Local and State Gardening News
Bed bugs are quickly becoming major household nuisance pests. California has recently experienced a multitude of bed bug reports, with San Francisco now considered one of the Top 10 most infested cities in the country. Bed bug detection can be very difficult and almost always requires special training since bugs prefer to hide in dark, inaccessible cracks and crevices near their hosts’ resting spots. An experienced pest management professional can examine all possible harborages in a home, searching for the bugs themselves and signs of infestation such as the characteristic black fecal spotting and cast nymphal skins, although low-density infestations may escape detection.
Thankfully, several monitors are available that attract or intercept bed bugs. Bed bug monitors fall within one of two categories: active monitors and passive monitors. Active monitors employ attractants—heat, carbon dioxide, host odors (kairomones), pheromones, or a combination of these—to lure bed bugs out of their hiding areas and into a pitfall or sticky trap within the monitor. These devices have the potential to detect bed bugs in the absence of a host (vacant room). Passive monitors either exploit a bed bug’s affinity for dark crevices or rely on chance encounters with pitfalls or sticky traps. Interceptor monitors are pitfall devices that rely on the presence of a host (a sleeping human) to attract hungry bugs and trap them en route to their meal.
A team of UC researchers led by UC Berkeley entomologist Vernard Lewis recently evaluated a series of five bed bug monitors. Overall the study concluded that active monitors recovered a steady proportion of bed bugs as densities increased and that all monitors tested were able to detect bed bugs at low densities.
First identified in California in 2004, the goldspotted oak borer (GSOB), Agrilus auroguttatus, has killed more than 24,000 oak trees in San Diego County since its arrival, probably in the late 1990s. In 2012, it was detected in Riverside County and it is expected to spread northward in the state.
The most seriously damaged oaks are those in the red oak group including coast live oak, Quercus agrifolia, and black oak, Q. kelloggi. It also infests canyon live oak, Q. chrysolepis but has not been found to kill the other native oak species in the area, the Englemann oak, Q. englemanni. So far losses have been most serious in parks and forested areas, but landscape trees are also being killed.
A new Pest Note from the UC IPM program outlines management guidelines for this serious pest. Flatheaded borers such as GSOB are difficult to manage and seriously infested trees cannot be saved. The primary way GSOB spreads into new areas is through the movement of infested wood and the authors recommend leaving infested wood on site for 2 years. If wood is to be moved, the Pest Note provides guidelines for treating it through containment, grinding, and debarking. Guidelines for replanting infested areas, less susceptible oak species, biological control, insecticide applications and developing GSOB management plans are also described.
Many other borers attack oaks but do not kill trees. GSOB infested trees can be distinguished by the characteristic D-shaped emergence holes it leaves behind. A special feature of the Pest Note is a table illustrating the emergence holes of borer species on southern California oaks. Many photos are also included.
The information in this Pest Note: Goldspotted Oak Borer is based primarily on research studies by the authors: Mary Louise Flint (UCIPM and Entomology/UC Davis), Tom Coleman and Steve Seybold (USDA/US Forest Service), and Mike Jones (Entomology/UC Davis). Find it at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74163.html
The City of Parlier’s Earth Day celebration on March 30th attracted about 2000 attendees. Events included a tree planting, Easter egg hunt, family walk, folk dancing, zumba dancing, free raffles for prizes, games for youth, and face painting. Representatives from many local service organizations had booths that provided families with free items ranging from food to dental screening. KARE’s booth provided 1000 strawberry crowns and 2500 leaf lettuce transplants to the public. Youth from the local Leo club helped with handing out the plants and discussing the benefits of eating fruits and vegetables.
Youth from Parlier's Leo club helping set up KARE's booth at Parlier Earth Day.
Families attending Parlier Earth Day collecting leaf lettuce transplants, strawberry crowns and information on healthy food choices at the KARE booth.
In 2003, the Polyphagous Shot Hole Borer (PSHB) was observed in Southern California. This beetle has a Fusarium sp. symbiont that causes susceptible host tree damage. The PSHB appears to be established in Los Angeles, Orange, and Riverside Counties. In the Los Angeles area, PSHB has attacked over 200 species of native, ornamental and horticultural trees, including the native Coast Live Oak, California sycamore, and about 57% of the commonly used street trees in the area. Avocado trees are susceptible; the beetle and fungus have been found in several backyard avocado trees as well as some commercial avocado orchards in Los Angeles and Orange counties. The PSHB has caused severe damage to commercial avocado orchards in Israel, and is a threat to California’s avocado crop which is worth about $460.6 million and accounts for about 87% of the US production.
To better understand the biology of and potential management strategies for the PSHB Fusarium complex threatening California’s avocado trees, Mary Lu Arpaia, Subtropical Horticulture Extension Specialist in the UC Riverside Botany and Plant Sciences Department and Kearney Agricultural Research and Extension Center, and David Obenland, Plant Physiologist, at USDA-ARS in Parlier, California, visited Israel in March, 2013. The PSHB is an invasive pest in Israel and was found in Israel’s commercial avocado orchards in 2009. The PSHB in Israel is causing serious damage, and Israeli research may help us develop detection and management strategies in California.
Biology and Behavior: A visit with Drs. Zvi Mendel and Stanley Freeman, Israel’s lead PSHB researchers provided insight into research on the biology and behavior of the PSHB Fusarium complex. Drs. Mendel and Freeman contend that even though the beetle uses several tree species as hosts, it is monophagous, only feeding on the Fusarium symbiont. According to their research, the beetle’s reproductive cycle in susceptible trees is: the adult pregnant female beetle bores through a tree’s bark, creates galleries under the bark, infests the galleries with a Fusarium fungal symbiont carried in the adult beetle’s mycangium (a specialized structure at the back of the jaw), and lays eggs in the galleries. Larvae are mostly female. While the larvae develop, the Fusarium sporulates. The developing larvae eat the fungus, develop into adults in about a month, and mate while in the gallery. The pregnant females exit the gallery through exit holes in the bark. To survive, the emerged pregnant female has about 48 hours to find a suitable host location and continue the life cycle.
Hygiene: The geographic area where the beetle is found in Israel appears to be expanding, even though the infested avocado trees in the primary infested area were destroyed. The PSHB is thought to have been transported in bins originating from the infested area. A best practice for California growers and packers will be to use clean bins and ensure that there is no vegetative matter in the bins prior to transport. This practice will also help reduce the spread of avocado thrips and persea mite.
Chemical control of the beetle or the fungus: There has been limited success in controlled lab situations, but field applications are not effective. So far, no effective chemical control technologies have been developed for the beetle.
Infestation: A mature orchard that was infested approximately 5 to 6 years ago became heavily infested within 2 to 3 years, and will be bulldozed. Infestations may require bulldozing orchards.
Detection: Mature avocado orchards with heavy infestation have severe limb dieback, many broken branches littering the orchard floor, dropped mature fruit, abnormally small mature fruit, and sugar exudates caused by the bore holes. A 2-year-old infested orchard did not exhibit very much limb dieback; when infestation of young trees is observed, it is usually on the base of the trunk (found in either the rootstock or the scion wood).
Spread to native and landscape hosts: Israel has seen the spread of the beetle to native oaks and the box elder. California will need to educate the public to help safeguard our native and landscape trees from the spread of the PSHB and Fusarium complex. Native and landscape tree infestations may make it difficult to control the spread of infestations into commercial avocado orchards.
California outlook: California must be diligent in looking for tree infestation. The avocado industry is working with the landscape industry and forestry service in California to understand the rate of infestation and range of susceptible hosts. Funding for surveys; understanding the beetle and fungal biology; developing control strategies, technologies and practices; and basic work on the origin of the beetle is essential. California researchers should collaborate with and learn from their Israeli colleagues.
Avocado tree in Israel with limb breakage and branch dieback due to PSHB infestation and its Fusarium symbiont (photo by M. L. Arpaia).
External symptoms of PSHB infestation, including sugar exudate, bark darkening, and wood staining due to Fusarium infection of the woody tissue (photo by M. L. Arpaia).
PHSB infested avocado branch in later stages of decline. The white larvae are termites that infested the branch after dieback started. Note the staining of the wood and evidence of the PHSB galleries. (photo by M.L. Arpaia)
UC helps the Fresno Farm and Nutrition Day increase student awareness of healthful food and where it comes from.
More than 1,600 third-graders and 330 teachers and chaperones from 24 Fresno County schools attended Farm and Nutrition Day March 22 at the Big Fresno Fairgrounds. Attendees had the opportunity to tour 50 stations with educational handouts, experiential workshops, presentations and demonstrations. Fresno County Farm Bureau organized the event with the assistance of several presenter groups, sponsors and volunteers, including two UC Agriculture and Natural Resources units.
KARE provided short presentations on what it takes to be a healthy plant and what it takes to be a healthy person, followed immediately by workshops where the students planted leaf lettuce transplants to take home and enjoy. This workshop was made possible with donations and volunteers. Valley Soil & Forest Products donated soil, The Plant People donated pots, and Greenheart Farms donated lettuce transplants. Ten volunteers helped ensure that all of the participants were able to pot up and take home leaf lettuce plants.
Fresno County UC Cooperative Extension provided nutritional presentations and demonstrations. Fresno’s community 4-H clubs brought farm animals to interact with the mostly urban students. Richard Molinar, UC Cooperative Extension advisor in Fresno County, small farm program, displayed Southeast Asian vegetables and discussed Southeast Asian culture with the students.
Students at the Fresno Farm and Nutrition Day discussing what it takes to be a healthy plant and what it takes to be a healthy person.
Students potting up leaf lettuce transplants to take home and grow.
Richard Molinar displaying Southeast Asian vegetables and discussing Southeast Asian culture with students attending the Fresno Farm and Nutrition Day (photo by Fresno Farm Bureau).