Sandbur Control Part 2

Home Grown  by Keith Reed
As mentioned last week, even the best herbicide program is not enough to keep sandburs under control. The turfgrass must be strong and healthy so it is better suited to out-compete this pesky weed. This begins with proper fertility. As the name might imply, sandburs are usually a bigger problem on sandy soils. All else being equal, sandy soils do not retain water or nutrients as well as heavier soils and are more likely to be low in key nutrients. Dry soils low in phosphorus are especially prone to sandbur infestation.

A basic soil test can establish baseline information for nutrient levels, especially phosphorus and potassium. Once these nutrients are brought up to an adequate level, nitrogen will need to be applied on a regular basis to support turfgrass growth. Rainfall or irrigation is a critical player here as turf grass should not be fertilized unless enough water is present to move the fertilizer down into the soil and provide enough water for basic plant functions.

It is also important to note that nitrogen will move freely through a sandy soil with excess rainfall or irrigation, causing potential groundwater contamination. Lighter, frequent applications of nitrogen are preferable to heavier rates. Slow release nitrogen fertilizers are also helpful.

Keeping sandy soil as moist as needed to support proper growth can be difficult to do, especially during periods of drought. .

Sometimes, sandburs can develop in small pockets throughout a landscape. Learn to identify these when small and pull or hoe them out early before the seeds mature. The seeds are the “stickers” and are mature when they turn brown and fall easily from the stem. Regular mowing before seedheads form is also beneficial. This also helps discourage these weeds in another way. By regularly mowing bermudagrass at a lower height, the turf becomes denser, giving it a competitive edge against the weed.

The better you can contain sandburs to a given area, the better your chances of success will be. Consider mowing the areas infested with sandburs last taking care to clean your mower tires before the next mowing. While we generally discourage bagging clippings, in this case it is not a bad idea, especially if the seeds have been allowed to mature.

It is a common practice for people to drag old carpet or rugs around in hope of collecting the seeds. While this can certainly reduce the numbers present, it may be doing more harm than good by spreading the seeds to a wider area. Proceed with caution here, perhaps be experimenting on a small area for a season or two.

This is a tough problem that requires consistency and patience. However, success is attainable. Just remember that seeds can remain viable in the soil for several years so continue with those fertility and herbicide programs even if you think you’ve eliminated them.

For more information on this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at keith.reed@okstate.edu, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.

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