Monthly Archives: April 2015

Fungicide Sensitivity Testing

UGA Extension Horticulturalist Dr. Lenny Wells says scab will likely start showing up on the developing foliage in another week or so with ongoing rain. Scab grows best on this rapidly expanding, tender leaf tissue. While we certainly don’t want to see another repeat of the scab issues we’ve seen in the last couple of years, this may provide an opportunity to sample orchards for fungicide sensitivity. Dr. Katherine Stevenson’s testing program, which began in 2014, has provided valuable information to help us better manage pecan scab. Last year’s results can be seen in Dr. Stevenson’s presentation here:  2015 GPGA Stevenson.

The program will continue during this growing season thanks to funding from the Georgia Agricultural Commodity Commission for Pecans. However, there are a few changes of which to take note. Samples may be submitted free of charge until July 31 (Last year’s experience showed the best results are obtained early in the season). There is also a limit this year of 5 samples per grower. Sampling instructions can be found here: Pecan Scab Fungicide Sensitivity Forms.

ScabSensitivityForm-2015

Below are clips from Dr. Stevenson’s power point summarizing last year’s sensitivities test:

ScabSensitivityPowerPoint-1

ScabSensitivityPowerPoint-2

 

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Slime Mold

SlimeMold

I’ve had two few calls today about a purple color, powdery substance showing up in circles in the yard.  Someone also brought in a few weeds with the same purple dots on the leaf. These recent rains have created the environment for slime molds to appear. It causes no problems other than being unsightly.

Slime molds belong to the Myxomycete fungi class that obtain their nutrients from dead, organic matter. They can also be seen in the flower beds and gardens where they may appear as the ‘blob’ or plasmodium. They don’t cause any direct injury to the plants, but can inhibit photosynthesis. Control does not require any chemicals. You can mow the lawn or wash off with a water hose to remove it. Here are some pictures of slime mold I have taken in centipedegrass. Here is a UGA publication on The Truth About Slime Molds, Spanish Moss, Lichens, and Mistletoe for more information.

SlimeMold-Centipede (3)

 

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Pond Weeds – Soft Rush

I’ve been looking at quite a few ponds for weed issues the past few weeks. Algae is showing up as well as water lilies and alligator weed. For pond weed management, it is generally best to begin with a chemical approach followed by the stocking of grass carp. Once weed growth has covered more than 10% of a pond, weed control expenses may exceed the desire or ability to pay. If fish are present in the pond, treat no more than 1/3 of the weed infestation as oxygen depletion from dying weeds may kill fish.

SoftRush

Here is some soft rush (Juncus effuses) growing on the edges of a pond. Rushes are perennial plants that are easily confused with grasses and sedges. They can grow in shallow water or moist soils. Soft rush grows in dense clusters from rhizomes, up to 3 1/2 feet in height. This rush can be controlled with a chemical treatment, but UGA Extension Aquaculture Specialist Dr. Gary Burtle says soft rush is good for shoreline stability and wildlife, so it is not usually considered for treatment.

Soft Rush

Soft Rush – Flower

More about Soft Rush can be found on the Texas A & M Aquaplant Website – Soft Rush.

 

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Grain Sorghum Planting

PlantingSorghum 002

We have an increase interest in planting grain sorghum (milo) in Thomas County this year. Here is some going into a field this week (above). Milo performs best on soils suitable for corn production and is more tolerant than corn to short term drought stress. We need to have 65 degree soil temperature for five consecutive days to play. Many of our plantations use the seed for wildlife. Most, if not all, of our fields planted in milo are non-irrigated, and this changes things in terms of plant population. Without water, we don’t want to plant too much with higher input need. Here are planting population recomendedations from UGA Grain Agronomist Dr. Dewey Lee:

Dryland Fields

  • 40-45K in very sandy soils
  • 50-60K in sandy loams and 60K in heavier soils.

Irrigated Fields

  • 60 to 75K in very sandy soils
  • 75 to 100K in sandy loam soils
  • 100K + in heavier soils
PlantingSorghum 006

Twin row grain sorghum

 

We’ve also looked at twin row. Dr. Lee says we can increase our population for twin row sorghum. It is not recommended to go any higher than 10%. Basically, we want to divide the single row population in half and plant that in both twin rows.

Example:  100,000 seeds per acre is roughly 7 seeds per row foot (6.89) in 36 inch rows.  Set the twin row planter (if its is set on 36″ row centers) to drop 3.5 seeds per row.

Below is a table from the Planting Guide for Row Crops in GA that can help when looking at plant population.

GrainSorghumPlantPopulation

 

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Fungicide Sprays And Surfactants

Leaves are coming out and expanding as you can see the catkins (male flowers). Many of our producers have begun their second fungicide applications this week. Lack of rain is a factor in scab pressure not high. UGA Extension Horticulturalist Dr. Lenny Wells has these comments on fungicide and surfactants:

Pecan Leaves (2)An 80/20 or 90/10 surfactant can be helpful in providing better scab control when used with DMI fungicides (Enable, Tebuconazole, Orbit, Propimax, Bumper), strobilurins (Abound, Sovran, etc.), and combination products like Absolute, Quadris Top, and Quilt. But you will likely see no benefit to adding a surfactant unless there is significant scab pressure.

Thankfully, from the standpoint of scab management, its been a much drier spring so far. As a result, we haven’t really had any serious scab pressure yet. So, a surfactant would not really be justified at this point until we see the development of more consistent rainfall patterns. If the rain returns, a surfactant will help. Growers are aware that every addition to that spray tank runs up the cost of production and understandably, many are wary following the previous 2 wet years. Bear in mind scab won’t develop without the right weather conditions. So, we need to save money while we can because the weather can change at any time. If conditions become more favorable for scab and the addition of a surfactant with fungicide sprays is needed, check the label of the surfactant used for the appropriate rate.

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Planting Date Considerations

Weather conditions now are nearly opposite of last year’s conditions as we were waiting for dry weather to plant. We are now in need for rain. Last year, Easter was April 20th. Easter has now past and it is warm.  With warmer soil temperatures, many are asking if we can go ahead and plant.

For cotton, we need to have 65 degree soil temperature for 3 days and future warming conditions projected. For peanuts, we want 68 degree soil temperature. We are seeing warmer soil temperatures now, but we need to be aware of other early planting risks.

We  struggled with thrips last season. Thrips live on field edges and along roadsides in weeds during the winter. When plants emerge, they move to our fields. If we are planting before May 10th, we know we will have an increase risk of Tomato Spotted Wilt Virus in peanuts. Irrigated cotton should usually be planted after May 1, since the risk of having adequate moisture is eliminated, thrips pressure is less, and the possibility of boll rot from August rains is reduced. Boll opening and harvest-time rainfall risks are reduced and harvest can be completed from late September through November, normally lower rainfall.

We were looking at planting date curves from different crops. Below is a graph UGA Extension Agronomist Dr. Scott Tubbs showed at our peanut meeting. Our largest yield window is late April through mid-May.

2014 Peanut Plant Date Slide - Tubbs1

We also have a graph from UGA Extension Cotton/Soybean Agronomst Dr. Jared Whitaker on soybean yield with planting dates. For cotton, long term research has shown little yield difference in planting dates between late April and May 20th. We can show a yield loss in soybeans, because soybeans are a determinate plant. The plant must have a full vegetative set before it can produce fruit. Cotton is indeterminate, meaning it produces vegetative and reproductive growth at the same time. Remember to follow the Georgia Weather website for planting information.

SoybeanYieldPlantingDate

 

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Corn Growing Fast

Corn-V4- 017

Rain slowed down a few weeks ago and corn planting began. We have corn coming up now with good growing conditions. This field had great emergence. I did a stand count this morning. To check stands, we start with our row width. The 2015 UGA Corn Guide has the calculations from this point.

RowLengthForPlantPopulation

We also want to be checking for seedling insects. Many of our seedling pests are not an issue when corn moves into the whorl stage. Check around  and on the plant and in the soil. Below is some etching on the leaves caused by thrips. Unless damage is severe – not here – plants will grow out of this by whorl stage (V5 – V7).

Corn-Thrips 024

Corn-V4 021(b)

4th Leaf Collar

Also, we want to check growth stage. I noticed that the first leaf is already shriveling up and hard to find. The tip of the first leaf is oval shaped in contrast to all other leaves, which are pointed. From the bottom, count all leaves with a collar on the backside. This collar indicates which growth stage the plant is in. This field is at V4. This is inportant in terms of weed management. UGA Extension Weed Scientist Dr. Eric Prostko likes to have our post emergent application done before V5. This is becuase these are the weeds more competing with corn growth. We certainly do not want to go past V7 since research indicates a loss of corn yield. The earlier, the better. Photo above shows the collar on the plant.

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UGA Pecan Grafting Clinic

Pecan Grafting - Dr. Lenny Wells

Pecan Grafting – Dr. Lenny Wells

UGA Extension Pecan Horticulturalist Dr. Lenny Wells has announced a pecan grafting clinic to take place at the UGA Ponder Research Farm pecan orchard on Tuesday April 21, 2015. Grafting techniques discussed will be 4-flap or banana grafting and bark grafting. The clinic will begin at 10:00 a.m. See below for directions:

UGA Ponder Farm Directions

28 Ty Ty Whiddon Mill RD Ty Ty, GA 31795

From I-75 take Exit 62 to Hwy 82 West (towards Albany). Travel 8.9 miles and turn right onto Inman Street (there is a Caution Light at this intersection) Inman St. Inman Street which becomes Ty Ty Whiddon Mill Road. Travel 7 miles on Ty Ty Whiddon Mill Road and the Ponder Farm will be on your Left.

If you are coming from the Albany area on Hwy 82, you will come into Ty Ty and at the caution light, turn left on Inman St. which becomes Ty Ty Whiddon Mill Road. Travel 7 miles on Ty Ty Whiddon Mill Road. Ponder Farm will be on your Left.

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Jefferson County Cool Season Field Day

Rye 016Jefferson County Livestock Agent Jed Dillard has put together a Cool Season Annual Field Day on Saturday April 11th from 10:00am to 1:00pm at Ashville, Fl.

Program speakers include Dr. Anne Blount, UF Forage specialist; Joel Love, FDACS BMP specialist, Mac Finlayson, cattleman and Jed Dillard, Jefferson County Livestock Agent. Steve Tullar of USDA NRCS will also be on hand to discuss cost share programs through EQUIP.

You’ll see 33 plots of oats, rye, triticale, rye grass, clover, medic, winter peas and vetch, plus some blends. Old standards to new releases were all overseeded on an Argentine Bahia pasture. The plots have been rotationally grazed and provide a side by side comparison through a winter that has been less than perfect for cool season grazing.

The event is free to all, but please contact Jed Dillard at dillardjed@ufl.edu or 850-342-0187 to register and get more details. We want to make sure we have enough materials and refreshments for all of you. Please share this as you see fit, but don’t forget to spread the need for registration as well.

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Peanut Insect Update

Below is an update from UGA Extension Peanut Entomologist Dr. Mark Abney:

After two seasons of relatively heavy and late thrips pressure in Georgia, it is understandable that growers are asking questions about thrips management options for 2015. The most common questions I received recently involve the use of imidacloprid (Admire Pro or a generic formulation) as a liquid in-furrow at plant. Here are a few options for growers in 2015 and some points to remember as decisions are being made:

1. Phorate (Thimet 20G) in furrow – Thimet has been around for a long time, and we have years (decades really) of data that show Thimet does a good job of reducing thrips injury and that it can also reduce the incidence of tomato spotted wilt virus. Thimet is an organophosphate insecticide, and as with all pesticides, read and follow label instructions. Some phytotoxicity (aka “Thimet burn”) is commonly observed when Thimet is applied to peanut, but this injury has not been associated with lost productivity.

2. Thiamethoxam (CruiserMaxx Peanut) seed treatment – Thiamethoxam is the active ingredient in CruiserMaxx Peanut seed treatment. In some research trials and grower fields in 2013 and 2014 we saw elevated thrips damage on CruiserMaxx treated peanut where pest pressure was high. Growers should be aware that thimethoxam on the seed is not expected to give control of thrips beyond 21 days after planting. This can lead to problems when thrips migrations occur later than normal. We do not recommend an automatic foliar insecticide application at 21 days after planting, but we highly recommend that growers scout their fields for the presence of immature thrips around 15 days after planting. Thiamethoxam does not reduce the risk of tomato spotted wilt in peanut.

3. Imidacloprid (Admire Pro, Velum Total, various generics) liquid in-furrow – Imidacloprid applied as a liquid in the furrow at planting has given good control of thrips in trials at UGA and other Southeastern universities in recent years. Imidacloprid has been shown to be compatible with most liquid inoculants and fungicides (not all combinations of products have been tested). Like thiamethoxam, imidacloprid will not reduce the risk of tomato spotted wilt in peanut. Growers should  note of the product formulation they plan to use as rates vary by formulation. Applying a 2F product at a 4F product rate will result in significantly less active ingredient than the label recommendation. Velum Total contains both imidacloprid and an active ingredient targeting nematodes. Growers who want to use imidacloprid for thrips but who do not have a nematode problem do not need to invest in the additional AI, but should choose a stand alone imidacloprid product (e.g. Admire Pro).

4. Acephate (Orthene) foliar spray – Orthene will still kill thrips, and we use it regularly in GA when at-plant insecticides “run out of steam”. The problem associated with leaving off an at-plant application in favor of a foliar spray alone is timing. This approach requires careful scouting (something that is much less common on our peanut acreage than it should be) and the ability to get into the field on short notice to make an application. Given the hectic schedule of most growers in the spring and the potential for unfavorable weather, being able to cover large acreage with a foliar application is a gamble most growers should avoid.

No matter what thrips management tactic is chosen, scouting is still a good idea. Nothing provides 100% control 100% of the time, and the only way to know if a problem is developing is to monitor fields regularly. Price of inputs will be an important factor in decision making in 2015. We need to be sure not to cut labeled rates in an effort to save money…reduced rates will likely lead to reduced efficacy and can ultimately cost more in supplemental treatments and/or lost productivity. Another thing to consider is that peanuts planted before 10 May are at an increased risk for tomato spotted wilt virus; none of the insecticides registered for thips control in peanut will reduce the risk of the disease except Thimet.

We have started our thrips flight monitoring program for 2015, and will begin posting weekly updates on this blog in the near future.

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Filed under Entomology, Peanuts