Need help on getting rid of weeds on driveway (pic)
I desperately need some help on how to control/get rid of the weeds in the rocky area on both sides of the driveway. Link to pic:
The driveway is about 300 feet long, with rock areas on both sides of driveway (9 feet wide each), so we are talking about 5400 sq feet. There is a protective weed fabric and it is covered with rocks about 2 inches thick. There are about 20 mature trees (locust, 20 feet high) planted just on border of rock area, there is no doubt that roots from trees are underneath the rocky area as the dripline is reaching the concrete driveway.
It has been about 12 years since this rock has been put in and in some places quite a substantial amount of soil (1/4-1/2" thick) has been washed on top of the protective weed fabric so the weeds have found the way to implant in this thin layer of soil.
I tried to re-do the portion of rocky area last year (removed rocks, put new weed fabric in, covered back with rocks). This helped somewhat, but this year I am noticing that some weeds even managed to establish on brand new fabric :( So re-doing the whole driveway with new fabric is probably not an option due to size and somewhat questionalble outcome (pretty sure it will be back to same problem 2-3 years from now).
Most of the weed control we do is manually pulling the weeds and applying post emergent (glyphosate). It is a very time consuming process due to the size of the area, yet a month or so later they all come back.
Can somebody recommend a better solution ? Will applying pre-emergent going to help ? If yes then what kind ? I am concerned that applying some type of chemical pre-emergent is going to damage roots of the trees :( I've read a lot about Corn Gluten pre-emergent, do you think this might help ? If yes, whould you recommend an affordable place to buy it from.
Any advice will be appreciated !!!