Wooly Croton - Ask Extension
Hi. I have been battling goat weed (wooly Croton) in my pastures since purchasing my property 5 years ago. At purchase, the pastures were infested wit...
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Wooly Croton #723916
Asked September 14, 2020, 4:41 PM EDT
Hi. I have been battling goat weed (wooly Croton) in my pastures since purchasing my property 5 years ago. At purchase, the pastures were infested with the plant. I have been spraying with 2-4-d amine in spring when the plants are small. This works well to kill the goatweed plants that are there at time of spraying. However, throughout the summer, any rain encourages a new crop of them to germinate and grow. Is there a pre-emergent herbicide that I can apply to my pastures that would help control this? If so, when is the best time of year to apply it?
Cass County Texas
Expert Response
Dear Cass County landowner:
Your question is a very good one at this time. The woolly croton, Croton capitatus, is a native, warm season annual plant that comes up on rangeland and pasturelands after each rain in the growing season as early as April through July. This ability to germinate multiple times, and especially after we have already sprayed for it in the spring, creates a big problem. What you are doing and how you are treating this issue is the current control understanding that we have and currently recommend. But new research has been conducted in 2019 and 2020 to produce a new control recommendation. This research effort is being conducted in Limestone County using several new approaches and several new chemicals not previously recommended for the control of woolly croton. This effort includes the use of herbicides that do have pre-emerge and post-emerge activity. Success is being found but the first and hardest issue we have to overcome is the large amount of seed that exist in the soil profile. Woolly croton is not like turnip greens and radishes where all the seed germinate in one year. The seed of woolly croton have a longer dormancy in the soil and as you know, our herbicides are geared toward killing living tissue and not the seed in the soil. So to be successful, the soil seed bank has to be reduced in the beginning of management practices to eliminate this weed. The data for 2020 from Limestone County is being worked up right now and will be combined with knowledge gained in 2019 growing season. It is expected that we will have a new herbicide control recommendation in 2021 or for the beginning spray season of 2022.
Right now and for 2021, please consider how much grass cover, density and height that you will maintain in grazed and haying pastures. This may mean not grazing as close to the soil surface or haying as low to the ground this fall, but a tool of management where grass left now and through the winter will help in reducing the bare or open soil surface where woolly croton seeds germinate. The grass you grow can be helpful in reducing the germination of this weed. Then I hope you will re-contact us through eXtension next season when the data has been analyzed and a new plan set forward and approved. We are very optomistic about the new research effort that has been conducted. Thanks for contacting us through the eXtension system..
Barron Rector, Associate Professor and Extension Range Specialist
Texas A&M AgriLife Extension Service
Your question is a very good one at this time. The woolly croton, Croton capitatus, is a native, warm season annual plant that comes up on rangeland and pasturelands after each rain in the growing season as early as April through July. This ability to germinate multiple times, and especially after we have already sprayed for it in the spring, creates a big problem. What you are doing and how you are treating this issue is the current control understanding that we have and currently recommend. But new research has been conducted in 2019 and 2020 to produce a new control recommendation. This research effort is being conducted in Limestone County using several new approaches and several new chemicals not previously recommended for the control of woolly croton. This effort includes the use of herbicides that do have pre-emerge and post-emerge activity. Success is being found but the first and hardest issue we have to overcome is the large amount of seed that exist in the soil profile. Woolly croton is not like turnip greens and radishes where all the seed germinate in one year. The seed of woolly croton have a longer dormancy in the soil and as you know, our herbicides are geared toward killing living tissue and not the seed in the soil. So to be successful, the soil seed bank has to be reduced in the beginning of management practices to eliminate this weed. The data for 2020 from Limestone County is being worked up right now and will be combined with knowledge gained in 2019 growing season. It is expected that we will have a new herbicide control recommendation in 2021 or for the beginning spray season of 2022.
Right now and for 2021, please consider how much grass cover, density and height that you will maintain in grazed and haying pastures. This may mean not grazing as close to the soil surface or haying as low to the ground this fall, but a tool of management where grass left now and through the winter will help in reducing the bare or open soil surface where woolly croton seeds germinate. The grass you grow can be helpful in reducing the germination of this weed. Then I hope you will re-contact us through eXtension next season when the data has been analyzed and a new plan set forward and approved. We are very optomistic about the new research effort that has been conducted. Thanks for contacting us through the eXtension system..
Barron Rector, Associate Professor and Extension Range Specialist
Texas A&M AgriLife Extension Service
Thank you for responding with a thorough and easy to understand answer to my question.
Is there a general consensus on how many years the seeds can lay dormant and germinate once conditions are optimal? I know it has to be past the 5 year mark as I have tried to manually pull up all that I see sprouted after my initial spraying. (yes, I know, ALOT of work).
Looking forward to good results from current and ongoing research. I will definitely be watching.
Is there a general consensus on how many years the seeds can lay dormant and germinate once conditions are optimal? I know it has to be past the 5 year mark as I have tried to manually pull up all that I see sprouted after my initial spraying. (yes, I know, ALOT of work).
Looking forward to good results from current and ongoing research. I will definitely be watching.
Cass County Landowner and Longevity of Woolly Croton seeds
I have checked the literature on this plant that I have and resources that occur on the internet. What I have determined is that no study has been done to determine how long the seeds of woolly croton are actually viable in the soil seed bank. This is tedious work and takes a long time as the procedure emcompasses the collection of seeds in the field, holding the seeds until maturity for helping break any dormancy factrors that control germination, then the burying of seeds in the top couple of inches in the ground in nylon bags so that the bag can be retrieved over years and germination and viability tests done in the lab. Generally successful weedy herbaceous species produce seed that have a fairly long life in the soil. Unlike perennial plants that live and produce seeds over years of time, annual plants basically survive in the earth ecosystem by being producers of large amounts of seed hoping that one seed will survive to come up in the future to extend the gene pool of that plant species into the future. So from studies on other species similar in survival tactis, broomweed seeds have been studied and shown to have viable seeds in the soil seed bank for more than 15 years. An annual invader species from Italy and northern African, woolly distaff thistle (Carthamus lanatus L.) has been shown in Australian research to have viable seed in the soil seed bank up to 19 years. Although you may not want these plants in question to grass or row crop production, the survival of the seed is important as a strategy of plant survival that promotes plant biodiversity and production of a large group of plants that will come up from a natural or man-made disturbance to give plant cover of the open bare soils produced by disturbance. So in the Eastern half of Texas, we have a lot of woolly croton and in many situations, we do not want it as it gets in the way of human goals for the land. In this case, we do not have a lot of information on the longevity of woolly croton seed. This is a missing piece of knowledge that would be helpful to our understanding of the management of the species. As our investigations and science of the land continues, at some time we will know more. Thank you for the kind response you have made to us in this discussion.
Barron S. Rector
Associate Professor and Extension Range Specialist
BSR/
I have checked the literature on this plant that I have and resources that occur on the internet. What I have determined is that no study has been done to determine how long the seeds of woolly croton are actually viable in the soil seed bank. This is tedious work and takes a long time as the procedure emcompasses the collection of seeds in the field, holding the seeds until maturity for helping break any dormancy factrors that control germination, then the burying of seeds in the top couple of inches in the ground in nylon bags so that the bag can be retrieved over years and germination and viability tests done in the lab. Generally successful weedy herbaceous species produce seed that have a fairly long life in the soil. Unlike perennial plants that live and produce seeds over years of time, annual plants basically survive in the earth ecosystem by being producers of large amounts of seed hoping that one seed will survive to come up in the future to extend the gene pool of that plant species into the future. So from studies on other species similar in survival tactis, broomweed seeds have been studied and shown to have viable seeds in the soil seed bank for more than 15 years. An annual invader species from Italy and northern African, woolly distaff thistle (Carthamus lanatus L.) has been shown in Australian research to have viable seed in the soil seed bank up to 19 years. Although you may not want these plants in question to grass or row crop production, the survival of the seed is important as a strategy of plant survival that promotes plant biodiversity and production of a large group of plants that will come up from a natural or man-made disturbance to give plant cover of the open bare soils produced by disturbance. So in the Eastern half of Texas, we have a lot of woolly croton and in many situations, we do not want it as it gets in the way of human goals for the land. In this case, we do not have a lot of information on the longevity of woolly croton seed. This is a missing piece of knowledge that would be helpful to our understanding of the management of the species. As our investigations and science of the land continues, at some time we will know more. Thank you for the kind response you have made to us in this discussion.
Barron S. Rector
Associate Professor and Extension Range Specialist
BSR/
