Burke – Jenkins Ag News

Farming with Saturated Soils

The month of June and first part of July have been one of the wettest on record. According to the Midville Weather Station, 18.79” of rain has fallen so far. The rivers are overflowing and creeks have water in them that were filled up for the first time in years. Rain is good in normal amounts, but our soils have reached “field capacity” and we must have drier conditions needed to complete timely field work. Our cotton and peanuts are not growing like they should. I am concerned that our cotton is not developing an adequate root system. We must have a root system that will enable our plants to take up needed nutrients and be able to withstand possible dry weather at a later date. As fields begin to dry; I am hopeful heat with plenty of sunshine will turn this crop around. No, we cannot bring back acres that have been flooded or may have severe root damage. However, I feel that once we get top-dress Nitrogen applied, things will improve. Some of you have asked about certifying acres that have been drowned out. I have asked this question, and have been told that if a grower planted the acres, then they need to be certified and reported. From an insurance standpoint, an indemnity payment will have to be decided at harvest. If you have any questions pertaining to stand loss or abandoned acres, contact your crop insurance agent or FSA Office. For now, we will just have to wait and see.

midville 7-6As you can see, 18.79″ of rain has fallen in our area since July 5. The line graphs demonstrates a comparison for past years. (Click on the image for a closer view)

This cotton situation is a common site around the area the past week. The cotton on the left was at the four or five leaf stage as the monsoons of June and July rolled in. The cotton on the right was a little bit older and hopefully will be able to withstand more stress.  It will be a couple of weeks before we know the total extent of the damage.

Peanut N-Fixation

Cotton is not the only crop that is suffering with all of this wet weather. As peanuts endure excess soil moisture, their ability to fix nitrogen will be adversely affected. The following is an excerpt from Dr. Scott Tubbs, UGA Cropping Specialist, discusses peanut nodulation under the current conditions.

(Tubbs)

It is recommended to check fields that have received abundant amounts of rain recently for nodule activity and active N-fixation.  To do so, select several plants from low spots in the field that may have experienced prolonged saturated soil conditions.  Slice several of the nodules open on each plant.  If the nodules are pink, red, or dark purple in color and appear moist on the interior, then those nodules are healthy and there are no concerns of reduced N-fixation.  However, if the interior of the nodules are gray, white, green, or brown in color and they appear dry on the interior, then those nodules are most likely no longer active, so the chances of N deficiency will be greater as we enter into pegging and pod-fill – a very N demanding period of crop development.

When peanut roots and nodules are saturated and cannot access oxygen, N-fixation can cease either temporarily or permanently.  Conditions can vary by soil type and micro-climate, and we do not have data to determine exactly how long a peanut plant can withstand adverse conditions, but we theorize that if a field was in saturated soil conditions for 48 hours or less, then the crop may experience brief yellowing from temporary shut-down of nodule activity, but the crop likely will not experience any serious injury or yield loss.  Longer periods of water-logged conditions start to carry concern of damage which may need to be addressed.

In the event of heavy nodule failure (I’d say greater than 50% of nodules inactive), then a foliar application of N fertilizer (ammonium sulfate is often considered the best bet) may be necessary.  A grower should be cautioned about the potential economic impact of making an in-season N application though.  The supplemental N could cause the remaining active nodules to cease N-fixation, which may require multiple N applications to meet the high N needs of the crop for the remainder of the season.  I have published data that shows the application of fertilizer N to peanut will reduce nodulation compared to where no N was applied to the crop (those were at-plant applications, but the principle remains during high N-demand periods of crop development), so be cautious of when to pull the trigger on addition of supplemental N to peanut or any other leguminous crop.

pnut7

(Picture from left) These young peanuts were planted on June 10th and have grown very little. The roots are yellow/brown with few nitrogen fixing nodules. Hopefully, they will improve with some sunshine and dry weather.

Disease Management Update

One topic that I know that is on people’s mind is managing diseases in our row-crops. With all of this wet weather, disease issues could very well explode in the upcoming weeks. The following is a general row-crop disease update from Dr. Bob Kemerait, Extension Plant Pathologist. He has some very interesting points pertaining to managing diseases.

Greetings! (Bob Kemerait, Extension Plant Pathologist)

For a plant pathologist, the weather in Georgia could not be better…. for a row crop farmer- not so much. While rain is a good thing, the abundance of rain is not only creating the PERFECT storm for fungal diseases.  Not only are the storms moving spores and helping infection and development of disease, but they are also keeping growers out of the field.

Here is a list of row crop diseases that I feel are at a critical phase now:

1.  White mold of peanut- warm conditions and abundant moisture will bring this disease out in force.  Dr. Tim Brenneman reports that white mold is aggressive enough in Attapulgus to kill young peanut plants.   Starting a white mold program early and sticking with effective products applied on a timely basis is critical.

2.  This weather is also PERFECT for development of Rhizoctonia limb rot.  I have not seen any yet, but I have no doubt it is there..  Again, a strong fungicide program for soilborne diseases is critical.

3.  Dr. Albert Culbreath and I strongly advises growers to be prepared for leaf spot diseases- the weather could not be better.  The most important thing is for growers to stay on schedule- and use the most effective fungicides with the best systemic activity.  Certainly, Headline was made for these kind of conditions.. quick drying time, strong efficacy against leaf spot.  Whether you use 6 fl oz or 9 fl oz (better at 45 days) for leaf spot, you may also consider tank-mixing 7.2 fl oz/A tebuconazole for an early start to your soilborne program.

NOTE:  THIS IS THE KIND OF WEATHER WHERE GROWERS USING PEANUT RX SHOULD BE MORE CONSERVATIVE EVEN IF A FIELD IS DEEMED “REDUCED RISK”

Cotton:

LOOK FOR TARGET SPOT, ASCOCYTA WET-WEATHER Blight and FUSARIUM WILT.  My laptop crashed this morning and I do not have the pictures readily available.. But I will try to get the soon of Ascochyta and Fusarium wilt.. both are favored by this weather it seems.  Ascochyta wet-weather blight is described as spots with a deep purple border and pepper-grain like structures in the spot… Ascochyta blight can look a lot like target spot.

I have not seen any target spot in Georgia to date, but I have seen pictures out of Florida of early stages of development.

Remember: 1) Conditions are perfect for target spot.  2) Effective timing requires application before a complete canopy develops and before disease is established.  3) From our limited data, the single BEST timing last season for management (not control..) was the 3rd week of bloom.  The best results were from the applications at 1st week of bloom followed by a second application at the 3rd week of bloom.  We should learn a great deal more this season….

Corn:  Northern Corn leaf blight and Southern Corn leaf blight are out there.  It is my experience that if these diseases are not a problem in a field by tassel, they are unlikely to become a problem; management is most critical for young corn to keep the disease from developing.  IN this weather- growers with late planted corn should consider if a fungicide application is needed on corn PRIOR to tassel.

Corn: Southern corn rust is present in the state, but has been slow to develop outside of extreme southern Georgia along the Florida line, but I expect it to move quickly in this weather.  Corn should be protected from rust from approaching the tassel stage until the dough stage.  If you are a corn grower in east Georgia of central Georgia and have corn at the late milk stage and no problem with NCLB or SCLB, you are probably ok for the remainder of the season.  If you have corn younger than that you need to be vigilant for rust and consider benefits of a fungicide application.

Soybeans:  Soybean rust is at the Florida line… when your beans reach late bloom and early pod development stage.. I would treat them with fungicide.. I think it is a good investment.

I hope this information helps! Have a good week!