Lygus Reach ET in a Few Fields

Lygus have been a common occurrence in our cotton fields so far this season, but we had not seen any fields at economic threshold (ET) until today.  This morning we double checked a couple of fields in Swisher County behind our field scouts and confirmed that Lygus were at ET at those sites.  We would now like to get the word out to consultants and producers alike.  It is very likely a few other area cotton fields are now at or nearing ET as well.  These two fields (two fields so far) are far from the majority.  Only through careful scouting were the problematic populations found.

A useable threshold for Lygus is 1 insect every 2.5 feet with a quick 10% increase in Lygus caused fruit drop, but we tend to start considering a spray when we find 1 insect every 3.5 feet with the associated fruit loss.  Normal plant fruit loss is currently picking up also as fields set more and more blooms to bolls so there is a need to make certain you are dealing with Lygus induced fruit shed.  A cotton plant will commonly shed some of its bolls is doesn’t think it will be able to support them later in the season for multiple reasons. This is quite common as it is impossible for a cotton plant to mature into harvestable bolls every square put on, especially this season with our fruit set riding so high.  Plant induced fruit loss tends to be limited to dime sized bolls, while Lygus can impact anything from squares to larger bolls.  Often a Lygus feeding “dot” or site can be found on the damaged squares and bolls just before they are shed.  If your fruit loss looks like it covers several different sized squares and bolls and a few are noted with the feeding “dots”, it is more likely insect induced than normal plant drop.  If that drop is more than 10-15% of the plants’ fruit and there is a Lygus every 3.5 feet or less, it is probably time to consider applying some insecticide.  Keep a sharp lookout for these insects to prevent them from causing your field yield loss!

 

 

 

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

        Kate                                                                                                                     Blayne

Fleahoppers and Lygus Populations

Right now, we have seeing both Lygus and fleahoppers in our Hale & Swisher County program fields, but not at economic threshold (ET) yet.  Because several of our program cotton fields have been so close to economic levels, it is likely several other area fields are nearing or are at ET.  We have been finding some high beneficial populations and they have probably kept the fleahoppers from reaching ET so far in our fields.  We recommend keeping a very close eye on your cotton’s square drop percent and plant bug populations.

            Cotton fleahoppers are very flighty, small, pale green to whitish color.  The adults can fly, and the wings rest flat across the back.  The nymphs are pale green and very small, ranging from the size of a grain of dust to almost the size of the adults.  Feeding with their stylet-like sucking mouthparts fleahoppers can kill a square on a cotton plant.  The ET for these insects is 25% to 35% plants infested or roughly 1fh. / 1.5 - 2 ft., with square drop considerations.  In match head squaring stage cotton, this would be about 10% square drop, while in three fourths grown square cotton it would be 15 - 20% drop.  Once a cotton field’s stage can be measured by nodes above white flower (NAWF) fleahoppers are rarely an economic concern.

            Lygus are larger than a cotton fleahopper, and can range in color from pale green or almost yellow.  They always have a distinct triangle on the thorax, which is made by the crossing of their wings across their ‘backs’.  The larvae tend to be greenish and have dark, distinct black spots on their backs.  The ET for Lygus also requires similar fruit drop considerations, but their ET is usually considered in Lygus per row ft.  The official Lygus ET is 1 Lygus / 2 ft. but in most entomologists consider this per foot ET something of a sliding scale with crop stage as well as fruit retention considerations.  If you have 1 Lygus / 3.5 ft. in a field with match head squares and a significant amount of dropped squares, it may be time to consider spraying.  One Lygus / 2.5 ft. for blooming cotton with the same square drop considerations seems to be a practical ET.  Lygus do cause economic injury to developing bolls causing drop and/ or damage to the boll up to 350 heat units.  For fields nearing cut-out, an ET of one Lygus per 1.5 ft. seems to work well.  Adult Lygus can fly in and out of a cotton field, and often will when they are just passing by.  It is not uncommon to find a sharp increase in square drop, but not find any Lygus present.  This usually indicates that Lygus stopped briefly in route for a more preferred host.  In these situations keep an eye out for Lygus nymphs soon as it is possible that the passing Lygus adults laid eggs in the cotton.  Unfortunately, the eggs are too small to be found.  The nymphs lack wings and cannot easily leave the area. 

            We prefer to use drop cloths in conjunction with whole plant inspections to evaluate in field plant bug populations and influence upon fruit loss.  Drop cloths can be used to find both of these true bugs and, if the insects are sufficiently stunned from the ‘thrashing’ of the cotton plants, can provide a good platform to identify these pest’s rather distinctive appearance.  We are keeping a very close watch on these guy’s populations now and would be surprised if no area fields are at currently at ET.  We recommend or area producers and consultants stay vigulant.  Lygus bugs and fleahoppers are both hazards for developing squares and we have both of them here now.

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.

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

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

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

Early Season Thrips

          Thrips pressure in the area is higher than I have seen in several years and they are rapidly moving into cotton as it establishes.  At this early stage, predators are a little slow in following the cotton migration. 

Adult thrips are straw colored insects 1/12 to 1/16 inch long.  The wings are fringed and held flat directly over the body when at rest.  Immature thrips look somewhat similar to the adult but have no wings and are somewhat lighter in color.  All thrips have rasping mouthparts which include a single mandible which the thrips uses to scrape and jab host plant tissue.  The thrips then consume the resulting ‘bleeding’ of plant juices.  Thrips often feed in the more sheltered and tender terminal or growing point of the cotton plant requiring very close inspections to acquire an accurate population count.  The ensuing damage causes scaring and malformation of the young leaves at a time when plants need healthy leaves for energy and a good start.  In the worst cases heavy and un-checked thrips damage can become severe enough to damage the terminal and delay squaring for several weeks. 

            Economic threshold (ET) for thrips remains at one thrips per true leaf stage, but there are multiple factors to consider in conjunction with that threshold.  The presence or absence of thrips larva should represent the primary additional consideration.  The presence of thrips larva indicates that the thrips are reproducing in that field and will be there causing damage for some time.  Some other factors include the recognition of light thrips damage, plant stage, and predator populations.  Thrips are one pest producers may want to consider treatments for before thrips reach ET if reproducing populations are confirmed.  Because thrips can move and reproduce so rapidly, thrips can cause serious damage faster than timely applications can be made.

Thrips pressure is progressively higher as we move north across Hale and Swisher Counties.  Our lowest thrips pressure area so far is in southwestern Hale.  Here we are still finding thrips at or above ET.  Cotton planted in dry wheat stubble that have been able to establish a stand, regardless of location, has so far shown the lowest thrips numbers.  Seed treatments and in-furrow insecticide treatments are showing good control for the dollars spent this season.  We have found little or no reproduction in these preventatively treated fields yet but, overwhelming numbers of adults are moving in causing light to moderate damage before being controlled.  I would recommend vigilance in the scouting of these fields for early thrips damage.  If producers will already be treating these fields with herbicides for weed control this week, they may want to consider adding a treatment for thrips to aid the preventative control measures.

Cotton fields with no preventative thrips control applied need to be scouted very quickly.  These fields might be at risk of developing serious and economic thrips damage much earlier than normal this year.  In many of these cases, thrips will need to be controlled as soon as possible. 

Please call or come by if I can help in any way,

Blayne