Technical Abstract: Almond leaf scorch disease (ALS) has been present in California for more than 60 years. The disease is present in orchards throughout the state, but usually affects only a small proportion of trees and large increases in the number of infected trees within orchards between years is typically not observed. A major question for growers is whether or not to remove infected trees. As tree-to-tree spread of ALS appears to be rare, the decision to remove infected trees should focus on productivity. To address this issue we compared the yields of ALS-affected and unaffected trees for the cultivars Sonora and Nonpareil. Averaged across sites and years, ALS-affected Sonora trees produced 40% fewer kg of kernel relative to unaffected Sonora trees. Averaged over years, ALS-affected trees produced 20% fewer kg of kernel relative to unaffected trees. Due to the reduced productivity of ALS-affected trees, it has been hypothesized that healthy trees which are next to infected trees may produce greater yields than healthy trees which are next to other healthy trees. If true, such compensatory effects could negate losses due to ALS. We tested this hypothesis for the cultivars Sonora and Nonpareil. Averaged over three sites, healthy Sonora trees which were next to ALS-affected Sonora trees produced 10% more kg’s of kernel than healthy trees which were next to other healthy trees, although this effect was not significant. For the cultivar Nonpareil, we found that healthy trees next to ALS-affected trees produced 8% more kg’s of kernel than healthy trees next to other healthy trees, although this effect was also not significant. After one year of testing it appears that compensatory effects are minimal. The information collected in this study will be used to parameterize a model that will aid in determining when the economic benefits of replacing an infected tree exceed that of leaving the infected tree in place.