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Thursday, June 27, 2013

Early Use of Plant Growth Regulators in Cotton


 

            A cotton plant is an indeterminate perennial, and produces vegetative and reproductive growth simultaneously. PGRs, or Plant Growth Regulators, are synthetic plant hormones that can be used to balance vegetative and reproductive growth in cotton.  When PGRs are applied, there is good potential for change in the plants energy allocation away from potentially wasteful vegetative growth.  Generally PGRs keep developing cells from elongating, leaving the plants with shorter and more efficient internodes.  This does not necessarily increase yield, but it does help keep the plant more compact and potentially more water efficient.  Producers often make use of PGRs at the match head square stage to better prepare for expected hot and dry conditions latter during the growing season. 

            There are three types of growth hormones that PGRs can impact in the plant, gibberellins, cytokinins and auxins.  Gibberellins are most closely related to vegetative growth and promote cell division and expansion.  Most PGRs reduce the concentration of this hormone in the plant, and prevents the cells from elongating, leaving a more compact plant (1).  This compact plant has the potential to be more drought efficient, and consume less water than it would if it were larger.  These synthetic hormones can also alter where the plant tends to bear fruit, and can cause a more compact fruiting zone. 

Plant hormones work in very low quantities, and since PGRs are synthetic plant hormones, they work in very low doses as well.  Increasing the amount of PGRs early will not increase or lengthen their effects.  As the season progresses, PGRs can be applied several times in the season, but they should never be applied to a stressed plant (2).  If they are applied to a plant that is stressed later in the season, PGRs can push a plant to cutout and reduce its yield potential.

We are one of the few areas in the country that commonly uses cotton strippers instead of cotton pickers.  A cotton stripper’s efficiency is at its maximum when the cotton height is below 36 inches.  Another reason to keep our cotton shorter than 36 inches is that tall, rank cotton plants tend to produce too much late fruit or bolls with little hope of maturing before an average freeze date.  This means we need to watch our cotton’s height a little more closely than other regions might need to.  Latter in the growing season, the top five internodes on our blooming cotton fields ideally would average to be about 1 inch in length.  If those internodes start getting larger than 1.2 inches long, it would be time to consider applying a PGR.  Conversely, blooming cotton with internode lengths of 0.8 inches are already experiencing drought stress. 

Applying blanket PGRs very early in the season is not uncommon, especially in this area.  When the cotton reaches the match head square stage, many producers apply PGRs often mixed with a herbicide treatment in the effort to prepare for coming water stress latter in the growing season.  Fields with PGRs applied this early may fare better when the latter stress and heat inevitably set in during boll set.  Right now, our cotton has seen wind damage and has been exposed to some early hot and dry conditions, but few fields can be considered drought stressed yet.  Even in this drought, it should be safe to apply PGR for good benefit as fields reach that minimal match head square stage.

 

Good Luck!                                                                            Please call or come by the office if you have any questions.  Thanks!

                Kate                                                                                                                                     Blayne

 

Written by Kate Harrell, Intern with the Plains Pest Management Association and Texas A&M AgriLife Extension – IPM, Hale & Swisher County.

References

1          http://www.caes.uga.edu/extension/irwin/documents/PGRPublicationUGA.pdf . Philip

Jost,Jared Whitaker, Steve M. Brown, Craig Bednarz. Department of Crop and Soil Sciences College of Agriculture and Environmental Sciences Cooperative Extension Service. Bulletin 1305-Date April, 2006.  6/26/13

 

2          http://agfax.com/2013/06/26/texas-cotton-plant-growth-regulator-considerations/ . AG

 FAX Fields of Facts on June 26, 2013.  6/26/13

Thursday, June 20, 2013

Maximizing Pivot Irrigations


 

                As area producers struggle through though drought conditions, most seek to maximize returns from limited irrigation capacity.  Because our aquifer is not refilling nearly as quickly as we are pumping, careful management practices to conserve water are becoming even more pressing.   Many producers are making use of Low Energy Precision Application pivots, (LEPA) and similar pivot systems to maximize their irrigation efficiency.  When on the proper setting, these types of systems use lower pressure regulated nozzles hanging fairly close to the ground to limit evaporation waist and causes by limiting air exposure, crop overspray, and heavily wetting a smaller area of soil surface.   The nozzles of a LEPA type pivot have three settings; bubble, spray, and chemigate.  This allows the LEPA type systems some flexibility and practicality in use. 

                When irrigating a crop for a stand, most producers set their LEPA nozzles to spray mode.  This setting wets the entire soil seed bed and better ensures a profitable stand of young seedlings that cannot search very far through the soil for water on their own, but acts similarly to a conventional sprinkler in water use efficiency.   An older style conventional sprinkler system loses about 20 to 25% of the water pumped to wind and low humidity while it irrigates in normal operating conditions.  LEPA style systems only lose about 2 to 3% while in bubble mode in similar situations.  During very high and sustained winds, something most area producers are all too familiar with, both systems do lose some efficacy but the volume of water lost by conventional pivots is staggering.  In those situations, up to 94% of irrigation water applied can be lost.  The timing for producers to change the settings on their LEPA type systems to bubble mode quickly becomes very important as we face water (and money) loss issues.  To maximize irrigation efficiency, this switch to bubble needs to happen as early in the growing season as possible.

                Cotton, our most pertinent area crop, first becomes capable of searching for its best water source with its tap root system at match-head square stage.  Cotton at younger stages benefits more from the spray mode since it hasn’t developed the root system needed to take advantage of the bubble setting yet.  Producers who make the change to bubble too soon often experience serious stand and or yield reduction without the help of rainfall, which has been severely limited lately.  As cotton plants start getting bigger, they start developing their fruit set and water use increases drastically.  Producers waiting too long to change to bubble mode risk notable yield loss through fruit set, not to mention the painful waist of precious water.

Our area’s cotton fields are ranging from 1st true leaf to pinhead square stage.  For several fields, match head stage is only a few days away.  For this reason we urge producers and consultants to keep close tabs on the stage of their cotton fields.

Have a GREAT day,                                                            Please call or come by if we can help,

Kate                                                                             Blayne

Monday, June 10, 2013

Saving Storm Damaged Trees


Last week on June 5th, Hale and Swisher County experienced a storm that left some rainfall, some hail, and a great deal of wind.  The rain will help green up lawns, but hail and wind left some wreckage behind.  The wind speeds generated by this storm got up to 80 miles per hour, similar to hurricane conditions.  These conditions caused damage to the roofs and trees as well as the crops in the area.  Most of the hail was received in the southern part of Hale County, but high winds caused damage across Hale and Swisher County.

Winds did tear limbs from trees, and is some cases, even knock them completely down.  Trees damaged by severe weather were often stripped of some leaves.  While that is damaging, the problem that holds the largest IPM concern will be the broken and snapped branches.  What is left behind for the trees are jagged and open wounds that are ready targets for insects to attack or infest.  These open wounds heal best if sawed off to a flat surface.  Painting that smooth wound over with insecticidal paint can also help save the tree from possible infestation.  If left uncut and open, the tree could lose fluids and nutrients through continual bleeding of sap, but also wood borers and other insect pests will be attracted to that injury site.  Some of the pest insects that will flock to the tree to feed can spread throughout the tree, devouring it from the inside.  The damage can even lead to the death of the tree.  If insecticidal paint is hard to come by, Malathion mixed with a white or off white paint will work in a pinch.  Saving a tree that has already been infested with some of these pests is costly and often not successful.  Taking these preventative measures now will cost much less and could save an already damaged tree in the long run.

Checking the trees on your property soon after damaging weather events and taking appropriate action by cutting the injury to a flat surface and painting over it with insecticidal paint can save time and money.

 

Good Luck!

Kate

Wind and Hail Damage on Cotton Seedlings


 

Last week, Hale and Swisher County experienced some damaging weather.  The amount of rainfall received ranged from 0.12” to a little over 2”.  Most of the heavier rainfall came down hard and fast, and was accompanied by hail.  Hail can beat the cotton seedlings leaves to shreds or completely off.  The seedlings can survive such a beating from wind and hail if the plant still has a healthy growing point.  The plant can still be considered living if a growing point, terminal or alternate, still remains.  Those growth points should be re-growing leaves and green shoots soon after the damaging event.  Four to five days after a damaging event should be enough time to tell which plants have healthy growing points and which do not.  These plants will be unavoidably delayed, but should have more potential than a late season replant, if there remain enough plants per acre in the field.

We received a great deal of wind along with the rain and hail last week.  Some locations even had wind speeds up to 80 miles per hour.  Wind alone can damage young cotton leaving sand blasted, tattered, and burned looking plants.  Under the right conditions, winds can generate static electricity by lifting small soil particles and bouncing them along the soil surface.  The resulting electric discharge seriously affects seedling cotton as the now electrified particles are carried past. The impact of these tiny static electrical discharges have a cumulative impact upon seedling cotton causing cell rupturing which leads to leaf curl or burn, stem damage, and in the worst cases, seedling death.  Fields do not necessarily have to be ‘blowing’ for this type of damage to occur. 

Sand blasting causes similar damage but wind direction can usually be determined by the resulting damage to the seedling.  Plants along the edges of fields tend to catch more of the damage from wind and sandblasting, especially if they are near a road or any other area with bare ground.  A plant with stalk bruising from wind damage or hail will take longer to recover.  Ground cover or a rough soil surface can help to reduce the amount of damage a field takes.  Wheat trash and other stubble in a field can prevent blowing dirt or any lifting of small particles.  Very few fields in the area have lost large amounts of yield potential to wind damage alone.

Several producers have lost cotton fields to hail while many others will be evaluated this week.  Stand counts will help greatly in determining whether or not a field will make, or if it needs to be replanted.  A minimum of 27,000 fairly evenly distributed plants per acre need to have healthy growth points before the field loses profit potential.  Gaps in a field that are larger than a foot can cause significant yield loss, but cotton can compensate for gaps shorter than a foot if they aren’t repetitive.

Thrips pressure is rising again after a brief respite with the storm, and wind or hail damaged fields tolerate fewer thrips than a healthy field can.  Monti Vandiver, EA-IPM Parmer/Bailey, recommended an economic threshold of 0.5 thrips per leaf stage in hail or wind damaged fields.  Seed treatments for thrips control are showing signs of losing residual, and thrips are reproducing in the fields.

 When evaluating fields this week, be sure to check the stand of plants with healthy growing points, the number of thrips, as well as looking for wind and hail damage.

 

Thank You! 

Kate

 

Kate Harrell is the 2013 intern for the Plains Pest Management Association.  She is a native of Hale County and a veteran of our regional agriculture.  Kate has just finished her bachelor’s degree from Texas A&M University in Entomology and will be starting her master’s degree in the fall.  In between, we are happy to have Kate helping us this summer.  We can expect more helpful tidbits from Kate over the next few months.  Thanks, Kate!

 

Please call or come by if we can be of assistance,

Blayne