Is dolomite or lime effective in controlling sandspur? I’ve heard sandspur won’t grow if we sweeten the soil.
According to UF specialist and Extension agents, attempts to kill sandspur by liming or using dolomite is not effective. Additionally, unless a soil analysis calls for it, application of lime could contribute to decline of your warm season lawn grass. Keeping grass healthy and vigorous is one of the best ways to crowd out sandspur. Proper fertilization, irrigation, and mowing at correct height may improve lawn grass. View University of Florida online turf grass webpage and specific requirements for various lawn grasses by clicking HERE.
In late winter collect mature burr with bagger attachment, dragging a carpet remnant, cloth or blanket through the contaminated area ensuring good contact with the spiny burr. Each spiny burr may contain multiple seeds, each capable of producing a plant. Discard the cloth. This will reduce the seed bank, resulting in fewer plants in the spring. Easily accomplished in smaller lawn areas, for larger patches, contact your local extension office for recommendations.
Plagued by sandspur? Take action before they emerge in the spring.
Properly applied, pre-emergence herbicide in effective in controlling sandspur. The pre-emergent product should be in place before the seed germinates. Air temperature, soil temperature and soil moisture influence germination.
By understanding the life cycle of Southern Sandbur (Cenchrus echinatus) and the Coast or Field Sandspur (C. spinifex) we can better control this grass-like weed. Sandspur is an annual plant. It germinates from seed, grows and produces fruit (the burr) in one growing season.
Pre-emergence herbicide, used according to label recommendations, inhibits growth BEFORE you see above ground leaf. Follow label recommendations to incorporate and activate the product. Control is enhanced with irrigation or rainfall immediately following application. The chemical barrier must present in the soil before the seed comes up. Once leaves are present, a pre-emergent herbicide is not effective on that plant.
Pre-emergence herbicide may be purchased at big box store and garden centers. Follow label recommendations. When used according to label, the active ingredient would indicate safe for use on lawn grasses such as bahia grass, St. Augustine, centipede and Bermuda.
> Pendimethalin
> Bensulide
> Prodiamine
> Oryzalin
> Benefin + trifluarlin
Follow label precautions to prevent herbicide injury to ‘innocent bystanders’ such as nearby trees, shrubs, and ornamentals. Herbicide may injure or kill ‘innocent bystanders’ such as shrubs and flowers.
“On those areas where turf is to be established (including sod and winter over seeded areas), most preemergence herbicides should not be used 2–4 months before planting. Otherwise, root damage and germination reduction of the turf seed may result.” (Unruh, et. al, 2020)
During summer, dig/hoe/pull up sandspur plants. Clean mowing equipment and prevent spreading and blowing burr into uncontaminated areas. One day we may appreciate the design of sandspur and food web value. In the meantime, Nature Coast Master Gardeners will manage them at the Demonstration Garden, UF/IFAS Extension Levy County, Bronson. Until next time – Spread Joy!
J. Bryan Unruh, Laurie E. Trenholm, Erin E. Harlow, Ramon G. Leon, 2020, WEED MANAGEMENT GUIDE FOR FLORIDA LAWNS, askIFAS powered by Electronic Data Information Source (EDIS) document ENH884
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