A plant improvement program to develop varieties from Ramu, Papua New Guinea

New Guinea is a centre of diversity for the genus Saccharum with several species, S.officinarum (noble canes), s. edule (pit pit), S. robustum, and S. spontaneum being native. Many clones are grown in gardens (noble canes and pit pit), while the wild species are common along riverbanks. Commercial production of sugarcane in PNG began in the Ramu valley in 1979 and the first sugar was milled in 1982. In 1999, a production of 519 600 tonnes of cane producing some 44 500 tonnes of sugar was achieved. Ragnar, a CSR variety from Queensland, was the main variety in the early stages but a new disease, Ramu stunt, proved to be devastating to its production, and it was replaced by Cadmus. Also in the mid-1980s, the moth borer Sesamia grisescens caused significant damage with losses up to 32 t/ha since 1985. About 650 varieties have been imported and tested under Ramu conditions. However, more than 90% of these have been discarded due to poor agronomic response or susceptibility to diseases and pests. A breeding program was initiated and the first crosses were made in 1992. The objectives of the program are to develop high yielding, high sucrose varieties with resistance to the major diseases (Ramu Stunt, Downy Mildew, Leaf Scald, and Fiji disease) and tolerance to pests. The selection program is described. More than 100 clones have reached advanced stage trials, and preliminary results indicate the first locally developed varieties could be released within the next few years.