I can't answer the question about picloran, but can tell you that growing tomatoes in too rich soil and/or using too much N fertilizer definitely can increase the chances of BER fruits.

It's one of the many stresses, it causes the plants to grow too fast, that can induce BER.

THe good new is that the more mature the plants are they can withstand the many stresses that can lead to BER, but I think you'd better address the issues of growing in too rich soil, as that isn't going to go away, as well as maybe doing some Googling to find out about picloran. I know that many herbicides can affect plants directly by what's called drift, via air, but I don't know about any herbicides that are already in the soil in terms of what effects they might have.

Carolyn

Thanks. I will continue to watch the plants as more fruit sets and develops. Hard to find information directly relating picloram to BER but there may be a connection.

Some manures and other organic matter are contaminated with clopyralid, picloram or aminopyralid.

Here's info about clopyralid contamination which persists for a year
http://www.puyallup.wsu.edu/soilmgmt/clopyralid.htm

Here is a link that might be useful: contaminated manures, etc (WSU)

Jean, I did know that about the contamination, but didn't read all the links at the site you just put up, just a few, but saw no association with BER on tomatoes.

Or did I miss somthing, which is quite possible?

Carolyn