Mississippi Soybean Sentinel Plot Update and Regional Soybean Rust Situation

Tom Allen, Extension Plant Pathologist
By Tom Allen, Extension Plant Pathologist June 4, 2011 07:13

Mississippi Soybean Sentinel Plot Update and Regional Soybean Rust Situation

Funding has been secured to monitor for soybean rust from the United Soybean Board and to conduct a general soybean disease monitoring program through funding from the Mississippi Soybean Promotion Board.  As in the past, soybean sentinel plots were planted in Mississippi to monitor for the incidence and severity of soybean rust.  Twenty sentinel plot locations (Adams, Amite, Claiborne, Coahoma, DeSoto, Hancock, Harrison, Hinds, Issaquena, Jackson, Lee, Monroe, Noxubee, Pearl River, Pike, Tippah, Tishomingo, Walthall, Warren, Washington) were planted with either a Maturity Group III, mid-V, late-V, and MG VII (@ 16 locations), a late-V and MG VII (@ 3 locations), and a MG VII (@ 1 location).  The spring floods have erased two of those sentinel plots, one each in Adams and Warren counties.  At present, deer have eradicated the sentinel plot in Jackson County but once the wheat is harvested in the vicinity and soybeans are planted adjacent to the sentinel plot this plot should recover.

The telephone hotline is still available and will be updated on an as needed basis with regards to the presence of soybean rust in adjacent states as well as the general soybean disease situation in MS.  The telephone number is still: 866-641-1847.  This is a free telephone call and the information contained on the hotline will aid in soybean disease management decisions.  Also, updates will continue on the ipmPIPE website that is still available at www.sbrusa.net.  For the foreseeable future, counties will continue to be updated as either green (having been scouted and no soybean rust detected), red (having been scouted and soybean rust detected in either kudzu, soybean, or an additional host plant), and red hatched (soybean rust having been detected and no longer reported).  In the past there has been some consideration as to changing the color scheme to different colors to alert producers.  Please keep in mind that just because a county goes red this does NOT mean that a fungicide is automatically warranted.  Stay tuned to extension personnel, call the hotline, check the website, monitor the Mississippi Crop Situation Blog, or call me personally for more specific information.  I realize that in some cases, coloring an entire county red may cause undue angst but I am not in favor of changing this system since it has been in place for a number of years and adding/changing color schemes would likely cause more confusion.  At present, the suggested management schemes are still available through the University system and available at http://msucares.com/pubs/publications/p2371.pdf.

Following the national soybean rust telephone conference on Tuesday, May 31, 2011 the updates from other states in our region are as follows:

Alabama: Soybean sentinel plots have been planted at 20 locations throughout the state.  Plot planting was delayed compared to the past years due to inclement weather that occurred throughout the northern part of the state and drought in the southern part of the state.  At present there is no soybean rust in AL.  Extreme drought is occurring throughout the southern parts of AL.  Volunteer soybean plants are present at some locations and will continue to be scouted for as long as they remain alive.  Kudzu is beginning to wilt due to the dry conditions.

Florida: To date, soybean rust has been detected in 3 counties on kudzu.  The specific locations are traditionally positive; however, the kudzu site in south FL (Miami-Dade County) was just detected this season.  At present, much of FL is hot and dry but receiving rain in some localized areas.  Typically, April and May are dry months (along with October) and rain events will usually increase in June with the occurrence of pop-up rain showers during the afternoon. 

Georgia:  No soybean rust has been detected in the state.  Conditions are hot and dry throughout the southern reaches of GA.

Louisiana:  No rain in weeks and conditions continue to be hot and dry throughout most of the state.  Continued hot and dry conditions are expected over the next ten days.  Kudzu has begun to wilt throughout much of the state.  Essentially, nothing to report with regards to the presence of soybean rust at this time.

Mississippi:  No soybean rust to report at this time.  The sentinel plots that remain have generally reached a good stand save for the plots that have flooded.  Kudzu has leafed out throughout the state and continues to grow.  Hot and dry conditions are forecasted throughout the state for the better part of the next 10 days with almost no chance of rainfall.  Weather forecasters suggest that in some locations we are 6-12 inches of rain behind over the past 60 days (or longer).  Keep in mind that hot and dry conditions are not conducive for the development of soybean rust.

Texas: Scouting has focused on soybean planted in the lower Rio Grande River Valley.  However, an extensive drought has continued throughout south TX.  Scattered showers have relieved very little of the drought in the past few weeks. 

In other developments over the winter months.  Soybean rust was detected in a potted sentinel plot established and maintained by high school students at the Navy Base at Guantanamo Bay, Cuba.  The initial detection occurred on February 14, 2011.  Aside from one other report of soybean rust in Cuba during 2009 (through a publication in an international journal) this is the first winter report of soybean rust occurring on the island of Cuba.  In addition, soybean rust was detected in breeding plots in Puerto Rico on the northern side of the island.  Another report of soybean rust from this Caribbean island occurred on May 27 on soybean on the southern side of the island.  How this will impact the situation in the U.S. is unknown at this point.  However, it is widely thought that soybean rust blows into FL during the winter from somewhere in the Caribbean, and overwinters on kudzu in locations where kudzu doesn’t go dormant due to cold temperatures.

The updated fungicide list is included with this posting.  The one major change has to do with the addition of some new products.  Specifically Evito T and Stratego YLD, both combinations of a strobilurin and a triazole can be applied for soybean rust management.  Please note this product is a bit different than Stratego because it contains prothioconazole (Proline) and not propiconazole (Tilt).

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Tom Allen, Extension Plant Pathologist
By Tom Allen, Extension Plant Pathologist June 4, 2011 07:13
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