Preemergent for fall yard application - Ask Extension
Hello, I was wondering your suggestion on what product to use for a fall preemergent yard application. We live on a farm so there is a large area and ...
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Preemergent for fall yard application #876679
Asked July 10, 2024, 1:30 PM EDT
Hello, I was wondering your suggestion on what product to use for a fall preemergent yard application. We live on a farm so there is a large area and I use a pull behind sprayer and also have a granular applicator if needed. I have noticed within the last 4 years or so we have a lot of breakthru spurge even in good grass. In the past, I have sprayed Grazon in the fall. Thinking I may need something different to control spurge? Thank you for your help!
Montgomery County Iowa
Expert Response
Spotted and prostrate spurge are summer annual weeds that can be controlled using a preemergent herbicide. Timing when applying preemergent herbicides is important.
As a summer annual, plants emerge from seeds in early to mid-summer, grow, flower, and set seed. Seeds remain dormant over the winter months, then germinate and give rise to new plants in the summer of the following year. Preemergent herbicides disrupt the germination process and have no effect on plants that have already emerged and are growing. This means you need to apply the preemergence herbicide when the seeds are germinating, which for spurge would be in spring, not the fall.
Recommended preemergent herbicides for spurge include products with one or more of the following active ingredients: dithiopyr, prodiamine, or isoxaben.
It can also be beneficial to use post-emergence broadleaf herbicides to kill plants in summer before they set more seed. Utilize applications of two- or three-way mixtures of 2,4-D, dicamba, MCPP, or MCPA available in multiple product formulations at local retailers. Repeat applications may be necessary due to the germination of new seedlings.
Overall, continuing to promote healthy turf is going to be important for the long-term management of this weed (and others that are similar, like purslane). This would include regular fertilization to promote dense, thick growth and core aeration as spurge tolerates compacted soils better than turfgrass and will grow more readily in these conditions.
Below are some resources to help:
https://store.extension.iastate.edu/Product/4242
https://yardandgarden.extension.iastate.edu/how-to/core-aeration-lawns
https://store.extension.iastate.edu/product/4378
As a summer annual, plants emerge from seeds in early to mid-summer, grow, flower, and set seed. Seeds remain dormant over the winter months, then germinate and give rise to new plants in the summer of the following year. Preemergent herbicides disrupt the germination process and have no effect on plants that have already emerged and are growing. This means you need to apply the preemergence herbicide when the seeds are germinating, which for spurge would be in spring, not the fall.
Recommended preemergent herbicides for spurge include products with one or more of the following active ingredients: dithiopyr, prodiamine, or isoxaben.
It can also be beneficial to use post-emergence broadleaf herbicides to kill plants in summer before they set more seed. Utilize applications of two- or three-way mixtures of 2,4-D, dicamba, MCPP, or MCPA available in multiple product formulations at local retailers. Repeat applications may be necessary due to the germination of new seedlings.
Overall, continuing to promote healthy turf is going to be important for the long-term management of this weed (and others that are similar, like purslane). This would include regular fertilization to promote dense, thick growth and core aeration as spurge tolerates compacted soils better than turfgrass and will grow more readily in these conditions.
Below are some resources to help:
https://store.extension.iastate.edu/Product/4242
https://yardandgarden.extension.iastate.edu/how-to/core-aeration-lawns
https://store.extension.iastate.edu/product/4378
