The answer to 'why is my fence brown patches' is that it is likely due to sun damage, moisture issues, or pest infestations. Over time, the sun's UV rays can cause the wood to fade and discolor, leading to brown patches. Moisture from rain, sprinklers, or poor drainage can also lead to wood rot and discoloration. Additionally, pests like termites or wood-boring insects can burrow into the fence, creating unsightly brown spots.
To address the issue, start by inspecting the fence closely to identify the root cause. If it's sun damage, you may be able to restore the color with a wood stain or sealant. For moisture problems, ensure proper drainage around the fence and consider treating the wood with a preservative. If pests are the culprit, you may need to call in a professional exterminator to treat the infestation.