Sunday October 30, 2005

New Vigilant Herbicide Gel

Woody weed control can be an ongoing problem for small block owners and bush regeneration specialists - especially for those who want to approach the control in an environmentally-friendly manner.

Recognising that effective woody weed control was a problem, HortResearch scientists Brian Ward and Ron Henzell began investigating control options about 7 years ago in New Zealand. They formulated and trialled a range of herbicide active ingredients in gel formulations. Different application methods were also trialled as it was recognised that to solve a weed problem the application method, in combination with the gel, was a key to the success.

The end result of extensive field work was the development of a low toxicity herbicide gel containing 4.3 % picloram as the active ingredient. With a low percentage active ingredient, the level of toxicity is less than, for example, glyphosate. A safe-to-use product was something that was recognised as being important, in particular for casual users.

A practical solution, in the form of a low-toxicity herbicide gel, is now available for the control of problem weeds and vines including gorse, privet, wild tobacco, camphor laurel and cotoneaster to name a few. In this article we discuss some of the background trials that have gone into the development of this product.

Herbicide spraying is often not an appropriate or an acceptable weed control method, especially in ecologically sensitive areas. Ecological problems with foliar application can include chemical runoff and residue build-up in the soil.

There is increasing public pressure against the foliar application of herbicides in sensitive and urban areas, with some city councils now avoiding herbicide sprays in their weed control programmes. Landowners are seeking a responsible and clean approach to weed control whereby chemical spray drift will not trespass on their own or neighbouring properties. Yet, vegetative removal or cutting back of many noxious weeds is often impractical, or at best, only a temporary solution. Many woody weed species have a propensity to re-shoot if not treated with a herbicide.

The gel is packaged in a brush bottle, which is small enough to be carried around the farm easily and is ready to be used at any time. This eliminates the need for a knapsack sprayer and avoids the user having to mix up any chemicals.

The gel can be either applied by cutting the plant with a pruning saw or loppers and then directly squeezing the gel on to the cut stem from a brush bottle.

The gel is absorbed directly into the plant and, provided the gel is applied carefully, there is no runoff and hence no soil or adjacent plant contamination. The best results are achieved by applying a 5 millimetre thick layer of the gel over the entire cut stem. As an indication, about 2 grams of gel are normally applied onto a 25 mm cut stem. Therefore, the 240 gram brush bottle can treat 120 stems of 25 mm diameter.

Picloram was consistently found to be extremely active on all plants tested. When used correctly, 100 % kill of the treated weed species was achieved in research trials on, Japanese honeysuckle (Lonicera japonica), Grey Willow saplings (Salix cinerea) Cotoneaster (Cotoneaster simonsii), Kahili ginger (Hedychium gardnerianum), Tree privet (Ligustrum lucidum), Chinese privet (Ligustrum sinense), Gorse (Ulex europaeus), Wandering jew (Tradescantia fluminensis), Agapanthus (Agapanthus praecox), Lantana (Lantana camara), Mysore thorn (Caesalpinia decapetala), Senna (Senna spp.), African olive (Olea africana), Umberella tree (Schefflera actinophyla), Camphor laurel (Cinnamomum camphora), Chinese celtis (Celtis sinensis), Golden rain tree (Koelreuteria paniculate), Slash pine (Pinus elliottii X carribea), Canna lily (Canna indica), Madeira vine (Anredera cordifolia), Moth vine (Araujia sericifera). Further trials are currently underway on other species including Cats claw creeper (Macfadyena ungus-cati) and Broad-leafed pepper (Schinus terebinthifolia).

The research trials were undertaken at different times of the year to determine if temperature affects gel uptake and subsequent weed control. Although the gel penetration can take slightly longer in colder weather (1-2 days compared with 2 - 4 hours), good efficacy was achieved throughout the year. Successful control was even obtained when the gel was applied in light drizzle, although it is recommended to use the gel in fine weather.

Contact your local Macspred Representative for additional information and pricing.