Sound management practices can help protect your crop from sugarcane aphids.
There have been many articles written on sugarcane aphids (SCA) and grain sorghum, but very few on SCA and forage sorghums. In grain sorghum we have come a long way in developing sound management practices for dealing with SCA; however, forage sorghum in many ways is a completely different crop.
The downward trend of having to apply an insecticide to control SCA continued in 2020. Where hot spots occurred, growers acted quickly to protect their crop. In most cases, a single insecticide application was sufficient to provide season-long control. The exception was in silage sorghum where, in a few fields, a second application was required. These outbreaks were typically in fields where a particularly susceptible hybrid was planted.
In grain sorghum, planting a tolerant hybrid in regions where SCA are a potential annual problem is often the first step many growers take to manage the aphid. Most seed companies now have several SCA-tolerant grain sorghum hybrid options, and these hybrids are getting better all the time.
Unfortunately, with forage sorghum, there are only a few hybrids with a significant tolerance that have been identified. With the exception of these few, at best, all we can say is that certain hybrids are less susceptible than others. On a positive note, companies have been working to incorporate SCA tolerance into their forage sorghum, particularly those used for silage. It is expected that SCA-tolerant silage sorghum hybrids will be introduced to the market over the next couple of years.
In sorghum silage, Texas A&M University research has shown yield can be reduced as much as 40 percent prior to sorghum flowering if a high infestation of SCA occurs and is left uncontrolled.(1) Additionally, quality of the silage is reduced, primarily because of a reduction in starch. Both yield and quality are affected much less if the SCA infestation occurs after the grain milk stage. However, late infestations can produce honey dew in sufficient quantities that could interfere with harvest.
The insecticides labeled and most recommended for use in forage sorghum are the same as those used in grain sorghum. These are Corteva’s Transform and Bayer’s Sivanto Prime, and its soon-to-be replacement, Sivanto HL. The label for Sivanto HL includes soil applied application. This is new and will be especially useful in forage sorghum. A third product, Sefina from BASF, recently received a federal label for sorghum with state labels expected soon.
(1) Ed Bynum and Jourdan Bell. 2019. Sugarcane Aphid Damage to Forage Sorghum Silage Yield and Quality induced by different Infestation Levels for the Texas High Plains. TGSP Final Report. https://www.sorghumcheckoff.com/for-farmers/forage-production/.
This story originally appeared in the Fall 2020 Issue of Sorghum Grower magazine the From the Field department.