Cotton Coming Up, Variety Trial Planted, Scout Thrips

Cotton is anywhere from just planted to cotyledon to 4 leaf at this time. Recent rains have growers planting and we hope to have more this weekend. It’s past our thrips date of May 10th and we have reason to believe thrips may crash soon this year – since we had a warm winter, they were active sooner. But remember, thrips live in the winter weeds along roadsides and move to our cotton and peanuts following germination.

From 0 to level 5, I’m seeing damage from none to about level 3, sporadic in most fields. Neonic seed treatments (imidacloprid, thiametoxam) are active on thrips for up to 14 – 21 days after planting. If we have no seed treatment, we need to be in the field checking the first true leaf. This is the best time when we need to apply a foliar application. Once we have 4 true leaves and the plant is growing fast, thrips foliar sprays are not economical.

Thrips injury on 1st true leaf

Threshold

Research has shown that foliar applications are still needed when thrips infestations are high. The best way to make this decision is based on current threshold of: 2 – 3 thrips per plant AND/OR presence of immatures. The immature (wingless) thrips will be yellow/green in color; the adult (winged) thrips are black. Take a white piece of paper and slap a plant on it. Give it a second for the thrips to start crawling. In this field, I have immature thrips present. This suggests are at-plant insecticides are no longer active, and reproduction is taking place.

Here is a note from UGA Extension Entomologist Dr. Phillip Roberts from 2016. It may still answer some question today:

Should we follow with a second acephate spray? Dr. Roberts has conducted trials with 1 +3 leaf sprays, and they showed no difference from a 1 leaf ONLY spray. Something I noticed rating our thrips trials (2016) is not only the effectiveness of 1 leaf sprays, but also how fast the plants grow in 14 days. If we have a timely insecticide spray, AND growing conditions are good, cotton will outgrow potential thrips issues. The only reason to consider a second foliar application is if 1) cotton is not growing fast 2) thrips are still highly active. It would be a judgment call at best.

How long does this foliar spray of orthene last? Research entomologist Dr. Michael Toews, and Dr. Roberts have data on this that hasn’t been totally put together, but the best analysis is maybe 3 -4 days. Pyrethroids, on the other hand, photodegrade fast. Dr. Roberts says pyrethroids will kill thrips, but the reason we do not recommend them is 7 days after treatment, thrips populations are higher where pyrethroids were sprayed than where orthene was sprayed.

We were able to plant our variety trial last Friday. I visited the field today, and cotton is just now coming up. The field is at the end of Centennial Road where it touches Airline Road. It is the one on the right. We ended up participating in the UGA On Farm Variety Trial. Most of the varieties I asked for were in the trial. We were able to get in all varieties I wanted plus these for a total of 15. We replicated three times in the field; reps are actually stacked on top of each other.

2017 UGA On-Farm Variety Trial

We got done real fast, thanks to Brandon’s precision planting. Thanks to growers Mike, Brandon and Chandler Barnes for planting the trial this year and Jodie Stringer (Boston Gin) for helping and Jessica Jones, owner of Barbaritoes, for feeding us in the field.

Jodie and Brandon fixing flags

Brandon Barnes, Mike Barnes, Chandler Barnes, Jodie Stringer, Andrew Sawyer

 Jodie and Brandon fixing flags

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Corn Update

Both irrigated and dryland corn are looking okay. Dryland is looking as good as it can. We’ve had less rain as we move east in the county. Corn on the central and west side has had almost an 1nch of rain for the last few weeks. There is rain expected for the weekend also.

This corn is our rust sentinel plot in Thomas County and has only nitrogen burn from foliar fertilizer. You can also see a few spots from Gramoxone drift as we’re planting cotton. None of this is anything to worry about.

We’re past most of our weed control. There are only a few fields where preemergent herbicides didn’t get activated and we’re dealing with pigweed.

Etching done by thrips

Burn from gramoxone

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Satsuma Insect Issues

This may not be the case everywhere, but here we avoided some serious freeze injury on our 3 year old trees. These satsumas are going on 4 years old, so next year is the year we hope to harvest these. Some of these fruit are pulled off the tree this year to allow the tree to focus on vegetative growth.

Leafminers

We haven’t been hit too much with leafminers here, but in other parts of the county and with younger trees, damage is evident. It’s difficult to drench imidacloprid to time killing the initial infestation. Lowndes County Ag Agent Jake Price says this about leafminers and leaf footed bugs:

Leaf miners are starting to emerge. Usually our first flush is safe from leaf miners but they can be a problem at the end of the first flush and every flush thereafter. If you had frost damage and your trees are flushing again, you may want to go ahead and make a treatment. Imidacloprid drenches last about two months. Micromite and Ari-Mek are also labeled to control leaf miners if you are having issues with mites as well. If you do make a foliar application of anything, try to wait until all your blooms are gone as to protect the bees.

Mining trail from leafminer fly. Egg is laid on leaf. Larvae hatches and goes under leaf cuticule where it mines, curling the leaves and comes out to pupate. This one came out where my thumb is.

Leaf-footed Bug

A second insect I have been seeing is the leaf footed bug or what many call “stink bugs”. They can damage fruit and cause them to drop from the tree.  Now they are feeding on young blooms and shoots. I see these insects on a variety of things from muscadines, cotton, soybeans, peaches, plums, and blueberries, etc. They tend to congregate on certain trees. In general, I do not think these are a major pest of Florida citrus but they look like they will be a problem in satsumas because they damage fruit.  Again thoughts are no control is needed at this time unless you just have them throughout your grove.  If needed you may want to treat certain trees where they tend to congregate.

Leaf-footed bugs – Photo: Doug Collins

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Look For Cogongrass Following Spring Burns

We looked at a new spot of cogongrass Monday which came just after burn. This is probably why the leaves appear lighter in color.UGA Extension Forester Dr. David Moorhead says this is typical cogongrass response to a spring burn. Two to three weeks following a burn is always a good time to look for cogongrass.

Off-center midrib is key ID feature of cogongrass

Identification

If you look at other blog posts I have on cogongrass, you will see a difference in this color. We thought this was actually Johnsongrass. Once we walked into the patch, we found some off-center midribs and sharp rhizomes. Those are the two, key ID features you want to look for. Cogongrass spreads by rhizomes, which is why you see it in this circular pattern.

When you rub down the blade, you’ll feel a ‘rough’ texture, like shark skin. Quail definitely do not like to move through this grass. It’s extremely invasive and will wipe out an ecosystem in your forest. This is huge for us in Thomas County where so much timber is managed for wildlife as well.

Sharp rhizomes are another key ID feature of cogongrass. A lot of times you can place your hand on the ground (softly) and feel the rhizomes poking up.

Burning

We actually want to be cautious about burning cogongrass since it can burns around 850 degrees F. Georgia Forestry Commision Forest Health Specilist Mark McClure says most timber on our plantations are widely spaced and damage from burning cogongrass is not a high risk. Mark says this is actually a good time to burn cogongrass and is a good idea to burn it if we see it. This is because fresh growth of cogongrass helps when treated.

Control

We are very, very fortunate in Georgia to have help from the Georgia Forestry Commission on treating these spots at no charge. Mark McClure coordinates the Task Force of the Georgia Forestry Commission which treats reported cogongrass. If you see what looks like cogongrass, call the Georgia Forestry Commission or the Thomas County Extension Office (225-4130) to get a positive ID so it can be treated.

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Filed under Forestry, Weed Science

Cotton Market Update

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Filed under Cotton, Economics

Field Corn Weed & Disease Update

Some of our earlier planted corn is moving through the v8 growth stage. In this field corn, we are nearly past the time for over-the-top herbicide applications without yield loss. We’ve been applying mostly one shot Atrazine+RU+Prowl H2O when corn has about 3 leaves. It’s working great. We have a one or two fields were pigweed got past it and hurting us.

Weed Control Update

Here is an update from UGA Extension Weed Scientist Dr. Eric Prostko:

Field corn weed control does not have to be difficult.  Just about any of the herbicide programs that growers are using in Georgia do a good job of controlling most weeds, especially Palmer amaranth, when applied to small plants (<3″ tall). Check out the following pictures from my field corn plots that I rated earlier today.  These herbicide treatments were applied 17 days after planting with a CO2-powered backpack sprayer calibrated to deliver 15 GPA at 3.5 MPH using AIXR 11002 nozzles.

The most troublesome weed in Georgia field corn, in my opinion, is annual morningglory.  Field corn growers who struggle with morningglory should seriously consider a post-directed/lay-by application of Evik (ametryn) sometime after their initial POST treatment was applied. (Check out page 70 of the 2017 UGA Pest Control Handbook for more information about Evik.) The minimum corn height for post-directed applications of Evik is 12″.  If Evik is tank-mixed with glyphosate, post-directed applications can be applied up until 48″ tall corn (RR2 hybrids).

 

Halex+Atrazine+Adept, Dr. Eric Prostko

Atrazine+RU+Prowl H2O, Dr. Eric Prostko

Laudis+Atrazine+MES, Dr. Eric Prostko

Revulin+Atrazine+Adept, Dr. Eric Prostko

Disease Update

This is from UGA Extension Pathologist Dr. Bob Kemerait on 5/1/17:

Our earliest planted corn crop is beginning to approach times where we need to consider use of a fungicide (or not).  Here are some notes…

  1. There is no need at this point to protect against rust. 
  2.  Some growers might put out a fungicide application as early as the V6-V8 stage to protect against leaf blights.  Before doing so (unless the grower simply feels better doing the application anyway) scout for detection of the easily diagnosed lesions of northern corn leaf blight.  Simply finding one or two scattered in the field is NO BIG DEAL. Finding the disease more widely scattered, on a susceptible variety, could be. DO NOT MIX AN ADJUVANT OR CROP OIL with fungicide applications made prior to tassel.  This can result in significant ear deformation.

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Peanuts Cracking

Dryland peanuts are coming up in the northwest part of the county. This is where we have had more rain. We’re talking about thrips, herbicides and some disease issues now. Below is a graph from UGA Extension Peanut Entomologist Dr. Mark Abney on latest thrips counts:

Thrips numbers on our traps have remained relatively steady for the last 3 weeks, though we did see a spike last week in Colquitt County. My first thrips trials are just now emerging from the ground, and I have not heard any reports of thrips control problems on early planted peanut as of today.

I have had questions this week about rates of imidacloprid for in-furrow applications. I recommend the upper end of the rate range for whichever formulation a grower is using….We should NOT be doubling the rate or cutting the rate in half. Be sure to check the label of the product you are using as rates vary by formulation.

Weed Control

We may not have as much Valor as preemerge out there since we are dry and concern of no activation. Where we have Valor on the ground with good activation (0.5 – 0.75″ within 7 days), it usually gets us through our “at cracking ” treatments until we use Cadre. If we don’t have Valor, we will need to be gearing up for our cracking spray 15 – 25 days after planting. But we only need to apply ‘cracking’ sprays if weeds have come up.

Disease Control

The only note to make is this week’s rainfall this week could help to cool soils, at least in the short term, and reduce risk to Aspergillus crown rot of peanut.

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Filed under Disease, Peanuts, Weed Science