Peanut Update – Vigor

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

There have been some instances of j-rooting and poor vigor this year. Dual has a tendency to get the blame for j-rooting, but often times it is a result of poor seedling vigor. When combined with suboptimal growing conditions, seed with lower vigor have a more difficult time rising to the challenge of good growth. Drought periods the southeast experienced during the 2016 growing season set the stage for less than ideal seed production, and seed lots with lower vigor are one of its symptoms. Even seed that came from irrigated fields can be affected, particularly if excessive water loss through evapotranspiration reduced the effective amount of water that was made available to the crop.

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J-rooted peanut.  Photo from Dan Anco.

What can we do? Vigor can be a little more elusive to get a feel for before planting than say something like germination. One thing we can try is to obtain the standard germination rate of each individual seed lot and compare that with the cold germination rate for that lot. If there is a wide difference between the two, then this might hint at a lower relative vigor for the lot. More work needs to be done to provide guidance and specifically determine how big of a difference becomes important, and until then this may seem a bit like a guessing game. In the absence of explicit vigor estimates of each lot, another thing we can try if planting conditions allow is to plant slightly shallower (e.g., 1.5 in versus 2 in) in years following stressful years if our seed was sourced from regions affected by drought. Planting into moisture is still more important than starting the seed closer to the surface. These are certainly compromises, and they are no substitution for healthy seed. While most peanut planting in the state is well underway, in future plantings, saving a bit a seed from each lot could be used to check germ and vigor if you have stand issues. As an added reminder, when possible seed stores best in a cool environment protected from the sun or heat for extended periods of time.

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Cotton Marketing News – 5/11/17

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Question of the Week: Assassin Bug

Last week the question was:  What insect laid these eggs on this wheat head?

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These are the eggs of an assassin bug (F: Reduviidae).  There are lots of species of assassin bugs and they are excellent predators.  They have piercing/sucking mouthparts which they stick into their prey and then use to suck it dry.  If handled improperly, some species may “bite” people.  Take a look at this page for more info.

 

Here is this week’s question:  What is this disease growing at the base of this tomato plant?

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Fumigant Systems for Vegetable Weed Control 2017

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Cotton Weed Control Programs For 2017

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Question of the Week: Glyphosate

Last week the question was:  What is happening to these tomato leaves?

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These leaves are turning yellow starting at the base of the petioles because they have been exposed to glyphosate.  Glyphosate is a great herbicide so long as it stays off the plants we don’t want to kill.  This grower probably sprayed a little too close to his tomatoes and it drifted over.  Some of the steps we can take to avoid accidental exposure include using hood sprayers, spraying when winds are low, using low sprayer pressure, large droplet sizes, establishing buffer zones, etc.

 

Here is this week’s question:  What insect laid these eggs on this wheat head?

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Good Spray Day or Bad Spray Day: Part 2

Thursday afternoon was pretty breezy, so I pulled out the wind meter to get an idea for exactly what the wind speed was.  The average as shown below was about 9.4 mph.

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At times the wind was gusting up to 13-14 mph.

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According to the new auxin herbicides we will have this season, was this a good day or a bad day to spray?

Enlist Duo:  0-15 mph

XtendiMax:  3-10 mph

Engenia:  0-15 mph, if spraying in less than 3 mph, steps need to be taken to make sure there is no inversion.

The Xtendimax label says 3-10 mph, so with the wind gusting up to 14 mph, spraying would be off label.  Enlist Duo and Engenia both allow spraying in wind speeds up to 15 mph, so spraying with a 9 mph wind with 14 mph gusts is allowed.  Even though spraying in this wind is allowed, it probably wouldn’t be the wisest decision. 14 mph is a pretty stout wind.  While you’re making the decision whether or not to spray, just keep in mind these labels clearly state the applicator is solely responsible for controlling drift.

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Dryland Foot Rot

Overall we have a pretty good looking wheat crop.  In some fields we have some bleached heads showing up.  In a few cases this is due to wheat stem maggot, but mostly it appears to be dryland foot rot.  This isn’t very serious in most fields, just its something to be aware of.

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Bleached heads from dryland foot rot.

Dryland foot rot is caused by the Fusarium fungus.  It infects the crown of the plants and is worsened in times of stress including drought or too much water, extreme heat or cold, or excessive nitrogen.  It’s usually pretty easy to ID dryland foot rot because the infected tiller will pull off the plant easily and there is frequently pink or purple discoloration under the leaf sheaths near the crown.

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Two tillers infected with dryland foot rot.  The leaf sheaths are pulled off of the tiller on top to reveal pink discoloration.

The fungus kills the tiller and the grains in the head will shrivel up because they are no longer developing.  They will more than likely blow out the back of the combine.  This publication gives some more details on the disease cycle of dryland foot rot.

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Grains from healthy tillers on the right, grains from tillers infected with dryland foot rot on the left.

The best ways to avoid dryland foot rot are to use clean seed, crop rotation, and proper N rates.

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Question of the Week: Syrphid Fly

Last week the question was:  What is happening at the base of this wheat leaf?

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There is a syrphid fly larva feeding on another fly.  Syrphid fly larvae are excellent predators, normally of aphids, and we like to see them in our fields.  The adults are not predacious and feed mostly on pollen and nectar.  For more info on syrphid flies, take a look at this page.

 

Here is this week’s question:  What is happening to these tomato leaves?

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Good Spray Day or Bad Spray Day?

With some of the new herbicide technology labeled for use this year, growers need to be paying more attention than ever to the wind in order to reduce drift.  I would urge everyone that plans to apply auxin herbicides to invest in a wind meter.  There are a wide range that wind meters that go for $25-$600.  The one pictured below goes for $74 on Amazon.

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This meter is reading a 4.1 mph wind speed.  So is good or bad for spraying?  Consider the following wind speed requirements on these herbicide labels:

Enlist Duo:  0-15 mph

XtendiMax:  3-10 mph

Engenia:  0-15 mph, if spraying in less than 3 mph, steps need to be taken to make sure there is no inversion.

According to all three labels, 4.1 mph is a good speed for spraying.  What this photo doesn’t show, and what the wind meter can’t tell you, is wind direction.  Applicators also need to pay close attention to wind direction as well as what lies downwind.  It would be a good idea to make some flags (a 6 ft piece of rebar and some flagging tape would be cheap and easy) and put them in a couple places on the edge of the field you are about to spray.  That way you can look at those flags while you are spraying and be aware of any changes in the wind.

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