Evergreen bushes stay green year-round. However if they contract diseases or are under stress, sections of the plant may turn brown. In some cases there is nothing you can do, and the plant will eventually die, but there are many times when immediate action will save the overall bush. Try some methods of saving the shrub before disposing of it; it may bounce back.
Test the soil around the shrub. Dig 8 to 10 inches and remove soil for the test kit. Place the soil in the test containers, and follow the directions on the kit to test the levels of nutrients in the soil.
Adjust the soil nutrients if the tests show that the levels are low. Pay close attention to the pH level. Evergreen plants prefer a slightly acidic soil. If the test shows that it is alkaline -- 7.0 and above -- then apply an acid-based fertilizer to improve it. However if the test shows an extremely acidic soil -- 4.0 or lower -- then apply an alkaline fertilizer to lower the acid level.
Cut out dead limbs back to the main truck or stem. This way the plant will not use energy to heal a limb that cannot be saved. Use loppers or a tree trimmer to take out the limb.
Snip off diseased limbs at least 3 or 4 inches back from the diseased area to insure that you remove all the disease. Rake up needles or leaves that have fallen to prevent the disease from spreading to other areas of the garden.
Check the dampness of the soil around the bush. It could be stressed from lack of water. The soil needs to be damp down to a depth of at least 3 or 4 inches. Water the soil to improve the moisture content.
Recheck the soil to see if the water reached the level you needed. Apply more water if necessary. Water several inches per week until dry weather subsides.