Common causes of abiotic disorders include too much or not enough water, compacted soil, nutrient deficiency (often caused by imbalanced soil pH), excess soil salinity, too much heat or sunlight, herbicides, air pollution, and mechanical injuries.
Abiotic disorders can develop for several reasons:
- the site was not well prepared before landscaping,
- the plants were improperly planted,
- the plant species is not well adapted to conditions at that location,
- the plants did not receive the correct cultural care.
Avoid abiotic disorders by giving plants the right amount of water, sunlight, and nutrients. You must water plants properly, and the soil must drain well. The soil must contain the correct nutrient levels, pH, and salinity. Fix any extreme light or temperatures issues like too much sunlight. Protect plants from herbicide and fertilizer damage as well as from mechanical injuries.
When you suspect an abiotic disorder, find out both the species and variety of the plant so you know the plant's expected appearance and its specific cultural needs. Inspect the plant and surrounding plants for symptoms. Some abiotic disorders can be recognized by their characteristic damage symptoms (e.g., distorted, discolored, or dying foliage). However, diagnosing the cause of disorders can be difficult. Plants will react differently to abiotic issues depending on their age and specific variety. Different abiotic causes can produce the same symptoms, and more than one cause can affect plants at the same time.
To solve plant problems, it's important to distinguish abiotic disorders from similar-looking damage caused by pests such as insects, mites, nematodes, pathogens, and vertebrates. See Table 1 for details.
|Plants affected||Unrelated||One type or closely related|
|Plant age||Various ages||Same age more likely|
|Pattern of symptoms||Regular or uniform||Random or irregular|
|Rate of development||Sudden onset||Slow, worsens over time|
|Spread||Does not spread||Infectious, spreads on host over time|
|Signs||No evidence of pest or pathogen||Presence of pest, mycelium, mushrooms, rust, pustules, bacterial ooze, honeydew, frass|
For more information about abiotic plant problems, see the UC ANR publications Abiotic Disorders of Landscape Plants and Pests of Landscape Trees and Shrubs. Content adapted from Abiotic Disorders of Landscape Plants and Pests of Landscape Trees and Shrubs.
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- Author: Ben Faber
If you see significant leaf drop in your groves due to excessive heat, the following actions are recommended:
- As soon as possible, whitewash branches exposed to the sun with special attention paid to branches on the west and south sides of the tree.
- Trees that lose a significant portion of leaves cannot efficiently move water, therefore restrict irrigation amounts to ensure you avoid creating wet, soggy conditions that can lead to root rot. It's best to irrigate less frequently and with smaller amounts of water.
- Do not prune your trees — leave hanging leaves in place to protect the tree from sunburn. Once new tree growth has occurred (in the next 3 – 6 months), pruning can take place on living wood.
- Adjust fertilization as you would with a frost-damaged tree: reducing the amount of fertilizer until the tree is re-established. If you see signs of a particular nutrient deficiency, adjust fertilization accordingly.
For more information about managing heat in avocado groves, growers can view the following articles on the California avocado growers' website:
By Julie Clark, Community Education Specialist III
Goldspotted borer (GSOB) is a beetle invasive to oaks in California. Infestations have ravaged oak woodlands in San Diego and Riverside counties the last 12 years and in Anaheim Hills, Angeles and San Bernardino National Forests the last few years. Preferred hosts are black oak, canyon oak, coast live oak, and occasionally Engelmann oak.
Oak woodlands are highly valued ecosystems that support numerous species of fauna. Oak trees serve as the anchor for these systems and support over 5000 insect species, over 105 bird species, 105 mammal species, 58 species of amphibians and reptiles during their respective life cycles. Many beneficial insects rely on oaks to complete their life cycles and do not damage the trees in doing so.
The insects damage the water and food transfer structures (xylem and phloem) of the tree, causing crown die-back and eventual death in heavily infested (amplifier) trees. Widespread loss of oaks from GSOB has occurred in Idyllwild and San Diego County mountain areas.
Although GSOB are winged, they do not fly long distance. UC researchers, partners with CAL FIRE and the California Firewood Task Force discovered that several of the infestations throughout Southern California were caused by introduction of firewood imported from infestations in other areas.
D-shaped GSOB exit holes. Credit: UC ANR
Ventura County is vulnerable to attack by the beetle and other invasive tree pests that are on watchlists for the area. Best ways of being assured your firewood is safe include purchasing locally source material or selecting kiln-dried or certified firewood.
For more information:
Report suspected GSOB infestation:
- Author: Ben Faber
Heat Mitigation Around the World
A chance to hear what can and is being done by growers
to reduce the damage inflicted on avocado fruit and trees
World wide Speakers:
- Author: Elaine Lander
While you are outside gardening or inside doing your spring cleaning, you may have recently found small, round, speckled beetles you've never seen before. We've had several questions this past week about insects crawling around windowsills, found on screens, or noticed on outdoor plants, or fuzzy, oblong insects on carpets or rugs. What are they? While there are many insects starting to emerge from their winter rest, if you are finding small beetles like these, they could be carpet beetles!
Carpet beetles are pests of homes, warehouses, and museums. In California, there are 3 species that damage fabrics, carpets, and stored foods including the varied carpet beetle, Anthrenus verbasci. The beetles are round like lady beetles (“ladybugs”), but much smaller in size. Varied carpet beetles are about 1/10 inch long, with black, white, brown and dark yellow patterns.
Carpet beetles adults feed on pollen and nectar of flowers. They often fly into homes from flowers in the landscape or may be accidentally brought indoors on cut flowers. A few adult beetles inside your home are typically not a problem. However, if you find larvae, the fuzzy immature beetles on fabric, carpet, or other natural materials in your home, you may need to manage the infestation.
See our Pest Notes: Carpet Beetles for more identification, prevention, and management information.
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