Sugarcane Aphid

The sugarcane aphid, Melanaphis sacchari, was discovered late in the 2013 growing season in the coastal sorghum regions of Texas. Public and private crop protection partners have researched and learned a great deal about the pest over the last seven growing seasons, and today farmers are effectively managing the aphid. Occasionally growers and consultants may refer to the sugarcane aphid as the ‘white aphid’ or ‘SCA’.

Diligence is key, and it is important for producers to scout fields and apply a recommended insecticide when the economic threshold is reached. Sugarcane aphids will only survive and multiply significantly in sorghum genotypes, including Johnsongrass, shattercane, sorghum-sudangrass, sudangrass, forage sorghum and grain sorghum. Sugarcane aphids will not survive on any of the major crops such as corn, cotton, soybeans or wheat. However, sugarcane aphids are distributed by the wind, so small colonies can be found in these crops, but at this time, they have not been found to be of economic importance. The sugarcane aphid that infests sorghum is a different biotype than the sugarcane aphid that is found in sugarcane but they look identical in appearance.

Resources

• Defense Against the Sugarcane Aphid Booklet
• Best Management Practices to Combat the Sugarcane Aphid

1. Fields should be scouted once a week for signs of the aphid. Once they are found, begin scouting at least twice a week. Look for small colonies of aphids that are bunched together on the underside of leaves.
2. Honeydew buildup on leaves is an obvious sign that can indicate the presence of the sugarcane aphid buildup. To determine if an insecticide treatment is needed, note the presence and number of aphids on leaves in at least four acres of the field.
3. In each area of the field examined, collect a leaf from the bottom and top of 20 plants, and observe the presence and number of aphids.

Source: Texas A&M AgriLife Extension

Two herbicides, Sivanto Prime and Transform WG, have proven to be effective products for controlling sugarcane aphid. In late 2020, Sefina received approval from EPA for use in sorghum. Sefina is an effective insecticide on sugarcane aphid, and has a different mode-of-action than Sivanto Prime and Transform. Growers are encouraged to rotate insecticides used to lower the risk of aphids developing resistance to the products.

One of the benefits of all three products is they are not harmful to beneficial insects, which is important for the control of sugarcane aphids. Care should be taken in adding other insecticides to the mix that could be harmful to beneficial insects.

Additionally, movement of Sivanto Prime, Transform and Sefina in the plant is minimal, making coverage essential for adequate control.

When other insects such as headworms and midge are present at threshold levels it is tempting to use one of the cheaper pyrethroids to control these insects. However, if sugarcane aphids are present in the field the use of pyrethroids may cause the aphids to quickly multiply due to the reduction in the beneficial population. Under these conditions consider using Prevathon, Blackhawk or other appropriate insecticides that maintain the beneficial insect population critical for keeping sugarcane aphid numbers in check.

Seed companies have now had multiple growing seasons to observe their hybrids and should have a good grasp of their tolerance level to sugarcane aphids. Growers in those regions where sugarcane aphid has been a reoccurring issue should visit with their seed company representative as well as seek advice from regional extension agronomists and entomologists when choosing hybrids.

When choosing a sugarcane aphid tolerant hybrid, all of the criteria used for selecting a non-tolerant hybrid should be considered. Growers are better off to plant a regionally adapted non-tolerant hybrid with good yield potential over a poorly adapted tolerant hybrid. Sugarcane aphid can be controlled with good scouting and timely insecticide application, if needed.

Current commercially available tolerant hybrids are NOT immune from sugarcane aphid. However, research has consistently shown that sugarcane aphids reproduce slower on tolerant hybrids and in some cases are able to withstand a higher sugarcane aphid population without a reduction in yield compared to susceptible hybrids. Tolerant hybrids should be scouted and an insecticide should be applied once the economic threshold has been reached.

Private companies and university sorghum breeders continue investigating tolerance and resistance. They have identified better sources of sugarcane aphid resistance and tolerance and are working to incorporate these qualities into commercially available hybrids.

Check with your seed company on which of their hybrids are most tolerant to sugarcane aphid. Many companies are now designating their most tolerant hybrids with a brand. For example, Alta Seeds brands their most tolerant hybrids with the APHIX brand.

If sugarcane aphids are in significant numbers in the sorghum head or on the upper leaves, harvesting can be impeded due to honeydew. There is not a good threshold level at this time for when to spray sugarcane aphids to assist in harvest.

If sugarcane aphids are present and produce a significant amount of honeydew that can gum up the combine, growers should consider applying the lowest labeled rate of insecticide to control the aphids. Check the pre-harvest interval as this can vary depending on the state and insecticide used.

A false assumption is that using a harvest-aid such as glyphosate will control sugarcane aphid prior to harvest. This is not the case, and may make the problem worse by causing the aphids to migrate from the dessicated leaves to the sorghum head. If a harvest-aid is used as sugarcane aphids are present in significant numbers, it is recommended that an insecticide be added to the application.