May 2005. A farmer from Taveuni, Fiji, (who is also a processor), has cassava with fibrous inclusions within the root tissues. Although the photo here only shows one, he says that often there are two or three distributed around tuber. There appear to be no exit/entry points, the fibres are totally discreet within the tuber.
It means that for processing (freezing), they have to cut them out and now they are losing too much because of all the cutting out of these parts.
The farmer knows that there is zinc deficiency in the area, so he added zinc, but the problem has not changed. He is now wondering about boron. The problem is worse in rocky soil.
The reference book for nutrient problems in cassava is: Asher CJ, Edwards DG, Howeler RH (1980) Nutritional disorders of cassava (Manihot esculenta Crantz). Dept. of Agriculture, University of Queensland, St Lucia, Qld.