Ohio State extension agent Pam Sherratt addresses a question about how many dandelions are too much for a sports field. The sports turf manager that contacted her looks after several schools fields. He thinks the small dandelion population on his football field does not warrant a herbicide treatment, as he has an IPM program there and tries to limit pesticide use. Some members of the community have complained and want them sprayed, especially since they are flowering right now and stand-out.
The question is, what is the threshold for dandelions on an athletic field? How many dandelions would create unsafe playing conditions?The Ohio State University’s Field Evaluation Document (FED) Guidelines state that >40% weeds is unacceptable and 0-5% is best. The STMA Playing Conditions Index (PCI) states that >40% weed cover is unacceptable and 0-9% best. In addition, they consider dandelions “moderate” and crabgrass “severe” weeds. In talking with our weed expert, he suggests no more than 5% weed cover for high quality fields.
Now, for the sake of getting down to numbers, I calculated it out: There are about 6 dandelions per square foot. A standard football field is 54,000 sq. ft. If just 1% of the field surface was covered in dandelions there were be 3,240 dandelion plants on the field, which seems like a huge number of weeds!
Maybe weed thresholds shouldn’t be determined by percent cover, but by numbers. The field manager needs to determine what that number is, dependent upon the expectations of his community and end users. That number might be 10, 100, or 1,000. One thing is for certain, I’ll never tell a field manager that 10% dandelion cover is okay, as that would be 32,400 plants!