The Rise of Eucalyptus
How can an outsider become an insider?
Just ask the Eucalyptus tree.
How can an insider become an outsider?
Just ask the Eucalyptus tree.
A Eucalyptus Story
First proliferated in the 1850s following the California Gold Rush of 1848, Eucalyptus trees (Eucalyptus sp.) had a good PR team backing them.
Also known as the Gum tree, Eucalyptus trees grow fast, proliferate even faster, and their smell calms the nerves. Urban developers sought Eucalyptus trees as easy means to provide shade, especially lining the coastal towns where windbreaks and respite from the California sun were needed.
Non-native to California, Eucalyptus species have undergone public praise and scrutiny. They are beautiful, yet highly flammable in wild-fire-prone California. They are tall, but the wood isn’t suitable for building. They proliferate but dominate native habitats.
For all their beauty, Eucalyptus trees tend to be prone to sudden limb drop. This is not an uncommon concern that our ISA Certified Arborists address.
Still, we are captivated, and so are pests and diseases!
HAVE YOU SEEN THIS BEETLE?
Colloquially named for its infamous orange dots, the tan-colored adult Dotted Paropsine Leaf Beetle originates from Down Under (Australia). Taking a note from this year’s New York Fashion Week, the larvae are easy to spot with their yellow bodies and black spots running down their sides (think yellow track jackets with black trim).
First spotted in Los Angeles in 2022, the Dotted Paropsine Leaf Beetle (Paropsis atomaria) made its United States debut on a lemon-scented Eucalyptus gum tree. Think of this beetle as the larger and worse relative of the Trachymela sloanei, (the Small Eucalyptus Tortoise Beetle), which has been hanging out in California since the 1990s.
Since then, this raucous beetle has made a happy residency (much to the dirge of the local residents’ trees) in local areas of Southern California.
The infamous Dotted Paropsine Leaf Beetle has found fun in the sun in areas like Rancho Palos Verdes, Palos Verdes Estates, Redondo Beach, Riverside, and in the OC.
Eucalyptus trees push out new growth after a typical beetle’s initial feeding, but if left untreated, the Paropsine Leaf Beetle will devour all new growth, starving the tree of photosynthesis and unalive the tree—as the internet teens would say!
Beetles emerge in the late spring through the early summer. Treating them six weeks before they start their initial feeding is best. Current treatments may call for systemic insecticides to be applied to the soil in the spring and again in the summer. Speak with your trusted ISA Certified Arborist at Sims Tree Health Specialists, Inc. to learn the best treatment plan for your Eucalyptus!
Other Common Eucalyptus Pests
Setting aside the flashy news headlines, other pests can take down a Eucalyptus tree!
The Eucalyptus Longhorned Borer (Phoracantha semipunctata), reigning champion of So-Cal Eucalyptus pests, strikes fear in the hearts of tree-lovers. They bore into the bark and compromise a tree’s vascular system. Dying of thirst, Eucalyptus trees suffer internal damage, leading eventually to tree death.
Discovered in the OC in 1984, Eucalyptus Longhorned Borers grow to at least one inch long and have extravagant antennae and wings! If sapping of the trunk is noticed, Phoracantha semipunctata may be present.
Stressors, such as newly trimmed wood and drought, cause Eucalyptus to be more susceptible to Eucalyptus Longhorned Borers. Eggs laid under the loose bark eventually hatch into larvae. They gnaw through the bark and feed on the cambial layer (the “living” part of a tree).
Feasting on phloem and xylem, borers can cause extensive internal feeding damage. Nasty work!
The Red Gum Lerp Psyllids, Glycaspis briblecomei, are messy pests that suck out all of the sugars in a leaf. The leaves will still hang on, but they won’t be happy.
Though not as quick to damage as the Big Bad Wolf (the Paropsis Leaf Beetle), Psyllids drop honeydew when sucking out a tree’s sugars, and they leave behind black sooty mold under the tree and on cars.
Don’t consider handing a hankie to the Psyllids as they feast; it could be considered an invitation to an open banquet in your garden!
Common Diseases on Eucalyptus
Per our ISA Certified Arborists at Sims Tree Health Specialists, Inc., the most common disease found among Eucalyptus is heart rot (ganoderma).
This wood-decaying fungus may cause a tree to decline and can lead to tree failure. Generally speaking, heart rot occurs when an open wound is left uncared for.
The evil twins, Phytophthora and Pythium, are common oomycetes that cause vascular wilt. Similar to fungi, these bad buds are more closely related to humans!
Pythium root rot, Pythium, occurs due to excessively wet conditions, primarily from poor soil drainage. It attacks young tissues such as root tips. The oomycete rapidly spreads the brownish-blackish rot, moving up the stem tissue of a primary root.
Phytophthora – try spelling that without looking it up! This is caused by poor soil drainage as well. Incredibly common in California, it takes a perfect storm of climate, moisture, and heat factors to wreak havoc. Affected trees have wilted leaves that have turned dullish green, yellow, or even red. Roots and crowns may darken, resulting in gumming!
Summary
Eucalyptus trees are spotted throughout Southern California, interspersing a highly biodiverse landscape. The California public's complex embrace of them has solidified their role in our history and our land.
The trained professionals of ISA Certified Arborists at Sims Tree Health Specialists, Inc., are equipped to fight the good fight and help Eucalyptus thrive.
About Sims Tree Health Specialists, Inc.
Sims Tree Health Specialists, Inc. is dedicated to the preservation, education, improved health, and safety of trees. Sims THS has provided California’s Urban Forests with premium healthcare since 1972. To learn more, visit our website: https://www.simsths.com/
Sims THS offers services with our ISA Certified Arborists in the following:
Diagnosis and Disease Management, Pest Suppression, Organic Solutions, Fruit Suppression, Drought Protection, and Arborist Assessment Reports and Preservation Plans.
In addition to providing quality tree health services, the Sims family is known for their educational pursuits. In 1996, they started the Sims Tree Learning Center (TLC), a 6-acre botanical garden and research facility sponsored by Sims Tree Health Specialists, Inc. The facility houses multiple types of gardens including a cactus and succulent garden and one of the largest collections of Palms in the Inland Empire. Learn with us!
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