RATNAGIRI DISTRICT, India — When the cashew harvest starts here, the orchards clinging to the lush, wrinkled hills are blanketed by a brilliant yellow, orange and red carpet, created after farmers pluck the nut and toss its stem to the ground. There, the cashew apples, as the stems are known, quickly rot, except for a few used to brew a local spirit called fen that is popular in neighboring Goa.