Turf Disease Showing Up

BrownPatch

With warm days and cool nights, we are beginning to see turfgrass diseases like this I found yesterday. I was able to look at some centipede turfgrass under the microscope and confirmed it to be Large/Brown Patch (below).

Rhizoctonia Solani

Rhizoctonia Solani

Rhizoctonia produces distinct mycelia with three characteristics for diagnostics: 1) septate hyphae that branch at 90 degree angles, 2) constrictions at the base of the branching, and is 3) tan to light brown color. Large/Brown Patch will infect in the Fall and Spring when temperatures reach over 80 degrees during the day and stay above 60 degrees at night. During the summer, I commonly find Take-All Patch which can really cause problems.

If this disease persists, UGA Extension Pathologist, Dr. Alfredo Martinez, recommends a fungicide application in the Fall followed by one in the Spring. As with most turf diseases, long-term cultural management is best. Here are some management  for Brown Patch:

  • Use low to moderate amounts of nitrogen, moderate amounts of phosphorous and moderate to high amounts of potash.
  • Avoid nitrogen applications when the disease is active.
  • Increase the height of cut.
  • Increase the air circulation.
  • Minimize the amount of shade.
  • Irrigate turf early in the day.
  • Improve the drainage of the turf.
  • Reduce thatch.
  • Apply lime if soil pH is less than 6.5
  • Remove dew from turf early in the day.
  • Fungicides are available to control the disease. Consult the 2014 UGA Georgia Pest Management Handbook.

Centipedegrass also succumbs to an environmental disordered termed “Centipede Decline.” Dead patches can be caused by this where centipede has been stressed and over-fertilized/managed. It is good to avoid weed control during green up. Make sure not to fertilize too early – generally late April/Early May is good fertilizing timing. Centipede does not like more than 1 lb of nitrogen/1000 sq ft in a season, so do not over-fertilize.

Here is a link to the Turfgrass Diseases in Georgia: Identification and Control.

 

 

 

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Row Crop Disease Update – #1

The 2014 field season is upon us and diseases, nematodes, and recommendations promise to have a HUGE impact once again for growers.  UGA Extension Pathologist, Dr. Bob Kemerait, has some points to consider:

1.  Weather Conditions:  Abundant rainfall and cooler soil temperatures early in the season will increase the risk to seedling diseases and stand loss; especially in cotton. Growers can reduce the risk to seedling diseases by a) delaying planting until conditions (warmer soils, less threat of a cold, drenching rain) are more favorable for rapid germination and vigorous growth and b) use of fungicide seed treatments to protect the seed and the young seedlings.

2. Use of foliar fungicides on field corn : A)  Corn growers who plant in late March or early April have less risk to disease than do those who plant in later April and beyond. B) Growers with increased risk to Northern corn leaf blight (e.g., a more susceptible corn hybrid) should scout their crop and consider a fungicide application prior to tasseling; for example between the V8 and V10 stage.  It may be possible to use ground equipment to accomplish this.  NOTE:  DO NOT MIX a surfactant or crop oil with the fungicide when applied prior to tassel in order to reduce chance for injury to the developing ear.

3.  Sentinel Plots for Soybeans (www.sbrusa.net) and Corn (scr.ipmpipe.org) have been or are being established across the state for early warning in 2014.  TO DATE NO ASIAN SOYBEAN RUST OR SOUTHERN CORN RUST IS KNOWN IN GEORGIA.

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Woodland Management Meeting

Thomas & Brooks County Extension are holding a Woodland Management Meeting for landowners on Thursday, April 17th from 9:30am through lunch. The meeting will take place at the Brooks County Extension Office located at 400 E. Courtland Ave. Quitman, GA 31643. See flyer below:

ForestryMeeting

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Preplant Burndown Options For Peanuts

UGA Extension Peanut Weed Scientist, Dr. Eric Prostko has a few thoughts to consider about preplant burndown options for peanuts:

A) Primary burndown herbicides will either be glyphosate or paraquat.  As we get closer to planting, paraquat might be preferred if a quicker burndown is needed.

B) Potential tank-mix partners with either of the above herbicides include the following:

  1. 2,4-D (16 oz/A) – will help improve the control of wild radish and primrose.  Plant-back restriction for peanut based upon UGA research is 7 days.
  2. FirstShot (0.5-0.8 oz/A) – will also help improve the control of radish and primrose.  May also be useful in fields were off-target movement of 2,4-D is a concern.  Peanut plant-back restriction for FirstShot is 30 days.
  3. Aim or ET (1-2 oz/A) – either one of these herbicides can be useful in preplant burndown situations where annual morningglory plants (except smallflower) have already emerged. Aim can be applied anytime preplant up until 24 hours after planting. ET can be applied anytime preplant but before peanut emergence.

C) Growers who want to get early residual control of pigweed, especially when there is a potential long delay between application and planting, may want to include Dual Magnum (16 oz/A), Warrant (48 oz/A) or Valor (2 oz/A) in the burndown.  If Valor is used in the preplant burndown at least 30 DBP, an additional 2 oz/A can be used PRE after planting.  Valor will also help improve the POST control of radish and primrose (+10-15%).   I must admit that I would prefer either Dual or Warrant for residual control in this situation to help protect Valor from potential resistance issues.  There are no peanut plant-back restrictions for Dual or Warrant.

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Pecan Budbreak

Budbreak-CatkinsComingOut 010

Many pecan orchards have received their first fungicide spray of the season. Many are starting with a spray of Absolute and sometimes mixing that with another. Weed control and some fertilizing is still going on. Mowing has also started up, although the rain has slowed it all down. I looked at this orchard today before the storm came in. Most Desirables here are popping out. They will be a few days ahead of the Stuarts. Above is a picture of catkins coming out. They bear the male flowers.

UGA Extension Pecan Horticulturalist, Dr. Lenny Wells says the catkins coming out is a good sign. “Although catkins don’t guarantee a good crop of female flowers, a good catkin crop is usually associated with a good female flower crop.” We should see our Female flowers in another couple of weeks. Dr. Wells says female flowers (pistillate flowers) are actually induced in August but not detectable until the next spring. This means the current year’s crops was largely determined during the previous growing season. Female flowers will form on the spikes at the tips of new branches.

This orchard did pretty well last year managing scab disease. Still, the disease hurt Thomas County and the rest of the state last season with the rain. Here is a link to the 2014 UGA Pecan Spray Guide.

 

 

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Wheat Disease Update

WheatBooting 001

Most wheat in the county is booting and some is starting to head out. It is important to protect the flag leaf since it is supplying phtotosynthate to the developing grain. This time last year, rust was identified in Thomas County. Wheat rust has just been identified in Plains, GA now and UGA Extension Pathologist, Dr. Alfredo Martinez has a disease update:

Wheat Leaf Rust- Leaf rust was observed on an early-planted, highly susceptible variety in the UGA CAES Southwest Georgia Research and Education Center in Plains GA on April 2. There are no indications or reports of wheat leaf rust in other areas of GA. However, environmental conditions are becoming conducive for leaf rust epidemics to develop. Therefore, field monitoring for leaf rust and/or Stagonospora (leaf-glume blotch) in your area is advised.

If leaf rust is present in your field this warrants a fungicide application, the options are:

WheatBooting-003triazoles

metconazole (Caramba)

propiconazole (Tilt, Propimax)

prothioconazole (Proline)

prothioconazole + tebuconazole (Prosaro)

tebuconazole-containing products (Folicur, others)

Strobilurins

azoxystrobin (Quadris)

fluxastrobin (Evito)

picoxystrobin (Aproach)

pyraclostrobin (Headline)

Mixed mode of action

fluoxapyroxad + pyraclostrobin (Priaxor)

propiconazole + azoxystrobin (Quilt, QuiltXcel)

propiconazole + trifloxystrobin (Stratego)

prothioconazole + trifloxystrobin (Stratego YLD)

pyraclostrobin + metconazole (Twinline)

tebuconazole + trifloxystrobin (Absolute)

A complete list of wheat fungicides, rates and specific remarks and precautions can be found on page 58 of the 2013-14 Wheat Production Guide or on page 484 of the 2014 Georgia Pest Management Handbook. Always read product label for fungicide applications restrictions. Take a look at pages 9 to 11 of the 2013-14 Wheat Production Guide for wheat variety responses against leaf rust.

http://www.caes.uga.edu/commodities/fieldcrops/gagrains/documents/2013-14WheatProductionGuide.pdf

For more information on wheat leaf rust go to:

http://plantpath.caes.uga.edu/extension/plants/fieldcrops/WheatLeafRust.html

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Peanut Inoculant Considerations

It’s been a cool and wet winter, and we’re coming out of what was the wettest year on record in many locations.  Here is a refresh on peanut inoculant applications from UGA Agronomist, Dr. Scott Tubbs:

Because of the conditions mentioned above, the rate of survivability of native Bradyrhizobia present in the soil is likely to be much lower than in most years (regardless of how many years it has been since the last time peanut or a cross-inoculating species was grown in a field).  Therefore, I would highly recommend growers to strongly consider the investment in a peanut inoculant at-planting this year, especially in poor draining fields that had standing water for more than a couple days.  When soils are saturated, oxygen is depleted and several things can occur with respect to these bacteria.  First, if heavy rainfall occurred shortly after a liquid inoculant was applied the last time peanuts were grown in a field, it is possible that the concentration of the Bradyrhizobia bacteria was drawn away from seed furrow from dilution or leaching.  Saturated conditions can also kill the bacteria leaving lower native populations for infecting future peanut plantings.  When saturated conditions occur while peanuts are growing in a field, N-fixation is halted since oxygen is needed in this process, but is not readily available in the soil pore space since water occupies all of that volume.

Also 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, therefore a twin row planting inoculant application will double the amount of inoculant applied compared to a single row planting.  I have no data 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.

Some additional reminders regarding inoculant formulation decisions:

  • When applied at labeled recommendations, the amount of viable cells delivered on a per acre basis does vary by formulation, with the liquid inoculants supplying the most (8.3 x 1011 cells/A), followed by sterile peat products (5.8 x 1011 cells/A), and granular supplying the least (2.4 x 1011 cells/A).  However, this should not be the primary deciding factor on which formulation to select.
  • Sterile peat/powder formulations are only recommended if there is no way of applying the other formulations.  To get good coverage/sticking of the product to the seed, the seed need to be moistened.  This requires drying time to prevent messy planter problems.  When applied dry, there will be inadequate seed coverage.  I have data showing reduced nodulation and yields using this formulation compared to the other formulations.
  • Do not confuse the granular inoculant formulation with the sterile peat/powder formulation, they are not the same.  The granular formulation, while also a dry product, is not applied to the seed prior to planting, it is metered through a dry metering box such as an insecticide/herbicide hopper and placed in-furrow.
  • Regardless of formulation, these are living organisms.  If you want them to remain alive/viable, then don’t leave them sitting in the cab of a hot pickup truck or tractor, nor exposed to direct sunlight.
  • Likewise, since this is a living medium, exposure to certain pesticides designed to kill living organisms (insecticides, fungicides, etc.) may adversely affect the product.  Minimize exposure to such products, and consult the labels/websites/representatives for more information about mixing of products.  There should be minimal concerns of exposure to typical peanut seed treatments, and short-term exposure to common in-furrow fungicides in the case of tank-mixes.  But a chlorine-free water source must be used as the carrier for liquid inoculants.
  • When soil conditions are relatively dry, liquid inoculants will disperse away from the intended target, thus the concentration of Bradyrhizobia near the seedling upon emergence and early season growth when infection should be occurring may be hindered.  The granular formulation will remain at the bottom of the seed furrow, where intended.  Therefore, in non-irrigated conditions with only marginal soil moisture, granular products should be considered.

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