Blackberry Treatment Guide
Weedy blackberry (Rubus fruticosus aggregate) is classed as a weed of national importance (WoNS) in Australia covering some 8.8 million Hectares since introduction in the 1830’s. Weedy blackberry includes some 16 introduced species of European and American varieties including blackberry, loganberry raspberry and more. We use the generic weed name of ‘Blackberry’ to cover all these weed species. They have similar structure, ecology and control methods.There are ten native species of blackberry which are protected, luckily it is relatively straightforward to distinguish native species from weed species.
Why is blackberry problem?Blackberry is a fast growing and spreading weed which can takeover large areas of land very quickly. It out competes other plant life and kills off the understory due to extensive coverage and light deprivation. It propagates from cane tips as well as from seeds. The fruit and seeds are spread easily by fauna that find the fruit attractive although the plant itself is thorny and unpalatable to most fauna and stock animals.
Infestations can reduce the ability to farm crops and graze livestock. It can affect the other primary industries by reducing the ability of hard and softwood forest seedlings from growing.
Blackberry is responsible for vast amounts of native flora and fauna displacement. It is also known to cause large scale land degradation and soil erosion when infesting creek beds and riparian zones.
In the urban setting blackberry harbors vermin such as mice and rats.
Blackberry species are a scrambling, perennial semi deciduous woody scrub. The canes cross and entangle forming a formidable prickly barrier. They reproduce from both seed and vegetatively ie non sexually from the canes. Blackberry can reach several meters in height and many square meters in area.
Canes can extend up to 7 meters and are green to purple depending on the exposure to sunlight. They are also covered in sharp prickles.
The leaves are compound, palmate with 3 to 5 leaflets. Leaves appear on the canes alternately. The leaves are generally a bright green on the top and a light green to grey on the bottom.
The flowers are 2-3 cm in diameter and are white or pink and occur in clusters, flowering periods are between November and Febuary.
The fruit changes from green to dark red/black as it matures, it is between 1 and 3 cm in diameter and can be found between December and April.
How to Kill Blackberry
The most effective control methods for the suburban, small property and hobby farm landholders is chemical treatment.
Option 1. Glyphosate
Glyphosate based products are a broad-spectrum herbicide which will kill blackberry. Multiple applications over time will be needed. For application to actively growing plants mix 25-35gm of Tuffweed 680 Granular per 5 Litres of water and apply to foliage and cane. Use the higher rate where for dense infestations.
- Spray in early morning or late afternoon
- Avoid application to stressed plants
- Ensure direct application to blackberry as Glyphosate is non-selective and will affect most plants
Option 2. Grazon Extra
Mix and apply Grazon Extra to blackberry anytime after flowering has commenced. Spray plant thoroughly ensuring all canes and foliage are wet. Blackberry that is moisture deprived or has been under insect attack should be treated at the higher rate.
- Ideal time for spraying is January- March but can treat November-May provided conditions are right
- Do not treat plants that are stressed (not actively growing) due to prolonged periods of extreme cold, moisture stress (water-logged or drought affected), poor nutrition, presence of disease, damage or previous herbicide treatment, as reduced levels of control may result.
- Do not burn off, cut or clear blackberry or other woody weeds for at least 6 months after spraying
Due to the hardiness of the blackberry, continued use of a single product may cause resistance. It would be suggested to alternate treatments for maximum effectiveness.
Always read product label prior to use.