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Weather Forecast

Feb 9, 2017

Sulfoxaflor Emergency Exemption

Sulfoxaflor (Transform) has been granted an emergency exemption for use on sorghum (targeting the sugarcane aphid) in 2017. You can read the details here.

Both Sivanto and Transform are highly effective against the sugarcane aphid (SCA) in sorghum where other aphid insecticides tend to fall short. Having both chemistries in our tool belt is vital to slowing the development of resistance. Sivanto has longer residual action, up to 3 weeks or more in the right conditions.

SCA move to the heads as the sorghum plants reach maturity. This is possibly because the nutrient availability in the plants change or the leaves lose moisture. 

Brief SCA Review for 2017

Managing the SCA truly requires an integrated approach. With recent developments in variety selection for tolerance to SCA, its starts with making the right choice in seed. In 2016, over 20 varieties have been identified as being tolerant or resistant to SCA: either SCA populations don't develop as quickly on these varieties, or they can withstand much higher infestations without yield loss than susceptible varieties. Varieties don't always preform the same in one region to another, so be sure to reference local data as much as possible when selecting them.

The next important decision to make is planting timing. Research and field observations consistently show that earlier planted fields have fewer SCA problems and can often avoid being treated at all. Seed treatments also play a large part in early season infestation levels.

Because SCA reproduce so quickly in the right environment, scouting fields on a regular basis is key to preventing yield losses. Populations can literally go from in the 20's per leaf to in the 100's within a week. Some research from Georgia shows that a treatment delayed by 5 days can cause a 75% reduction in yield compared to a timely spray.

It is unclear what kind of effect biological control plays on SCA populations at this time. Due to the sheer number the aphid can produce, and the fact that SCA are rarely parasitized by wasps, natural enemies may not be able to suppress them at certain levels. However, choosing the right treatments and keeping impacts on beneficials low is still important.

As grain sorghum nears harvest, some producers choose to desiccate entire fields instead of applying insecticide. This method has many benefits: no insecticide pressure means lower chance of resistance development, usually aphids don't have time to move into the head and create honeydew build-up, and it allows for timely harvest. However this does not fit every field in every situation and heavily depends on timing.

These few plants were missed by the glyphosate applications. SCA flocked to them as the only source of food in the field and they became drenched in honeydew.
If you need help making an "attack plan" for SCA this season, your local AgriLife office has specialists and agents on hand to answer any questions.

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