2017 ASHS Annual Conference

Starting in 2006, California has undergone a ten year drought. Precipitation, especially in Southern California, was 50% below average in several years during the period. Normal rains returned in 2016-17. At the height of the drought (fall of 2016), we surveyed over 1500 residential shade trees in three Southern California cities (Ventura, Simi Valley, and Norco). Trees viewed in front yards of residences along randomly selected north-south streets. All trees were identified and given quality ratings ranging from: 1= dead; to 5=perfect quality for that taxon. Over 90 taxa were rated. In each landscape, an irrigation level was assigned based on the overall performance of plants in the yard. A yard where everything had died (except the tree being rated) was assigned a low or dry irrigation level, whereas trees growing in manicured turf with no obvious dry spots were assigned a wet level. Two intermediate levels were also assigned. Significant quality differences were only observed (average of all taxa) in the dry landscapes. Trees in landscapes receiving some irrigation had visual quality ratings not significantly different than frequently irrigated landscapes. Trees most likely to survive in non-irrigated landscapes were Peruvian Pepper (Schinus mole L.), Tamarix (Tamarix spp.), and various species of Ficus.