Quick Answer Box hedges die or deteriorate mainly from two causes: box blight, a fungal disease causing brown leaves, black stem streaks, and bare patches in damp conditions; or box tree moth caterpillar, a pest that strips foliage and leaves distinctive white webbing. Both can kill established plants if left untreated. Correct diagnosis is essential … Continue reading Why Is My Box Hedge Dying? Box Blight and Caterpillar Guide