Mowed a yard where the live oaks were dropping catkins and pollen like crazy, carpeting parts of the lawn. eMark wb made it thru but 21" trim mower didn't. Had to replace the air filter on both machines before doing the next lawn. Washed the old filters (1 week and 2 weeks old) later and they cleaned up fine, but can't wash & dry filters in between lawns. Compressed air only gets the big clumps of pollen out. I explained to the customer that new filters would have to be installed after each mowing in dry weather until the live oaks were done dropping the stuff -- and I would have to pass these operational costs on to him because they are specific to his property. The customer thought it was not his problem, so I lost him. The money was fair except for this oak problem. Has anybody come up against this, and did I overlook an easy solution that could have kept the customer? I can put up with the green jeans and wash the machines that night, but I'm not willing to eat the cost of the filters or wash them for free. I have no idea about how long this stuff keeps falling from live oaks, but it is really nasty to mow over it. I understand my quote should have been higher to cover the problem in the first place, but I didn't think it would be so bad.