The sugarcane aphid is now being found in grain sorghum fields of Calhoun, Refugio and Victoria Counties. However, I have yet to see this aphid in numbers greater than 5 per leaf. I expect their numbers will increase over the next few weeks and we will see economic levels in May.
Several effective economic thresholds have been suggested for this pest. I think all of them are similar and will result in field treatment at about the same time.
To manage the sugarcane aphid, choose from these thresholds:
- Spray when a field reaches a level of 50 to 125 aphids per leaf (my ET).
- Spray when 25% of the plants are infested with a minimum of 50 aphids per leaf.
- Spray when 20 – 30% of plants are infested with localized areas of honeydew and established colonies are present.
The best practices for managing aphids in your grain sorghum include:
- Scout fields weekly then biweekly after sugarcane aphids are found.
- Resistant hybrids are available but are not immune to the sugarcane aphid. Scout them as frequently as susceptible hybrids.
- Treat fields before aphids get out of hand. Insecticides may be less effective in controlling very high populations. Especially when excessive honeydew is on the leaves.
- Good coverage is essential.
- Transform and Sivanto are effective for control of sugarcane aphids when applied timely and properly.
- Do not expect more than 7-10 days residual control. Continue to scout the field.
- Treat Sorghum Midge when they reach threshold, but watch aphids closely following a pyrethroid application.