With wipe applications, a device is used to “physically wipe” an herbicide onto a plant. Johnson et al. 2012 (link). Because these applications are precise and controlled and generally made only to a portion of the plant, the herbicide concentration in the spray solution typically used is higher than with other foliar applications. Green et al. 2003 (link). For example, for AquaMaster (an herbicide containing glyphosate), the label recommends solutions having from 18% active ingredient to 54% active ingredient for wiper applicators.
The herbicide wiping method can be used very effectively with the foam herbicide dispenser from Green Shoots (link). The photos above show an application of foam herbicide I made with the Green Shoots Foam Herbicide Dispenser to a weed tree (maple seedling) located in a planting bed.
The herbicide solution used in this case had approximately 20% active ingredient (i.e., a low concentration for the typical wiper applications). Moreover, I applied very small amounts of herbicide foam to the leaves. Nonetheless, it appears the woody weed completely died. We will keep testing less concentrated solutions in order to minimize herbicide usage as much as possible.
Wiping with an herbicide foam has real advantages. The wiped foam herbicide is much less prone to drip. Traditional herbicide wipers work with sponges or canvas which can become saturated and drip. Moreover, clumps of herbicide foam stick better to plant surfaces than large herbicide droplets from a standard wiper system. Finally, with foam herbicide wiping, there are no sponges or canvas cloths that may become contaminated with dirt and dust or that need to be cleaned afterwards.
We will keep testing wipe application techniques on various plants and will post blog updates and videos.