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Invasive Plant Management

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Weed management considerations

Considerations about weeds

Managing invasive weeds while greatly reducing or even eliminating herbicide use requires careful Integrated Weed Management plans. It also involves accepting the presence of some weeds, but also keeping them below an harmful threshold for the farm (and wildlife/workers)

There are many weeds that, while they are a nuisance, can provide some benefits. Dandelions have recently become recognised as helping bees and pollinators with their ever=present flowers.  Mullein may be a nuisance in front of the mower or tractor, however it provides perches for insect-eating birds in summer and sustains seed-eating birds in the winter with its above-ground seed heads. It is these types of minor weeds for which management can easily be relaxed with little to no harm to the farm, and possibly even some small benefits.

Allowing some weeds to persist on the farm, or tackling minor weeds with cultural and mechanical techniques also allows selective herbicide use when really needed with worst offenders. 

Best Management Practices

Best Management Practices

Preventative Control
A lot of success with invasive plant management cen be obtained with good preventative measures. Tractors, mowers, sprayers, and other farm equipment can be literal seed vehicles, spreading each invasive plants all over the farm, and boot soles, gloves, and backpacks are also notorious for spreading weeds.  Having policies in place around cleaning off equipment and clothing can go a long way in reducing the spread of unwanted weeds.   Spraying down the tires, undercarriages, and blades of mower and other equipment between blocks is a good start, as is installing boot brush blocks at entry gates.  Have workers regularly inspect their pant legs , gloves, and backpacks to hitchhiking weed seeds and plant material.

Cultural Control

Not all seed spread can be prevented, so it is also important to make the areas between rows less hospitable to weeds. Many invasive plants thrive in disturbed soils, such as the tilled areas between trees and orchard rows.  Using cover cropping techniques and hefty amounts of mulch between trees and help make it harder for weed seeds to germinate.

Mechanical Control

When weeds do start growing, it can be tempting to nuke them all with herbicide, however overuse of chemical control can result in herbicide-resistant weeds, and resulting bare soil from spraying just creates good growing conditions for other weeds.  Mowing or flaming (but only outside of fire danger season!) can keep the weeds down and prevent them from setting seed without opening the door to more weeds.

Weeds with biocontrol agents

Know your weeds

When making an Weed Management Plan,  its important to know the characteristics of the weeds you are aiming to control. Annual plants will have different strategies than perennial plants, and some species may have certain growth characteristics that need to be taken into consideration (e.g. field bindweed cannot be mowed, as it will snarl in the mower and will also re-root where pieces of stem land).

Identify your weeds and control methods at the Okanagan Invasive Species website

There are several biocontrol insects working to help manage some invasive plant species in the Okanagan and Similkemeen.  Biocontrol insects are an insect that is originally from the same part of the world as a specific invasive plant, and these insects live, eat, and reproduce solely on that one invasive species (years of research has determines this before they are released so there is no risk of upsetting ecological balance. By contrast, because these insects are essentially very specific 'predators' of these invasive plants, introducing the insects here is essentially adding some balance back by levelling the playing field.

It is important to realize that these insects will never eat or reproduce on another plant other than their host,. This means they will never fully eradicate the invasive species on which they live, as this means they would have eradicated their only food source!  In order to have these insects continue to weaken and slow the spread of these unwanted plants, they need SOME of the invasive plant to be kept around.  This is where integrated weed management comes in! Biocontrol insects can help keep their plants from taking over completely, but some cultural and mechanical control can reduce the population to a further manageable level.

Further Reading

The following resources are information-only. Find the Financial Assistance page here

University of California Agriculture and Natural Resources Department: Integrated Weed Management

Okanagan Invasive Species Online:

Okanagan and Invasive Species Society

BC Invasive Species Council Resource Library

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