Chemical ripening in South Sumatra

Two semi-commercial trials with four chemicals are described which were car ried out during 1999 and 2000 on the Gula Putih Mataram Group's three estat es in Indonesia. The first trial determined the optimum time for harvest af ter sprayings i.e. between two and eight weeks. The chemicals used were Eth rel (ethephon), Moddus (trinexapac-ethyl), Roundup (glyphosate-isopropylamm onium), and Touchdown (glyphosate-trimesium). While all four improved sugar yields, Touchdown was the most cost-effective ripener increasing the yield s by between 0.5 and 1.5 t sugar/ha. This improvement depended when the che mical was applied, and the time the treated crop was harvested. Only the gl yphosates affected the early growth of some varieties, however, this was tr ansient. There was no effect on the cane yield. Based on these data, the Gr oup's management has therefore decided to chemically ripen around 60 % of t he area to be harvested during 2001.