Macadamia Tree Health Initiative This bill amends the Food, Agriculture, Conservation, and Trade Act of 1990 to authorize the Department of Agriculture to provide competitive research and extension grants for a macadamia tree health initiative to: (1) develop and disseminate science-based tools and treatments to combat the insect known as the macadamia felted coccid (Eriococcus ironsidei); and (2) establish an area-wide integrated pest management program in areas affected, or at risk of being affected by, the insect.