Category Archives: Peanuts

Disease & Nematode Management Considerations For 2017 Peanut Planting

Peanut growers can use a different products at planting time for the management of diseases and nematodes. Decisions as too what product to use over another, or to use a product at all, can be very confusing. Fighting seedling disease used to be simple- all growers used a fungicide seed treatment, and if they wanted some “stand insurance” they could also spray Abound in-furrow. Today, in-furrow applications are important considerations for the management of tomato spotted wilt, seedling diseases, Cylindrocladium black rot, white mold, and nematodes, not to mention thrips! Below are management options for the growers put together by UGA Extension Pathologists Dr. Bob Kemerait, Dr. Tim Brenneman and Dr. Albert Culbreath:

Note: The rates provided here are on a “per/A” basis. Typically, the full rate can be placed in single rows; the rate is typically halved per twin row. For example, Abound, 6.0 fl oz/A in-furrow for single rows becomes Abound, 3.0 fl oz/A in each of the twin rows:

Management of Tomato Spotted Wilt

Tomato Spotted Wilt Virus

A number of products can be used to manage thrips on peanuts. However, only one product, Thimet (ai: phorate) is effective in reducing the risk to this disease. The reduction in risk to tomato spotted wilt is not related to the thrips control that it provides, rather is seems to be associated with the response of the plant to Thimet. Thimet likely activates defense-response genes in the peanut plant that help to protect the plant from the virus. Growers who want to plant early (before May 1), or who want to use cultivars with spotted wilt risk points greater than those of Georgia-06G, might especially want to consider to using Thimet for management of tomato spotted wilt.

Management of Seedling Diseases

Peanut seed and young seedlings are susceptible to attack from a number of fungal pathogens. The two most important fungal pathogens causing death of peanut seedings in Georgia are Rhizoctonia solani and Aspergillus niger. Fungicide seed treatments are a critical tool to manage seed rots and seedling diseases; currently nearly all seed is treated with Dynasty PD. Dynasy PD is composed of azoxystrobin, fludioxonil, and mefenoxam. However, growers can also protect the developing plants from seedling diseases with in-furrow fungicide applications of fungicides like Abound (5.7-11.4 fl oz/A), Proline (5.7 fl oz/A), and Evito (2.3-3.5 fl oz/A). These fungicides are typically used to compliment seed already treated with a fungicide seed treatment.

Aspergillus Crown Rot

The most effective in furrow spray for stand establishment has been Abound, although Proline also has activity on these pathogens and Evito is labeled for this use as well. The benefits of these products have not been as consistent in recent years, and research is underway to determine the factors involved.

Management of Cylindrocladium black rot (CBR) and early-season white mold

Proline (5.7 fl oz/A) applied in-furrow has been an important treatment for the management of CBR. Though this disease has been less widespread in recent years, an application of Proline in-furrow is still useful where there is a threat of CBR. When favorable conditions, such as very warm weather, occur early in the season, in-furrow applications of Proline also offer some protection from early-season white mold. The extent of the protection is likely less than that provided by banded applications of Proline 3-5 weeks after planting. Decisions to use Proline in-furrow should be made based upon a) risk to CBR, and b) risk to early-season white mold (although there are effective alternatives for white mold).

Mycelium and sclerotia (yellow bee bee’s) from white mold

Management of Nematodes

Nematode-resistant cultivars continue to hold up well against even high populations of root knot nematodes. However, growers electing to plant a susceptible cultivar like Georgia-06G in fields infested with the peanut root-knot nematode should consider the use of a nematicide. Popular nematicides for peanut production in Georgia include Telone II (4.5-6 gal/A), Velum Total (18 fl oz/A) and AgLogic 15G (7 lb/A). To prevent injury to seed and seedlings, fumigation with Telone II should occur 10-14 days prior to planting and when soil conditions are not too dry (powder) nor too wet (mud). Fumigation with Telone II can provide excellent control of nematodes but DOES NOT control thrips. Growers who use Telone II must still apply something for management of thrips.

Velum Total is a combination of fluopyram for management of nematodes and also imidicloprid for management of thrips. Growers who use Velum Total do not need to add any additional thrips control product in the open furrow. (Note that imidicloprid does not reduce the risk to tomato spotted wilt.) Also, use of Velum Total does provide additional early-season management of leaf spot diseases. The extent of this protection from leaf spot is such that growers should be able to skip the 30-day after planting fungicide application for leaf spot, unless they have planted a very susceptible cultivar like ‘Georgia-13M’ or TUFRunnerTM’511’.

A question that often arises is, “If I use Velum Total, do I get any protection against seedling diseases as well?” The “bottom line” to this question is that use of Velum Total should complement a seed treatment and be good “stand insurance” and we would not add anything else. The biggest factor by far to reduce the impact of seedling disease is the quality of the seed and putting that seed in the right soil conditions at the right time.

AgLogic 15G (7 lb/A) is for management of thrips and nematodes. AgLogic does not reduce the risk to tomato spotted wilt. The rate is lower than what was historically used for Temik 15G (10 lb/A). Additional research is needed to assess the efficacy of the 7 lb/A rate on management of nematodes. In high risk field it may be advisable to use a combination of these nematicide options.

Leave a comment

Filed under Disease, Peanuts

Planting Peanuts

A few growers have started planting peanuts late this week as subsoil moisture comes more of an issue. Most growers will want to pull the trigger next week. We’re planting right now with some fungicide and inoculant in furrow. Here is a few pointers from UGA Extension Agronomist, Dr. Scott Monfort and Dr. Scott Tubbs:

Soil Temperature

It is recommended that the average daily soil temperature remain above 68 degrees for 3 consecutive days and without cold temperatures in the forecast for the next week before making the decision to start planting peanut. With a warm winter so far, the temperatures had been in the “acceptable” range of conditions … during the last week of March.

armer temperatures are expected to return during the week of April 10-16, and I anticipate the 4-inch soil temperature will warm quickly to a point acceptable for planting by the middle of that week. There are no other cool spells showing in the extended weather forecast through April 21, so I anticipate peanut planting should be in favorable conditions sometime next week including adequate soil moisture because of this past week’s rainfall.

It is important to watch for additional rainfall in the forecast, especially under non-irrigated conditions, in order to activate herbicides after planting. Even with soil temperatures above 68 degrees, it will often take peanuts 7-14 days to emerge from the ground in these conditions (with cooler night temperatures still causing some fluctuations in soil temperatures). In ideal conditions, growers would want to plant with adequate moisture, sustained 68 degrees at the 4-inch soil depth, no cool temperatures expected in the 10 day forecast, but some rain expected within one week of planting in order to ensure optimal peanut emergence and herbicide activation to give the best possible growing conditions from the beginning. Hopefully we can get some peanuts in the ground a few days on either side of Easter this year and catch a rain the following week to get this season off to a great start.

Inoculants

Last year was a very hot and dry year. In those conditions, the survivability of the living Bradyrhizobia bacteria needed to inoculate peanuts is generally reduced. Thus, there may less than adequate nodulation of peanut in some fields or some parts of fields if relying solely on native soil Bradyrhizobia to infect the roots of peanut for N-fixation this season. This is true even if planting in short rotation where peanut was planted within the last few years.

I would recommend growers strongly consider the investment in a peanut inoculant at-planting this year, especially in fields that did not have any cover crop residue on them last year to minimize direct heat impact and reduce evaporation of soil moisture in the upper portion of the soil profile. It has been stated before by my predecessors and colleagues, an inoculant application is one of the most cost-effective “insurance policies” at a grower’s disposal.

Depending on the product used and contract price received for peanuts, it usually takes in the neighborhood of 100 lb/ac yield increase to cover the cost of the product. It is common in my research trials and in reviewing research from colleagues to get greater than 100 lb/ac yield increase on average over multiple years of trials even in a standard rotation. More importantly is to consider the cost of NOT applying an inoculant and having a nodulation failure where there is not adequate N-fixation. The cost of applying the amount of N needed by peanut would greatly exceed the cost of applying an inoculant over the course of many, many years. The risk of not getting a return on investment for an inoculant compared to the risk of potentially losing a large proportion of yield potential one year is not an equal level of risk in my opinion.

Keep in mind that the product is listed on the label to be delivered at around 1.0 fl oz per 1,000 linear row feet (may differ slightly depending on which product is selected). This is developed for single row application! Inoculant application is not like adjusting seeding rate, where you are pulling half of the amount out and moving it over to the adjacent twin furrow. With an inoculant, the applied amount needs to be per furrow according to label instructions. Therefore, a twin row planting inoculant application will double the amount of inoculant applied compared to a single row planting. I have no data at this time to support using a half-rate of inoculant per furrow to keep the total application rate per acre the same as a single row planting.

Leave a comment

Filed under Peanuts

December Row Crop Disease Update

A few things to think about with regards to disease and nematode management in preparation for the 2017 field season.

La Nina:  Our UGA Extension climatologist Pam Knox has good information available on our current conditions, but here are my thoughts:

We are currently in a “weak” La Nina situation, “weak” because the equatorial waters of the cost of Ecuador are more than a half degree COOLER than normal.  As best I can tell, the waters have been about 7/10 of a degree cooler which barely qualifies as a La Nina (as opposed to last year where we had a robust and sure-enough El Nino).  So what does this mean? During La Nina years, the Southeast tends to (“tends to” means more often than not, but not always..) experience warmer and drier winters. Because we have a weak La Nina, this forecast could change.

Pigweed seedhead in broccoli before Thanksgiving. We are yet to have frost to knock back pigweed growth.

Pigweed seedhead in broccoli before Thanksgiving. We are yet to have frost to knock back pigweed growth.

How does our current “La Nina” impact our recommendations?

  1.  Drier is not a good thing as it may mean we don’t fill up irrigation ponds for next year.  It my mean we have a lot of trouble establishing cover crops this fall.
  2.  Warmer temperatures may mean that kudzu, volunteer peanuts, corn, cotton-regrowth, etc. pathogens (like those that cause soybean rust and southern corn rust) may survive and increase longer than they would with an earlier “killing” frost.  Also, as long as the crops and volunteers are active in the field, nematode populations can continue to increase and build.  This will lead to larger populations for next season. Once the plants are killed, the nematodes can no longer feed. Once soil temps drop below 65F, the activity of the todes drops off as well.
  3.  We may get some very cold weather soon, so we may not need to worry that much; however the general prediction is that we will have a warmer winter.
  4.  The weather this winter will have some effect on TSWV and insects for next year.  It remains to be seen what and how… but it will impact them.

Leave a comment

Filed under Corn, Cotton, Disease, Peanuts, Soybeans, Weather

Peanut Harvest & Row Crop Disease Update

Boston Peanut

Boston Peanut

Golden Peanut in Meigs

Golden Peanut in Meigs

After afternoon showers and rain last week, we are really getting back to picking this week. Growers are also wide open on defoliating cotton. I saw some cotton being picked yesterday.

I visited our buying points this week and looked at grades and other issues. Thankfully, we are not having many Seg 2 burrower bug hits as last year and the year before. Between both buying points, I only know of one known burrowing bug Seg 2. In every other Seg 2 case, they’ve turned around and cleaned them and they were fine.

Grades are probably a little down this year compared to last, but are definitely not bad. Many good grades overall and low percentage of our sound splits and other kernels (pops). We could be pulling the trigger early on the some of the fields. Almost all growers are checking maturity twice in fields before digging, and many have checked more than two times. We’ve not seen maturity develop at a normal pace with our dryland peanuts which has made digging decisions tough. With more peanuts in the ground, growers are having to dig when they have help, or wagons are available, or weather permits. Vine condition is also a factor in our decision at this time. Overall, we’ve had good harvest conditions this week. Even with afternoon storms or showers, sunny days have been able to dry peanuts quickly.

Collecting grading samples at Boston Peanut

Collecting grading samples at Boston Peanut

UGA Extension Pathologist Dr. Bob Kemerait has this information on current disease issues:

Peanuts

Harvest is well under way by this time, but disease issues still affect peanuts that won’t be harvested for another three weeks or more. I have seen some fields where harvest is approaching and where white mold (stem rot) is still active, and I have recommended growers late in the season apply a mixture of tebuconazole and chlorothalonil to finish the season (both products have a 14-day preharvest interval). Other white mold products could also be applied (check preharvest interval first), but with time running out in the season, the value of tebuconazole is certainly a consideration.

Late Leafspot

Late Leaf Spot

I have also observed where leaf spot, especially late leaf spot, is aggressive late in the season, primarily on a susceptible variety like ‘Georgia-13M’. If less than two weeks to go before digging, it is doubtful anything should be applied (or legally can be applied). If peanuts are 30 days or more away from harvest, then the grower can mix a pint of chlorothalonil with 5.5 fl oz/A of Alto. If harvest is more than 14 days away from harvest, the grower can mix 5-10 fl oz/A Topsin with a pint of chlorothalonil. Fields where defoliation from leaf spot diseases has reached 50% or more and have not yet reached the optimal digging date should be considered for an early digging.

Soybeans

Soybean producers in southern Georgia have experienced losses to Asian soybean rust this year; however it appears that most have successfully protected their crop with judicious fungicide applications. MORE IMPORTANTLY, I have observed a SIGNIFICANT amount of frogeye leaf spot (Cercpospora sojina) disease in a number of fields this year; something I have not seen in many years. I am not sure why this is so; however it is something we will need to watch again next season as well. Additionally, I am seeing pre-mature defoliation to Cercospora blight (Cercospora kikuchii) in a number of fields; this disease often results in purple stain of the soybean seed. Cercospora blight is diagnosed, in part, by the prominent loss of leaves in the top of the plant leaving only the petioles, reaching like bony fingers to the sky.

Cotton

Bacterial blight (Xanthomonas citrii pv malvacearum) continues to cause concern to many growers in the state. From your reports, reports from our consultants, and from my own observations, it is clear that bacterial blight can be found in a number of fields across the Coastal Plain. Classic symptoms or bacterial blight on leaves, bracts, bolls, stems and petioles are fairly easy to diagnose; still symptoms of other diseases may inadvertently be diagnosed as “bacterial blight”. 

It is my belief, based upon my observations and discussions with a number of experienced individuals, that losses to this disease are likely to be small and even negligible in many fields. Finding a little bit of disease in a field is an important contribution to understanding the occurrence of bacterial blight in 2016; but incidence alone does not mean significant yield loss.

Certainly there are some fields, especially in extreme SW Georgia, were boll rots appear to be closely associated with bacterial blight and losses are likely to occur. Effective management of bacterial blight by a grower revolves around variety selection (we are composing such a list for Georgia cotton producers now) and management of crop debris/residue as the pathogen can overwinter in such. Crop rotation and burying of crop debris can help to minimize the development and spread of the disease in upcoming seasons.

Bacterial Blight

Bacterial Blight

Leave a comment

Filed under Cotton, Disease, Peanuts, Soybeans

Digging & Picking Peanuts

picking-diggingpeanuts-017

If there was anything done in the field this week, it has been digging and picking. We really got heavy digging last week, and many of those peanuts have already been picked. Our conditions have overall been good. If anything, we are worried about it getting a little dry for digging. Some irrigated peanuts have been watered to soften up dirt.

We had lots of rain in forecast this week, but we really didn’t get any. Early in the week, we were cloudy and this stalled picking a day or so as it took longer for peanuts to dry. We have been sunny for the past 3 days however, and growers are super busy now.

picking-diggingpeanuts-020

picking-diggingpeanuts-014

peanuts-dug-2016-001

Peanut Maturity

So many of our o6G’s – especially irrigated – are coming out of the ground between 130 and 140 days. I’ve talked with other agents around us who are seeing the same thing. UGA Peanut Agronomist Dr. Scott Monfort has also reported peanuts ready at this time also. He says GA 09B may be a little earlier than 06G with many of the other High Oleic varieties running near 140-150 days. GA 14N may be 145 to 150 days.

For our dryland crop, we are seeing results from extreme drought and heat on the peanut boards. We will see peanuts with varying color, peanuts turning loose in the hull, and insect damage. In dryland situations, the Tropical Storm made plants look better, but no necessarily pods. Dr. Monfort says some fields will be on the early due to lack of blooming in latter part of growing season. With moisture running low for advance, we are starting to look at vine condition in the field.

Split Crop

When we see a “split crop” it is not easy to determine when to dig. Dr. Monfort says that typically, a profile that is split evenly, we make the decision to dig on the leading edge. But, if the leading edge is minimal compared to the fruit load behind the “split”, then the decision is more difficult.

peanutmaturity-splitcrop-002

**And last, do not take risk in contaminating good quality peanuts with non-irrigated peanuts that might have aflatoxin (dryland corners.) A few bad pods can cause a trailer load to move to SEG 2 or SEG 3.

 

Leave a comment

Filed under Peanuts

Peanut Maturity

We’re getting closer to looking at peanuts to check maturity. I checked my first sample yesterday. We were really just wanting to see how far away we were to make decisions on last fungicides. Peanuts looked further along than expected.

PeanutMaturitySample-PlantedApril27 002

These 06G’s were planted April 27th and 28th, and show a maturity between 14 and  days away. We didn’t have a perfect representative sample, so this may affect it. Peanuts mature based on temperature and available moisture. With high temperatures since June, questions have been about crops maturing early. UGA Agronomist Dr. Scott Monfort says this won’t necessarily affect everything the same. For instance, our early April planted peanuts (in cooler temperature) will stall, then later April planted peanuts will mature faster. Every field situation is going to be different, so sampling is the best way to really know.

In this sample, I was finding a lot ‘turning loose’ in the hull. We need to remember to crack open the pods to observe the funiculous. This is the umbilical cord that connects the kernel to the pod. Once it turns loose, the next rain can make them sprout.

Sometimes it’s hard to see the ‘umbilical cord’ before you break it yourself. Another way to make this observation is just look at the kernel. If the kernel is white with few oil spots, it’s still feeding. If the kernel is dark and shriveled, it has turned loose. I took a picture of these two. They are not always this easy to tell, but looking at them this way has helped me. I start on the right side (mature pods) and work my way back. I cracked 35 pods in this same and 6 were turned loose. 17% is pretty significant.

Top peanut still feeding; bottom peanut turned loose in the hull

Top peanut still feeding; bottom peanut turned loose in the hull

Sampling Procedure

Growers, make sure you have a good representative sample. Get plants from at least 3 spots in the field. Also, don’t just pick off the larger pods. We really need to pick off small pods as well. If we pick off large pods, it can bias the sample toward digging early. There is enough data to show that we lose as much as yield if we dig a week early than a week late. If we dig a week late, there is no difference. We don’t see difference again until we dig 2 weeks too late. We still have to consider the condition of the vines. Definitely look at the vines well as you pull off pods. Also, 180 – 200 pods is good for a sample.

Prevent Digging Losses

Miller County Ag Agent, Brock Ward was talking with me about losses just from the digger. He went back and found good information from former UGA Agronomist Dr. John Beasley on digging losses that I think is good to share:

You can do everything just right during the season to maximize yield and grade potential but blow it all at harvest.  It is very easy to lose several hundred pounds per acre in yield by not being careful when digging. Growers need to take their time and set the digger-shaker up properly and then run at the proper ground speed to maximize digging and inverting efficiency.

In 1990, Dr. Mike Bader and I conducted a digging efficiency trial at the Sunbelt Expo Farm. We had a replicated trial in which we dug as close to perfect as possible, too fast, too slow, too shallow, and too far left or right. We took an area the width of the planted bed (6 feet) by 3 feet in length from each plot within the trial and collected pods on the soil surface and from the top three inches of the soil. We threw out the obviously diseased or non-harvestable pods, and weighed the harvestable pods that would have yielded and graded.

Even where we dug as close to perfect as possible we calculated losing approximately 120 pounds per acre. We know that producers do not harvest too shallow on purpose, but if they are not paying attention the digger blades can ride up more shallow if the soil is too hard. We measured pod yield losses in the range of 1,000-1,200 pounds per acre in the too shallow, too far left or right, and the too fast treatments.

Bottom line is that digging losses can take a significant chunk of yield potential. Another critical factor is to make sure they are using sharp digger blades. A set of digger blades is usually good for a limited number of acres, depending on soil type. On the heavier soils 15-20 acres may be the limit on a set of digger blades so check them often to make sure they are wearing evenly.  Growers need to be very careful at digging to reduce harvest losses.

Leave a comment

Filed under Peanuts

August Peanut Insect Update

Peanuts-06G

This is kind of been a cotton week for me; I haven’t looked at many peanuts this week. Here’s a field I was going to pop in and scout for disease until I saw this water. I’m tired of losing my boots in these kinds of fields.

UGA Entomologist Dr. Mark Abney wrote an insect update I’ll pass along for everyone:

Drs. Monfort, Srinivasan, and I spent several days last week walking peanut fields to get a measure of how severe tomato spotted wilt is in this year’s crop. Incidence of virus symptoms varied from 0 to over 30% in the fields that were surveyed. This effort also gave me an opportunity to see first hand what else was happening in terms of insect and mite activity over a large area of South Georgia. As a general rule, insect pressure was low, but there were a few fields with real or developing problems.

Redneck Peanut Worm & Lesser Cornstalk Borer

Several non-irrigated fields had lesser cornstalk borer infestations, and a couple fields had two spotted spider mites. Redneck peanutworm was the most common foliage feeder I saw. This insect has been very abundant in my test plots this year. I thought the redneck peanutworms had run their course a week or so ago, but we seem to have another generation showing up on the research farms around Tifton. There are no thresholds for this insect, and I doubt that it will cause measurable yield loss in most situations. It does however, make the foliage look ragged.

Southern Corn Rootworm

Southern Corn Rootworm - Adult - Dr. Mark Abney

Southern Corn Rootworm – Adult – Dr. Mark Abney

Some fields had relatively high numbers of southern corn rootworm (cucumber beetle) adults, and I received a couple more reports of pod damage this week. As I mentioned in a post last week, there is little that can be done to manage rootworm infestations in peanut once the larvae are feeding on pods.

Caterpillars

I have not seen much in the way of caterpillar pressure, but I have gotten calls that indicate some fields are experiencing moderate to heavy infestations. There are velvetbean caterpillars, soybean loopers, and armyworms in spots. Most of the moths I saw in fields last week were tobacco budworm. I will be watching my plots closely for caterpillars in the coming weeks.

Whiteflies

Whiteflies are not typically a pest of peanut, but we are seeing some whitefly activity in peanut fields in Tift and surrounding counties. So far, there have been no reports of reproduction occurring in peanut, and we should all hope that does not change. There are few options available for whitefly management in peanut, and most fields still have a long way to go before harvest. If anyone observes whitefly nymphs on peanut, please let me know.

Garden Fleahopper

Garden Fleahopper

Garden Fleahopper

Folks are seeing garden fleahopper in peanut again this year. The impact of this insect on peanut is unknown, but some fields were treated in 2015 due to very high populations and subsequent defoliation. We do not have a good option for controlling garden fleahopper; pyrethroids have generally provided only partial control.

Growers should be aware that there is a “little bit of everything” in terms of insect and mite pressure in Georgia peanut fields right now, but that does not mean every field is infested or will need to be treated.

Leave a comment

Filed under Entomology, Peanuts

Herbicide, Fungicide, Foliar Fertilizer Combinations In Peanut

We have been fortunate in our county with adequate rainfall – in most areas anyway. Peanut crop is looking good, we have set pods and kernels are developing in our oldest peanuts. With many questions concerning mixing chemicals, and foliar fertilizers, here is an update on current peanut condition from UGA Extension Agronomist Dr. Scott Monfort:

We tend to think July is the half way mark for the season but the truth is we have a long season ahead of us due to the late plantings throughout the state. There are many acres that are lapped and are setting pods while others are barely 8 to 10 inches wide and are struggling to grow. The good news is a majority of the crop looks good with a large part of the area receiving some rains over the last couple of weeks. However, there are many dry areas that need rain. In some of these areas, a few peanuts have stopped growing and blooming as well as showing signs of elevated leaf burn (with some leaf scorch) as a result of applications of different combinations of adjuvants, herbicides, fungicides, and foliar fertilizers being made in extremely hot and dry conditions (mid to upper 90’s and bright sunny days). A few of these fields have lost more than a third of their leaves. Growers should use caution regarding potential burn as a result of these applications but it’s not something you can eliminate due to weeds and diseases need to be addressed.

Foliar Fertilizer?

I have noticed foliar fertilizers being recommended in these situations to turn the dry land field around. The problem is, the peanuts have shut down due to lack of moisture and are not going to recover until they receive rain. The use of the foliar fertilizer is only costing the growers money and adding to the excessive foliar burn. The best thing to do is to not add these products to their fungicide or herbicide applications under these conditions. Growers can also limit burn by not spraying during the middle of the day (again this might not be an option as growers have a lot of acres to cover).

Leaf Scorch - Dr. Scott Monfort

Leaf Scorch – Dr. Scott Monfort

Leave a comment

Filed under Fertility, Peanuts

Peanut Pest Update

Our peanuts have been lapping for a few weeks now. They are looking good so far. We are more or less 60 days old now. Seeds are developing inside pods, and growers are starting another round of fungicides. Here is some information from specialists concerning insects and disease:

Peanuts-Lapping-Insects 019

Peanuts-Lapping-Insects 020Insects

Here is an update from UGA Extension Entomologist Dr. Mark Abney:

There continues to be lesser cornstalk borers (LCB) in Georgia peanut fields, and I do not see any reason that should change over the next few weeks. Interestingly, most of the heavy pressure has not been in the Southwest but in the middle and eastern portions of South GA. I expect that some of the infestations we were seeing in irrigated fields prior to the vines covering the row middles will be diminishing as irrigation water is applied with greater frequency.

I have not received a call about two spotted spider mite on peanut in 2016, but I am betting it is coming soon. Mites have been hanging around on cotton now for several weeks, and with continued hot, dry conditions I think we will be seeing mites move into peanut fields. If this happens, it is going to create a lot of headaches for growers, Extension agents, and crop consultants. 

  1. We need to catch mite infestations early to have any chance of getting good control. 
  2. With the one miticide available for use in peanut (Comite), we need to use a minimum of 20 gallons of water per acre, and two applications may be needed because egg mortality is low.
  3. The yield potential of some of our non-irrigated peanut acres is rapidly deteriorating; knowing when to pull the plug on inputs in these fields is going to be difficult, and most growers will be reluctant to “give up” on the crop. When making treatment decisions, we need to be realistic about the crop we already have set and our potential to add harvestable pods to it.
  4. I say this a lot, but we need to be sure to avoid pyrethroid insecticides in fields where spider mites are present or in fields at high risk for mites (hot and dry) in areas where mites have been found in surrounding fields. There are a couple pyrethroids that will suppress mites, but “suppression followed by resurgence” is a better description of what usually happens.

Rain tends to be the best treatment for LCB and spider mites, but a single rainfall event will not eliminate either of these pests once they are established in a field.

I have not heard of damage from potato leaf hopper, but have seen threecorned alfalfa hopper. Here is a picture of their damage. Immatures girdle the stem, and sometimes adventitious roots will grow.

Three-cornered Alfalfa Leaf Hopper damage

Three-cornered Alfalfa Leaf Hopper damage

Disease

Tomato Spotted Wilt Virus

Tomato Spotted Wilt Virus

This week we saw some spotted wilt, and there are other reports of spotted wilt – especially early planted peanuts.We are having the right conditions for white mold with the heat and afternoon rain showers. Only timely fungicides will protect us during this time. Here is a link to the 2016-PeanutRxwithVariousFungicidePrograms for the companies that provide them (BASF, Bayer, DuPont, Nichino, & Syngenta). We watch for white mold outbreaks now.

Brooks County Ag Agent Stephanie Hollifield makes a good point, that “If you have missed the afternoon thunderstorms and are experiencing the other extreme of dry weather, keep in mind that white mold control can be more difficult during drought. This is due to the fact that, dry weather prevents the ease of movement of the fungicide product from leaves of peanut plant to our target application spot in the crown of plant. To ensure white mold control products get down to crown/ground; irrigate if possible or apply white mold control fungicides with presence of dew on peanut plant and/or while leaves are still closed up.”

I’ve also had questions of mixing other products now. We should use caution with tank mix applications, especially during extreme hot and dry weather. The likelihood of plant burn can increase with any product, with the increase in environmental temperatures and tank mix partners.

Leave a comment

Filed under Disease, Entomology, Peanuts

Peanut Insects

July is the month when our most serious insect problems in peanuts show up. We need to watch for threecornered alfalfa hoppers, foliage feeding caterpillars, lesser cornstalk borers, two spotted spider mites, and potato leaf hoppers and just anything else that may hang out in a peanut field.

UGA Extension Extension Entomologist Dr. Mark Abney shared some things that we do know about these pests right now:

1. We tend to spray caterpillar infestations when they are below threshold. This may help us sleep better at night, but it does not provide economic benefit to the grower. There are a lot of factors that go into making insecticide applications in peanut, and not the least of these is when is the next scheduled fungicide application.

Our threshold is 4 – 8 caterpillars per row foot. We use the upper threshold when peanuts are not stressed, and lower threshold if peanuts do not look good.

Two-spotted spider mites with webbing

Two-spotted spider mites with webbing

2. Spider mites have been hanging around on cotton this year, and they can devastate non-irrigated peanuts in hot dry years. We need to be diligent about checking peanuts for the first signs of spider mite infestations. Once mites are identified in a field, we should avoid the use of pyrethroids in that field and watch to see if the mites begin to spread. If mites are moving, and the forecast calls for continued hot dry weather it is time to treat. Coverage will be critical to achieving control. A miticide application in 10 gallons of water per acre is most likely a waste of time and money; increase the water, increase the pressure, kill the mites.

Adult Three Cornered Alfalfa Leaf Hopper

Adult Three-Cornered Alfalfa Leaf Hopper – Photo by Dr. Mark Abney

3. Threecornered alfalfa hoppers (TCAH) are going to be in fields. Our threshold (research) does suggest that this insect can cause yield reduction in peanut, but I have seen some very high yielding peanuts with a lot of TCAH stem girdles. If spider mites and TCAH are in the same field, let the TCAHs eat. Anything we spray on TCAH will almost certainly make the mites worse, and that is not what we want to do. Otherwise, pyrethroids are still the first choice for TCAH in peanut.

4. I have received plenty of calls about lesser cornstalk borers in the last two weeks. The weather will be the biggest factor determining what happens from here. If it is hot and dry we could be in for problems; if we get some timely rain, populations are not likely to explode.

Lesser Cornstalk Borer - Photo by Andy Shirley

Lesser Cornstalk Borer – Photo by Andy Shirley

2 Comments

Filed under Entomology, Peanuts