Monthly Archives: April 2015

Leafminer Damage In Satsuma’s

There is more and more interest in planting Satsumas in Georgia. They are a very tasty orange that is self-fruitful and ripens its fruit well ahead of any freeze problems (September to November). Although Satsuma’s have the best cold hardiness of citrus, they still need cold protection and irrigation. Fellow county agent, Jake Price in Lowndes County is researching varieties of Satsuma’s that do best in South Georgia. Here are about 100 new Satsuma trees recently planted after cold killed most this winter. These varieties are Owari and Sharanui.

Satsumas 003

I was asked to check on the leaves which were curling up as a result of a leafminer. The leafminers are either a fly or a moth. This is common in citrus and doesn’t cause much of a problem unless damage is very heavy. In a commercial field, treatment is still recommended. Eggs are laid on new leaves and the larvae mine underneath the cuticle of the leaf. The leaf will most times curl if damage is severe.

Leafminer in new Satsuma leaf

Leafminer in new Satsuma leaf

We can use imidacloprid to treat for leafminers. We can spray on the foliage which will stay for some time. Imidacloprid, like pyrethroids photodegrades. We can also drench imidacloprid into the soil which is taken up by the roots and provide longer control. UGA Extension Entomologist Dr. Will Hudson has this to say about drenching:

The drench rate for Admire (a 4.6 lb/gal formulation) varies according to the tree size, but it ranges from 10-20 trees per fluid oz. (14 oz/acre).  The amount to add to a bucket depends on how many trees will be treated with that batch.  You probably need to pour 1-2 qt. per tree, depending on the size (I use 2 gal per tree for pecan trees 8-10 inches DBH).  So, decide how many trees will be drenched, and add 0.05 fl. oz. per 3′ tree.  For the 2 lb material, the label suggests 3-6 ml per inch DBH (5 ml = 1 tsp) or about 1 tsp per 3′ tree.

I also saw some white flies. That along with the big Orange Dog caterpillars are some things we need to look for now. The Orange Dog caterpillar eggs will be orange under the leaves.

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Filed under Citrus, Entomology

Tobacco Off To A Good Start

All tobacco in the county has been transplanted in what they say has been the best transplanting conditions in a year long time. Transplanting started for us March 31 and finished up a few days later. UGA Extension Tobacco Specialist Dr. J. Michael Moore came down Wednesday and we got to see everything that was set. Below are some pictures of the fields.

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TobaccoSet-010

In one of the earliest fields, Tomato Spotted Wilt Virus has showed up in a hand full of plants. It has been two weeks to the day of transplant, and Dr. Moore says two weeks is the magic number for TSWV. You can see the reddish-brown necrotic ringspots and also where the bottom half of the leaf stops growing and the other half continues to grow, the leaf will distort. Even immature thrips are present in other fields and field edges which means they are not only out, but reproducing. Virus was showing up only on the edge of this field that also has pecans surrounding it.

Tomato Spotted Wilt Virus

Tomato Spotted Wilt Virus

We also saw a little chewing in the leaves from flea beetles. Greenhouse treatments usually control flea beetles. Field treatment for young plants starts at 4 beetles per plant.

Flea Beetle Damage

Flea Beetle Damage

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Filed under Disease, Entomology, Tobacco

Turf Disease Or Weather?

“When it rains, it pours.” And it has brought lots of issues with our yards other than slime mold. Even growers are asking about these issues they are seeing. Why is the grass is turning yellow and dying in irregular shapes? In between our commercial ag calls, us county agents answer residential calls about landscape issues also. I’ve learned a lot about centipede and St. Augustinegrass in 3 1/2 years, but some of the things I’m seeing for the first time this week.

Rain and humidity provide the environment for disease. Usually, Large Patch (Rhizoctonia solani) will show up in centipedegrass during this time. You will see brown spots in the lawn with a nearly perfect expanding circle. St. Augustine generally gets Take-All Patch (Gaeumannomyces graminis) with significant damage. Another common issue during periods of rain is yellowing of the grass blades. This is result of nitrogen and potassium leaching out with rain (below).

Centipede nutrient deficiency from rain

Centipede nutrient deficiency from rain

The reason I wrote this post is because I visited a centipede lawn earlier this week with dead grass in irregular shapes. The symptoms did not look at all biotic (disease, insect damage) but abiotic (environmental, cultural). The lawn held lots of water and you could clearly see where water sat for long periods, and roots went without oxygen and died. However, I saw a few small circles, but not typical sign of Rhizoctonia. I took some samples and looked under the microscope. Under the dissecting scope, when you see these black dots…. they are usually hyphopodia (puzzle pieces) from Take-All Patch…

Centipede-Dissecting

Mycelium on base of centipedegrass blade

……however, we always look under the compound scope to confirm it. In this case, the “hyphopodia” turned out to be clumps of mycelia. The issue was that these mycelia did not have all the key ID features of Rhizoctonia (Brown color, crosswalls, 90 degree branch angle, and taper at the branch).

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Clumps of mycelium on centipedegrass

Below is actual key ID feature of Take-All Patch…

Hyphopodia from Take-All Patch on St. Augustine

Hyphopodia from Take-All Patch on St. Augustine

I sent to UGA Pathologist Dr. Elizabeth Little who responded saying sometimes the mycelia will clump as it enters the cell, but she and her diagnostician was not convinced this was Rhizoctonia. Below is the response from Dr. Little. To summarize, she believes the weather conditions are causing lots of issues with lawn now, and Rhizoctonia found in the samples is secondary:

I showed this to our diagnostician who sees lots of Rhizocontia and she was not convinced this is Rhizoctonia. She thought it was too erratic. However, the runner hyphae of rhizoctonia will make infection cushions of balled up hyphae where they enter the plant. That is what these look like to me. So this could be a random saprophytic fungus or possibly Rhizoctonia but you would need to look some more to confirm. When conditions are wet like this Rhizoctonia and other fungi are everywhere. I am getting many centipede samples of poor greenup but I am thinking any Rhizoctonia is probably secondary to the environmental stress, especially if there is no distinct pattern of large patch.

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Filed under Disease, Turf

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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Filed under Disease, Pecans

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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Filed under Disease, Turf

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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Filed under Aquatic Environments, Weed Science

Grain Sorghum Planting

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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
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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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Filed under Grain Sorghum