Budrot (BR) and premature nutfall (PNF) caused by Phytophthora spp. are the major plant disease problems affecting coconut in Indonesia, notably PB121: a variety promoted under various smallholder coconut rehabilitation programmes. This project aimed to increase our knowledge of BR and PNF in Indonesia through socio-economic review of smallholder coconut based cropping systems and analysis of the genetic structure, host specificity and distribution of Phytophthora spp. populations.