We’ve had some rain early this week in the county. Most of it is in the east side of the county and some in Thomasville. Georgia Weather.net shows almost an inch in Dixie, and there has been over in inch near Thomasville the past few days. Above is a peanut field in Barwick with an afternoon shower.
We were looking at cotton yesterday that is lodging at 9-10 leaves. It was also falling over before at around 4 leaves. Sometimes, there is a problem with herbicides and it leaves a swollen area of the stalk at the soil line. We did not have that here, it has simply been result of heavy wind and rain.
UGA Extension Cotton Agronomist, Dr. Guy Collins said for plants that are touching the ground, they may start growing back from the terminal. Most plants are not touching the ground, and it shouldn’t be a problem and nothing we can do regardless. It does not have anything to do with variety, its just heavy winds and rain.
Aphids are rarely on seedling cotton, and this is because Neonic Seed Treatments are good on aphids. But in most years, UGA Extension Enotmologist, Dr. Phillip Roberts, says we will see them build to high numbers. So far there are no consistent yield response on aphid tests. There are very effective treatments however. The main thing we are looking for is the naturally occurring fungal epizootic that cause population to crash. It usually happens in later part of June or early July. We look for grey, fuzzy, aphid cadavers. Once we see these, Dr. Roberts says, the population will crash in next few days. Below is a picture of some aphids. The white bugs here are just cast skins of the aphids.
Michael Murray with Meherrin has also reported seeing snails seen on cotton plants. Here is one of a few we saw on a plant. Dr. Roberts says he has received a few calls about them this year also. Even though snails can sometimes be present in large numbers, they rarely cause economic injury. In contrast, many slugs will feed on cotton. They make odd-shaped holes, usually around the leaf margins. Severe feeding sometimes results in “cut plants,” similar to the damage caused by cutworms. One or two here and there is no problem at all, but 20 on a young plant – especially seedling – would be a concern. Here is some information on Slugs and Snails from UT Extension.
Tarnished plant bugs are not a consistent pest in Georgia as they are in the Mid South. However, we will sometimes spray for them. Here are some fields where sprays have been done for plant bugs. We still want to do retention counts and check for damage. Cotton scout, Andrew Taylor has come across some retention counts below 80% and was showing me evidence of plant bugs. Here is Andrew checking squares while scouting.
The general treatment threshold for plant bugs is 80%. According to UGA Extension Entomologist, Dr. Phillip Roberts, we want our retention count to remain about 80% through 1st week of bloom. When checking squares, check at least the top three squares. You will notice a normal abscission proccess taking place on squares that were hit. They will turn yellow, then black (right), and then abort. It is good to still check all squares on some plants to note any major changes.
Below is some information on plant bugs and thresholds from Dr. Roberts:
Corn is really progressing. We’re past tassel in most fileds and through milk stage (R3) in this field. Looking at corn yesterday, I noticed some leaves with rust postules which later confirmed to be southern rust.
Initially, it looked similar to common rust, which we do not worry about. But there were no postules on the back of the leaf (as with common rust). Plus, our hot temperatures are more conducive for southern corn rust.
Southern Corn Rust
Southern corn rust has appeared at least 2 weeks earlier in 2014 than it did in 2009, 2010, 2011, 2012 or 2013. Appearing earlier means that this disease will likely be more problematic in 2014 than in recent years – and it has been. Below are comments from UGA Pathologist, Dr. Bob Kemerait:
Sporadic afternoon and evening thunderstorms are likely to further move rust spores and also provide the moisture important for infection.
- I believe that this is the most significant threat of southern rust in Georgia in the past 10 years.
- Southern corn rust (SCR) reduces the photosynthetic capacity of infected leaves. More importantly, a field where SCR is not controlled may develop extensive lodging problems as the stalk is cannibalized for nutrients to feed the ear.
- Dr. Dewey Lee and I agree that protecting a crop from rust though the dough stage (R4) is beneficial.
- I recommend that growers spray by tassel growth stage and then again 2-3 weeks later, depending on the product used in the first application.
- On corn where rust is a severe problem, we have seen fungicides protect 25+ bu/A.
Southern corn rust has been on the move and covering many counties across the state. Here is the current map on its location: (http://scr.ipmpipe.org/).
Filed under Corn, Disease
Here are some peanuts that are looking very good and now flowering. I also saw a few leaves with what appear to be early leaf spot showing up. We are now starting to think about our fungicide programs. Mitchell County Agent, Andy Shirley, posted good information about spray schedules on his blog: Peanut Spray Schedules.
Also, there have been some reports of a shortage of Chlorothalonil (Bravo, Echo, Chloranil, and others) this season. Here are some recent comments from UGA Extension Plant Pathologist, Dr. Bob Kemerait, on the current Peanut Disease control situation:
You may hear reports that chlorothalonil could be in short supply this season. For now, growers should be assured that although chlorothalonil is an important fungicide, our peanut leaf spot programs are in no way compromised. Here are some suggestions as to how to manage if chlorothalonil supply is short this season:
1. Current conditions (warm weather with developing afternoon thunderstorms) create favorable conditions for leaf spot diseases and white mold.
2. Here are our UGA strategies for dealing with the shortage of chlorothalonil in peanut production:
- Consider using a strong leaf spot fungicide like “Headline” (9 fl oz/a, 45 days after planting) to initiate an excellent leaf spot program and to replace potentially 2 applications of chlorothalonil (30 and 44 days after planting).
- Reduce the rate of chlorothalonil used in a leaf spot applications by partnering with another fungicide. Examples include mixing chlorothalonil (1 pt/A) with Tilt (propiconazole, 2 fl oz/A) or Alto (cyproconazole, 5.5 fl oz/A) or Topsin-M (5 fl oz/A).
- PEANUT Rx: Using “prescription” fungicide programs based upon risk assessment in the field may also be an excellent strategy to reduce use of fungicides in general
Filed under Disease, Peanuts
Cotton planted in late April is now squaring and about 9 – 10 leaves. Later planted cotton is around 5 to 6 leaves and not yet squaring. There has been discussion over irrigating during squaring and pushing the plant to develop roots. UGA Cotton Extension Agronomist, Dr. Guy Collins and Dr. Jared Whitaker, have research on this subject and found prebloom irrigation has impact on cotton yields. Where it was originally thought that stressing cotton during squaring increases its root system, cotton does not rebound if stressed from no irrigation through squaring. Below is yield response showing to prebloom irrigation:
Dr. Collins says regardless of variety, yield is reduced if we don’t irrigate during squaring. Also, we do not want to wait until cotton is wilting before we apply irrigation. 1 inch at prebloom is recommended over 2 inches. The best method of application is split-apply weekly rates. Instead of one inch of water one day each week, do 1/2 inch two times during the week.
Below is irrigation recommended irrigation from squaring to 8th week of bloom:
We are little behind in nut development, but are likely to move in the period of rapid nut sizing stage in the next few weeks. With our scab fungicide programs ongoing, UGA Extension Pathologist, Dr. Tim Brenneman’s fungicide results reveal that adding a surfactant to the DMI/Strobilurin mix fungicide products like Absolute significantly reduce the incidence and severity of leaf scab over the fungicide alone.
UGA Extension Pecan Horticulturalist, Dr. Lenny Wells, says similar results are expected with the effect on nut scab. Dr. Brenneman used a 90/10 surfactant but expects the same results could be obtained with an 80/20 surfactant. Also, similar results would be expected with the other DMI/Strobi mix fungicides like Quadris Top and Quilt. The inclusion of a surfactant with DMI’s like Enable, Tebuconazole, Orbit, Propimax or Bumper mixed with Tin would likely be of benefit as well.
Be sure to jar test for compatibility when using any new tank mix. With the at least temporary shortage of Elast, this provides us with another good tool to fight scab. DO NOT ADD A SURFACTANT WHEN USING ELAST due to the increased risk for burn.
Filed under Disease, Pecans
Thanks to the cooperative efforts between UGA Cooperative Extension Service and our friends with Pioneer, UGA Extension Pathologist, Dr. Bob Kemerait, reports two cases of SOUTHERN CORN RUST: 1) Early County (Agent Brian Cresswell) and in Florida just below the Echols County (Agent Justin Shealey).
Below are pictures of southern rust attached that Rome Ethredge took from the Early County sample and points from Dr. Kemerait to consider:
- SOUTHERN CORN RUST is early this year.
- Currently, southern rust likely is a threat to corn across the southern part of the state.
- Southern corn rust is out most important disease of corn.
- Rain is back in the forecast for late this weekend; early next week, which will be favorable for development of rust.
- I think that corn that is approaching (or has passed) the tassel growth stage is worth protecting if the yield potential is there. I generally would wait to spray for southern rust until your crop is approaching tassel.
- Triazole fungicides (like tebuconazole) are effective against rust (but lack the broader activity against northern corn leaf blight) and have a two week protective window. Strobilurin products and combination strobilurin/triazole of strobilurin/SDHI (Priaxor) have 3 week protective intervals and also a broader spectrum of activity.
- Northern corn leaf blight is generally in check this year.
Filed under Corn, Disease
Mr. Felix Horne, from Action Lawn Care, brought in some samples of St. Augustinegrass yesterday which appeared to have very suncken, wilted patches. It is down on a plantation where take all root rot (Gaeumannomyces graminis) has been an issue and pH has been high in areas. This is important because take-all patch typically occurs in areas with a high soil pH – most severe at pH 6.5 or above. It is also more severe on less fertile and sandy soils.
Hyphopodia seen on take all root rot with mycelium from large patch
Under the microscope, some of the roots were dark colored and looked stubby. There is actually some large patch (Rhizoctonia solani) mycelium here too. Under the compound microscope, you can see the hyphae and hypopodium referred to as “puzzle pieces.” We see more into the summer. Home lawns with this disease will really show damamge and is hard to control.
Here are some management tips for take all root rot:
- Use acidifying fertilizers.
- Apply moderate to high levels of phosphorous, potash and minor elements where these nutrients are depleted from the soil.
- Improve the drainage of the turf.
- Reduce thatch.
- Fungicides are available to control the disease. Consult the current Georgia Pest Management Handbook.
Filed under Disease, Turf
Cotton is up and some pushing four and five leaves. We are still evaluating stands seeing thrips on seedling cotton. Some plants are growing rapidly which is helping. We are also getting ready close to putting out our POST 1 herbicide applications. Generally, that application and a thrips spray will not coincide, except in the case of the need for an early POST 1 application. The field below has a huge spot of spiderwort, in which early POST 1 is needed. The same field has damage from thrips.
UGA Extension Entomologist, Dr. Phillip Roberts, says of all options orthene has the least likely burn with our POST 1 application. However, the best option is to completely separate thrips spray and POST 1 application. Thrips spray mixed with POST 1 application will result in burn.
This is the second season in a row where thrips movement has been delayed. Dr. Roberts says this is because of our cool, wet springs which delay thrips reproduction. We also see this when alternate plant hosts are late to dry down.