hours if wet when sprayed, and Miravis 1 hour rainfast following application. Bravo WeatherStik is generally good to go in 30 minutes. Generic chlorothalonil may take a little longer but should be pretty good in a couple hours. The attached picture is a combination of physiological leaf spot and some early stages of leaf scorch. These generally are not associated with economic impact. Sometimes physiological leaf spot can be observed following Provost applications (on runners for example), but this should not be a cause for worry, more of a reminder that when seeing possible leaf spots, the best characteristic to determine if it is late leaf spot is to look for little bumby conidiophores on the underside of leaf lesions. For susceptible varieties (Virginia types and TUFRunner 511 for example), if Provost Opti or Priaxor are applied alone, the maximum labeled rate is preferred, 10.7 fl oz for Provost or 8 fl oz for Priaxor. Lower labeled rates can be alright for lower pressure situations alone or when mixed with 1 pt chlorothalonil.
In recent years, Gregory peanut has been having so variation in pod size, with some characteristically large pods and some smaller pods roughly reminiscent of runner pods. Not entirely sure of the mechanism of the reason for this, but it seems to be generally a case of things not quite working the way they used to, similar to us sometimes as we age. For what it is worth, the different size pods taste good to me.
- July 20, 2018 - Recent rains, R2 to R5, leaf scorch, TSW, late leaf spot
Recent rains have been bringing much needed moisture to the state but continues to be hit or miss. Growth stage for most of the crop ranges from pegging (R2) to pod fill (R5), with canopies ranging from not yet lapping the row to being full and closed in the row middles.
If you see leaf scorch in peanuts, it usually looks worse than it really is, and sometimes it doesn’t look that bad. Leaf scorch is caused by the same fungus that causes pepper spot (Leptosphaerulina). Most of the fungicides we use to manage late/early leaf spot also have activity against this fungus, and it typically isn’t associated with a negative impact on yield.
Tomato spotted wilt symptoms have been spotty (no pun intended) across fields. While symptoms may now be becoming more visible for TSW, practically speaking there is not much we can do once we are past the early portion of the growing season to manage this disease. Management of thrips (the vector for this disease) is usually the last thing we do that affects TSW development.
Keep an eye out for foliage feeders (e.g., corn earworm/tobacco budworm and fall armyworm) as we move into the end of July and into August.
Like the Tom Jones song goes, “It’s not unusual” for late leaf spot to get started in the bottom of the canopy, but it can also get started in the tops of the plants (where we might more expect to see surfactant/crop oil burn).
Weather conditions have been ripe for leaf spot and white mold development. Fungicide applications going out should target both diseases.
Peanut Scouting School is set for Thursday, August 2nd in St. Matthews View Peanut Scouting School Flier .
Peanut Field Day is set for Thursday, September 6th at the Edisto Research and Education Center in Blackville. Agenda to come out later.
- July 14, 2018 - Late leaf spot, fungicides
Just a quick note to keep an eye out for leaf spot. Late leaf spot has been starting to show up in the 2018 crop, mostly in susceptible irrigated situations with more pressure. Lesions usually get started in the bottom of the canopy, making the lower leaves a key place to look when out and about scouting for early disease development. If we only look at the tops of peanuts and first find leaf spot in the upper part of the canopy after it has been there awhile and already established in the canopy, it is similar to trying to manage weeds when they are too large for optimal control, a situation we would like to prevent if possible.
In addition to some of the fungicides mentioned previously, comments about effectiveness and mixing requirements (e.g., Topsin must be tank mixed with Bravo/chlorothalonil for example) of additional products including Fontelis (more of a white mold material) can be found on pages 51 – 53 of the production guide.
- July 6, 2018 - Late leaf spot, droplet size, 60 DAP reminders, fungicides, manganese, herbicide spot spray
Charles Davis and Drake Perrow are finding late leaf spot in some fields that were sprayed earlier with Alto + Bravo. However, an important piece of information they have noticed beyond chemistry was that in these fields the fungicides were being applied with ultra-coarse Dicamba tips (e.g., TTI11004). These tips were designed for a larger droplet size and to minimize herbicide drift. In contrast, more moderate droplet sizes generally allow for better coverage, which is important for fungicides particularly those with protectant activity (one example of a moderate droplet size nozzle is DG8002). It would be great and convenient if one tip could rule them all, but until then the rotating multi-tip nozzle bodies are a good friend to have, and a good one to remember to use when matching the appropriate tip with the agricultural product being applied at the time.
We ran a trial last year to look at different nozzle tips under two fungicide programs (protectant vs. systemic activity), but the trial had too much non-target disease come in and was a bust in terms of data. To be on the safe side, I would reserve ultra-coarse dicamba tips for their intended application of dicamba products.
60 DAP Reminders
Fungicides: Depending on variety, field conditions, etc., leaf spot and white mold both are primary concerns, and for both prevention is our friend.
Options for leaf spot include Miravis (requires tank mix for soil activity, e.g., tebuconazole or Convoy), Priaxor, Provost Opti, or chlorothalonil (requires tank mix for soil activity, other products are generally more effective at this timing).
Options for white mold include Elatus, Provost Opti, Convoy (requires tank mix for foliar activity, e.g., chlorothalonil…), or tebuconazole (requires tank mix for foliar activity, teb is still an effective product but is generally less effective than other options). Virginia types and Georgia 12Y have effective white mold resistance but still benefit from tebuconazole application.
Manganese: If soil test (sufficiency levels in table below) or foliar symptoms (yellowing between leaf veins near top of plant) indicate a possible manganese deficiency, apply 0.5 lb Mn with the 60 and 75 DAP fungicide sprays. Individual product rates can be found on page 16 of the production guide. With Mn deficiency, new growth may still appear deficient following foliar Mn application.
pH-Mn Relationship pH Mn lb/a 5.8 6 5.9 7 6.0 8 6.1 9 6.2 10 6.3 10.5 6.4 11 6.5 12
Herbicide cleanup/spot spray: Sometimes parts of fields can get carried away if we get large amounts of rain or they are in a soggy bottom and we cannot get to them during smaller more manageable growth stages. If an overgrown or challenging weed problem is present in a limited part of a field that would not respond well to a standard broadcast application (for example, large morningglory that is up and over the rows and is covering the peanuts), we might consider preventing additional weed seed buildup by applying a non-selective applicator such as Gramoxone as a spot spray application (less than 10% of a field, different from the 28 days past cracking limit on broadcast application). Weed Specialist Mike Marshall has additional details on page 40 of the production guide, but briefly the rate for spot spray non-selective application of Gramoxone is first preparing a 33% solution by mixing 1 part paraquat with 2 parts water, adding NIS at 0.25% v/v, and then applying up to 2 pt/A of this mixture. The peanuts may not look pretty afterwards, but neither would the alternative of a growing weed problem.
- June 22, 2018 - 40-45 day reminders (fungicides, boron), Miravis
A lot of good peanuts out there. County Extension Agents Hannah Mikell (Clarendon County), Trish DeHond (Chesterfield, Darlington, Marlboro Counties), and William Hardee (Dillon, Horry and Marion Counties) are seeing no major issues in peanuts so far. Rainfall as usual has varied from field to field, with some fields very dry and others getting plenty of rain.
40-45 Day Reminders
Fungicides: Planting dates and field age are spread out a bit this year. Earlier planted fields have already or are soon reaching the 40-45 day mark and applying fungicides. If fungicide protection hasn't already started earlier due to increased late leaf spot pressure, 40 - 45 DAP is when we want to make sure our fields are getting protected. If the planned fungicide does not have soil activity against white mold (e.g., chlorothalonil or tetraconazole), addition of tebuconazole (generic Folicur) helps provide economical early season white mold protection. The critical control period for white mold in SC generally starts 60 DAP.
Boron: If soil tests show boron levels below 0.4 lb/A, addition of 0.3 to 0.5 lb elemental boron/A (e.g., 1.5 - 2.5 lb Solubor, additional product rates on page 16 of the production guide) helps prevent boron deficiency. Boron can go out with a fungicide or herbicide application. Watch application rates, more is not always better -- applying more than 0.5 lb elemental boron in a season can cause boron toxicity.
More on Miravis
As with most any new product, the approved registration and (limited) availability of Miravis fungicide for peanuts this year has interest and questions. A previous update listed some of its strengths and weaknesses as far as foliar and soil diseases are concerned.
Miravis is a Group 7 fungicide with a labeled rate of 3.4 fl oz/A, and it is going to cost more than an average fungicide. There may be thoughts of wanting to try a reduced rate application to reduce the overall price, however at this point I would advise against this to preserve its efficacy as long as possible and to reduce the chance of resistance developing. Along these lines, Miravis would be best reserved for fields and situations where it can be used preventatively (as a general example, not later than 60 DAP) and where yield potential is high and leaf spot pressure or risk is also high. Irrigated Virginia types or highly susceptible runners like TUFRunner 511 are two examples. With dryland production, we can certainly still have good yield potential and/or high leaf spot pressure, but a lot of the yield potential there is also more dependent on the weather, which simply means there is more uncertainty to the return on investment. Runners with more late leaf spot resistance like Georgia 12Y and Georgia 14N would not see the same level of benefit from Miravis as more susceptible varieties and could be managed effectively with other products. Georgia 06G in most cases could also be managed effectively with other chemistries, with the emphasis there primarily being on white mold (e.g., Elatus, Convoy, Provost Opti...).
- June 20, 2018 - Domark fungicide
Domark has received a label for use in peanuts this year. The active ingredient in Domark is tetraconazole (same as in Eminent fungicide and one of the components in Mazinga ADV) which has systemic activity. Domark has a standalone rate (5.25 to 6.9 fl oz/A) and a tank mixture rate (2.5 fl oz/A) for when it is combined with another fungicide (e.g., 1 pt/A chlorothalonil). Tetraconazole has more leaf spot activity than tebuconazole (late leaf spot in SC is largely resistant to tebuconazole = generic Folicur), but tetraconazole has no soil disease activity (whereas tebuconazole is active against soil diseases like white mold).
Most of the available data I’ve seen included tetraconazole products in combination with chlorothalonil, with results being generally competitive with straight chlorothalonil. At this point the safest approach when using Domark would be to use it in a tank mix with chlorothalonil (and tebuconazole to provide white mold activity) when we want to add systemic activity and/or stretch available chlorothalonil supplies. Domark can be roughly thought of as another option similar to how propiconazole (Tilt) was previously used.View Domark Fungicide Label
View Domark Fungicide Label Supplement
- June 7, 2018 - LLS volunteer follow up
Depending on the age of the field, related risk details and other issues like herbicide need, I would primarily go with one of two options for an at risk field with or near volunteers with LLS.
If the field also needs paraquat I would add chlorothalonil in with the paraquat application and then come in with a systemic product at the next application. If the field already had paraquat applied and when they green up a bit (or if paraquat was not needed) I would go over them with Proline. In both cases I would not wait for the 45 day spray to start protection.
- June 6, 2018 - Late leaf spot on volunteers
April showers may bring May flowers, but it would appear in a couple cases that our May rain has brought June peanut volunteers late leaf spot pain. Jonathan Croft confirmed late leaf spot on volunteers in a field planted to peanut last year in Orangeburg County. In one of our non-rotated research fields at the station in Barnwell County, we have found additional volunteers infected with late leaf spot, whereas other fields have volunteers but have yet to show lesions. Keep a scouter's eye out near your fields, early pressure calls for early action.
- May 30, 2018 - Peanut update
Parts of the state may see more rain this week, but the long term forecast includes drier conditions eventually coming our way. Planting dates are a bit spread out, with some fields still being planted and some that have been in the ground near 30 days. Coming up after the one month mark (35-45 DAP) is when land plaster is traditionally applied to supply calcium for developing pegs. If land plaster is applied too early, the concern is minimal protection from small peanut canopies combined with possible wash off from heavy rains (more than 5 inches in a short time). The risk of applying land plaster too late (approximately after 60 DAP) is reduced productivity and quality as the pods begin to fill if soil calcium levels are inadequate. Early is generally better than late, but late is still better than never.
In thinking about whether we should start our leaf spot fungicide programs at 45 days or closer to 30 days, the rain and how wet the field is may end up doing the deciding for us, but we can still consider a few items, including looking at how our individual programs performed last year. Two of the big items are how susceptible a variety is and how conducive the production conditions are (earlier planting in late April and early May, as well as longer rotations decrease risk). Susceptible varieties include Virginia types (Bailey, Sullivan, Wynne…) and the runner types TUFRunner 511 and Georgia 13M (Georgia 09B is also fairly susceptible). If volunteer peanuts are a problem nearby or were an issue last year when rotation crops were grown, we might err on the side of caution and consider applying fungicide closer to 30 days to provide additional protection, if possible. In a “normal” year we generally do not see leaf spot infections in SC this early, but all the rain and moisture we’ve had has created favorable conditions for spore production. Every field may not equally benefit from earlier fungicide application, but for those that do it is much more effective to have the protection up front than trying to negotiate with defoliation once it begins. If a field is ready for fungicide application but it is too wet to get it applied on time, consider adding a systemic product (Alto, Domark, or Priaxor) to Bravo/chlorothalonil 1 pt/A, or using Proline.
The rain over the past few weeks may have caused some plans to change. As we enter into June, we still have a bit of time to get peanuts planted and obtain a reasonable window of conditions for growth and harvesting. Mid-May has generally been the best time to plant peanuts in SC, though peanuts can still be made if planted into early June. Once planting dates reach June 10, we are looking at approximate digging dates near October 20 for a 132 DAP variety like Bailey or digging dates entering into November for moderate maturity varieties like Georgia 06G. One of the concerns around that time of year becomes slow drying conditions prior to combining that can lead to quality issues if they sit out in damp conditions too long. Every year is a little different, but overall the combination of lower yield potentials, higher late leaf spot pressure and generally unfavorable harvesting conditions for peanuts planted after about June 10 makes it better to finish planting what peanuts we can before then.
- May 25, 2018 - Peanut update
Showers have continued coming and going, and subtropical storm Alberto is working its way into the Gulf of Mexico. We’ll have a better idea which way it may go after a couple days, and hopefully the way it goes is more or less away. Still, for peanuts that made it in the ground earlier and are now up, they look really good. Charles Davis said thrips numbers are high in Calhoun and Richland Counties. If time and field conditions allow between planting and rain, a foliar application of acephate (Orthene 12 oz/A) can help keep thrips damage at bay.
On another note, Syngenta’s Miravis fungicide (label attached) recently received registration at the federal level from the EPA. State approvals are anticipated later this year but are currently pending. Supplies will be very limited in 2018. Miravis fungicide does not have much activity against soil diseases like white mold, but what it lacks there it more than makes up for with particularly excellent activity against late leaf spot (early too).View Miravis Label
- May 17, 2018 - Early-Season Herbicide Considerations for SC Peanut
Attached are several items from Mike Marshall regarding early-season herbicide considerations for SC peanut.
Thrips feeding injury is starting to show in places but so far hasn’t been too bad. Low thrips injury also helps us out for planted fields that could benefit from paraquat application, since the combination of the two when severe can lead to noticeable effects on yield, but we can usually tolerate either one or the combination when not severe (severe thrips damage makes the peanut leaves look all mangled up, twisted and stunted). Before this week, many areas were in need of rain, and as the saying goes “when it rains, it pours” most fields are certainly catching up with the rain we’ve been receiving.View Early-Season Herbicide Considerations for SC Peanut - 2018
- May 9, 2018 - Recent peanut questions
I have the option of planting some of the TUFRunner varieties, are they any good?
Two TUFRunner varieties are available in some quantity this year, TUFRunner 511 and TUFRunner 297. Of the two, TUFRunner 297 has had excellent yields in multiple tests over the past few years and does not display extreme susceptibility to common diseases. I would certainly try TUFRunner 297 if you have access to it. TUFRunner 511 also has strong yield potential (not as strong as 297) and has been competitive if not better yielding than Georgia 06G in our trials. Unlike 297, TUFRunner 511 is highly susceptible to both spotted wilt and late leaf spot. This is a variety that in most cases I would recommend planting with Thimet. Varieties with good resistance to spotted wilt such as Bailey or Sullivan provide more flexibility and can readily be planted with Thimet or imidacloprid products based on preference and/or insecticide price.
A few acres of Bailey got planted without an in-furrow insecticide, should we come back the next day with Admire over the top?
Fortunately Bailey has good resistance to spotted wilt. In this case, I would leave the seeds planted the way they are and then come back at early emergence with an application of Orthene (acephate) to provide some buffer against thrips.
There have been some questions on whether or not imidacloprid negatively affects the performance of peanut inoculant when applied together.
These products have been around for a while and have been applied on a good number of acres without compatibility issues being observed. So far I have not seen enough evidence to suggest there is a problem combining inoculant with imidacloprid, but certainly let myself and/or your agent or consultant know if you suspect an issue in your field. Page 14 in the production guide has some reminders of good handling practices for inoculants.
How much potassium per acre causes excess pops?
For most practical applications, potassium levels being too high really only becomes an issue if there isn't enough calcium in the pegging zone. As long as we have at least 3 times as much calcium as there is potassium in the pegging zone, then we shouldn't get excess pops, provided recommended amounts of gypsum are being applied (~1500 lb/A for Virginia types). If we get excessive drought in a dryland field we can still get pops even with gypsum application, but that is a separate factor and would be that much more worse if the potassium levels are more than one third the calcium levels.
- March 19, 2018 - 2018 Peanut Rx
Attached is a copy of the 2018 version of the Peanut Rx Disease Risk Index. This is another tool that can be used to see how much “risk” is associated with different combinations of peanut production practices.View 2018 Peanut Rx Disease Risk Index
- December 21, 2017 - Anticipated chemical shortages in 2018
Several industry reps have indicated that it looks like we will see another shortage of chlorothalonil (active ingredient in Bravo) in 2018. Exactly how much we will be short remains to be seen, but it will likely be noticeable. This shortage appears to be stemming from production facilities in China undergoing upgrades to operate cleaner. Similarly, tebuconazole (generic Folicur) may also be in short supply and/or available at a higher price. The tebuconazole shortage is anticipated to more-so affect individual tebuconazole products and less-so affect combination products like Provost Opti.
- June 7, 2016 - 45 DAP Fungicide spray, boron, and nodulation
- June 10, 2019 - Wet Weather Following Dry Weather