As we work out way through and into late summer, I will start to receive questions on plants that have annoyingly painful seeds with sharp points or spines on them. They will collectively be called sandburs both correctly and incorrectly. While both are painfully annoying the control of the two are quite different but it needs to start right now.

The two plants are technically long-spine (grassy) sandbur and puncture vine. Sandbur looks like any other grass plant until it starts to put the seeds on. They are round and covered with 30 to 60 sharp spines. These seeds often get stuck in pant’s cuffs, socks and shoe laces. Puncture vine is a broadleaf sprawling plant. It has a central taproot with prostrate stems radiating out in all directions. These stems can be five feet long or more. It has little yellow flowers and the seed is made up of four or five segments that easily break apart. Each segment is hard and angular with 1 or 2 sharp very stout spines. This is the one that gets into the soles of your shoes and flattens bicycle and lawnmower tires very effectively.

Both plants are warm season summer annuals. They are just now starting to grow. We are most often going to find them in thin areas of yards, waste areas, along compacted soils like driveways or walking paths. Sandburs are very adept at growing in sandy soils. The hotter and sunnier it is the more these plants like it. Most crabgrass preventers will reduce the number of sandbur plants but they won’t totally eliminate them in part because of the challenging areas these plants grow in. Puncturevine is poorly controlled by most yard weed preventers. Both weeds likely need to be treated with post-emerge weed control products. Ultimately a good thick stand of turf will prevent these from getting established, but where we frequently find them is on the edge of these good lawn areas.

We have several newer products today to deal with sandburs. Older products that are arsenical based, like MSMA or DSMA, will still work, but there are better options. Many homeowners report that when they have used post emergent crabgrass control that the small sandburs seem to be well controlled as well. The good news is that about two years of concentrated control will usually clear them out. With a little effort and practice you will also find that the sandburs can be very easy to identify and easily hand weeded in small areas.

Puncture vine is a broadleaf weed so we have many options to control it. Basically any of our lawn weed control products (think dandelion killers) will control puncture vine. You need to be careful with these products however as in warm and windy weather, vapors can drift to sensitive plants and ultimately cause leaf distortion or in some cases damage. Spray only when it’s below 85 degrees and hopefully not very windy.

Where you’ve had problems with these two weeds in the past you will likely have problems again. Concentrate your control efforts in these areas. Don’t waste time treating the entire lawn. The other tricky part of this is that both of these plants will germinate throughout the summer and especially late in the summer they can germinate, bloom and start setting seed in a matter of two or three weeks. Therefore you likely need to treat about once a month in June, July and August. If you are going to do any fall reseeding do not apply after the early August treatment. If you aren’t reseeding you may want to apply an early September treatment as well! Remember that about two years of good control should clear the problem up for you!

CHUCK OTTE is the agricultural and natural resources agent with the Geary County Extension Office.

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