Pecan Pollination

Caddo-PecansThere has been some questions on pollination that UGA Extension Pecan Horticulturalist Dr. Lenny Wells has a commented:

The occurrence of last week’s rainfall during the pecan flower bloom has many growers concerned that the weather had a negative effect on pecan pollination. While cool, rainy conditions are certainly poor conditions for pecan pollination, I think we are still in pretty good shape. Most of the female flowers I was seeing last week where not yet receptive, and the catkins or male flowers of some type I varieties were just beginning to mature and release some pollen. This week’s weather is much more conducive to pollination, and it looks as though the female flowers of many varieties are receptive this week as the pollen begins to fly.

Its a common misconception that the stigma color of the female flower tells you when the flower has been pollinated. While the stigmas do turn dark brown, color can be misleading. It all depends on what you see as “brown”.  Stigma color varies with variety as you can see from the images below:

Moreland (Green Stigma) - Photo by Dr. Patrick Conner

Moreland (Green Stigma) – Photo by Dr. Patrick Conner

Kiowa (Pink Stigma)

Kiowa (Pink Stigma)

Pawnee (Burgandy Stigma)

Pawnee (Burgandy Stigma)

Many varieties have a burgundy stigma color that to the eyes of some may be considered brown. All of the stigmas you see in the image above are receptive, even thought he Kiowa and Pawnee flowers have a brownish appearance. The real key to determining whether or not the female flowers are still receptive is found in their texture. Receptive flowers have a waxy or shiny appearance, while flowers which have reached beyond the receptive stage appear dry or dull as in the photo below:

Post Pollinating Stigma

Post Pollinating Stigma

Female flowers are usually receptive for 5-12 days. When humidity is low and winds are warm, the stigma has a tendency to dry out early, limiting receptivity. High humidity in the form of rain or fog may limit pollen shed.

The appearance of catkins can tell you when they have developed beyond maturity. As the catkins mature, they begin to take on a brownish tinge. When the first hint of brown begins to become noticeable, some of the pollen is nearing maturity and beginning to shed. This tinge will darken as the catkins continue to mature.

Catkins - Immature, Shedding, Past Maturity

Catkins – Immature, Shedding, Past Maturity

Pollen maturity can be easily tested by shaking a few catkins in your hand. If the pollen is mature, the yellow pollen grains will shake out into your hand. After the catkin has completed maturity and released its pollen it will turn dark brown and dry.

In the Southern half of our state’s pecan belt, this is a big week for pollination of many varieties. As you go north, female flowers and catkins are getting close as well. We have a long way to go with this season, but our crop potential looks pretty good at this point if we continue with good weather conditions over the next couple of weeks and we can win the battle with pecan scab over the course of the season.

All photo credits to Dr. Patrick Conner.

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Stagnospora Glume Blotch

Wheat-Fusarium 002

Here are the symptoms on heads are from stagosnospora (formely known as Septoria) glume blotch on triticale. We will see dark brown or purple lesions form on the heads. Lesions are often more intense at the top of the flume, with brown blotches or streaks going down to the base of the spikelet. The central stem is often not affected. UGA Extension Grain Pathologist Dr. Alfredo Martinez says, “Stagonospora  usually diminish as temperatures warm up drastically or if dry periods occur. Strobilurin and triazole fungicides are highly efficacious in controlling the disease.”

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Stagnospora Glume Blotch

I also saw spores from Pyrenophora or Helminthosporium causing Tan Spot (Yellow leaf spot or Blotch). Dr. Martinez says , “This disease is more problematic in susceptible varieties, poor fertility and in fields with wheat residue left on soil surface. Initial infections come from diseased crop debris in the soil, or from diseased grass hosts. Usually the lower leaves are infected first, and the disease progresses to the upper leaves and leaf sheaths if conditions are favorable. This disease develops over a wide range of temperatures and is favored by long periods of dew or rain. Crop rotation with non-host crops reduces the severity of tan spot. Seed treatment seem to be effective in reducing the disease. Fungicides applied timely are effective in reducing the disease severity and improving yield.”

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Wind On Corn

Corn-Wind 001

I looked at corn yesterday setting in the V8 growth stage. Thankfully, we had a small dry period in the early week to get out our post emergent herbicides in this field. Weed control here is good. But the rain and wind have left corn lodging. You can see it throughout the whole field. In very few spots, plants are laying completely on the ground. Saturated soils have slowed the development of nodal roots because of less oxygen in the soil. UGA Extension Corn Agronomist Dr. Dewey Lee says while corn doesn’t like to live in saturated soils, it generally can handle it in the coastal plains soils of south Georgia as those soils typically drain well….

“Most of the time, corn will begin to straighten up in a few days (if the rain stops) or at least ‘gooseneck’ a little as it begins to straighten. What current conditions have done is to prevent any field work until the corn plants clear the middles so a tractor can travel the area without running over stalks. Given any sunshine over the next few days, the crop will begin to straighten as the stalks continue to lengthen and soils dry. Hopefully field work such as herbicide or nitrogen applications will resume and ease the pain of the last several days.

On deep sands or loamy sand soils, you can expect that some of the applied N has already leached below the root zone and you may consider adding a little more.  Applying  N through the pivot, though, will make this an easier task. Unfortunately for those farms where corn is between the V7 and V9 stages, the cloudy conditions and wet soils have already had its negative effects on the number of rows due to lower irradiation and temporary nutrient deficiencies.”

Wind blown corn

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Grain Development In Wheat

Wheat 004

All wheat in Thomas County is heading and most if not all has been sprayed with fungicide. We want to protect the head and the flag leaf for disease, especially rust. Our wheat is in the Feekes 11.0 growth stage where the kernel is ripening. The grain fill period can last from 30 – 50 days depending on stress of environment. A low stress and high yield environment, it will take closer to 50 days.

Fusarium Head Blight

Last year was a bad year for Fusarium Head Blight. It infects during the flower stage, and we had wet conditions during that time last year. Wheat flowers 4 – 5 days after heading and lasts a few days. We are past flower stage now so possibility of head blight may only be for later planted or later blooming wheat. However, we are having the weather conditions that favor it, which you can see at the Fusarium Head Blight Prediction Center.

FusariumHeadBlight-Website

UGA Plant Pathologist Dr. Alfredo Martinez says about the use of chemical control:

“Control using fungicides can be difficult due to the specific time the fungicides need to be deployed and because selection of fungicides labeled for FHB is limited. Timing of fungicide applications is crucial for the control of FHB. Foliar sprays must be applied at the first sign of anthers extruding from the wheat (anthesis). Triazoles work best when applied right before or at early flowering on the main stem heads. The use of nozzles that provide good coverage of the spike is essential for proper disease management. The fungicides labeled for FHB disease-suppression only are listed in Table 3.″

Fungicides-HeadBlight

Leaf And Glume Blotch

This is another disease wheat can have during grain development. I wanted to share some pictures from Terrell County Ag Agent Nick McGhee he has seen on the Alabama line. Here is an excerpt from the UGA Wheat Production Guide:

Lesions (spots) are initially water-soaked and then become dry, yellow, and finally brown. Lesions are generally oblong, sometimes containing small black spore producing structures called pycnidia. The lesions are often surrounded by a yellow halo. Lower leaves are generally more heavily infected, with lesions joining together to cause entire leaves to turn brown and die. If pycnidia are present on lower leaves when the uppermost leaf and the head begin to emerge, infective spores will move to the top of the plant in splashing rain even after a brief shower. Symptoms may not appear for 10-15 days on the top leaves or glumes on the head. By the time lesions are seen on the head, it is too late for effective fungicide use. Therefore, it is important to examine the lower leaves for lesions when making decisions about fungicide application, not just the top leaves. Lesions are first tan or brown on the upper portion of the glume while the lower part remains green. As the head matures, it becomes purplish to black in appearance from glume blotch. Leaf and glume blotch can reduce yield as much as 20% and reduce test weight due to grain shriveling even when disease severity is low.

Leaf & Glume Blotch - Photo by Nick McGhee

Leaf & Glume Blotch – Photo by Nick McGhee

Leaf & Glume Blotch - Photo by Nick McGhee

Glume Blotch – Photo by Nick McGhee

 

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No Counter On Cotton In 2015

Here is an update from UGA Extension Pathologist Dr. Bob Kemerait about Counter nematicide use this season:

“I received official word from the Georgia Department of Ag that the EPA has denied our request to use Counter 20G on cotton. (It is still legal on field corn.)  The reason given basically says that use on cotton would exceed the appropriate amount for the ‘risk cup’ for terbufos (active ingredient) in the state.

So, I am disappointed with this decision but I truly appreciate the efforts of Commissioner Gary Black, the Georgia Department of Agriculture, Mr. Richey Seaton and the Georgia Cotton Commission, Cotton, Inc., and also AMVAC for their efforts to provide cotton growers in Georgia with a tool to manage nematodes.

However we must respect the decision by the EPA.  To be very clear, Counter 20G applied to cotton in 2015 is an illegal application.”

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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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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.

TobaccoSet-Wheat 029

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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