Peanut Update – 75 DAP

The following update was prepared by Clemson Peanut Specialist Dan Anco.

Most of the state’s peanut crop is continuing to look good into this latter half of July. We have been fortunate in many places to have received a healthy amount of rain at pretty decent intervals, and this has provided needed moisture to flush out canopies and encourage healthy pod development. We all know it ain’t over till it’s over, but this is a good place to be in at this time of year. Late leaf spot has started popping up in some fields (bottom of the canopy), with this being more common in fields that either followed peanuts last year or had peanut volunteers this year.


Late leaf spot.

Many fields are at the 75 days after planting mark and are typically receiving their third fungicide spray. As a reminder to prevent late leaf spot resistance development, our recommended practices avoid using products with the same mode of action back-to-back, unless chlorothalonil is tank mixed with the application. We can double check fungicide modes of action by looking at the label, or pages 50 and 51 of the Money-Maker. Also keep an eye out for manganese deficiency showing up as yellowing between the veins on the leaf.


Mn deficiency.  Yellowing between the veins.

I Zinc, Therefore I am…in Trouble?  Peanuts can have a tendency to show some interesting stress symptoms from time to time. This can show up across an entire field after making an application (like with surfactant or various herbicide injuries), or it can occur in scattered pockets that at first-look don’t seem to have a rhyme or reason why we would see it in one place and not another. The pictures below are from one of these fields. Some spots were completely dead, some parts looked great, and others had leaves with yellow splotches.


Closer inspection revealed that the problem areas were largely accompanied by different degrees of stem splitting. This is a characteristic symptom of zinc toxicity.


Stem splitting from Zn toxicity. 


Stem splitting from Zn toxicity. 


Soil tests came back with clearly elevated zinc levels, being about 95 lb/A in the dead zones (pH under 6.0). Depending on the pH of our fields, we want to start being careful with zinc levels much over 10 lb/A. We can lime fields that have moderate amounts of zinc before we plant to decrease its availability, but as with most things there is a practical limit. Looking at the numbers from this field and the symptoms, there isn’t much we can do this year but take this as an opportunity to reinforce the value of pre-plant soil tests, particularly when going into a field we don’t know the history of. Other than this the peanuts looked great.

Also as a friendly reminder, think twice if considering inexpensive fertilizer options such as steel mill filings – what we put into the soil may not be so easy to take out later.

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Question of the Week: Eyed Click Beetle

Last week the question was:  What is this insect?


This is an eyed click beetle.  They are named for the clicking sound they often make if handles or threatened.  They have a hinge between their head and thorax and make the clicking sound by quickly snapping their head forward, almost like head banging.  They can also use this movement to right themselves if flipped over on their back.  For more info, take a look at this page.


Here is this week’s question:  What are the bugs all over the side of this dock?


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Row Crop Scouting Workshops – 8/1/17 and 8/3/17


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Corn Update

This has been a warm and dry week and our corn is really showing it right now.  most dryland fields are rolling up like in the photo below.  There is a good chance of rain in the forecast this weekend and we really need it.


Most of our corn is in the R5 stage where the moisture content in the kernels is decreasing.  Water stress at this time can lead to lower kernel weight (test weight).  The ear pictured below is a little past 1/4 milk line (R5.25), so it will have just under 30 days until it reaches physiological maturity, or black layer.  If the next 30 days continue to be as dry as it was this week, we may see some poor test weights.


Corn at R5.25 (1/4 milk line).

Earlier this week, Clemson Grain Specialist David Gunter sent out a notice about a new corn disease that is showing up in parts of SC called Physoderma brown spot.  In the places its been found it is reported to be fairly serious and requires a fungicide treatment to hold it in check.


Physoderma brown spot on corn leaf.  Photo from David Gunter.

Physoderma brown spot has been observed on leaves and stalks and can compromise stalk strength and cause lodging.  This fungal disease is believed to survive in the soil and on plant debris, so fields that are corn behind corn should be the first ones that we scout for this.


Physoderma brown spot.  Photo from David Gunter.


Severe Physoderma brown spot infection.  Photo from David Gunter.

We really need to be out there scouting and if any Physoderma is found, a fungicide may be necessary if that particular field is not past the R5.5 stage (1/2 milk line).  According to David Gunter, the fungicides typically used for rust are probably our best options, if needed.  Pay close attention to pre harvest intervals on fungicides if you decide to use one this late in the season.

Fungicides labeled for disease control on corn can be found in the UGA Pest Management guide on pages 62-63.

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Strawberry Production Meeting – 8/17/17


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Question of the Week: 2,4-D

Last week the question was:  What happened to this pigweed?


This pigweed is suffering from a dose of 2,4-D.  This was in an Enlist cotton field.  There are lots of growers taking advantage of new Enlist and Xtend technology this year in their cotton and soybean fields.  These systems seem to be working well controlling pigweed, though off target damage is being found as well.  Please be careful when using auxin herbicides.


Here is this week’s question:  What is this insect?


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Cotton Blooming

Our older cotton is blooming now and everything is looking good so far this year.  Its been hot this week, though we’ve had fairly regular rainfall, so our fields are growing well.  Some folks are putting out pix to slow down the growth.



First day bloom on the left, three day old bloom on the right.

Pests are light right now.  About the only thing out in some places are aphids.  The population numbers are growing in spots, while other fields are almost completely clean.  Lots of natural enemies are present and as humid as its been, it shouldn’t take the aphid fungus (Neozygites fresenii) long to clean out the fields once it shows up.  For these reasons, hold off on spraying broad spectrum insecticides unless absolutely necessary.


Cotton aphids and ladybug eggs (on the left) on the bottom of a cotton leaf.

In Clemson Entomologist Jeremy Greene’s latest Cotton/Soybean Insect Newsletter, Dr. Greene cautions growers to concentrate on stinkbugs and bollworms now that we are moving into bloom.  Scout regularly and make treatments based on the thresholds below.


For more information, take a look at the 2017 SC Cotton Growers Guide or the 2017 SC Pest Management Guide.

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Cotton Marketing – 7/5/17


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Question of the Week: Leafcutter Bee

Last week the question was:  What made this nearly perfect circle in this leaf?


This was done by a leafcutter bee.  These are common native pollinators in South Carolina.  Leafcutter bees are solitary bees and make their nests in cavities of trees.  They line their nests with pieces of leaves they cut out of nearby vegetation.  Here is a webpage with some more great information.


Here is this week’s question:  What happened to this pigweed?


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Peanut Update – 60 DAP

The following update was prepared by Clemson Peanut Specialist Dan Anco.

While some of this year’s peanuts are right at 45 days old, others were planted about 60 days ago. Classically, 60 DAP marks the beginning of the critical period to manage white mold in SC. With regards to leaf spots, 60 DAP is also when we typically would start supplementing our fungicide programs with chemistries beyond chlorothalonil and tebuconazole (Bravo + Folicur). We have lots of products to choose from, and the production guide lists relative efficacies of the majority of available chemistry products (page 52).


Late leaf spot on peanut leaves.

As a reminder to help reduce the effect of possible strobilurin resistance in late leaf spot populations, when applying azoxystrobin (Abound) or pyraclostrobin (Headline) we can buffer ourselves by mixing these with different chemistries, in addition to limiting our total strobilurin application to a max of 2 per season per field. Elatus and Priaxor are jug mixes of these individual group 11 strobilurins in combination with a group 7 carboxamide: benzovindiflupyr + azoxystrobin in the case of Elatus and fluxapyroxad + pyraclostrobin in the case of Priaxor. Convoy (flutolanil) has been an excellent product for white mold, but it needs to be tank mixed with products that have foliar disease activity (e.g., 1 pt Bravo + 5.5 fl oz Alto) to also manage leaf spots. As an added boost in managing high white mold disease risk situations, we can apply fungicides at night when the peanut leaves are folded up. This helps get more active ingredient closer to their action site in the soil for white mold, particularly when canopies are larger. If we do spray at night or in the early morning before the leaves unfold, we’ll need a systemic product to cover the bases for leaf spot (page 48 to 51). While the chlorothalonil in Bravo is not systemic, many other options are.


White mold (Sclerotium rolfsii)

Leafhoppers are also becoming more noticeable in some fields. Below is a picture of the yellow V-shaped hopperburn they leave on the tips of leaflets after they feed. This burn doesn’t typically appear until about a week or so after the actual feeding.


“Hopperburn” symptom of leafhopper feeding.

The threshold for treating leafhoppers is 15 to 20% hopperburn across the entire field, with adult leafhoppers still present. The adults are about 3 to 5 mm long and are light green to yellow.


Leafhopper on a peanut leaf.  Photo from UGA.

Leafhoppers are one of several pests (spider mites included) that typically start on the edge of a field and then move inwards. This is good to keep in mind when evaluating each field so that we don’t pull the trigger too soon. Currently labeled options for leafhoppers are broad spectrum chemistries (page 55). This warrants caution and reserve to prevent flaring spider mites, particularly in and around dry spells.

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