Curative Activity of Watery Fermented Compost Extract as a Bark Treatment against Tapping Panel Dryness

Abstract

Background: Tapping panel dryness (TPD) is a stress-related disorder that afflicts rubber trees, contributing to yield losses in nearly every rubber-growing region. Method: We demonstrated the curative effects of biostimulants containing a fermented watery extract of shrimp waste-enriched compost (SWCE) on TPD in field trials. Undiluted SWCE was applied to lightly scraped bark in the first, third, and fourth trials, and applied directly without bark scraping in the second trial. Results: Bark treatment significantly (p < 0.05) reduced tapping cut dryness and increased latex yield, suggesting recovery from the disorder. When SWCE was applied to pre-scraped bark, 80% and 30% of trees with partial and complete TPD, respectively, recovered from tapping dryness within 2 months. The latex dry weight of treated trees with partial and complete TPD was 77.5% and 21.1% that of healthy trees, respectively. We observed slight recovery from TPD in trees treated without bark scraping and in trees with a history of ethephon stimulation. No curative effect of SWCE was demonstrated in treated trees without a tapping rest period. These findings suggest that compost extract could be a useful treatment for partial TPD.