Excessive Blanking in Pistacia vera cv. 'Pete 1'

There is limited breeding done to improve the commercial pistachio varieties. One promising new cultivar, 'Pete 1', has been planted commercially in the past 7 years. It has become a concern to growers that the nuts produced on this cultivar tend to have a high blanking percentage. Our investigation has been in response to grower's observations of possible causes for such a widespread and economically detrimental development. In the first year, we conclusively disproved the idea that the cause of the blanking was due to insect pressures from pests such as lygus and calocoris. In this second year, we propose to investigate the fungal communities and their effects on early bloom and nut set. We will also approach the problem from a physiological point of view and perform a thinning study to see if 'Pete 1' is over-producing fruits to an amount which it cannot fill from a photosynthetic resource point of view.