Posts Tagged: fusarium dieback
Watch Out For Invasive Shot Hole Borers on Your Landscape Trees
Watch out for these insects! Invasive shot hole borers (ISHB) represent two related species of beetles (polyphagous and Kuroshio) in the genus Euwallacea. Both spread fusarium dieback, a disease that restricts the flow of water and nutrients in the tree, resulting in dead branches, dropped limbs, and even death. Over 60 species of native and non-native ornamental trees and avocados in Southern California are susceptible the ISHB/fusarium dieback complex.Examples of known hosts of the ISHB/fusarium dieback complex include: Box Elder (Acer negundo), Avocado (Persea americana), English Oak (Quercus robur), Valley Oak (Quercus lobata), California coast live oak (Quercus agrifolia), Big leaf maple (Acer macrophyhllum) silk tree (Albizia julibrissin) Liquidambar (Liquidambar styraciflua), Coral tree (Erythrina coralladendron), California sycamore (Platanus racemose), Blue Palo Verde (Cercidium floridum), Purple orchid tree (Bauhinia variegate), Kurrajong (Brachychiton populneus); and many species of Acacia.
The beetles are native to Southeast Asia and were likely introduced into California in shipped goods, wood products, or packaging. While tiny (about the size of a sesame seed), they are prolific, tunneling into host trees and living and reproducing in galleries while feasting on the disease-causing fungus they spread from tree to tree. Females are black and much more common than the small wingless brown males, which are rarely found.
While the initial infestation occurred in Los Angeles County in 2003, beetles travel about 12 miles a year and have now spread fusarium dieback into Orange, San Diego, Riverside, San Bernardino, Ventura, and Santa Barbara Counties. Orange County alone has spent millions of dollars removing infested trees and managing the spread of the ISHB/fusarium dieback complex.
Identifying ISHB in a timely way is essential to reduce damage and slow its spread. Look for round borer entry holes about the size of the tip of a medium ballpoint pen. Staining, gumming, discoloration of wood beneath the bark, and/or frass (sawdust-like material) are other common signs and symptoms. There may also be white powdery exudate around beetle entry holes. Keep in mind that there are many other disorders that have similar symptoms. For example, other fungal diseases produce exudate and staining and other types of borers leave entry holes of various shapes and sizes.
To date, no effective control measures have been found once trees are infested, although entomologists and plant pathologists from the University of California, The USDA Forest Service and other agencies continue to research viable integrated pest management options including biological control.
To prevent and/or reduce spread of ISHB/fusarium dieback:
- Bring only ISHB-free greenwaste (used for mulch and soil amendments) and firewood onsite. Both products can harbor ISHB which can persist for months.
- Treat infected wood onsite whenever possible. Wrap or completely cover wood that cannot be immediately treated and wood that is moved offsite for treatment elsewhere.
- Chipping infested wood to 1 inch or less can kill 95% of the beetles, while solarizing it using a clear tarp eliminates both ISHB and spores produced by the fungus. Logs can also be solarized. Composting is another option that, when done correctly, can kill both beetles and fungal spores.
- Untreated logs, branches, or woodchips infested with ISHB should not be used for firewood or mulch.
- Remove stumps as well as dead trees.
- Follow International Society of Arboriculture pruning standards and never top or flush cut trees which leave open wounds.
- Spray a 70% ethanol solution on equipment and tools since fusarium fungi can adhere to both.
- Keep trees healthy (water mature trees deeply and infrequently, avoid over or under-fertilization, etc.).
- Monitor susceptible tree species often to identify damage as early as possible. Useful detection and reporting tools and more detailed information on the ISHB/fusarium dieback complex can be found here: ucanr.edu/sites/pshb
For more detailed information on the ISHB/fusarium dieback complex, please visit these websites: https://ucanr.edu/sites/pshb/ https://www2.ipm.ucanr.edu/agriculture/avocado/polyphagous-shot-hole-borer-and-kuroshio-shot-hole-borer/ https://cisr.ucr.edu/invasive-species/polyphagous-shot-hole-borer https://californiareleaf.org/pests/
How to Attract an Ambrosia Beetle that Attacks Avocado and Sycamore
There's a lot of work being done in Florida on a pest/disease complex like we have here with Shot Hole Borer and Fusarium fungus – Fusarium Dieback. This hits avocados and a lot of other native trees like sycamore, willow and coast live oak. Some of the success in Florida may be applicable and we are working with their researchers there to adapt some of the techniques here.
Redbay ambrosia beetle, Xyleborus glabratus, is a wood-boring pest that has now invaded nine states in the southeastern United States. The beetle's dominant fungal symbiont (Raffaelea lauricola) is phytopathogenic, inducing laurel wilt in trees within the family Lauraceae. Members of the genus Persea are particularly susceptible to the lethal disease, including native redbay (P. borbonia) and swampbay (P. palustris), as well as commercial avocado. Cubeb oil lures are the current standard for detection of X. glabratus, but recently eucalyptol and a 50% α-copaene oil have been identified as additional attractants. This study used a combination of choice bioassays, field cage release-and-recapture assays, and a 12-week field trial to compare efficacy of eucalyptol and copaene lures relative to commercial cubeb lures. In addition, gas chromatography (analyzer for volatiles) was used to quantify emissions from lures field-aged for 12 wk. In field cage assays, copaene lures recaptured a higher percentage of released beetles than cubeb lures. In the field test, cubeb lures captured fewer beetles than copaene lures, and lowest captures were obtained with eucalyptol lures. Both copaene and cubeb lures were effective in attracting X. glabratus for 12 weeks, but field life of eucalyptol lures was only 4 weeks, consistent with the quantification of lure emissions. Results suggest that the 50% α-copaene lure provides the best pest detection currently available for X. glabratus.
So why is this important? For one, it will serve as a tool for more effectively monitoring the presents of the beetle. But more importantly, it might be used as a lure to attract them away from trees. Fool them into going somewhere else, like to die.
shot hole borer
Reproductive host list for polyphagous shot hole borer expands to thirty five species
The reproductive host list for tree species affected by the polyphagous shot hole borer has topped...
monitoring PSHB in the arroyo