An ever-present weed, learning to tackle bindii is a great starting point for pest managers looking to enter the lawn care industry.
The scourge of many Aussie backyards, bindii (Soliva sessilis) can be a fickle and tricky to kill weed. Success in controlling bindii all comes down to timing, with an ill-timed application often proving futile in preventing the formation of the spiky burrs familiar to many barefooted children and backyard cricketers.
Bindii is a winter annual weed, meaning it germinates, grows, seeds and dies all within one year, and then does it all again the next year, and its active growing season is during winter. The challenge with bindii control is that the weeds are not visible until quite late in its lifecycle. This commonly results in chemical controls being applied too late, after the development of those nasty seed heads. In actual fact, chemical control of bindii is best undertaken much earlier in the lifecycle of the plant, when it is actively growing and better suited to metabolise any chemical active ingredients.
Bindii will typically reach ideal germination conditions when night-time temperatures consistently reach 12-15 degrees for a week straight; depending on where you are in the country this could be anywhere between March and July. Once germinated, bindii will begin developing rapidly in a low-growing habit, shooting new roots and stems to creep into a mat-like structure that can be near impossible to remove by hand.
Given that bindii has such a low growth habit, its presence is often masked by the cover of turf. As with many weed and insect pests of lawns, it’s important to get down on your hands and knees and take a closer look! The delicate leaves of the bindii plant can resemble miniature carrot leaves upon close inspection, which occasionally leads to its misidentification as a different lawn weed with similar leaves.
Once the plant has become established, the seed heads begin to form at intervals along each branch or stem. The seed head is comprised of a vertically layered cluster of sheet-like seeds all tapering to a point. The seeds are typically small and inconspicuous until later in the season when they begin to harden and turn a darker brown colour. It is at or before the point of seed head formation that chemical treatment must occur for effective control of the summer burrs.
Unlike some other annual weeds, bindii has proven fairly difficult to control with pre-emergent herbicides, which traditionally work well in preventing the germination of annual weeds. Instead, the ‘go-to’ chemical control options for bindii are post-emergent herbicides (those that are applied to a developed or growing weed). A number of chemical control options are registered for the control of bindii, and they all have their strengths and weaknesses – actually there really are too many to mention!
Often these products contain a combination of herbicides and provide efficacy on a broad range of weeds. However, make sure the product specifically mentions bindii as a target weed. With all of these control options timing is crucial, and the fact the bindii germinates over a fairly broad temperature range can mean that more than one application may be required.
As with any herbicide application, it is critical you know the turf variety you are dealing with (often household lawns will contain more than one type of grass), as some products will cause discolouration or injury if applied to the wrong turf species or varieties. If ever in doubt, take a photo and email it into Globe for a quick opinion.
Like pests, some seasons are better for weeds (and worse for homeowners), but bindii always seems to thrive! Now’s the time for pest managers to be offering bindii treatments, as for most regions of Australia, spring may well be too late!
