Each of the practices in the program will be given application points. In 1997, total statewide acreage devoted to macadamia nut production was estimated at 20,200 acres, of which 19,200 acres, or 95 percent were harvested. Grower identified priorities include better management strategies for pests and diseases that reduce marketable yields. Although already the subject of extensive research, the interaction of organisms and environmental factors contributing to the disease syndrome have not been fully elucidated. Development of effective cultural and chemical control methods depends on the completion of these studies.
Some cultivars are more resistant than others.
There are several other diseases of significance in macadamia culture. In particular, industry recognized Phytophthora raceme blight and Kretzschmaria root rot as problematic and in need of improved control strategies. Raceme blight may lower yields by affecting fruit set. Root rot also affects yields and results in a slow decline that eventually kills the affected tree. Chemical controls have not been identified that are effective against either disease.