–by Anthony Zukoff — Southwest Research and Extension Center

The recent freeze and a lack of flowering sorghum has ended adult sorghum midge activity in the area. Adult midges were observed on station grounds in Garden City starting the first week of July and were still present on late flowering panicles into the first week of September.   As sorghum reaches maturity, it is easy to find evidence of midge activity even if you did not see adults when the fields were blooming.  Simply look for flattened, blank zones on the heads.  These seeds never developed because the maggots consumed them from the inside.  A general recommendation for avoiding losses due to midge is to make sure the field blooms uniformly and before mid to late August.  For comparison, in the Texas panhandle, growers are encouraged to have fields blooming no later than the first of August to avoid issues with sorghum midge.  Beginning the last week of July, sorghum on the station this year bloomed over a long period of time, which allowed some general observations to be made regarding blooming time and midge damage once heads reached maturity.  Plants that began blooming on July 25 were free of noticeable midge damage.  Those that began blooming around August 5 experienced damage to the upper 1/5^th of the panicles.  A final location that bloomed very unevenly starting August 11 experienced significant losses with most panicles being almost completely blank (Figure 1).  While midge damage is very easy to spot on varieties with red panicles, it might be more challenging to see on varieties with white panicles; however, damage will show up the same regardless of color (Figure 2).  In addition to midge damage, headworm and bird damage were prevalent in the later blooming field but are easy to differentiate (Figure 3).  If you have observed midge damage this season anywhere in the state, consider sending me a report including an estimate of acreage impacted and panicle damage.  For additional information and control options, please refer to the Sorghum Insect Management Guide.  https://bookstore.ksre.ksu.edu/pubs/MF742.PDF

Figure 1.  From left to right: example of undamaged panicle from plants that began blooming July 25, slightly damaged panicles from plants that began blooming August 5 and severely damaged panicle from plants that began blooming August 11.

Figure 2. White panicle variety: undamaged head on the left severely damaged head on the right from a plant blooming the first week of September.

Figure 3. Various types of damage to sorghum heads.  Left to right: undamaged head, severe sorghum midge damaged head, a head with heavy bird damage and on the right, a head exhibiting headworm damage.