Weeds- Chateau and Stylet Oil.  Last week we saw a situation where the grower had applied a foliar spray with JMS Stylet Oil, following use of the same tank to apply herbicides, including Chateau, the newly registered pre-emergent herbicide from Valent.   Apparently the oil in the stylet oil acted as a solvent for residual chateau that coated the sprayer tank.  This could only be a problem if: 1) you use your foliar sprayer tank for applying herbicides, 2) you applied JMS Stylet Oil, or another oil-based product, and 3) you didn't thoroughly clean your sprayer.  The Chateau label gives detailed instructions on cleaning your sprayer following use of chateau.  See the note below from Regina Rieckenberg:

From Regina Rieckenberg, Valent:
Clean Your Sprayer after Chateau Application.   Chateau is a highly active pre-emergent that also has some post-emergent activity.  Because of that, it is essential to clean out your sprayer properly after Chateau application, especially if the same sprayer is used to spray fungicides or insecticides over the top of vines.
The full clean-out procedure can be found on the Chateau label or the technical bulletin can be downloaded at::
http://www.cdms.net/ldat/ld6ED009.pdf