Shoot drying and its cause in Calamus simplicifolius at Nanmeiling, Hainan, China

Abstract

Many stems are subject to shoot drying in the plantations of Calamus simplicifolius Wei at the Nanmeiling Base of the Forestry Bureau of Baisha County, Hainan Province. As a palm, stems of C. simplicifolius stop growing and later die if the shoots are dry. Generally, shoot drying means reduced cane production and reduced profit for a rattan plantation. We aimed to quantify the incidence of shoot drying and determine its reason. We sampled eight 20 m × 20 m plots in the C. simplicifolius plantations. In each plot, we counted stems and categorized them as drying shoot or normal shoot, and mother stem or sucker stem. We measured stem length and categorized them as drying shoot and normal shoot for mother stems. We cut open each shoot-drying stem to determine the cause of drying from drying part to fresh part. The frequency of mother stems (259 stem·ha⁻¹), was significantly lower than sucker stems (588 stem·ha⁻¹). The percentage of shoot drying was 33.8% for mother stems, not significantly higher than that for sucker stems (18.9%). The mother shoot stems were significantly shorter if they were drying than if normal. 80% of stems with a drying shoot were hollow within the leaf sheath, whereas 10% hosted lively mature larvae (one larvae per shoot) and 10% hosted several lively young larvae. Mature larvae were identified as the Red Palm Weevil, Rhynchophorus ferrugineus Oliver. To confirm the present of the weevil, three pheromone traps for the weevil were set up in the plantations and adult weevils were trapped on the next day and identified as the Red Palm Weevil. We conclude that shoot drying of C. simplicifolius is probably caused by the Red Palm Weevil.