As farmers make decisions on what to plant this year, grain sorghum is receiving some skepticism due to last year’s late-season invasion of the sugarcane aphid, a new pest to the southeast. Bayer has now received a label for sugarcane aphid in sorghum, and Frank Ritteman with Bayer’s horticulture division explains the history of the product, Sivanto insecticide:
“It really has been driven by some colleagues we have in south Texas, who, I think in 2013, the sugarcane aphid moved in there, and they started when they were developing Sivanto, they started to also test it out on sorghum to see if it would help out with sugarcane aphid, and realized that it was a great fit in there. So, from that point on sorghum was also on the map for a focus crop for Sivanto to developed but it took until early 2015 for the registration from the EPA.”
Ritteman outlines the timing of application:
“Just a number of things that growers will want to consider, this season there’s more varieties available that are somewhat resistant to sugarcane aphid, which could play a role for the timing of the Sivanto application. Also whether growers apply an insecticide (seed) treatment could play a role, I think they’ve been proven to show a 30 to 45 days of control for that pest. So, if you have a seed a treatment, you may need to use Sivanto later on.
I think many university Extension specialist are still trying to identify the best threshold for each geography, but basically once the threshold is met, and currently the threshold is seen at the 50 aphids per leaf mark.”
As producers learned last year, populations of sugarcane aphid can explode exponentially overnight. Ritteman says like any other pesticides, using the product before that happens is beneficial to control:
“Its systemic but it’s moving from the point of contact on the plant to the outside of the plant..of the leaves. So, thorough coverage through the application is important, and especially if you have coverage lower in the crop the product will move up into the head, and up in the leaves to protect that crop.
When you say ‘preventative’, you really want to apply that product before the populations get out of hand.”
As far as residual:
“It largely depends on when the product is applied, if it is applied at the right time early on into the building population then we’ve seen good residual control…two to three weeks, two weeks plus. A lot of growers in many parts of the country had their first experience with sugarcane aphid for the first time last year, I think they’ve learned a lot about the pest, and when to treat, how to treat, and how to apply insecticides, and will be better prepared going into next year.
But, last year, some may have seen lower residuals because they, for example may have been a little late in their insecticide application into a building population.”
Ambient temperature at application also plays a role in effective control says Ritteman:
“Also, one thing we have seen which I think is really interesting is that there seems to be a temperature dependency of the control of Sivanto, which isn’t so much related to the product itself, but more to the feeding pattern of the aphid. We’ve seen better residual control of the pest at high temperatures, around the 80’s, versus somewhat lower residuals around 60 degrees. We attribute this mostly to aphids being more active when its warm, and then also feeding on the sorghum that’s treated with the Sivanto, and I mentioned earlier, Sivanto works better when it’s ingested, so activity is better when it’s hot.”
Frank Ritteman with Bayer.