Abstract:
Weed management is essential in agriculture to prevent Economic Crop Damage in farm products due to quality and quantity
losses. Herbicides are profusely being used to meet this objective despite their hazardous nature on human health and the
environment caused by residual contamination of food and drinking water. Sri Lanka imported 7,967,852 kg and 5,675,611kg of
Herbicide chemicals in the forms of bulk and ready to use formulations in year 2013 and 2014 respectively and Commercial Tea
Plantations too are heavily depend on herbicides to maintain “Clean and Clear Ground Concept” (CCGC) based mind set
established in the sector. However, CCGC is not recommended by Tea Research Institute of Sri Lanka due to severe degradation
in the tea soils resulted. Many of the so called weed species has the ability to thrive in degraded poor soils forming a quick ground
cover arresting further depletion in soil and upgrade same by addition of Organic Carbon as leaf litter and root secretions feeding
soil microbes. This study explored the diversity and perennial behaviour of the Natural Vegetative Regeneration (NVR) in
Commercial Tea Soil under herbicide-Free Conditions to demonstrate the possibility of practicing Herbicide-Free Integrated Weed
Management (HFIWM) in the Tea Industry at commercial scale in Sri Lankan conditions. The survey commenced in Hapugastenne
estate Maskeliya Plantations PLC., following to pruning, on a weed free, exposed Tea field in an extent of one hectare, where
natural regeneration of vegetation was allowed and monitored, under a Treatment of “Herbicide - Free Integrated Weed
Management” (HFIWM), for three years. Non-IWM (Control) area of similar extent was demarcated adjoining to said area and
sprayed with Diuron, Paraquat and Glyphosate, as recommended by the Tea Research Institute of Sri Lanka. The naturally
regenerated Terrestrial Vegetation in treated and control areas, was surveyed periodically and simultaneously, by investigating 3m
X 3m sample plots with four replicates each time, concerning species diversity and recorded the variations observed. Non-IWM
section displayed a continuous increase in plant diversity up to 76 species, within three years, dominated by Herbicide tolerant
weed species. Vegetation established on HFIWM area reached a peak of 64 plant species within the first year itself, forming a
complete ground cover whilst effectively suppressing many of the targeted notorious weeds which cause severe economic damage
in Commercial Tea Plantations.
