The sugarcane aphid (SCA) was reported in Kentucky last week in Woodford County on sweet sorghum. This invasive pest can cause up to 100% crop loss if left untreated on grain, forage, and sweet sorghum. SCA cannot survive Kentucky winters and migrates from southern Texas every summer. While low numbers of this aphid were found last week, their presence in central Kentucky indicates that SCA is likely present in many Kentucky counties already. SCA can be identified by the black antennae, tarsi (feet), and cornicles (tailpipes). Scouting for SCA in sorghum should begin immediately.
Management
Growers should begin scouting their sorghum weekly by searching the undersides of 40 leaves between knee and chest height in a field. If SCA is found, scouting should be increased to twice a week as SCA can reproduce rapidly. If over 25% of those leaves have 40 or more aphids, management action is recommended. Preventive insecticide sprays are not recommended before this as infestations do not always reach damaging levels. For example, the leaf in Figure 1 at https://bit.ly/3QEq2qB contains 160 SCA, which makes this plant infested. However, only one of the 40 leaves checked had aphids, so no action was needed.
The only labeled conventional insecticide for SCA management for sweet sorghum growers producing cane for syrup is Sivanto Prime. Sivanto Prime may be applied to grain, forage, and sweet sorghum either as a foliar spray or soil application. Regardless of application method, no more than 28 fluid ounces may be applied per year. There must be a minimum of 21 days between foliar application and harvest and 45 days between soil application and harvest.
Categories: Kentucky, Crops, Sorghum