I received an inquiry from a customer today that included the above picture. From the picture, I thought this was possibly a herbicide injury. After reviewing our records, I noticed it had been a month since our 1st treatment of this lawn, but the injury appeared last week after a mowing. We assessed all 10 properties treated the same day with a granular polyon slow release fertilizer with preemergent incorporated on the granular. Weeds were only spot sprayed. Only 2 yards treated out of 10 had this damage. However, there was a 3rd yard beside the other 2 that had same symptoms. That yard was treated 45 days ago. The one common denominator was all 3 yards were mowed the same day, same height, by the same company. The damage is confined to the wheel tracks. These 3 lawns were mowed last week during cold snap, and the lush spring growth had frost on it when they were mowed, causing foliar damage by crushing plant cells with frozen moisture inside the leaf blades. The good news here is that it only crushes the foliage, so new growth will soon replace the damaged turf. It will probably take 2 mowings and more warm wet weather for all damage to heal.
1. Never mow or even walk on frozen green grass.
2. It is important to keep accurate pesticide records un to be able to determine if herbicide damage could be a cause of plant injuries.
Glad it was not herbicide related!