November 16, 2012

90-Day Soy Free Period Moved Earlier for Producers in M.T. do Sul

Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.

Starting in 2013, the 90-day soybean free period in the state of Mato Grosso do Sul will start and end 15 days earlier than what had been in effect for the last several years. In 2013, the period during which any live soybean plants must be eliminated will start on June 15 and end on September 15. The reason why volunteer soybean plants must be eliminated during this period is SEto slow the spread of soybean rust from one growing season to the next. With this change, the state of Mato Grosso do Sul will have the same 90-day soybean free period as the other two center-west states of Mato Grosso and Goias. The change has made because farmers in the state wanted to be able to plant their soybeans earlier in order to allow enough time for a second crop of corn to be planted after the soybeans are harvested.

As a result of this change, farmers in the state may need to modify their rust control procedures as a result. First and foremost, farmers will need to start eliminating volunteer soybeans fifteen days earlier than what they have done in the past. The earlier these volunteer soybeans are eliminated, the less likely it is that the disease will remain viable during the 90-day period.

For soybean planted as soon as the prohibition period ends, the recommended control measures will remain unchanged. But, for later planted soybeans, farmers need to start their control measures earlier than what they have been accustomed to. The earlier planted soybeans may now be infected earlier as well making the later planted soybeans more vulnerable to the disease.

Farmers in the state are advised to start checking for the disease in their fields even though the soybeans might still be in vegetative development. A preventive fungicide application is recommended as soon as the canopy closes (the leaves cover the rows) or the soybeans start to flower, whichever comes first.

Once fungicide applications begin, they should be reapplied at intervals of 25 to 35 days for the remainder of the growing season. Application intervals should be shortened during times of frequent rainfall when the fungicide might be washed off the plants.

Earlier this week, two cases of soybean rust were confirmed in Brazil. One case was confirmed in the state of Mato Grosso and one was confirmed in the southern state of Santa Catarina. In both instances, the disease was found on volunteer soybeans growing along the side of the highway. Even though the disease has not yet been found in commercial soybean fields, it is probably just a matter of time before it will be found in the newly planted soybeans.

As the summer rains pick up in Brazil, the chances of the disease spreading from field to field also increases. Farmers do not have the option of ignoring the disease, because left untreated; it can reduce soybean yields by as much as 80%, especially if the plants are infected early in the growing season.