The Situation: Red gum lerp psyllid is an insect that is native to Australia. In June 1998, this insect invaded California and was first found in Los Angeles County. This pest feeds exclusively on species of Eucalyptus and in California it exhibits high preference for river red gum ( Eucalyptus camaldulensis), flooded gum ( E...
The Situation: Russian thistle, commonly known as tumbleweed, is a profusely branched annual herb. Its efficient taproot, abundant seed production and reduced leaf surface adapt this weed well to disturbed semiarid agricultural environments, rangeland and nonagricultural areas such as vacant resident lots and railroad or highway rights-of-way. It has become pervasive as an exotic weed...
Damage: Once established, saltcedar is tolerant to high salinity and secretes salt at a high rate which is deposited on the soil surface to the detriment of native plant species. Saltcedar increases fire frequency within the riparian habitats it dominates because of its high levels of dead leaves and branches that provide fuel for fires...
The Situation: When the silverleaf whitefly (SLW) (also known as Bemisia tabaci strain B) struck southern California’s desert valleys in fall 1991, clouds of these tiny insects could be seen moving across the region, which produces 90 percent of the fall and winter vegetables grown in the U.S. Research conducted at the University of California...
The Situation: The Sting nematode is an important pathogen on most agricultural and horticultural crops, including turf, citrus and grapes. This ectoparasite is native to sandy soils in the southeastern and Midwestern United States. In 1992, UC Riverside nematologists discovered that several golf courses in the Coachella Valley were heavily infested with sting nematodes. The...
The Situation: In southern California, the native western flower thrips (WFT) Frankliniella occidentalis is the most common vector responsible for transmission of an exotic plant virus, Tomato Spotted Wilt Virus (TSWV). The pathogen was discovered on tomatoes in 1915 in Australia, and has been spreading around the world ever since. TSWV is a tospovirus (Bunyaviridae)...
The Situation: The Asian Woolly Hackberry aphid Shivaphis celtiwas first detected in North America on native hackberry trees ( Celtis occidentalis) in Georgia in 1996 and has been subsequently found throughout the southeastern states. In 2002 the aphid was detected in several counties in the San Joaquin Valley of California on the commonly planted Chinese...
The Situation: Eucalyptus is a ubiquitous landscape, shade, and windbreak tree throughout southern and central California. The trees are valued for their fast growth and tolerance of poor soils and drought. Eucalyptus is now threatened by several pest insects accidentally introduced into California from Australia, one of which is the Australian gum tree weevil. Description...
The Situation: Avocado lace bug, Pseudacysta perseae, was first described in Florida in 1908 from specimens collected in this state over the period 1897-1907. Avocado lace bug is a true bug with sucking mouth parts. The common name “lace bug”, is derived from the highly reticulate “lace-like-patterning” of the thorax and wings of adults. There...
The Situation: Avocados are subtropical perennial fruit trees 6-10 meters in height. California produces 95% of the nation’s crop, and 85% of this harvest is from one cultivar, the black fruit Hass avocado. Annually, 6,000 growers in California produce 260 million pounds of fruit on 65,000 acres, and the harvest in 2007 was worth $245...
The Situation: In California, black scale is a periodic pest of citrus in southern California and a consistent pest of olives in the San Joaquin Valley. It was introduced into the United States and California sometime before 1880. It now occurs in many regions of the world and infests a wide range of plants. It...
The Situation: The brown citrus aphid (BrCA), is an insect pest of all citrus varieties. It is not a pest of non-citrus crops. The brown citrus aphid infests the stems and new leaves of citrus trees and in addition to feeding damage, it is a highly efficient vector of citrus tristeza virus (CTV). CTV can...
The Situation: California red scale was introduced into California between 1868 and 1875, apparently on citrus seedlings from Australia. The scale insect is native to Southeast Asia but has been transported on citrus seedlings to all arid and semiarid regions of the world where citrus is grown. It occurs in all of California’s citrus growing...
The Situation: In California, citricola scale is a serious pest . This pest is a particular nuisance in the San Joaquin Valley when broad-spectrum pesticide use is reduced as these insecticides typically keep this pest under good control. It was also a serious pest in the inland areas of southern California until 1935, when Metaphycus...
The Situation: Citrus huanglongbing (HLB), previously called citrus greening disease, is one of the most destructive diseases of citrus worldwide. Originally thought to be caused by a virus, it is now known to be caused by unculturable phloem-limited bacteria. There are three forms of greening that have been described. The African form produces symptoms only...
The Situation: Diaprepes root weevil is a large (3/8-3/4 inch long) colorful weevil with color forms that range from gray to yellow to orange and black. Diaprepes is originally from the Caribbean and was introduced into Florida in the 1960s. The larval stage feeds on roots and causes serious damage to ornamentals, citrus and a...
The Situation: Elms are a common shade tree planted throughout the U.S. and are valued for their large, high canopies and the shade they provide. The elm leaf beetle was accidentally introduced into the U.S. in the 1830s and is now one of the most important urban forest pests in California. Damage and Economic Impact:Both...
The Situation: Approximately 90 of the more than 700 species in the tree genus Eucalyptushave been introduced into North America over the last 150 years. Eucalyptusspp. are native to Australia and New Guinea. Many residents of California find the growth form, evergreen foliage, floral show, and other horticultural qualities such as drought tolerance highly desirable...
The Situation: In southern California, the most widespread yellowjacket has historically been the native, western yellowjacket, Vespula pensylvanica. The German yellowjacket, V. germanica, became established in the Northeastern U.S. in the 1970s and then the Pacific Northwest in the 1980s where it spread down the coast. It reached southern California in 1991 becoming part of...
The Situation: Persea mite, Oligonychus perseae, was first described in 1975 from specimens collected from avocado foliage intercepted from Mexico at an El Paso, Texas, quarantine facility. Persea mite is native to Mexico and damages avocados in arid regions, a pest in the state of Michoacan where Hass avocado production is greatest. Persea mite has...
