Sorghum Midge 2014

Sorghum Midge

                Much of our later planted sorghum will be coming into bloom this week.  This means that the long anticipated sorghum midge season is starting.  Today, August 18, 2014, I was in a southwestern Swisher County sorghum field that was at boot to bloom stage.  Only about 5 % of the heads had blooms yet, but every head with blooms also had a midge.  This is not a treatable level of midge… yet.  As the field progresses farther into bloom I would expect to find additional midge infesting an economic level of heads.

Midge are tiny Dipterans, or flies, that feed exclusively on sorghum type plants.  The adult midge only lives less than one day, just long enough to lay eggs into blooming sorghum.  The tiny resulting maggot feasts on a single developing grain from within consuming it fully only to emerge as an adult a short time later (usually about 2 weeks) as an adult to start the process over.  Midge cannot overwinter in our area and must migrate from the south every growing season, usually hopping generationally from blooming sorghum field to blooming sorghum field.  Johnson grass can also harbor the midge life cycle.  Sorghum fields blooming early in the growing season are normally immune to midge damage, as the midge typically do not arrive in force until an average date of August 4^th. 

We have been finding midge at sub-economic levels in sorghum since late July.  So far we have not had any fields reach ET (economic threshold) for midge but I really think that is about to change.  The midge population has been gradually growing on our early planted sorghum and the abundant Johnson grass population that our early summer rains have fired.  As sorghum fields enter bloom, I recommend scouting daily, and if your later sorghum planted sorghum is near a healthy Johnson grass population or an earlier planted field I recommend extra caution. 

                When scouting for midge, I prefer to make use of beat buckets or jugs by placing the bucket over the blooming head, tiling downward and shaking vigorously.  Midge should be shaken loose and counted.  A minimum of thirty plants per field should be checked, but total number needed to be checked will vary depending upon field size.  Another good method for use on windy days involves enveloping the blooming head in clear plastic, disturbing the head and counting midge trying to escape.  While in bloom, sorghum should be checked daily for midge starting about 11AM, temperature depending.

                The ET for sorghum midge at the current market level for grain sorghum should be near 1 midge per head during bloom stage.  This ET level should be slightly lower for seed milo, contracted grain value depending. 

Please call or come by with any questions,

Blayne Reed

White Lined Sphinx Moths

The Sudden Appearance of Large Horned Caterpillars Cause Concerns

Blayne Reed, Dr. Pat Porter, Dr. Ed Bynum

                In the past few days I have received multiple phone calls and questions regarding some very large, horned caterpillars.  This appears to be the annual arrival of the white lined sphinx moth.  I alluded to these hornworms being thus far strangely absent from Hale & Swisher in the June 27 edition of the Plains Pest Management Newsletter.  Since that time they have made their presence known from Hale Center to Vigo and beyond.  Dr. Ed Bynum reports finding this caterpillar north of Amarillo and Dr. Pat Porter has reports of it near Muleshoe.   

                As an adult moth the white lined sphinx is also commonly referred to as the humming bird moth or the hawk moth.  The moths are large, somewhat motley colored interesting Lepidoptera that lean toward mimicking humming birds in behavior and body shape when in flight.  There are actually several species of sphinx moths, but these tend to be the most predominate in this area.  We noted several in the area through the months of April and May.  The larva can typically grow to be surprisingly large, up to 3 ½ inches in length, are very plump, colored with a light green base with yellow, black, and sometimes white markings, and a large usually yellowish spine or horn near the tip of the abdomen.  These hornworms are known to feed on a variety of plants which include portulaca, primrose, wild grapes, and a few types of succulent trees.  Despite a fairly lengthy list of host plants, they do appear to be very picky eaters.  Over the past few years, I have noted them mostly feeding on purslane weeds, almost completely ignoring other plants and healthy foliage nearby. 

                The massive group population and potential movement of the white lined sphinx caterpillars can be very impressive, with many describing it as downright intimidating.  These worms only seem to appear in mass populations of at least thousands (if not by the million) with just one local generation annually.  The larva will feast on their preferred vegetation, devouring it quickly and fully before moving to find another pocket of that preferred vegetation with a mass migration that many describe with a statement like, “the ground seemed to be moving and wiggling.”  Meanwhile the pasture, sorghum, and cotton plants they were near or fields they were in are left almost completely untouched with any damage being coincidental. 

                Just about all of my encounters with this hornworm over the past 15 years have ended pretty well.  The sheer number of veracious larva of this size moving into production fields or healthy pasture is enough to make anyone nervous and is most certainly worth keeping daily tabs on.  To date, I have never been forced into recommending treatment for these hornworms.  The fields they have infested are eventually left almost completely unscathed with a serious hit to the weed population following either their migration away from, or eventual pupation of the larva.  I can state with some confidence this pattern of nerve racking benefit to production fields should continue this season.  I cannot be nearly so certain of a respectable outcome of this hornworm’s impact to a grape vineyard or garden plot, horticultural or vegetable.  There is likelihood that something within those situations could be what the white lined sphinx moths picky diet would find delicious. 

                If treatment for these hornworms becomes necessary it is believed a good general pyrethroid would do a good job of achieving control.  Thus far, there has not been a need for an efficacy trial in this region so this assumption has not been verified.

Please call or come by with any questions,          

Blayne Reed

Assessing a Cotton Field’s Viability after Damage

                It has been an interesting spring trying to establish viable stands of cotton this season.  We have had ridiculously dry conditions, followed by cold fronts, followed by long periods of cool wet weather with heavy rain, followed by baking conditions, followed by more rain, hail, wireworms, and of course the wind.  I have met no one who would trade the blessings of the recent rains to be rid of the troubles it has brought to the always temperamental cotton seedlings. 

Many producer’s fields from Plainview north through Swisher have had irrigated cotton seed in the ground through it all while those producers though southern Hale were a little more timid in planting this season and avoided much of the early challenges.  With each successive adversity faced, our irrigated cotton seedling stands have dwindled and several fields have lost viability.  Whether your cotton has been through one nasty event or the 10,000 pinpricks of this spring, some serious evaluations of each field needs to take place.  Luckily, there is a wealth of research and experience to help us determine whether a field has the potential to remain profitable, or if it needs to be replanted to a secondary crop.

Stand counts are the primary tool in determining whether or not a field will make, or if it needs to be replanted.  With this comes a discerning eye about what makes a surviving cotton plant.  A minimum of 27,000 fairly evenly distributed plants per acre that have a healthy growth point on June 20 have proven to maintain their profit potential, assuming no more plants are lost throughout the remainder of the season.  Gaps in a field that are larger than a foot can cause significant yield loss regardless of plants per acre counts, but cotton can compensate for gaps shorter than a foot if they aren’t repetitive.

To gather stand counts from your respective fields, the following should be helpful:

40 inch rows: 13,068 row ft. = 1 acre

38 inch rows; 13,756 row ft. = 1 acre

36 inch rows; 14,520 row ft. = 1 acre

32 inch rows; 16,334 row ft. = 1 acre

30 inch rows; 17,424 row ft. = 1 acre

I recommend measuring 1/1000 of a row ft. acre for your actual stand counts.  All surviving seedlings within this 1/1000 of an acre should be counted, and if possible, health needs ascertained if the field is viable.  I suggest taking these counts at least 4 to 5 times from across your fields taking into account stronger and weaker areas.  Often many more counts are required for borderline stands or stands that are highly variable.  When finished, simply average all stand counts for that field, multiply by 1000, and make your decision about the future of that field this season.  The 27,000 plants per acre mark is a pretty good yardstick.  Other factors such as field history, water availability, expected pest pressure, current pest pressure, root health, rotation needs, weed pressure, and nutrient availability are just a few factors that could come into play.

Most producers would like to know a damaged field’s potential immediately following damage.  This is almost impossible to ascertain and giving the fields 2 to 7 days, situation depending, following damage will be helpful.  Many times seedlings can look healthy, or at least have a respectable “re-growing” point shortly after any new hail or wind damage, but seedling disease, additional blowing conditions, or some other factor will inevitably and unpredictably finish many off.   By the same token, seedlings that look to be little more than sticks can recover quite rapidly if there are any soft and active growing points left on the plant and the root system is not ravaged to severely.  

I hope this short blog has been helpful for your decision process.  Please call or come by with any questions,

Blayne Reed

May Wheat

           All totaled, our area wheat could be much worse off considering the environment and drought we have been forced to grow it in.  I see no major pest issues in the Hale & Swisher fields I have been able to check these past few weeks.  The largest concern has been potential damage from the April freeze event and detection of wheat virus in fields producers are pushing for grain yields.  In our most recent newsletter, I estimated that the majority of wheat fields I had checked had only about 5% damage in the lower portions of the fields.  Now that the heads are emerging, this estimate looks fairly accurate.  There are a few unfortunate exceptions with much more damage.  One lusher than average field in south-central Swisher County had 70 – 80% damaged primary heads in the low laying areas of the field and 30 – 40% in the higher elevated areas.  There are secondary heads available to this field and should help mitigate some of the yield loss associated with this freeze damage loss. 

                With the high and dry winds we have had, and no moisture, there are additional concerns about how much grain the plants can possibly be filling in those still healthy heads.  I did have the opportunity to pull some wheat heads from irrigated for grain fields this week.  I am finding decent dough filling in most seed sites.  I spoke to a producer who concurred with my beliefs.  We how much weight that seed will have to it is another question.  I would expect it to be fairly light given the conditions.

                For producers pushing wheat for grain yields, be on the lookout for wheat virus symptoms.  Once a wheat field is confirmed to have any of these viruses, yield potential drops rapidly, regardless of additional inputs.   I received the following today from Jacob Price, of the Texas A&M AgriLife Plant Pathology Lab in Amarillo:

 

 

Wheat Virus Early Detection Alert System Update- 14 May 2014

Jacob Price, Senior Research Associate

Plant Pathology- Texas AgriLife Research, Amarillo TX

 

The following wheat viral pathogens have been identified from samples collected at the following dates and counties:

 

Hill county, TX - Wheat streak mosaic virus 4/28/14

                              Triticum mosaic virus 4/28/14

 

Hale County, TX-  Wheat streak mosaic virus 4/28/14

                                Triticum mosaic virus 4/28/14

 

Dallam County, TX- Wheat streak mosaic virus 5/8/14

 

Haskell County, TX- Wheat streak mosaic virus 5/8/14

                                    Triticum mosaic virus 5/8/14

                                     High Plains virus 5/8/14

 

Symptoms of wheat viral diseases are found to be more severe during early season infections and although these plant samples were collected in late April and early May, initial virus infection likely occurred in the fall or early spring.  Wheat viruses are also found either signally or during co-infection with multiple viruses which also increases disease severity.  These pathogens can cause significant yield losses and producers in these areas are encouraged to scout their fields for symptoms of possible virus infection.  Early identification of these pathogens is important to help reduce losses due to infection.  For further information on wheat virus disease management and identification, including diagnostic sampling and submission, please visit the Plant Pathology Wheat Virus Early Detection System website or contact Jacob Price.

 

Jacob Price

Senior Research Associate

Texas A&M AgriLife Research

Amarillo, TX

 

 

Please call or come by if you have any questions,

Blayne Reed