Entomology mission, Indonesia, Riau province, PT Musim Mas Group Plantations : identification of the root miner insect problem on oil palms planted on peat, 10 to 14 november 2007

The agronomy mission undertaken in May 2007 revealed the existence of a problem affecting the growth and yields of oil palms planted on peat at the Sorek plantation. Our mission confirmed the existence of a Lepidoptera caterpillar attacking the apex of oil palm primary roots; the attacks cause successive and repeated iterations of the root system. The tender tissues of the apex are targeted and the palm uses its reserves to reconstitute its root system to the detriment of growth and FFB production. The caterpillar displays the morphological traits of the Lepidoptera Sufetula sunidescalis Walker, but it will only be possible to identify the causal agent with certainty by rearing caterpillars to obtain the adult. Field observations clearly showed the need to set in place a series of trials in 2008 to identify one or more control methods to limit attack levels on the root system of the 15,000 ha of oil palms planted on peat at Sorek. The trials would consist in testing different treatments involving empty fruit bunches (EFB) spread around the stems to prevent females from laying eggs on the roots, spraying insecticides such as cyhalothrin or thiametoxan on the bottom 50 cm of the stem and on the soil near the stem, testing bare soil from which all debris has been removed, testing the planting of pineapples in the interrow to reduce infestation by adults and, lastly, testing ash spread around the stem. At the same time as those trials, it seems essential to take samples in plots planted on peat, to assess the level of Sufetula sp attacks on roots. In the longer term, by determining the attraction of adults in the field, it would be possible to trap the pest and reduce population levels below an economically acceptable level and estimate the spatio-temporal dynamics of the populations. This technique offers the advantage of being very ecofriendly and, ultimately, less costly. At the same time, it will be necessary to study the effect of the caterpillars on the development and yields of oil palms planted on peat. Lastly, it is proposed that training be organized, in the form of support missions, for PT Musim Mas staff at Sorek involved in Sufetula sp. control, which would include theoretical classes and practical demonstrations in the field of the different technical, experimental and observation techniques, in order to obtain statistically reliable results intended to promote control techniques on a plantation scale that are durable, ecofriendly and of no danger to human health