Replacement Recommendations for Oleanders Dying in Arcadia

 By Andy Gough, ACMNA Board Member

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Have you noticed oleanders dying and be removed in the Arcadia area?  A fatal disease, Oleander Leaf Scorch,  is spreading among oleanders. Once infected, they die over a 3-5 year period. Initial signs are leaves of certain branches being a lighter green in color. Then the outer margins of the leaves turn brown. As the disease progresses, more branches of the plant are affected and the plant dies. Note that if a branch shows signs of the disease, the whole plant is infected, and you cannot control it by simply pruning off branches.

Oleander Leaf Scorch is caused by a bacterium (Xylella fastidiosa) and is spread by small (1/4 inch) flying insects called sharpshooters. These insects become carries for the disease when they feed upon an infected oleander. They then carry it to the other oleanders they feed upon.  This disease was first diagnosed in  Southern California in the early 90’s and spread to Arizona in 2004.  There is no cure. Eventually, even oleander in the Salt River valley will die from it.

Therefore, when your oleanders die, do not replant oleanders!

Oleander Replacement Recommendations

·         Hop Bush (Dodonaea viscosa) – grows 8 to 10 feet tall and wide, with dense evergreen foliage that can act as a privacy or sun screen. Can be pruned into a formal hedge. Throws of very little litter, so is suitable around pools. Requires little to no pruning. The cultivar (variety) ‘Purpurea’ has purple foliage during cool weather, changing to mostly green during hot weather. Cultivar ‘Saratoga’ has deep purple foliage year round but is harder to find in nurseries.

·         Yellow Bells (Tecoma stans) – grows vigorously upright 15-20 feet, but can be pruned easy to 5 -10 feet and 4-8 feet wide. Works well as a privacy border or a sun screen. Dense evergreen foliage and blooms year round. Low water use. Many different cultivars available, with semi-dwarf growth characteristics and different colored flowers.

·         Arizona Rosewood (Vauquelinia californica) – a native of the Sonoran Desert, this low water use plant thrives in full sun or part shade, but only moderately tolerates reflected heat.  It can grow to 10-25 feet tall but can be easily managed to 6-8 feet with water and pruning management. Can be used as a privacy screen, an informal hedge, or pruned into a small tree. Small white flowers during short period, late April to May.

·         Laurel bay (Laurus nobilis) – Slow growing to 20 feet in height, evergreen shrub to tree. This tree is the culinary source of the herb, bay leaves. Partial sun is best in Phoenix; eastern exposure is best in Phoenix, as the plant will struggle when temperatures are above 105° F.

·         Glossy Privet (Ligustrum lucidum) – moderately upright and rounded growth habit to 25 feet, but can be maintained to 6-10 feet. A large evergreen shrub to small tree, it can be used as a informal hedge, or formed into a small tree. Partial sun is best, and avoid western exposure as it’s prone to sunscald in Phoenix. Messy litter, do not plant near patios or pools.

·         Silverberry (Elaeagnus pungens) – fast growing, can reach 12 feet in as little as 5 years; however, it has a wild, sprawling, out of control growth characteristic and will have a high pruning requirement. Prefers partial shade to full sun. Consider dwarf compact hybrid cultivar, E. pungens x. E. glabra ‘Knotts’ as a more behaved landscape plant.

·         Lemon Bottlebrush (Melaleuca citrina or Callistemon citrinus) – moderate growing, 8-15 feet, as a large shrub or small multiple-trunked tree. Prefers full sun. Good for privacy screening or an informal hedge.

·         Indian Hawthorn (Raphiolepis indica) – evergreen shrub, moderate to slow growing to 2-8 feet (depending on cultivar). Useful as a border shrub, small informal hedge, or accent shrub. Brilliant display of flowers in March. Many different cultivars available, with different growth characters and flower colors.

·         Spineless cactus (Optuntia ficus indica) – the only cactus in the list, this one is evergreen, with a  slow and upright growth habit up to 6-20 feet in height. Requires full sun (no shade). No watering required after establishment.  Lacks spines and prominent glochids, can be planted next to areas with high foot traffic.

References

1.       Pest Notes: Oleander Leaf Scorch, UC ANR Publication 7480, University of California

2.       Oleander Leaf Scorch: The Scourge of Phoenix Xeriscapes at xeriscape-today.com

3.       Dodonaea viscosa, Virtual Library of Phoenix Landscape Plants, by Chris A. Martin, Ph.D., Professor Emeritus of Horticulture, Arizona State University

4.       Plant Disease: Oleander Leaf Scorch, AZ Plant Lady

Resources

1.       Virtual Library of Phoenix Landscape Plants