Generally you can divide the weed control problem into three areas. Perennial weeds, annual weeds, and tree seedlings.
Perennial weeds are those weeds that are growing from shoots, tubers or existing plants growing in the soil now. Bermuda, Nut Grass, Morning Glory and Oxali are typical examples. Here it takes identifying the weed and finding a chemical that will kill it.
Masters Kleen Up is often the answer. It works on Bermuda grass, Morning glory and most other perennial weeds, Monterey Weed Hoe works on Nut Grass applied regularly. Apply the correct chemical as often as you see the weeds growing.
For annual weeds germinating from seed we recommend a two pronged approach. A thick mulch of Forest Humus together with a pre-emergent like Amaze or Surflan will dramatically reduce the weed problem. The Mulch keeps most weeds from germinating by keeping them shaded. The pre-emergent keeps any new weed seeds from sprouting. The pre-emergent needs to be reapplied every 4-6 months; the mulch every 2 years.
As far as tree seedlings are concerned basically we still recommend hand weeding. Sorry!

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