Sugar cane aphid (SCA) numbers in the county are starting to hit threshold levels on most sudan, hay grazer, forage sorghum and milo type crops. We have had an increase in acreage of forage sorghum and sudan-grass or hay grazer this year. If you have a crop of any of these or a cutting of Johnsongrass and you have not checked your fields in the last few days, chances are you will have the SCA. The SCA has been in the county all summer, but in most cases the infestation levels were not too bad until now. The SCA seems to like hot dry weather and their numbers will explode under these conditions.
Above all scouting is the key for anyone with a sorghum type crop. It is recommended that you scout all your fields once a week until you find colonies then scout twice a week until threshold levels are reached. The action threshold is 50 to 125 aphids per leaf average across the field, but not necessarily on every leaf. It is important to scout across the field, the aphids will have hot spots where they entered the field, if you are only scouting at the gate you may miss them until it is too late. When scouting, check a lower and upper leaf, be sure to check taller plants and field margins, remember they will be riding in on air currents and taller plants will be their first target. In most fields, the numbers are high enough now that they are not hard to find.
Once you have found SCA at threshold levels in your field you have two options harvest or treat. If the field is being grown for forage and the crop has reached a stage that harvest is economical then that is your best option. On forage sorghum and hay grazer type crops that have developed thick canopies treatment may not be a good option as your insecticide may not penetrate into the canopy for a good kill. On stands that are smaller there are two treatment options that have shown to be effective Transform at 1oz./acre or Sivanto at 5 to 8 oz./acre. Once sooty mold starts forming on the honey dew excreted by the SCA, treatments are not very effective.