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Soil Samples versus Tissue Samples

posted Mar 5, 2016, 6:37 PM by Bob Whitney   [ updated Mar 5, 2016, 6:40 PM ]

Tissue Testing Strawberry
How do you know if you need a soil sample or maybe a tissue sample?  What is a tissue sample?  Do I need both?

Most people are familiar with soil samples and we literally take hundreds every year.  Soil samples are very important where we are growing any annual crop like cotton, wheat, sorghum, etc.  And they are important if we are growing perennial crops like bermudagrass for hay, especially where we take multiple cuttings.

So what is a tissue sample?  Tissue samples are usually leaves but can be other plant parts that are taken or pulled during the growing season.  For instance, in pecans we would pull mature leaves from about the middle of the tree canopy.  These leaves are taken from several trees to make up a sample to send in to the lab.  These samples tell us if the plant is getting all the nutrients it needs from the soil and/or our fertilizer applications.  Sometimes we can supply a nutrient in the soil and the soil properties keep it from being available to the plant.  Or in the case of perennial plants like trees they may be getting nutrients from deeper down than the soil sample was taken.  The tissue sample along with a soil sample is a great way to make decisions  about crop fertility and know you are making a difference in crop yield.  As with soil samples it is important to take  tissue samples for several years to compare results from year to year.

Herbicide Modes of Action “Amino Acid Synthesis Inhibitors”

posted Mar 5, 2016, 6:33 PM by Bob Whitney   [ updated Mar 5, 2016, 6:34 PM ]

There are lots of herbicides available for controlling almost every kind of weed there is but knowing which one to use can be difficult.  Let me try to unscramble some of the confusing words we use all the time by talking in this newsletter about how herbicides work commonly known as “mode of action.”.

First we have at least 27 different modes of action (MOA) in herbicides.  What this means is that the herbicide chemical will go to a particular part or site of the plant and work to disrupt that process in the plant.  For instance, Plateau is a type of amino acid synthesis inhibitor.  It prevents the synthesis or formation of one or more amino acids in the plant.  These amino acids are essential to the plant for growth because they are the food for the plant.  So when you use an amino acid synthesis inhibitor the plant begins to starve to death.  This is the reason the “Plateau” or “Outrider,” has the reputation of working slow.

What else is in this family of herbicides?  You may recognize some of the common names of these imidizonaline herbicides like Cadre, Plateau, Pursuit.  Or maybe these in the sulfonylurea (SU) herbicides like Cimarron Plus, Glean, Ally, Amber, Permit, Sandea or Outrider.  All these are in the family of amino acid synthesis inhibitors and have the same mode of action.

Sugarcane Aphid

posted Aug 15, 2015, 5:01 PM by Bob Whitney   [ updated Aug 15, 2015, 5:03 PM ]

From Southwest Farm Press
I mentioned the Sugarcane Aphid in a newsletter last year and the insect did not go away over the winter.  This aphid is unique in that it has moved from sugarcane in the Rio Grande Valley up into the northern parts of Texas to sorghum.  I am getting weekly reports about the aphid movement and so far the rains and cool temperatures have kept them in low numbers but they are around.  At this point they did overwinter as far north as Hillsboro on Johnsonsgrass, something not expected.  Our challenge will be to keep scouting and treat any sorghum plants when aphid populations are low.  If you read the chart above you can see that treatments need to be made when insect numbers are between 50 and 125 per leaf.  This insect can blow through those numbers in a week so scouting is important.  

There are two insecticides for this insect that have shown to work well and keep populations low for weeks.  Transform and Sivanto both need to be sprayed when populations are low.  The threshold is 50-125 aphids per leaf.

Grasshoppers in Winter

posted Mar 9, 2015, 1:40 PM by Bob Whitney

You don't imagine that a grasshopper can survive a winter but here is one!  It is Sunday, February 8, 2015 on a warm, bright afternoon and out jumps this grasshopper. I was surprised that she even moved but she did more than that as I tried to catch her.  I sure hope we aren't plagued again this year like we have been the last few years! 

Chorti Agriculture Update

posted Nov 4, 2014, 8:51 AM by Bob Whitney   [ updated Nov 4, 2014, 8:52 AM ]

For nearly eight years (since 2004) I regularly made 1 - 3 trips a year to Copan Ruinas to visit the Chorti people and to help with their agriculture projects.  In September of 2011, I made one of three trips that year to work on further development of our Extension program but little did I know that it would be three years before I would be back!

So, it was a great phone call this summer from Dan asking if I might be interested in partnering with him and Baptist Rural Life Ministries as the project expands in Honduras on into Guatemala.  The last week of August I traveled to Honduras to visit old friends like Obando and to become acquainted with many new ones.  The project has grown tremendously under Dan’s leadership combined with the really great workers in the field.

Remember this is an agricultural society that is bound up in food production with some production of cash crops like coffee.  Our purpose is to glorify God through our agriculture training while sharing the Gospel in word and deed.  We begin with committed Christian extensionists who are sent out to villages.  Through them we identify possible leaders in villages that we intensely and consistently train.  These leaders are taught both agriculture and God’s word.  Our prayer is that these leaders will come to know Christ and lead others to Christ in their village as they themselves teach good agriculture practices in the village.IMG_2920.JPG

I regularly remind our extensionists, our leaders and any in the villages that participate in our agriculture training of these three principles:

  1. We are experts.  We intend to provide the best in training and experience known throughout the world.  We ourselves constantly improve through continuing education and we work hard to develop contacts with the best experts in the world.

  2. We are here to stay.  So many projects start strong, develop great interest and then leave as if they are finished.  We don't see an ending, we intend to continue to be there to provide agriculture education, share the gospel and disciple.

  3. We trust God in all we do.  We are quick to give God glory and to seek Him in all we do.  We believe firmly that because of our faith in God and our dependence on Him, He will bless our efforts and consequently, the Chorti.  This has been evident from the start.

As we see God working amongst the Chorti these things are evident and need our prayer:

  • For more Christian extensionists who will come along beside us to extend our outreach.  These extensionists would live in the middle of several villages and serve as a source of biblical discipleship, evangelism and agricultural training.

  • For the Spirit to move among the Chorti calling out leaders that we can train and disciple.

  • For the physical safety of everyone.  There have been many murders in the area and even our own people have had family members gunned down.  I gave an extension training while in Honduras and asked the participants to tell me the greatest problems the Chorti face today and they all voted murderers/killers as the second most important problem behind lack of good land!foto01_alessandro_ciapanna_roya_1200px.jpg

  • For productive crops.  There has been a tremendous drought this year and food is in short supply.   Also there is a worldwide problem in coffee called La Roya or coffee leaf rust.  This problem is especially bad in Central America and will affect small coffee growers and also coffee harvesters.  Coffee is a cash crop that provides needed money for school, clothes, shoes, etc.  This video is a good look at the problem. Just click the link.  Understanding La Roya

  • For Christian agriculturists who love agriculture and want to share the Gospel and hopefully speak Spanish.  We need people who will come alongside our workers teaching them and helping them in the work. It would be great to have a US team of agriculturists who would consistently and constantly be providing agriculture training and Christian encouragement.

Invasive Weeds in Our Fields

posted Oct 13, 2014, 6:34 AM by Bob Whitney   [ updated Oct 13, 2014, 6:34 AM ]

    The picture below is just one of the most invasive weeds we have in our fields today. Field bindweed, Horsenettle, and Silver Leaf Nightshade are all summer perennial weeds with extensive root systems. Over time they become established in fields and our typical weed control herbicides only burn back the tops leaving the roots to re-sprout again. Ideally, weeds like this are sprayed in the fall as they are moving energy into roots but unfortunately that is usually the time we are planting small grain
    This summer several customers decided they needed to get these weeds under control and gave us a chance to try. We used 3 quarts per acre of glyphosate (Roundup) along with a very good surfactant when the weeds were blooming. The treatment took a long time to work but it did work and planting small grains was easy this fall. Next year there will be seedlings that will come back but they are much easier to control with conventional broadleaf chemicals.

Sugarcane Aphid

posted Oct 13, 2014, 6:27 AM by Bob Whitney   [ updated Oct 13, 2014, 6:27 AM ]

Sugarcane Aphid (
It’s not like we don’t have enough insects to deal with but this year we have added a new one and its a bad one. There are several aphid species that attack sorghum including corn leaf aphid, greenbug, yellow sugarcane aphid and now sugarcane aphid.
    Aphids are a unique insect. They feed but inserting their stylet into phloem cells that transport plant nutrients. They suck the plant juices through their bodies and excrete excess which causes the honeydew (sticky mess on the leaves) that gets on leaves and windshields under trees.
    Aphids are also unique in that the female reproduces asexually in the summer giving birth to live young every few days. This means that populations can increase exponentially as you can see in the picture. For some reason the sugarcane aphid seems very adept at reproducing as you can see in the picture.
    The other problem with this aphid is that the typical chemical controls like imidacloprid don’t work well at all. This past year a TDA Section 18 was granted for Transformer from Dow because it was about the only product that worked. In some cases sorghum growers had to spray 3 times and still had problems.
    There is a little hope in this desperate situation. This aphid doesn’t survive well in cold weather and so experts believe it will die back to the Valley/Winter Garden area each year. This means it will have to migrate to this area each spring but as we saw this year it won’t take long!

Bermudagrass Stem Maggot

posted Aug 7, 2014, 4:47 AM by Bob Whitney   [ updated Aug 7, 2014, 4:48 AM ]

Late this past year a new forage insect that has been slowly making its way here from Georgia invaded bermudagrass fields in Texas. In 2010, entomologists in Georgia found the Bermudagrass Stem Maggot in hay fields and since that time this Central and Southeastern Asia insect has been steadily moving west.

Dr. Vanessa Corriher-Olson, Extension Forage Specialist at Overton in East Texas found damage in July last year in a number of East Texas coastal bermudagrass hay fields and she identified the insect causing the damage as the Bermudagrass Stem Maggot (BSM). In late August I was called to come by some fields north of De Leon to see a problem and the damage was something I had never seen. My first call was to Dr. Allen Knutson, Extension Entomologist and after a few email pictures he confirmed the damage as BSM.

The adult fly of the BSM lays its eggs on bermudagrass leaves. Once the eggs hatch, the larva or maggot goes into the stem and begins feeding on the leaf tissue right at the uppermost node. As a result of the feeding the top 2-3 leaves will die as you can see in the picture.

After the leaves die the maggot leaves the stem and goes into the soil to pupate. After pupating for 7-10 days the adult fly emerges to lay a new round of eggs. It is estimated that if the infestation is severe that over 80% of the tillers in a field can be affected. 

The field that I scouted north of De Leon, Texas had between 70-80% of the tillers dead and the hay yield was going to be severely affected by the maggot. The producer immediately cut the field and then a following last cutting was not damaged.

According to Dr. Dennis Hancock, University of Georgia Extension Forage Specialist the damage appears to begin toward the end of the first cutting through the middle of the second cutting. In general the damage begins to taper off as fall weather changes begin. I was not able to find any damaged fields by late September.

What can we do? There is not a lot we know about this insect and certainly not a lot of control measures. Here is a list of things that can help you manage for BSM:

  • The larva causes the damage by feeding inside the stem. Since the maggot is inside the stem, conventional insecticides will not touch them.
  • The adult fly does not move far, in fact they only move about 10 feet in any single flight. The flies stay deep in the canopy unless disturbed so chemical control has to penetrate the canopy to be effective.
  • If you see damage and are even within 10 days of harvest then harvest! When you harvest you will remove the maggot and help lower fly numbers.
  • If you do make a harvest and will have maggots again then treatment is an option. Dr. Hancock has found that you can apply an inexpensive pyrethroid insecticide like Silencer. Silencer does not have a label for BSM but it is labeled for most insects in bermudagrass including armyworm and grasshoppers. Apply a pyrethroid when the grass is growing 7-10 days after harvest and then again 7-10 days later. The cost of the two treatments is easily justified by the forage yield saved!
  • Alicia, Coastal and Tifton 44 are the most susceptible since they are finer textured bermudagrasses. Tifton 85, which is a coarser grass, has shown to have fewer tillers damaged and so less yield loss.

Training in the Republic of Georgia

posted Mar 16, 2014, 5:02 AM by Bob Whitney   [ updated Mar 16, 2014, 5:04 AM ]

    I have been traveling throughout the Republic of Georgia the last two weeks and have one more to go.  This project is training Georgians in Extension Methods.  About a year ago they started a national extension program and we are here helping them to better understand how to do extension.  Our main emphasis is how they can reach farmers with the intention of strengthening agriculture.  Over 50% of the population is on the farm and most farms are less than 2 hectares.  
    It has been a great trip and I have enjoyed conducting the training.  It will be interesting to come back in a year or two and see how things have developed.

Texas Toadflax

posted May 2, 2013, 9:34 AM by Bob Whitney   [ updated May 2, 2013, 9:34 AM ]

    It is hard to believe that this pretty flower could cause lots of problems in hay fields but it is!  Texas Toadflax is the only weed that survived 1.5 pts of Grazon Next HL herbicide applied on April 6.  It is not known to be a tough weed to kill but unfortunately the herbicide has selected it out of all the other weeds and now it is the dominant weed in the field.  Looks pretty but it sure will make the hay quality low.

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