n Arid Zone Trees Publication 2019 Volume 25 Issue 6
Cercidium praecox ‘AZT™’
Sonoran Palo Verde ‘AZT™’
If Sonoran Palo Verdes, Cercidium (Parkinsonia) praecox, did not exist in nature, someone would to have had to create them. In a way, AZT did reinvent them. Their uniquely graceful branching, green trunks and lacy canopies, combined with other physical and biological qualities make them unmistakably xeric. When evaluating potential ‘Mother’ trees for Sonoran Palo Verde, Cercidium (Parkinsonia) praecox ‘AZT™’, Sonoran Palo Verde ‘AZT™’ we wanted to incorporate greater cold hardiness, uniform and consistent flowers and flowering seasons and generous branch angles (to discourage the development of impacted bark).
Whether up-lit to produce dramatic silhouette on walls and hardscapes, exploding with bright sulphur-yellow spring and summer flowers or adding a rich sculptural quality, Cercidium praecox ‘AZT™’, Sonoran Palo Verde ‘AZT™’ brings beauty and desert elegance to the landscape. It is among the most popular and sought after trees in the arid landscape palette. This popularity is based on the tree's unique natural beauty, displays of bright yellow flowers, smooth green trunks and gracefully interwoven branches. Their strong visual impact makes them ideal as a theme tree for streetscape plantings, as accent trees and as specimens in entry monuments or at the focal point(s) of a landscape. With their distinctive visual qualities they can bring a strong unifying look to landscapes and are often used as the theme or dominant tree in large commercial designs, parking lot or street plantings. As a tree indigenous to the Sonoran desert it is durable even in the most challenging landscape settings. The characteristic that sets ‘AZT™’ selection of clone C. praecox apart from seed selections is improved cold hardiness to the upper teens to low 20’s F, a lacy, open branch canopy and a vigorous root system (the result of AZT’s Root Management Program). Parkinsonia (Cercidium) praecox 'AZT™' is propagated and available exclusively from Arid Zone Trees.
Variety 'AZT': Arid Zone Trees makes selections from thousands of trees propagated from seed. Only Individual trees having the most desirable physical qualities (branching habits, leaf color, leaf canopy, and flower color) and sound horticultural characteristics (rooting, cold hardiness and growth rate) are selected for further study. These trees are then cloned (vegetatively propagated) and planted at our nursery for further evaluation. Only the best of these trees are then used in our cloning production and are then designated Variety 'AZT™'. Since no one single selection of any desert tree species is best adapted to all landscape applications, we continually search for new additions to our Variety 'AZT™'.
Parkinsonia (Cercidium) praecox ‘AZT™’ we are so confident of the quality, we put our name on it.
Cultural Practices:
Foster the development of a more dispersed root system and reduce the risk of wind throw by arranging irrigation emitters at varying distances from the trunk to encourage roots to "seek out" water and nutrients. Irrigation emitter arrangement along with other information on irrigations practices for desert trees can be found at Irrigation Practices for Desert Trees. Cercidium praecox ‘AZT™’, Sonoran Palo Verde ‘AZT™’ can be planted in turf areas but it is not recommended. Mowing and trimming equipment can easily damage the soft outer bark and irrigations practices, particularly those associated with winter grass over seed, can make roots vulnerable to root rot.
Prune as needed to reinforce the structure and form of the tree. Periodic thinning is the most desirable method of pruning. Avoid hedging or heading back desert species, as this will only stimulate excessive branching. Do not remove more than 30% of the canopy during the summer as this can lead to sunburn injuries that can later be invaded by wood boring insects. Always use clean, sharp tools that are cleaned regularly in a 10% solution of bleach. For detail pruning guide see Pruning Desert Trees.
Periodically insect pests can be a problem on some desert trees. On young trees, insect infestation can slow typical seasonal growth. Inspect trees during the growing season for common garden sucking insects such as aphids, thrips, whiteflies or psyllids. During dry months, (May and June) in dusty conditions, spider mites can appear. Monitor for infestation and apply controls as needed. Spray applications of water or water and Safer Soap give short-term control (3 to 7 days) for small insect population. For heavy infestation or longer control use federally registered insecticides. A contact insecticide application will kill existing adults. An application with a systemic soil drench will provide 8 to 12 weeks control for any post application insect hatchings or migration of insects. Before using pesticide for the first time or on new plants or cultivar, treat a few plants and check for phytotoxicty. Always read label and follow label instruction before using pesticides. For pesticide control recommendations contact a licensed pest control advisor.
Cercidium praecox ‘AZT™’, Sonoran Palo Verde ‘AZT™’
Foliage: Semi-Deciduous
Mature Height: 20’ - 30’
Mature Width: 20’ - 40’
Growth Rate: Moderate to Fast
Hardiness: 18 degrees F
Exposure: Full Sun
Leaf Color: Green
Shade: Filtered
Flower Color: Yellow
Flower Shape: Funnel Shaped Petals
Flower Season: Spring
Thorns: Yes
Propagation Method: Cloning
Sizes Available: #25, #45, & 48"