Heard a story on the radio this morning, a company is producing a product which increases resin production in pine trees (used to ward off pine beetles which have become quite a problem here). Who knows how well it works but you can read about it on the links.
http://www.biocontrols.com/secure/shop/item.asp?itemid=141
http://www.epa.gov/pesticides/biopesticides/ingredients/factsheets/factsheet_128930.htm
http://www.biocontrols.com/secure/shop/item.asp?itemid=141
http://www.epa.gov/pesticides/biopesticides/ingredients/factsheets/factsheet_128930.htm