Sugarcane Aphid, How Far We’ve Come

The 2019 growing season will mark the seventh anniversary of the discovery of the sugarcane aphid in sorghum in the United States. Since that time, farmer and industry knowledge of the pest and how to deal with it has come a long way.

Article by Brent Bean

The 2019 growing season will mark the seventh anniversary of the discovery of the sugarcane aphid in sorghum in the United States. It was first detected along the Gulf Coast region of Texas and Louisiana in 2013.

Since that time, farmer and industry knowledge of the pest and how to deal with it has come a long way. How the sorghum community dealt with the sugarcane aphid has been a great example of how the Sorghum Checkoff, National Sorghum Producers, USDA-ARS, university research and extension, and industry can work together to solve problems facing growers.

The Problem

The aphid became a significant issue in the southern regions of the U.S. in 2014, and by 2015 it had spread to 17 states. In 2015, the sugarcane aphid invaded U.S. sorghum with a vengeance, infesting fields for the first time in the Texas south plains and panhandle, Oklahoma panhandle, Mid-South and western and central Kansas.

Growers were unfamiliar with the pest with few realizing just how fast the aphids could multiply and damage their crops. By the time many growers realized they had a problem, sugarcane aphid populations had reached levels that made them difficult to control or had already caused significant yield loss.

Many fields were sprayed multiple times in an attempt to control the aphid, while other fields were abandoned. The sorghum industry, at this time, realized this was a serious problem with a new pest that was not going away.

Response

In January 2016, the Sorghum Checkoff, in partnership with private industry, initiated a conference that brought together entomologists from across the nation to share information on the sugarcane aphid and its management.

Research and extension entomologists in the South, in many cases without any funding, had begun conducting sugarcane aphid trials in 2014 and 2015. Data and conclusions from these trials were shared at the conference, summarized by the Sorghum Checkoff and distributed to ag advisers throughout the sorghum-growing regions of the U.S.

This information was then shared in winter grower meetings, news releases and other media. Additionally, the Sorghum Checkoff funded research and worked with key entomologists to implement studies in 2016, and later in 2017 and 2018, to answer key questions about managing the sugarcane aphid.

At the same time, private industry was also doing their part. Sorghum seed companies quickly began screening their hybrid inventory for sugarcane aphid tolerance, while private industry and public sorghum breeders began searching for sources of sugarcane aphid resistance.

Dow AgroSciences supported multiple state Section 18 approval requests for the use of Transform insecticide, and Bayer Crop Science was able to obtain a 2EE label for the use of reduced Sivanto® rates in sorghum.

National Sorghum Producers began lobbying for federal funds to conduct research on the sugarcane aphid. This led to USDA-ARS providing $2.2 million for the funding of two five-year regional projects initiated in September 2016.

Where We Are Today

The sorghum industry now knows how to manage the sugarcane aphid, and the situation has greatly improved. As growers do a better job in controlling sugarcane aphids, everyone benefits.

Fewer aphids are available to migrate north when South Texas growers manage their aphids. Similarly, when better regional control of aphids occurs, the potential spread of aphids from field to field is greatly reduced.

Since 2015, the number of acres reaching sugarcane aphid threshold levels has decreased each year. The best estimate by entomologists is less than 15 percent of fields in South Texas and the Coastal Bend regions required an insecticide application for sugarcane aphid in 2018.

Acres requiring spraying in Central Texas and Oklahoma were also greatly reduced. Only a few acres were treated in western Kansas, and those acres treated in south-central Kansas normally required only a single application.

Acres in Mid-South and Mid-Atlantic states reaching threshold levels were also generally controlled with a single application. The hot-spot in the U.S. the last two years has been in the South Plains and the central and northeastern Texas Panhandle regions.

The best estimate is 50-60 percent of the grain sorghum acres in these regions were treated for sugarcane aphid in 2018. Even in this area, sugarcane aphid infestations levels have gradually decreased since 2015.

The Future

Entomologists expect beneficial insects to continue to adapt and take advantage of the sugarcane aphid as a new food source. Beneficials are critical to keep populations of sugarcane aphids at acceptable levels.

Seed companies will continue to identify hybrids with better tolerance, and breeders will develop new, improved sources of resistance. Additionally, it is expected sugarcane aphid scouting methods will be become more efficient with more precise threshold levels identified. Research is also ongoing to develop models to better predict the movement of the sugarcane aphid.

On the insecticide front, Bayer Crop Science will soon come out with a new, more concentrated Sivanto® formulation and with a different adjuvant load. The industry has primarily been relying on Transform® and Sivanto® to control sugarcane aphids once threshold levels are reached.

Although these two products have slightly different modes-of-action they are in the same chemical classification. BASF is anticipating labeling insecticide for sugarcane aphid control in sorghum for the 2020 growing season. The insecticide will contain a new active ingredient that will be sold under the name Sefena®. Having a new active ingredient that can be used in rotation with Transform® or Sivanto® is important to reduce the potential of sugarcane aphids becoming resistant to any given insecticide.

While challenges are still present for producers, collaboration between industry, the Sorghum Checkoff, NSP and growers has led to major advancements in battling the Sugarcane Aphid. Thanks to this collaboration, the future for you—the producer—is promising.