SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/54529
Q&A Weeds in my infield dirt BY DR. DAVID MINNER Professor, Iowa State University Questions? Send them to David Minner at Iowa State University, 106 Horti- culture Hall, Ames, IA 50011 or email dminner@iastate.edu. Or, send your question to Grady Miller at North Carolina State University, Box 7620, Raleigh, NC 27695-7620, or email grady_miller@ncsu.edu. Q Is there a good chemical strategy for control of unwanted vegetation on base- ball infields? We are currently using Glyphosate and Surflan. Is Casoron an option? Central Minnesota This is a good question where careful consideration should be given when herbicides are being used. Yes, there are herbicides labeled for use in turf, ornamentals, and non-cropland that can effectively remove and pre- vent weeds on skin infields; however, none of the products are specifically labeled for use on skin infields. Remember that pesticides are granted registration partially on how they are used. I have yet to find a pes- ticide specifically used for baseball skin infields. From my perspective I suggest that you do not use any pre or post emergent herbicides, except glyphosate, on the infield skin because of the intimate contact that players have with the infield dirt surface. Glyphosate offers a quick burn down with no residual soil affects so I still consider it a low-risk pesticide for use on infield skin areas. Even though preemergence herbi- cides like oryzalin, prodiamine, or imazapyr are often recommended in turf, ornamental, and non-crop areas they are not specifically cited for use on baseball infield skin areas. The same product used in a turf area may react differently in a baseball skin be- cause there is no organic matter in the infield dirt to tie up the herbicide or to break it down by feeding microbes. Another group of herbicides that provide total vegetation control are often considered for skin areas but should be avoided. Casoron (dichlobe- nil) can move with surface water so I would also exclude it from my baseball infield skin list because of its potential to run off the skin area and damage the surrounding turfgrass. Pramitol (prometon) is labeled for use around buildings, storage areas, roadways, air- ports, highway medians, lumberyards, 46 SportsTurf | February 2012 pipelines, fences, recreational areas, and similar areas where total weed and grass control is needed. It is described as a bare ground herbicide and it will allow nothing to grow for a year. It has a danger signal word and has the po- tential to be washed from the dirt area and damage the surrounding grass. It is another one I would eliminate from my infield skin management program. So what can you use to keep weeds out of the infield skin? For existing weeds use glyphosate herbicide. As an alternative vinegar and essential oil- based products seldom have a place for weed control in lawns, but they are ideally suited to quickly burn down the bare soils found on baseball in- fields. A 20% vinegar solution applied during the heat of the day will kill just about any plant it touches. The real key to keeping weeds out of the infield is to not neglect field grooming. Unfortunately, many fields are abandoned at summer's end and weeds take over. Field grooming once a week until frost begins is a good way to keep the fields from turning to weeds. More silt and clay equals more weed growth. Avoid blowing weed seeds into the infield skin. Infields in the Midwest constructed with 4 inches of ag lime help reduce weeds because of the unfavorable alkaline growing condition, but when groom- ing completely stops weeds like crab- grass, goosegrass, foxtail and knot weed can establish. Young weeds can be rouged out by the tines of various dragging and ball field rakes, however once the weed is past the seedling stage and begins to tiller or make a more aggressive root then it is more difficult to remove with a light weight nail drag. As weeds mature and begin to flower they are extremely difficult to remove. Grass like weeds such as goosegrass and nutsedge, and broadleaf weeds such as knotweed and purslane are es- pecially troublesome on skin infields; don't let them get big or you will be spending the better part of a day cleaning them out of the infield. A few large weeds can be removed by hoeing or hand pulling; they are easier to pull by hand when the infield is wet. If the field has totally gotten away from you and it is full of weeds then consider killing the weeds with a non-selective herbicide such as Roundup. Scalp mow the dead weeds to minimize plant debris. Try the most aggressive infield groomer you have on hand to see if it will remove the clumps of dead weeds. Some groomers such as the Infield Rascal are designed to remove over- grown infields by cutting the grass clumps and raking them into piles. I prefer cutting the weeds off about a half inch below the surface so the crown and top of the weed is dis- lodged from the roots. When the roots stay attached to the top of the plant it creates clumps that dislodge a lot of infield dirt making the operation more difficult and just removes dirt during clean up. If your equipment can't do the job then try a sod cutter followed by a York or Harley rake. It takes about 6 hours to clean up an overgrown infield and I prefer doing the operation when the field is totally dry and powdery. Sometimes a little moisture helps re- move the weeds but don't schedule this type of work when the field is wet. Operate the equipment slowly to windrow weeds for easy clean up. Many high school coaches that have to manage their own fields are switching to grass between home and first and home and third; less dirt to manage and fewer lips in the critical section of the field. Players come into intimate contact with the dust and wet soils found on baseball/softball infields. Unnecessary exposure of players to pesticides is what causes mistrust among con- cerned parents. If you think you are doing something wrong then you probably are! Some vinegar and a good grooming machine go a long way to making safe and attractive infields. ■ www.sportsturfonline.com