Pistachios and Poison Ivy

My daughter knows of my interest in all things agriculture and sent to me this image of a Pistachio orchard in New Mexico which she took on a recent trip there.  Pistacia vera is the primary cultivar of Pistachio grown in the United States.  The tree is a native of Central Asia and Iran still accounts for over half of the world's production.  The U.S. is the second largest producer with about half what is produced by Iran.

Like a number of other fruit and nut trees, Pistachios are vulnerable to many diseases so, they are frequently grafted onto root stocks from species that are more resistant.  Oak and Mesquite are commonly used to provide the root stock for many of the Pistachio orchards in the U.S.  Since Pistachios do best in dry climates, drought tolerance is also a consideration.  In the image above, there appears to be an irrigation system.

Pistachios are members of the Anacardiaceae Family which also includes poison ivy, sumac, mango and cashew.  Plants of that Family produce an oily substance called urushiol which is an irritant.  I am very familiar with this particular irritant since I am currently recovering from a recent brush with poison ivy.  Apparently there is varying sensitivity among people to the urushiol and I seem to be among the more sensitive.  The concentration of urushiol on the leaf surface of the poison ivy is often highest in the fall.  Silly me, I figured spring was the time to most fear the plant.

Urushiol is an oleoresin that is absorbed very quickly by the skin.  The toxin is recognized by the dendridic cells (Langerhans cells) which then migrate to the lymph nodes where they present the template for the toxin to the T-lymphocytes (aka "killer" T-cells), stimulating them to travel to the site of contact and begin production of cytokines and cytotoxins that seek out and destroy the urushiol.  This reaction is what causes the blistering and eventual death of the skin cells at the point of contact.  The T-cells literally kill the infected cells to rid the body of the toxin.

I have never been a big fan of Pistachios.  Others in my family absolutely love them.  I wonder if the affinity/adversity to them is related to susceptibility to the effects of the urushiol?  Something to ponder on this fine Monday morning....