Soybean rust website expands to include soybean aphids

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included

Many of you are aware of the soybean rust web site ( sponsored by USDA last year. That site provides a map that shows soybean rust detections in sentinel plots and on kudzu, an alternate rust host. There is also commentary provided by state specialists. Knowing the progression of the disease north will help producers target scouting and apply preventative fungicide applications.

For 2006, there is a new feature on the web site – maps for soybean aphid. When you enter the site, simply go to the drop down menu in the top right corner, under the date and select soybean aphid. Two maps appear on the right side of the screen. The top map shows “SB Aphid Observations.” As of this writing (May 25) this map is blank (it isn’t active yet), but once reports of soybean aphid come in, dots will appear. While USDA is funding the sampling some sentinel plots for aphids, additional research plots and production fields may be sampled in certain states by Extension educators, state government, university entomologists and others. Unlike the rust map, which only has two colors (green for no detection, red for detection), the color of the dots on the aphid map will reflect the number of SBA per plant with purple dots indicating fields or plots over the 250 per plant threshold. The second map has the “SB Aphid State Update,” commentary by state specialists. Note that the color of the state reflects when the commentary was last updated.

By clicking on Michigan, you can read commentary by me on aphids. I will also include my detailed management recommendations, if aphid populations increase. Some of this information may be redundant of the Field Crop CAT Alert, but I since can update the rust web site daily if needed, the information will be more up-to-date.

A note of caution about the soybean aphid web site – entomologists in the region agree it should not be used to make spray decisions in your individual fields. This is different from how the rust maps are used. Detections of rust near your location will help to time preventative fungicide applications across a region. However, detecting soybean aphid in your area and even having fields go over threshold do not necessarily indicate your individual fields should be treated. We definitely know from 2005 that soybean aphid populations during an outbreak differ dramatically from field to field and that some fields need to be treated while other do not. We also know from 2005 that optimal timing of insecticide applications protects yield, which argues for scouting as needed and making field-by-field decisions. Use the soybean aphid maps to get information about aphid populations in general, but do not use the maps to make a decision about whether or not to treat your own fields.

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