Non-native honeysuckles were imported as early as the 18th century to serve as garden ornamentals, stabilize soils, and provide wildlife habitat. Unfortunately, these species have naturalized and spread well beyond their original plantings to fields, pastures, and forests, where they cause problems for native flora and fauna. These invasive honeysuckles enjoy a variety of soil conditions and are often found along forest edges. Infestations of non-native honeysuckle occur across southern Ontario.
The four most problematic non-native species are:
Amur Honeysuckle (Lonicera maackii)
Tatarian Honeysuckle (Lonicera tatarica)
Morrow Honeysuckle (Lonicera morrowii)
Bells Honeysuckle (Lonicera xbella)
What to look for
The distinguishing common features of these four Lonicera shrubs are:
multi-stemmed, forming dense thickets, with stems up to 2.5 - 6m long
simple leaves with smooth edges that are arranged in pairs along the twig
showy flowers (white, light or dark pink, yellow)
berries (usually bright red or orange) clustered in multiples of 2 that remain on the plant through the winter
Invasive honeysuckles can be distinguished from native species by:
Stems: invasive; usually hollow / native; solid
Branch pith (the inside of the branch when cut): invasive; light-coloured / native; dark brown
Leaf out and retention: invasive leafs out earlier and retains leaves later into the fall
Non-native honeysuckles generate rapidly and profusely to dominate forest understories and outcompete native honeysuckles and other native forest shrubs. They grow in thick patches,
producing dense shade and exuding a chemical that inhibits native plants from growing under or near them. These changes to local vegetation also threaten a number of at-risk plant species. Lastly, non-native honeysuckles negatively affect forest wildlife in a variety of ways. For instance, they lower the nutrition and nesting success of songbirds, as their berries are less nutritious and predation rates are higher for birds nesting in them.
Non-native honeysuckle, while fast-growing and pernicious in its invasiveness, can be manually controlled. Ideally, these species are removed when the plants are young (before they bear fruit): young shrubs can be readily pulled by hand. As their root systems are shallow, even large specimens of invasive honeysuckle can be pulled out with the help of digging tools. Autumn is the best season for invasive honeysuckle control, as it avoids disturbing springtime plants.
Other control options include: repeated clipping; cutting or girdling with application of herbicide to stumps or girdled areas; mowing; grazing; or burning. Please note that anyone using an herbicide must comply with herbicide legislation and follow the label.
Restoration is best considered at the time the soil has been disturbed by control efforts. Seeding or mulching sites immediately afterwards can help native species to re-establish while preventing other invaders. Or, larger specimens of native species can be planted later.