Kendall County: You have an interesting question. Let me begin by stating that upright prairie-coneflower or Mexican hat, "Ratibida columnifera (Nutt.) Wooten and Standl." is a member of the Sunflower Family and is a native, cool and warm season perennial. As a long-lived perennial, the plant greens up in the fall and maintains rosette type leaves throughout the winter months. Stem elongation for flowering occurs in the spring and this species can be found flowering from April to October. Note that the plant comes back each fall from a perennial root stock underground and in the spring, new plants can emerge from previous years seed production. Several authors indicate that Mexican hat also can reproduce and produce new plants through a short underground rhizome that allows for increasing the density of a stand.The fruit of this plant is the many seeds packed in the long peduncled heads. Research demonstrates that a native weevil lives in the seedhead and larvae can be found eating the seeds (called achenes) or eating the stored energy of a seed or the endosperm. The larvae of this weevil also pupate in the seedhead prior to emerging as an adult.

I believe from your question, that the goal is to produce an environment that is not conducive for the further growth and cover of Mexican hat. A good grass cover may be required to achieve your goal and is dependent on what grasses are currently growing on the site and/or what seed of value species are currently in the soil seed bank that can response to an action on the land. From my short search, I do not find an agency, university or industry research report that indicates that repeated mowing will control this perennial plant. Certainly mowing will reduce the plants chlorophyl area, set back growth and can even be used to reduce flowering and seed production. A lot of the response of a perennial plant to mowing results from the time of season the mowing is conducted, present environmental conditions and the amount of time between mowing events. I can see that mowing would be an effective tool of plant suppression but I have no indication on the value of mowing to kill the plant. The winter growth of the plant often serves as a food source for whitetail deer and even cattle when fall conditions are dry an ample annual weeds do not come up. 

First with the mowing option, I would consider who would come up to replace the cover of the ground and prevent the response of producing open bare soil surfaces. Bare soils are where most annual weeds germinate and not in a good grass cover. Consider and check to see what plants are currently growing, like grass, underneath the present stand of Mexican hat. Whatever is growing there could response positive to the action of mowing and actually might be a species that would shade out the Mexican hat and provide good cover of the soil surface to benefit rainfall infiltration and reduce rainfall runoff. The other plants that will respond to mowing include those plants whose seed are currently in the soil seed bank awaiting a disturbance to allow for germination. Most abused or overgrazed sites in the Kendall County area will produce a greater variety of weeds once the soil surface has been disturbed and some fear that the reduction of a perennial cover might lead to a new annual weed cover that might be hard to control such as the Malta starthistle and woolly distaff thistle that now grow in your area. Whatever tool of management I choose to use, I do not want to open the land up to more bare ground which increases the opportunity for rainfall driven soil erosion. The remaining soil you have should be protected, as the amount of soil cover and it's depth determine the amount of water you can hold for producing a healthier  and more diverse landscape for grazing animals and wildlife. 

So in this case, mowing could be a valuable tool to reduce seed production and accumulation in the soil seed bank by Mexican hat, reduce Mexican hat interception of sunlight and shading effect and allow for the remaining native grasses to grow. A single mowing of Mexican hat will not kill the plants and as a perennial, the new growth will resprout from the root crown, a major difference here than dealing with annual plants. Mowing when the first Mexican hat flowers appear might achieve this goal. Kendall County is in the Edwards Plateau vegetation area. This area was originally described as an oak savannah, a grassland with scattered live oak and shin oak plants but with a great diversity of both plant and animal species. From an integrated pest management standpoint, the use of winter prescribed burning might also be a tool useful for setting this plant back or suppressing it. If you proceed with the mowing, begin by leaving a strip of Mexican hat unmowed so that you have something to compare to for gaining understanding if the mowing is meeting your objective.You should take pictures seasonally at permanent points on both the mowed and unmowed areas for comparison. Knowing if a tool of management is working or helping requires the use of an evaluation tool. 

As other landowners may have had this same issue in Kendall County, I would recommend that you contact the Kendall County Extension Agent for Agriculture and Natural Resources Mr. Stephen Zoeller who is located in Boerne and can be contacted by phone at 830/249-9343 or by email at <personal data hidden>. I hope this information will be of value to you as you proceed with a management decision on your land. Thank you for contacting us through the eXtension System.

Barron S. Rector
Associate Professor and Extension Range Specialist

BSR/