Biobarrier® consists of composite nodules injection-moulded through Typar® *, a spun bonded polypropylene geotextile fabric. The through injection moulding technique ensures permanent nodule attachment. Impregnated with trifluralin, the nodules function as a protective reservoir. The nodule composition is designed to slowly release trifluralin vapours, which adsorb in the soil.
Outside the nodule, the trifluralin degrades but is continuously replaced by new material, building and maintaining a root inhibition zone. Accurate nodule spacing ensures the individual nodule zones overlap and reinforce each other. At equilibrium, the inhibition zone becomes contiguous, enveloping the Biobarrier fabric.
When roots enter the inhibition zone, root tip cells cannot divide, preventing growth in that direction. Trifluralin is not systemic; therefore, it is not taken into the plant. As a result, the root system is diverted away from the Biobarrier-protected structure without adversely affecting the desirable plants or trees. Root branches outside of the zone are not affected.
By utilising a technology that combines a proven geotextile drainage fabric with an effective pre-emergence herbicide, Biobarrier also marketed as a pre-emergence weed control fabric for landscaping, prevents grass and weed growth without affecting desirable plants. When covered with 50 mm (2”) of mulch, stone, or other medium, the trifluralin inhibition zone both above and below the plane of the fabric blocks grass and weeds from establishing a viable root system needed to support growth. Additional protection is provided by the 136 g/sq. m (4 oz./sq.yd.) geotextile fabric, which blocks existing grass, and weeds from coming up through the fabric. New plants or desirable existing plants that have roots below the 50 mm (2”) inhibition zone are not adversely affected.
*Tekton is the trademark used for polypropylene products outside of North, Central and South America, Israel and South Africa.
The root inhibition zone is created and maintained by the trifluralin released from the nodules. Consequently, the highest trifluralin concentration in the soil is at the plane of the barrier, with concentration levels diminishing as distance from the barrier increases. The concentration level effective for all roots measured is less than 7.6 ppm. Plant species vary in resistance to trifluralin. This concentration level at zone equilibrium, based on field and laboratory measurements, occurs approximately 25 mm (1”) from the barrier. Some root branch elongation may occur after the root tip meets the effective concentration level, pushing the tip within the 25 mm (1”) zone.
With a water solubility of 0.3 ppm, trifluralin does not present a significant leaching problem. Additionally, trifluralin has a high soil adsorption and short half-life.
With a U.S. EPA Class IV rating and an Oral LD50 of 10,000, technical grade trifluralin is considered practically non-toxic, ranking it between sugar (29,700) and salt (3,000). Since only a minute amount of trifluralin is emitted from the Biobarrier nodules at any point in time, the hazard is minimized.
The hemispherical shaped nodules on Biobarrier contain one active ingredient (trifluralin) and two inactive ingredients (polyethylene and carbon black). Biobarrier is engineered to release the trifluralin very slowly in vapour form and establish a narrow (see chart below) protective chemical zone in soil adjacent to the fabric. This unique delivery method, combined with the chemical characteristics of trifluralin detailed below, ensure that the chemical zone remains very near the fabric and does not present a significant leaching problem. Trifluralin has been used extensively in commercial applications for over 40 years and widely recognised as a leading pre-emergence herbicide. See EPA Toxicity Rating for trifluralin below.
|Solubility in Water||< 0.3 ppm @ 25° C|
|Vapor Pressure||1 x 10^-4|
|Degradation in Soil||1 to 6 months|
|Air Photolysis||42 Minutes|
|Water Photolysis||9 Hours|
|Soil Photolysis ( Dark )||41 Days|
|Soil Photolysis ( Light )||66 Days|
|Classification||( mg. Kg. )|
|1. Extremely Toxic||50|
|2. Highly Toxic||50 to 500|
|3. Moderately Toxic||500 to 5,000|
|4. Practically Non-Toxic||5,000 to 15,000|