Seminole Crop E News

Agricultural News for Farmers and Agribusiness in SW Georgia

Archive for May, 2015

USDA Crop Insurance Deadline

Posted by romeethredge on May 28, 2015

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Cotton Market Update 5-27-15

Posted by romeethredge on May 28, 2015

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Question of the Week – Tradescantia

Posted by romeethredge on May 28, 2015

Last week I had a plant I wanted you to identify. It was Tradescantia virginiana,  Virginia Spiderwort. They can keep in in Virginia as far as many folks are concerned. It is a nice wildflower you could say but it’s a problem in yards as it is agressive and kind of invasive.

This week I want you to identify this insect that was sent to me for identification. It’s large, about 4 inches long.

 

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Posted in Agriculture, Entomology | Tagged: | 6 Comments »

Chlorothalonil Short, What do we do?

Posted by romeethredge on May 28, 2015

 Peanuts and the short supply of Bravo/cholothalonil:  What to do?? Here’s what Dr. Bob Kemerait, UGA Plant Pathologist says will be good. 

 

A.  Replace 1.5 pt/A chlorothalonil with 15 fl oz/A Elast

B.  Replace 1.5 pt/A chlorothalonil with 10 fl oz/A Topsin/thiophanate methyl, but ONLY one time!

C.  Replace 1.5 pt/A chlorothanil with 7.0 fl oz/A Stratego (concern about resistance management…)

D.  Replace 1.5 pt/A chlorothalonil with 3.5 fl oz/A Absolute (concern about resistance management…)

E.  Replace 1.5 pt/A chlorothalonil with 5.5 fl oz/A Alto (better to mix 1.0 pt/A chlorothalonil with 5.5 fl oz/A Alto, or at least SOME chlorothalonil with the Alto!)

F.  Replace 1.5 pt/A chlorothalonil with 5.5 fl oz/A Alto + 5 fl oz/A Topsin/thiophanate methyl

G.  Extend chlorothalonil with 1.0 pt/A chlorothalonil with 1.0 pt/A Kocide

H.  Extend chlorothalonil with 1.0 pt/A chlorothalonil with 5.0 fl oz/A Topsin/thiophanate methyl

I.  Extend chlorothalonil with 1.0 pt/A chlorothalonil with 2.0 fl oz/A propiconazole.

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Common Corn Rust 2015

Posted by romeethredge on May 28, 2015

We are now seeing some common corn rust in our fields. It is not the bad rust that causes us yield losses. This rust is a cooler season rust that perhaps infected when we had a series of cool nights a week or so back. It causes damage on both sides of the leaf whereas southern rust is just on the leaf tops usually. This rust is darker  brick red as well in color. The bad southern rust is a more orangish color.

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When you look at it under the mircoscope it is more round in shape and has thicker walls than southern rust. common rust2

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Purple Leaf Sheath

Posted by romeethredge on May 28, 2015

 Purple leaf sheath is a harmless disorder that results when pollen or other debris become trapped in the leaf sheaths by the stalk.  It looks bad and can be confused with one of the stalk rots. Upon cutting into the stalks there is no damage however with this. UGA Diagnostician Jason Brock confirmed the disorder on plants from Seminole County today. I see it often in fields, especially after pollination, sometimes it seems like fertilizer burn and other problems can make this worse.

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Herbicide Burn on Peanuts

Posted by romeethredge on May 23, 2015

With the showers we’ve had the last week and peanuts emerging, we have seen some Valor herbicide burn. This often happens when we get splashing rains as peanuts emerge. Especially apparent if they have not received much rain or irrigation previously to get the chemical in the dirt. It looks bad but peanuts are tough and will quickly grow out of this injury. Sometimes it’s worse around field edges where maybe a higher rate of chemical was applied or the end gun didn’t put out as much water to move it into the soil.

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Bacterial Stalk Rot in Corn

Posted by romeethredge on May 23, 2015

I’ve not seen this Bacterial Stalk Rot before but crop consultant, Jim Griffin, brought me some diseased plants from far eastern Decatur county yesterday. We confirmed it with Dr. Bob Kemerait, UGA plant pathology, by photos and discussion.

We scouted the fields and found it in the areas irrigated from a pond. In areas not irrigated by that pond, we didn’t see it. It is in low amounts maybe half of one percent of plants, more in some areas, but it is startling to see. Fortunately, it is reported not to usually spread within the field. The bacterium causes a type of meltdown and you can sometimes smell it before you see it. It really stinks, especially if you cut into the stems. Univ of Nebraska has a good writeup about it. Here’s an excerpt…

“The initial symptom is discoloration of the leaf sheath and stalk at a node. As the disease progresses, lesions develop on the leaves and sheath. Disease then develops in the stalk and rapidly spreads up the stalk and into the leaves. As the decay progresses, a foul odor can be detected and the top of the plant can be very easily removedfrom the rest of the plant. The stalk rots completely and the top collapses. Bacterial stalk rot can affect the plant at any node from the soil surface up to the ear leaves and tassels. Infections that occur high on the plant may impair normal tasseling and affect subsequent pollination. Although it may spread along the plant to infect additional nodes, the bacteria do not usually spread to neighboring plants unless vectored by an insect. Splitting the stalk reveals internal discoloration and soft slimy rot mostly initiating at the nodes. Because the bacteria usually do not spread from plant to plant, diseased plants are quite often found scattered throughout the field. However, there are reports of plant-to-plant transmission by certain insect vectors.

Bacterial stalk and top rot is favored by high temperatures and high relative humidity. It can be a problem in areas of heavy rainfall or where overhead irrigation is used and the water is pumped from a lake, pond, or slow-moving stream.”

 

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Posted in Corn, Plant Pathology | Tagged: , | Leave a Comment »

Corn Spraying

Posted by romeethredge on May 23, 2015

Some corn spraying is going on now by plane or helicopter. Much of our field corn is now tasseling and especially in fields where Northern corn leaf blight (NCLB) has been found and where growers are going for very high yields, they are choosing to apply a fungicide.  Fortunately the real bad yield stealer, southern rust, hasn’t been found yet and we’re hoping it will hold off a while.  Stink bugs aren’t at high levels at this time but a few have been sighted.

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We flew over a few corn fields this week and they are looking good. The heat this year is pushing the corn on and it is a week or more ahead of the past 2 years, which is good news. In cases where corn has been stressed due to water or nutrient needs, it is short and not looking as good.

Now is a very critical time in the corn fields, the slight cooling this week has been better for pollination and water use but may cause NCLB to increase.

I  read the following from the University of Nebraska:

“Corn was originally a tropical grass from the high elevation areas of central Mexico about 7,400 feet above sea level, 2,000 feet higher than Denver. Today, corn still prefers conditions typical of that area — warm daytime temperatures and cool nights. Areas that consistently produce high corn yields share some significant characteristics. These areas — central Chile, the west slope of Colorado, etc. — are usually very bright, clear, high light intensity areas with cool nights.

Corn maximizes its growth rate at 86°F. Days with temperatures hotter than that cause stress. In the high yield areas, cool night temperatures — at or below 50°F — reduce respiration rates. These are optimum conditions for corn.

In years when we get high day and nighttime temperatures coinciding with the peak pollination period, we can expect problems. Continual heat exposure before and during pollination worsens the response.

Corn is a “C4 Photosynthesis” plant, making it extremely efficient at capturing light and fixing CO2 into sugars. One drawback of this system is that with high daytime temperatures, the efficiency of photosynthesis decreases, so the plant makes less sugar to use or store. High nighttime temperatures increase the respiration rate of the plant, causing it to use up or waste sugars for growth and development. This results in the plant making less sugar and using up more than it would during cooler temperatures.

Heat, especially combined with lack of water, has devastating effects on silking. If plants are slow to silk, the bulk of the pollen may already be shed and gone. Often in dryland fields we see seed set problems because of “nick” problems between pollen and silking.

Even in some stressed areas within irrigated fields (extreme sandy spots, hard pans or compaction areas where water isn’t absorbed and held, and some “wet spots”) we can see stress-induced slow silking and resulting seed set issues. Once silks begin to desiccate, they lose their capacity for pollen tube growth and fertilization.

Heat also affects pollen production and viability. First, heat over 95°F depresses pollen production. Continuous heat, over several days before and during pollen-shed, results in only a fraction of normal pollen being formed, probably because of the reduced sugar available. In addition, heat reduces the period of pollen viability to a couple hours (or even less). While there is normally a surplus of pollen, heat can reduce the fertility and amount available for fertilization of silks. It’s been shown that prolonged exposure to temperatures reduced the volume of pollen shed. Even with adequate moisture and timely silking, heat alone can desiccate silks so that they become non-receptive to pollen.

For each kernel of grain to be produced, one silk needs to be fertilized by one pollen grain.”


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Posted in Corn, Entomology, Plant Pathology | Tagged: | Leave a Comment »

Peanuts starting to Bloom

Posted by romeethredge on May 23, 2015

Some of our oldest peanuts are blooming. They are over a month old now. They had some thrips chewing or as my entomology professor would say “rasping and sucking”,  earlier but they have recovered nicely and started to grow a nice plant. One month down and less than 4 months to go until digging time.  Protectant fungicides are going out now to keep them growing well.

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