A recent report from Dr. Clayton Hollier with Louisiana State University (LSU) documented the first find of soybean rust (SBR) on soybean in Louisiana and the U.S. for 2009. The find was in a soybean sentinel plot at the R4 (mid-pod) stage. That is a fairly early stage for a first find of SBR and it is cause for some concern (but NOT alarm). Usually, the first find of SBR in soybean for the year is made in beans that are at a later stage of development (late R5 or later).
According to a crop consultant I spoke with in southern Louisiana, this is the first time that SBR has been found in soybean BEFORE his growers had a chance to make fungicide applications. His point was not that they have “missed the boat”, but rather to indicate the earliness of this find relative to what they are used to seeing in southern Louisiana. To back up his statement, he told me about a rather large kudzu patch near an local apartment complex that LSU scientists regularly monitor, and that historically has developed massive SBR infections later in the summer. He said that patch is now heavily infected and is showing profuse sporulation. The weather conditions in much of Louisiana have been favorable for SBR for quite some time. So, this earlier than usual find does not come as a great surprise.
The US, from south to north, has a great many acres planted later than normal this year. This could increase the crop risk for SBR, but not necessarily so. We could have a late season dry period that shuts the disease down; or not. Time will tell, and I cannot rule anything in or out at this time. Thus, I encourage you to stay tapped into trusted sources of SBR information. As I learn more details, I will be certain to pass them along.