Soil temperatures are finally warm enough to plant sorghum. One pest that continues to be of concern to sorghum growers is the sugarcane aphid. This insect is here to stay, so producers simply need to be ready to deal with it if necessary. Fortunately, it does not overwinter in Oklahoma, so we tend to play a “waiting game” as to when it arrives in Oklahoma.
We will provide weekly reports of sugarcane aphid presence and numbers throughout the rest of the summer, along with control suggestions and updates on research activities regarding sugarcane aphids and sorghum.
Growers can check out the current sugarcane aphid map and its progress at the myFields web link.
We encourage growers to inspect their fields once a week. When aphids are detected in a field, increase sampling to two times per week. Look at three consecutive plants and examine one upper and one lower leaf on each plant.
Estimate the average number of aphids found per plant. Then move 5 feet and sample three more consecutive plants. This is considered one “stop”. Next, move 50 feet from the first spot using an inverted “U” shaped pattern in the field and sample six more plants for the next stop.
Collect counts for nine stops (for 54 plants) and estimate the percentage of plants that averaged at least 50-125 aphids per plant.
# plants with 50-125 aphids/54 * 100…….
The current recommendation for control of sugarcane aphid is to treat if 20% of plants are infested with 50-125 aphids per leaf before panicle emergence, and if 30% of plants are infested with 50-125 aphids per leaf after panicle emergence.
Do not spray until suggested thresholds are reached, but if needed; apply the spray with the highest amount of water carrier as possible (5 or more gallons/acre by air, or 10 or more gallons/acre by ground). Spraying too early and with inadequate coverage may require a second application from aphid recolonization.
Two insecticides will provide effective control of sugarcane aphid in sorghum. Sivanto (200 SL and Sivanto Prime) received a Section 2ee registration that allows producers to apply it at 4-7 fl oz per acre. Oklahoma will likely obtain a Section 18 Emergency Exemption label for the use of Transform WG that should be in effect until late November, 2018.
Transform should be registered for application at 0.75-1.5 oz. /acre. For pollinator protection, both products should be before 7:00 am or after 7:00 pm, or if temperatures are below 55 degrees F at the site of the application (an extremely rare event until later in the fall).