Blackberry invasions

Blackberry invasions

While for avid berry eaters, wild blackberries are just another delicious fruit producer, for many gardeners this hardy invader represents a foe that once established, becomes extremely difficult to fully eradicate. Once used to mark out fields and to fence in sheep, this plant has become naturalised, has spread  widely and is now one of Australia’s most invasive weeds. In most parts of Australia the wild blackberry is a declared weed - therefore it is illegal to grow it.


I)                   Cover up for summer

If you are growing improved (named) blackberry varieties purchased from the garden centre or a reputable berry grower, place netting around and over your blackberry patch during summer and autumn and set out reflective items like foil to deter birds from eating the fruit. Most of the named blackberry varieties do not set live (viable) seeds but there are some that do.

One of the main ways the blackberry is able to spread is though droppings.  Preventing birds from having access to the fruit is important. Be sure to harvest often, especially after sunny days, so there is little left on the canes to interest the birds. Blackberries freeze really well, so don’t worry about having too much fruit. If you run out of room in your freezer, blackberry and apple crumbles tend to disappear fast!


II)                 Prune back during winter

Keeping your blackberry plants in check is necessary to ensure it doesn’t get out of control and start to take over. Blackberries grow fast! They spread by natural layering, rooting in as soon as a cane touches the ground. They are sly invaders. While you are busy prepping your garden for the spring and summer harvest, it won’t hesitate to send out canes left right and centre. Using the dormant months of winter to cut out old canes and cut back any spreading growth will help maintain it. After pruning, tie up canes to keep them from getting out of control.


III)               Keep isolated

Wild blackberries that have not been controlled are able to propagate through droppings, with their seeds often taking root under trees and bushes. Keep an eye out for any  rogue bushes that have sprung up and taken root in your garden.  Getting rid of wild blackberries once they have rooted in can be difficult. As with all weed varieties, “kill the root and you will kill the weed”. You can hack them back as much as you like, but your best option is a glyphosate weedkiller that will go straight to the root, eradicating the entire plant. 

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