Endosulfan (Thionex) Cancellation Update

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Endosulfan (Thionex): As a reminder for the 2011 season, all registrations for endosulfan were canceled as of December 2010. Although there is a phase out plan, there is not an existing stocks provision past the end dates. That means that you can no longer legally use it on a crop after the end date for that crop – so be sure to look at the link below since dates vary with crops. Also, there are a number of important changes to the Phase Out Labels, regarding REIs and PHIs that did not make it into the 2011 vegetable recommendations so be sure to read the label before making any applications. As a reminder, the Commercial Recommendations are only a reference — the label is law and you are required to read and follow the label before making any pesticide application.

As indicated above, the phase out plan includes end use dates for all currently labeled crops as well as additional mitigation measures during the phase-out period. In addition to mitigation requirements placed on endosulfan labels in previous years, EPA is requiring new mitigation measures for many crops during the endosulfan phase-out period. As stated in the Federal Register, “although these additional mitigation measures are designed to reduce worker risks, restricting and phasing out all uses of endosulfan will also address risks to wildlife and the environment.” Additional mitigation required during the phase-out varies by crop and includes measures such as: canceling aerial use and specifying other application methods, extending Restricted Entry Intervals (REIs), extending Pre-Harvest Intervals (PHIs), and reducing maximum single and/or seasonal application rates. As always, the label is the law so it will be critical to read all labels carefully to be sure you are following all restrictions.

Just one example of the changes – and there are many more so reading the label is critical – is that the Restricted Entry Interval (REI) on melons, cucumbers and summer squash is now 4 days; for pumpkins and winter squash it is 7 days. The PHI (pre-harvest interval) has also been increased on all cucurbits and differs between cucurbits so be sure to check carefully. In addition, Thionex can still be applied by air on melons only. It can only be applied by ground on cucumbers, pumpkins, winter squash and summer squash. (http://www.cdms.net/LDat/ld9P4000.pdf).

Be sure to read all labels and check the following Federal Register Link for more details on the specific end use dates and mitigation required. http://www.epa.gov/pesticides/reregistration/endosulfan/endosulfan-agreement.html