Weed, insect, and disease control may also be required for pastures. A healthy, productive pasture will resist invasion from most poisonous weeds and provide good quality forage. When pastures are overgrazed, horses will eat the grass and legume species down to the soil, which allows weeds to take over.
These include: 1  Daily sunscreen use. 2  Since sunlight is one of the biggest triggers for melasma, daily sunscreen use is non-negotiable to keep it at bay. 3  Choose a sunscreen with broad-spectrum protection with an SPF of 30 or higher. 4  Outdoor hats. 5  Broad-brimmed hats help keep rays off vulnerable parts of the face.
Darker skinned individuals are more at risk than fair skinned individuals. Estrogen and progesterone sensitivity are also associated with the condition. This means birth control pills, pregnancy, and hormone therapy can all trigger melasma. Stress and thyroid disease have also been postulated to be causes of melasma. Sun exposure can also cause melasma because the ultraviolet rays affect the cells that control pigment (melanocytes).