Research looking at using kaolin clay to reflect warming from the sun on pistachio trees is showing good results. Cooperative Extension Pomology Farm Advisor David Doll says in hindsight growers could have made the application earlier in their trials which would have showed more of a yield increase. Growers could see significant benefits by applying the clay earlier and Doll added that the product is a fairly cheap tool to help during low chill years.
More About the Research
From The Almond Doctor blog: In attempts to increase chill unit accumulation in the winter of 2014-2015, several applications of Kaolin clay (Surround®) were made to a ‘Kerman’ with ‘Peters’ pistachio orchard located near Coalinga, CA. Seven rows were randomly selected and sprayed, and the remainder of the orchard was left untreated. The first application was made on January 10th, 2015 with 40 lbs/acre of Surround® applied by ground rig. Follow up applications were made after rains on January 23rd and February 10th, 2015. Data loggers were installed in four trees, two data-loggers per treatment, with three sensors per tree on February 6th, 2015. Sensors in untreated and treated trees were 100 feet apart.
Temperature sensors were wrapped around the wood in order to measure the temperature of the wood with one sensor in the northeast and southwest quadrant of the tree, while the third measured ambient air temperature. Upon data logger removal, chill portions were calculated by taking hourly temperature data and using the spreadsheet available at http://ucanr.edu/sites/fruittree/How-to_Guides/Dynamic_Model_-_Chill_Accumulation/. At harvest (September 15th, 2015), clusters were counter per tree and individual tree harvest were taken. Ten randomly selected trees in each treatment were measured for the paired study. Read more from The Almond Doctor blog.