Know your orchard weeds: cleavers

Orchard owners, managers and their teams are, year-by-year, battling a range of weeds within the orchard, ensuring they don’t take over. It’s good to know a bit more about the plants we often battle.

You know early spring has arrived when the weed known as cleavers (Galium aparine) grows up into and from shelter belts. This scrambling annual weed is a native of temperate Europe and Asia and was one of our earliest established weeds – first noticed about 140 years ago. It is a nuisance plant but one that can completely smother lower trunks and branches of especially shelter trees.

Cleavers is one of those “sticky” plants. Stems are square with inconspicuous hooked prickles on the four corners. Leaves are arranged in groups of five to eight around the stem and have backward pointing hairs which enable the leaf to readily cling to clothing. The green fruits are small (5mm across) and densely covered in hooked bristles that again stick to clothing, fur or wool.

The stems, which can grow to 2m or more long, tend to break from the parent plant very easily.

Cleavers is often confused with the native biddibiddi (Acaena novae-zelandiae) – also known as piripiri - but it has very much smaller fruits or bidibids.

The hooked bristles are a very effective mechanism to ensure the spread of cleavers. Most orchardists have brushed off dozens of small round fruits from their jerseys or shirts before going indoors.

Cleavers are quite easily hand-weeded. Just pull the stems, trace back to the rooted portion and pull this from the ground – best undertaken while the ground is damp. It is more persistent where the broken stems and fruits are left within a shelter belt. Persistent hand weeding will eventually reduce infestations.

Glyphosate is effective but the addition of a penetrant or spreader is essential. Any over-spray could harm other desirable plants, so care is essential.

KVH thanks Tim Senior, Bay of Plenty Regional Council, for some information reproduced here.