Pest Advice - General Publications
Annual bluegrass is one of the most common weeds of turf, ornamental plantings, and gardens in the United States. Commonly referred to as "Poa," it is a particular problem in golf course greens and fairways.
Anthracnose is a group of diseases found on many deciduous and evergreen trees and shrubs; some trees such as sycamore, ash, and evergreen elms can be noticeably blighted. Often called leaf, shoot, or twig blight, anthracnose results from infection by any of several different fungi.
Ants are among the most prevalent pests in households. They are also found in restaurants, hospitals, offices, warehouses, and other buildings where they can find food and water. On outdoor (and sometimes indoor) plants, ants protect and care for honeydew-producing insects such as aphids, soft scales, whiteflies, and mealybugs, increasing damage from these pests. Ants also perform many useful functions in the environment, such as feeding on other pests (e.g., fleas, caterpillars, termites), dead insects, and decomposing tissue from dead animals. Also available in Spanish through http://anrcatalog.ucdavis.edu.
Aphids are small, soft-bodied insects with long, slender mouth parts that they use to pierce stems, leaves, and other tender plant parts and suck out plant fluids. Low to moderate numbers of aphids are usually not damaging in gardens or on trees, but large populations can cause curling, yellowing, and distortion of leaves and stunting of shoots; they can also produce large quantities honeydew, which often turns black with the growth of a sooty mold fungus.
Apple and pear scab, caused by the fungus Venturia inaequalis, is generally considered a serious disease of apples and pears in California, causing loss or severe surface blemishing of fruit. Apple and pear scab is most severe in coastal areas where spring and early summer weather is cool and moist; however, it can be a problem wherever apples are grown when conditions are favorable for its development.
About the size of an aphid, Asian citrus psyllid (ACP) can carry Huanglongbing (HLB) disease, which poses a serious threat to citrus trees grown in California's home gardens and farms. Learn to identify and manage this pest and the disease it carries.
A plant pest in California only since 2004, Avocado Lace Bug is a problem mostly in San Diego County where it damages the trees' leaves, eventually exposing the fruit to sunburn damage. Learn to recognize and manage this pest.
Bark beetles, family Scolytidae, are common pests of conifers and some attack broadleaf trees. The most common species infesting pines in California are the western pine beetle (Dendroctonus brevicomis), engraver beetles (Ips spp.), and the red turpentine beetle (Dendroctonus valens). The species of tree attacked and the location of damage on the bark help in identifying the bark beetle species present.
Bats help with insect pest control, but there is a down side: they can carry parasites harmful to people, as well as rabies and other diseases. Learn how to encourage bats to nest and fly where they'll do the most good, and not too close to humans.
Bed bugs are in the insect family Cimicidae and include three species that attack people. Of these, the most important is Cimex lectularius, which may also bite bats, birds, and rodents. Until recently, bed bug infestations were thought to be associated primarily with crowded and dilapidated housing. However, such infestations have undergone a resurgence and can be found even in the finest hotel and living accommodations. The reasons for the resurgence are not totally understood but appear to involve increased human travel, ease of movement of infested luggage and items, and changes in the pesticides available to control this pest.
Nearly everyone has been stung by an insect at one time or another. It is an unpleasant experience that people hope not to repeat, but for most people the damage inflicted is only temporary pain. Only a very limited portion of the population (one to two people out of 1,000) is allergic or hypersensitive to bee or wasp stings. This publication is about stings from bees and wasps, but the information also pertains to stings from fire ants as well.
Bermudagrass (Cynodon dactylon) is a plant that is grown as a turfgrass or as forage for livestock, but it also can be an invasive weed. It was introduced from Africa (not Bermuda) in 1751 and is widely spread throughout the southwest and southern United States. It is found in most areas of California at elevations below 3,000 feet and is common in gardens, landscapes, turf areas, orchards, roadsides, vineyards, and industrial areas. Bermudagrass also has many other common names including couchgrass, devilgrass, wiregrass, or dogtooth grass.
Biological control is the beneficial action of predators, parasites, pathogens, and competitors in controlling pests and their damage. Learn to identify many of these remarkable natural helpers and encourage their useful work.
Wild birds are common, hungry visitors to backyard fruit and nut trees. Almonds and early ripening cherries are among the hardest hit, but most home fruit and nut crops are vulnerable. Learn how to keep these feathered friends out of your food supply.
Black scale causes economic damage to olive and citrus crops, and can also affect a large variety of fruit and nut trees and ornamental plants. Learn how to identify, manage, and control this insect pest.
Western Black Widows and Brown Widows (in Southern California) thrive in cluttered, little-used areas around the home. Their bite causes numbness, sweats, and worse -- but there is a good antivenom. Best advice: Keep your garage and yard clutter-free.
Bordeaux mixture is an outstanding fungicide and bactericide that has been used for decades to control some diseases of tree fruits and nuts, vine fruits, and ornamentals. The ability of Bordeaux mixture to weather the fall, winter, and spring rains and to adhere to plants makes it an excellent choice for a winter fungicide.
The western boxelder bug (Boisea rubrolineata) is often a nuisance pest. They do not cause significant damage to landscape plants, and management need only be directed at keeping them out of homes, where they may become a nuisance.
Scotch broom and other brooms are non-native shrubs that compete with California wildflowers. First planted by gardeners in the 1800s, brooms have since spread into wild areas. Learn to identify brooms and eliminate them from the landscape. Color photos.
The brown recluse is infrequently found in California. Yet people frequently relate stories in which a brown recluse in California bit them or someone they know. This publication was written in response to the confusion that exists regarding these spiders.
Burning nettles and stinging nettles are aptly named plants that cause a painful rash when they contact human skin. They can be a nuisance or even a health hazard to hikers or outdoor workers. Learn to identify and manage these troublesome plants.
The California ground squirrel, Spermophilus beecheyi, is one of the most troublesome pests to homeowners and gardeners. It is found in nearly all regions of California except for the Owens Valley southward into the desert regions.
The California oakworm is one of many species of caterpillar that feed on oaks in California. Damage is most common on coast live oak in the San Francisco Bay area and Monterey Bay region; but outbreaks can occur in many parts of the state.
Carpenter ants are capable of damaging wood in buildings and other structures. They cause problems mainly in mountainous and in forested rural areas along the central and northern coastlines of California; they may also invade buildings in urban locations.
Carpenter bees build nests in wood, creating galleries that can weaken structures; however, they rarely cause severe damage. People may be frightened by carpenter bees because of their large size, their similarity to bumble bees, and their annoying noise.
Carpenterworm is a common wood-boring insect that can cause significant damage to trees. Trees commonly infested include willow, ash, ornamental pears, black locust, cottonwood, maple, apricot, fruiting pear, birch, oak, and American elms.
Carpet beetles are pests in warehouses, homes, museums, and other locations where suitable food exists. In California, three species of these beetles cause serious damage to fabrics, carpets, furs, stored foods, and preserved specimens.
Catchweed bedstraw is a troublesome agricultural weed that also shows up in the garden, where it competes for water and nutrients. The tiny, curved hairs on stem and leaf help bedstraw to form a dense mat. Learn to identify and manage this weed.
Two species of chickweed, common (Stellaria media) and sticky (Cerastium glomeratum), are widespread in California. Both are winter annuals that grow easily in gardens, low-maintenance lawns, and agricultural areas.
Citrus leafminer larvae cause damage to new leaves on citrus plants and are particularly troublesome on younger trees. Learn how to control this pest using natural and chemical methods.
The larvae of several species of clearwing moths in the insect family Sesiidae are important wood-boring pests in landscapes. Hosts include alder, ash, birch, fir, oak, pine, poplar, sycamore, willow, and stone fruit trees such as apricot, cherry, peach, and plum.
Swallows, particularly cliff swallows, Hirundo pyrrhonota, often live in close proximity to people. While enjoyable to watch, cliff swallows nesting in colonies on buildings and other structures can become a nuisance.
The webbing clothes moth, Tineola bisselliella, and the casemaking clothes moth, Tinea pellionella, are occasional fabric pests in California. Clothes moths are weak flyers and are not attracted to lights. They tend to hide when disturbed, and for this reason, infestations of clothes moths are not usually noticed until damaged fabrics, furs, or feathers are found.
Clover can be a concern in turfgrass or landscaped areas for at least three reasons. First, during the flowering period bees are attracted to the clover blooms and people playing or using the turfgrass may be stung. Second, clovers reduce the uniformity of the turfgrass because its texture, color, and growth rate are different from that of grasses. And third, burclover has soft, spiny fruit that are objectionable when the burs mature; the burs are also a problem when they become attached to the fur of pets.
Cockroaches may become pests in homes, restaurants, hospitals, warehouses, offices, and virtually any structure that has food preparation or storage areas. They contaminate food and eating utensils, destroy fabric and paper products, and impart stains and unpleasant odors to surfaces they contact. Also available in Spanish through http://anrcatalog.ucdavis.edu.
Codling moth, Cydia (Laspeyresia) pomonella, is a serious insect pest of apples, pears, and English walnuts.
Common groundsel or old-man-of-the-spring is found throughout California. It can cause chronic liver poisoning to horses, cattle, and swine, even if only a small amount is eaten over a few weeks.
Common purslane is a weedy summer annual species that invades gardens, low-maintenance lawns, ornamental plantings, commercial orchards, and vegetable crop production areas. It is particularly well adapted to the warm, moist conditions found in California’s irrigated agricultural and ornamental sites. Because of its ability to produce large numbers of seeds, common purslane can rapidly colonize any warm, moist site. A few scattered plants in the first year can become an almost solid carpet of purslane the following year.
Conenose bugs are members of the family Reduviidae, commonly called assassin bugs. Most members of this family are predators of other insects, but the conenose, also known as kissing bugs, are bloodsucking parasites of a wide variety of animals and humans.
Cottony cushion scale, Icerya purchasi, can infest many woody ornamentals and certain crops. Common hosts in California are citrus, cocculus, nandina, and pittosporum. Its cottony egg sac and profuse honeydew production make cottony cushion scale easy to spot.
Coyotes have a reputation for causing trouble that goes back thousands of years. They are still at it today, damaging livestock and irrigation equipment and even straying into suburban areas. Learn to recognize coyotes and where to turn for help.
Crabgrass is a common weed that almost everyone knows. (The "great philosopher" Pogo said, "Work is the crabgrass in life.") There are two species of crabgrass common in California: smooth crabgrass, Digitaria ischaemum, and large or hairy crabgrass, D. sanguinalis. Crabgrass is found in turfgrasses (mostly smooth crabgrass) and in ornamental landscapes (primarily large crabgrass). Large crabgrass is also found in orchards, vineyards, and other agricultural areas. Crabgrass also has many other names including crowfoot grass and summer grass.
Creeping woodsorrel, Oxalis corniculata, is a major weed in lawns, flower beds, nurseries, gardens, and greenhouses. A related species, Bermuda buttercup (O. pes-caprae) is grown as an ornamental. Once planted it spreads throughout a garden, competing with other plants.
Dallisgrass, Paspalum dilatatum, is a perennial grass that is found throughout California except at high elevations. It has been used as a pasture grass in wet areas or irrigated sites but is primarily a weed in turfgrass, wet roadside areas, irrigation ditchbanks, and in some orchards and vineyards. Dallisgrass creates an unsightly clump in turfgrass that can be a problem in golf courses, sports playing fields, and home landscapes. The stiff clump it forms is different in texture from the other grasses in a turfgrass mixture and can present a hazard in sports fields, causing people to fall.
Damping-off diseases can attack seeds before they germinate, kill shoots before they emerge, or rot the stems of seedlings at the soil line. Find out how to guard against these insidious diseases that can stop your garden before it even starts.
Dandelion (Taraxacum officinale), also known as lion’s tooth, puffball, blowball, and monk’s head, is a major problem in turf, ornamental plantings, meadows, pastures, and alfalfa. While used for centuries as a medicinal plant, dandelion can be a major weed problem for turf and ornamental managers. In turf, it forms clumps that cause poor footing for athletic fields and golf courses. Dandelion’s texture and color vary from that of normal turfgrass and the yellow flowers reduce the aesthetic quality of the turfgrass.
The deer mouse carries hantavirus, which can be deadly to people. Searching for food, the mice enter houses and cabins through small holes and cracks, but what they leave behind can make you very ill. Learn to recognize, exclude, and control these pests.
Most people enjoy seeing deer in the wild. Unfortunately, however, deer can be very destructive to gardens, orchards, and landscaped areas, particularly in foothill and coastal districts where nearby woodlands provide cover. Mule deer, Odocoileus hemionus, and blacktailed deer, O. hemionus columbianus, are the two most common subspecies in California.
The sensation feels like bugs, worms, or mites that are biting, crawling over or burrowing into, under, or out of your skin. They must be there, because you can feel them and you are even pretty sure that you can see them. You may also believe that your home or furniture is infested, but you may be the only one who knows they are there. No one seems to think they exist except you. Nothing seems to get rid of them. So what are they?
Dodder is a parasitic annual plant that infests many crops, ornamentals, native plants, and weeds. There are over 150 species found throughout the world. Some species are found on many crops including alfalfa, asparagus, melons, safflower, sugarbeet, and tomato.
The western drywood termite, Incisitermes minor, is California's second most important termite pest after the western subterranean termite. It is a native insect that has been here millions of years, mostly attacking trees along river washes and arroyos. In California drywood termites are most prevalent in southern California and the Central Valley but also can be found infesting wood along the coast, in bay areas south of San Francisco, and in the southern California desert.
Earwigs can seriously damage seedling vegetables, annual flowers, maturing soft fruit, and corn silks. However, they also have a beneficial role in the landscape and have been shown to be important predators of aphids.
Elm leaf beetle, Xanthogaleruca (=Pyrrhalta) luteola, is one of the most important insects damaging urban forests in the United States and is the major pest of elm trees in California.
Longhorned borers are attracted to freshly cut wood, dying limbs, and trees suffering from stress, especially drought stress. The problem is exacerbated in California because many eucalyptus trees are growing in unmanaged or minimally managed environments with no supplemental irrigation. Eucalyptus species that naturally grow in wetter areas of Australia have been planted in California where they experience prolonged dry periods, which makes them susceptible to attack by these beetles.
Psyllids are plant-juice sucking homopterans in the insect family Psyllidae. Redgum lerp psyllid nymphs (immatures) form a cover called a "lerp," which is a small white, hemispherical cap composed of solidified honeydew and wax.
The eucalyptus tortoise beetle is an Australian leaf beetle (family Chrysomelidae), now found throughout southern California, in the Central Valley, and in the San Francisco Bay Area. Adult beetles and larvae chew semicircular or irregular notches along edges of eucalyptus leaves. The beetles can remove most of a leaf’s surface, leaving only the midvein.
False chinch bug, Nysius raphanus (Hemiptera: Lygaeidae), is common in the landscape and in most years only causes harm to seedlings. Plants wilt but will rarely die from the attack. At times larger numbers of the pest can kill young fruit or nut trees. Learn to identify and manage this pest.
Field bindweed, Convolvulus arvensis, is a native of Eurasia and was first documented in California in 1884 when it was collected in San Diego. By the first quarter of the twentieth century, field bindweed was proclaimed the worst weed in California and many of the western states. Field bindweed has been given many names including perennial morning glory, creeping jenny, bellbine, sheep-bine, and corn-bind.
Fire blight, caused by the bacterium Erwinia amylovora, is a common and frequently destructive bacterial disease of pome fruit trees and other related plants. Pear and quince trees are extremely susceptible. Apple and crabapple are also frequently damaged. Fire blight infections can destroy limbs and even entire shrubs or trees.
Cat fleas (Ctenocephalides felis) are frequently encountered in homes and are common pests on domestic cats and dogs. Dog fleas (Ctenocephalides canis) look like cat fleas, but are rare in California. Sticktight fleas (Echidnophaga gallinacea) can become a problem when pets frequent areas near poultry. Female sticktight fleas firmly attach themselves around the ears and eyes of their host. Fleas on either cats or dogs in California are most likely cat fleas. Also available in Spanish through http://anrcatalog.ucdavis.edu.
Of the thousands of species of flies, only a few are common pests in and around the home. These pests breed in animal wastes and decaying organic material from which they can pick up bacteria and viruses that may cause human diseases.
Full Title: Fungus Gnats, Shore Flies, Moth Flies, and March Flies: Pest Notes for Home and Landscape. Fungus gnats, shore flies, moth flies, and March flies occur around damp, decaying vegetation, algae, and fungi. These flies can appear in large numbers in or around buildings and also can be a problem in greenhouses, nurseries, and interior plantscapes.
Since its introduction into southern California in 1992, the giant whitefly has spread rapidly northward along the coast and into interior valleys. It can severely infest many ornamental plant species found in nurseries, landscapes, and home gardens.
The glassy-winged sharpshooter can spread the disease-causing bacterium Xylella fastidiosa which is the causal agent of devastating plant diseases such as Pierce’s disease, oleander leaf scorch, and almond leaf scorch.
Goldspotted oak borer attacks xylem and phloem layers near the base of oak trees and can girdle and kill mature oaks. A San Diego area pest, it may eventually spread to other areas of California. Learn identification and treatment methods.
Grasshoppers are sporadic pests in gardens. However, in some years large populations may build up in foothills and rangelands, especially after a wet spring and then migrate into nearby gardens, often defoliating everything in sight. Over 200 species of grasshoppers occur in California, but only a few of these cause significant problems in gardens.
Green kyllinga (Kyllinga brevifolia) is a weedy sedge that can be a major weed problem for turfgrass and landscape managers. In turf it forms a weak sod that gives poor footing for athletic fields and golf courses.
Hackberry woolly aphid, sometimes called Asian woolly hackberry aphid (Shivaphis celti), infests hackberry, especially Chinese hackberry (Celtis sinensis), throughout the state.
Many families with young children have at least one encounter with the head louse. The problem of head lice can be so rampant among preschool and school-aged children that often schools must work in conjunction with many families to control an infestation.
Although professional services may seem costly, the investment may be worth it to solve a serious problem. This guideline covers steps to take before and after hiring a company and a checklist to use when working with your selected company.
The potentially poisonous hobo spider does not live in California and has never been documented in the state. There are many cases, however, of common related spiders being misidentified as hobo spiders.
The hoplia beetle, Hoplia callipyge (family Scarabaeidae), is a common pest of roses and other plants in many parts of California, especially the Central Valley. Because it has just one generation a year, it is a problem only from late March to May when the adult beetles feed on light-colored blossoms.
Horsehair worms belong to the phylum Nematomorpha (from the Greek meaning "thread-shaped"), class Gordioida. They are also called Gordian worms because they will often twist into a loose, ball-shaped knot resembling the baffling one created by Gordius in the Greek myth. They occur in water sources such as ponds, rain puddles, swimming pools, animal drinking troughs, and even domestic water supplies.
The house mouse is one of the most troublesome rodents in the United States. They thrive under a variety of conditions; are found in and around homes and commercial structures as well as in open fields and agricultural lands. House mice consume and contaminate food meant for humans, pets, livestock, or other animals. In addition, they cause considerable damage to structures and property, and they can transmit pathogens that cause diseases such as salmonellosis, a form of food poisoning.
Walking stick insects came from India to California through the pet trade but have escaped the cage and are now found in the wild in southern and coastal areas. Newly emerged nymphs may feed heavily on new flush growth in landscape plants.
Invasive plants are a distinct group of weeds that occur in natural habitats. This Pest Note shows how invasive plants differ from common garden and agricultural weeds and discusses their occurrence, impact, spread, and management.
Kikuyugrass (Pennisetum clandestinum) is an extremely aggressive perennial weed of turfgrass, ornamental plantings, orchards, and noncrop areas in California. It is well adapted to warm, temperate climates such as those of the coast and inland valleys of southern and central California. Kikuyugrass was originally imported to California around 1918 as a ground cover to reduce erosion on ditchbanks. With its rapid stolon growth and thatch formation, it quickly moved from these sites and became a serious weed pest. In the past kikuyugrass was often confused with St. Augustinegrass and may have been mistakenly propagated and planted in its place.
Many kinds of lace bugs, family Tingidae, feed on landscape plants throughout the United States. Hosts include alder, ash, avocado, azalea, coyote bush, birch, ceanothus, fruit trees, photinia, poplar, sycamore, toyon, walnut, and willow.
Maintaining a healthy lawn is the best way to prevent a disease outbreak in a turfgrass. 75 to 85% of common lawn diseases can be avoided by optimizing practices to avoid stressed grass, which is more susceptible to disease outbreaks.
Insects are not a common cause of residential lawn damage in California, but certain species occasionally damage or kill turfgrass. Insect feeding can cause grass to turn yellow or brown, or die, especially if the grass is already stressed. Before taking any insect control action, be sure that it is insects causing the problem and not something else.
Fruittree leafroller, Archips argyrospila, can be a serious pest throughout California. It occurs on a very large number of ornamental trees and is particularly damaging to deciduous and live oaks.
Although some lizards eat plants, most feed on insects. In California, the most common types feed on beetles, ants, wasps, aphids, grasshoppers, and spiders. Lizards cause no measurable damage to plants in gardens and should be left alone.
Lyme disease is a potentially debilitating and sometimes chronic infection transmitted to humans and other animals by certain ticks. Of the 48 tick species found in California, the western black-legged tick, Ixodes pacificus, is the only tick thought to be responsible for transmitting the bacterium that causes the disease to people.
Weedy mallow plants are found growing widely in California. Although some of the wild mallow species can be eaten, mallows are less than desirable when found growing in crop fields, orchards, lawns, gardens, and landscapes.
Millipedes and centipedes are often seen in and around gardens and may be found wandering into homes. Unlike insects, which have three clearly defined body sections and three pairs of legs, they have numerous body segments and numerous legs.
Identification, life cycle, damage, and management of this evergreen parasitic plant that grows on a number of landscape tree species in California.
Moles live underground in a network of shallow tunnels where they capture worms, insects, and other invertebrates. Their burrowing can dislodge plants and dry out their roots; in lawn areas the resulting mounds and ridges are unsightly and disfiguring.
There are several species of mosquitoes in California that readily attack people, and some species are capable of transmitting microbial organisms that cause human diseases such as malaria and encephalitis.
Mushrooms, sometimes called toadstools, are the reproductive (fruiting) structures of some kinds of fungi. This publication covers mushroom-producing fungi that are lawn management or nuisance problems but do not necessarily cause lawn diseases. This is a
Nematodes are microscopic, eel-like roundworms. The most troublesome species in the garden are those that feed on plant roots. They are difficult to control and can be spread easily from garden to garden in soil and plant parts.
Nutsedges are common weeds in landscapes and gardens in the coastal valleys, Central Valley, and southern areas of California. They thrive in waterlogged soil and their presence often indicates that drainage is poor, irrigation is too frequent, or sprinklers are leaky. They are a problem in the lawn because they grow faster, have a more upright growth habit, and are lighter green in color than most grass species, resulting in a nonuniform turf. In gardens and landscapes, nutsedges will emerge through bark or rock mulches in shrub plantings and vegetable and flower beds throughout the growing season.
Several Asterolecanium species of pit scales attack many common deciduous and evergreen oaks in California. The valley oak is especially susceptible. Pit scales suck juices from twigs and cause twig dieback, which first becomes apparent in mid- to late summer. A severe infestation delays leafing-out for as long as 3 weeks in spring and heavy attacks year after year may kill young trees.
Oleander leaf scorch is a disease found mainly in southern California. It is caused by the bacterium Xylella fastidiosa, which is the same species (although a different strain) that causes Pierce's disease of grapevines and almond leaf scorch. Oleanders affected by this disease decline and then die, usually within 3-5 years of the first symptoms.
The rapid invasion of California by the olive fruit fly poses a severe economic threat for the state’s commercial olive growers. Feeding damage can cause premature fruit drop and reduce fruit quality for both table olive and olive oil production. Large numbers of rotting fruit on the ground can create an unwelcome mess, especially in landscape and backyard trees.
Olive knot is a bacteria-caused disease that kills affected twigs while giving an off-flavor to all the olives on a tree. Learn how to recognize the characteristic galls and keep the disease from spreading.
The opossum (Didelphis virginiana) is the only native North American marsupial. The opossum is not native to California, but was introduced many years ago from the east coast of the United States and has now become well established throughout much of the state. It is about the size of a house cat, has coarse grayish fur, a pointed face, and hairless, rounded ears.
Several major diseases can attack palm trees in California. Some come on gradually; others (like Sudden Crown Drop) are catastrophic. Learn to plant the right palm in the right place and then use an IPM approach to monitor and prevent potential disease.
Stored-product pests are usually brought into the home in an infested package of food. The most common insects infesting food in the home are meal moths or pantry beetles.
Perennial pepperweed (Lepidium latifolium) is invasive throughout the western United States. Recent surveys identify perennial pepperweed as a weed problem in nearly all of California, and both the California Department of Food and Agriculture (CDFA) and California Invasive Plant Council (Cal-IPC) list it as a noxious weed of greatest ecological concern.
Full title: Pesticides: Safe and Effective Use in the Home Landscape: Pest Notes for Home and Landscape. Also available in Spanish as Pesticidas: uso seguro y eficaz en el hogar y en jardines (Publication 74138). Pesticides are designed to be toxic to the pests they target when used properly. However, when label instructions are not followed correctly, you may damage your plants, injure yourself, and pesticides may add to soil, air, or water pollution.
Almost all fruit and nut trees, as well as most onamental trees and shrubs, can develop Phytophthora rot. Learn about simple steps you can take to help prevent this potentially fatal plant disease.
Broadleaf and buckhorn plantain are major weeds of turf, ornamentals, gardens, waste areas, forage legumes, and pastures. Broadleaf plantain is also known as common plantain and dooryard plantain; buckhorn plantain as narrow-leaf plantain, ribwart plantain, English plantain, and ribgrass.
Pocket gophers (Thomomys spp.) are burrowing rodents often invade yards and gardens, and feed on many garden crops, ornamental plants, vines, shrubs, and trees. A single gopher moving down a garden row can inflict considerable damage in a very short time. Gophers also gnaw and damage plastic water lines and lawn sprinkler systems. Their tunnels can divert and carry off irrigation water and lead to soil erosion. Mounds on lawns interfere with mowing equipment and ruin the aesthetics of well-kept turfgrass.
Poison oak or western poison oak, Toxicodendron diversilobum, is native to western North America, with a distribution extending from British Columbia south to the Baja California peninsula. Contact with poison oak leaves or stems at any time of the year can cause an allergic response.
Powdery mildew is a common disease on many types of plants. Powdery mildew fungi generally do not require moist conditions to establish and grow, and normally do well in warm climates. Thus they are more prevalent than many other diseases in California's dry summer weather. It can be serious on woody species such as grapevines, caneberries, and fruit trees where it attacks new growth including buds, shoots, and flowers as well as leaves.
Powdery mildew can be recognized easily on most plants by the white, powdery mycelial and spore growth that forms on both surfaces of leaves, sometimes on flowers and fruits, and on shoots. This disease can be serious on woody species such as rose, crape myrtle, and sycamore where it attacks new growth including buds, shoots, and flowers as well as leaves.
A wide variety of vegetable crops are affected by powdery mildews, including artichoke, beans, beets, carrot, cucumber, eggplant, lettuce, melons, parsnips, peas, peppers, pumpkins, radicchio, radishes, squash, tomatillo, tomatoes, and turnips. Leaves infected with powdery mildew may gradually turn completely yellow, die, and fall off, which may expose fruit to sunburn. Severely infected plants may have reduced yields, shortened production times, and fruit that has little flavor.
Psyllids resemble miniature cicadas and are sometimes called jumping plantlice. Over 100 species occur on both native and introduced landscape plants in the United States, but each kind of psyllid feeds on only one plant species or closely related groups of plants. Most psyllids native to the United States are relatively uncommon and rarely become pests. Most pest psyllids in California are exotic species inadvertently introduced from other countries.
Puncturevine (Tribulus terrestris) is an aptly named summer annual that thrives in hot, dry conditions. The seeds are enclosed in a hard case that can injure livestock, people, and pets when stepped on and can even puncture bicycle tires.
Rabbits are a form of wildlife enjoyed by many people but they can be very destructive to gardens and landscaped areas. Three species, the black-tailed hare or jackrabbit (Lepus californicus), the desert cottontail (Sylvilagus audubonii), and the brush rabbit (S. bachmani) are widespread and cause the majority of problems in California. Because of its greater size and abundance, the jackrabbit is the most destructive.
Raccoons are omnivorous, eating both plants and animals. In urban settings, in addition to feeding on backyard fruits, nuts, and vegetables, they scavenge from garbage cans, compost piles, and pet food left outside overnight. Damage to gardens may be relatively minor compared to the potential damage a raccoon can do to a house.
Rats are some of the most troublesome and damaging rodents in the United States. They consume and contaminate food, damage structures and property, and transmit parasites and diseases to other animals and humans. Rats live and thrive under a wide variety of climates and conditions; they are often found in and around homes and other buildings, farms, gardens, and open fields. In California the most troublesome rats are two introduced species: the roof rat and the Norway rat.
The rattlesnake is California’s only native venomous snake. Six species are found in various areas of the state. Rattlesnakes are an important part of the ecosystem, feeding on rodents, birds, and other small animals.
Although the red imported fire ant (Solenopsis invicta) is common in 12 southern states, it is new to California and has recently been found infesting numerous residential and commercial areas in Orange, Los Angeles, Riverside, San Bernardino, and to a lesser extent, San Diego counties. The spread of these ants has largely been a result of the movement of infested soil to uninfested areas.
The redhumped caterpillar, Schizura concinna, is found throughout much of California. Though the climate of the coastal regions usually does not favor development of destructive populations, it may be a serious problem in the warm Central Valley. Trees most commonly attacked are liquidambar (sweet gum), walnut, and plum, although it is also found on almond, apple, apricot, birch, cottonwood, cherry, pear, prune, redbud, willow, and others.
A mass of honeybees in a tree or on part of your house can be unsettling. But a swarm doesn't have to be dangerous and can be taken care of quickly if you take the right steps and make the right calls. This publication shows just what you need to do.
Through careful selection of plant varieties and management of environmental conditions with proper cultural practices, beautiful roses can be grown with a minimum of pest problems.
Full Title: Roses in the Garden and Landscape: Diseases and Abiotic Disorders: Pest Notes for Home and Landscape. A variety of plant pathogens may attack roses from time to time including powdery mildew, rust, black spot, botrytis, downy mildew, and anthracnose. In addition to diseases caused by bacterial, fungal, and viral pathogens, roses may display similar symptoms that are the result of chemical toxicities, mineral deficiencies, or environmental problems. These are called abiotic disorders.
Roses are among the most intensively managed plants in many home landscapes. Part of this intensive management is the frequent application of pesticides. However, while insects and mites may attack roses from time to time, many rose enthusiasts are able to maintain vigorous plants and produce high quality blooms with little or no use of insecticides, especially in California's dry interior valleys.
Russian thistle, also known as tumbleweed, is in the goosefoot family (Chenopodiaceae). Its scientific name is Salsola tragus. Russian thistle is primarily a weed in sites where the soil has been disturbed, such as along highways. It is also prevalent in vacant lots and other noncrop areas, in field and vegetable crops, and in poorly tended landscapes. It is rarely a problem in well-managed gardens or turfgrass.
Scale insects can be serious pests on trees, shrubs, and other perennials. The impact of infestations depends on the scale species, the plant species and cultivar, environmental factors, and natural enemies. Populations of some scales can increase dramatically within a few months, such as when honeydew-seeking ants or dusty conditions interfere with scale natural enemies. Plants are not harmed by a few scales, and even high populations of certain species apparently do not damage plants. Soft scales and some other species excrete honeydew, a sweet, sticky liquid produced by insects that ingest large quantities of plant sap. Sticky honeydew and the blackish sooty mold growing on honeydew can bother people even when scale populations are not harming plants.
Scorpions are nocturnal, predatory animals that feed on a variety of insects, spiders, centipedes, and other scorpions. Most scorpions live in warm, dry climates. Of the 70 or so species found in North America, only one, the bark scorpion, Centruroides exilicauda (formerly called C. sculpturatus), is considered dangerous to people.
The sequoia pitch moth, Synanthedon sequoiae, occurs from California north through British Columbia. In California it most often attacks pines, especially those in urban coastal areas of northern California, from Monterey Bay to the San Francisco Bay Area.
If the pages and bindings of books in your bookcase have been chewed on, suspect the look-alike household pests--silverfish and firebrats.
Learn to identify and control this common mite pest of plumeria (also called frangipani or lei flower), an increasingly popular ornamental in California gardens.
Two species of skunk are found in California, the striped skunk (Mephitis mephitis), which is the most commonly found species, and the spotted skunk (Spilogale gracilis). Both are members of the weasel family and are equipped with a powerful and protective scent gland that can shoot a potent and pungent liquid as far as 6 to 10 feet. The secretion is acrid enough to cause nausea and can produce severe burning and temporary blindness if it strikes the eyes.
Snails and slugs are among the most bothersome pests in many gardens and landscapes. The brown garden snail (Helix aspersa) is the most common snail in California gardens; it was introduced from France during the 1850s for use as food.
Soil solarization is a simple, nonchemical method for controlling soilborne pests. By covering the soil with a clear plastic tarp, you trap radiant energy from sunlight heating the top 12 to 18 inches. This heat can eliminate a wide range of soilborne pests, such as weeds, pathogens, nematodes, and insects.
Sooty mold is the common name applied to several species of fungi that grow on honeydew secretions on plant parts and other surfaces. Sooty molds do not infect plants but grow on surfaces where honeydew deposits accumulate. Honeydew is a sweet, sticky liquid that is excreted by plant-sucking insects as they ingest large quantities of sap from the plant.
Mites are common pests in landscapes and gardens and can be found feeding on many fruit trees, vines, berries, vegetables, and ornamental plants. Although related to insects, mites are not insects but members of the arachnid class along with spiders and ticks. The spider mites, also called webspinning mites, are the most common mite pests.
Many people fear or dislike spiders but, for the most part, spiders are beneficial because of their role as predators of insects and other arthropods, and most cannot harm people. Spiders that might injure people, black widows for example, generally spend most of their time hidden under furniture or boxes, or in woodpiles, corners, or crevices. The spiders commonly seen out in the open during the day are unlikely to bite people.
Spotted spurge is a low-growing annual plant that often forms a dense mat. It has dark green, opposite leaves that are 1/8 to 1/2-inch long and about 1/8-inch wide. Leaves are usually marked with a red spot midway down the center leaf vein.
Spotted wing drosophila (SWD or Drosophila suzukii) are different from the common vinegar fly (D. melanogaster): SWD will attack and spoil previously undamaged fruit. Learn to recognize and control this pest of fresh fruit.
Springtails jump, but they don't bite humans or animals like fleas and they cause only minor damage to plants. Still they can still be a nuisance around pools or damp indoor areas. Learn a few simple, nonchemical measures to keep them under control.
Squash bugs, Order Hemiptera, are common pests in vegetable gardens. Their specialized mouthparts let them pierce foliage and suck plant sap.
Sudden oak death is the name given to an epidemic, first detected in 1995, that affects three true oak species—coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and Shreve oak (Q. parvula var. shrevei)—and tanbark oak (Lithocarpus densiflorus). A previously undescribed pathogen, Phytophthora ramorum, has been identified as the infectious agent.
Sudden oak death is the name given to an epidemic, first detected in 1995, that affects three true oak species—coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and Shreve oak (Q. parvula var. shrevei)—and tanbark oak (Lithocarpus densiflorus). A previously undescribed pathogen, Phytophthora ramorum, has been identified as the infectious agent. Note that this updated publication replaces Sudden Oak Death in California.
Sycamore scale, Stomacoccus platani, occurs only on sycamore. It is considered the most important insect pest of sycamore trees in California. The sycamore scale is so tiny, about 1/16 inch long, that many people fail to recognize it as an insect and mistake it for a disease symptom.
Termites become a problem when they consume structural lumber. Each year thousands of housing units in the United States require treatment for the control of termites. Termite pests in California include drywood, dampwood, and subterranean species. These pests cause serious damage to wooden structures and posts and may also attack stored food, books, and household furniture.
Thrips, order Thysanoptera, are tiny, slender insects with fringed wings. They feed by puncturing their host plant or animal prey and sucking up exuding contents. Some are beneficial predators that feed on other insects and mites, others are pests that feed on plants and scar leaf, flower, or fruit surfaces. Many thrips species feed within buds and furled leaves or in other enclosed parts of the plant. Their damage is often observed before the thrips can be seen.
Squirrels sometimes cause damage around homes and gardens, where they feed on immature and mature almonds, English and black walnuts, oranges, avocados, apples, apricots, and a variety of other plants. They sometimes gnaw on telephone cables and may chew their way into wooden buildings or invade attics through gaps or broken vent screens.
Voles are mouselike rodents somewhat similar in appearance to pocket gophers. The clearest signs of their presence are the aboveground runways that connect burrow openings. Most problems around homes and gardens occur during outbreaks of vole populations.
The primary damage from the husk fly is staining of the nutshell; a problem in commercial orchards where nuts are grown for in-shell sale, but it can be tolerated in backyard situations. An early-season infestation may result in shriveled, moldy kernels.
Weed management in landscape plantings is often made difficult by the complexity of many plantings: usually more than one species is planted in the landscaped area and there is a mix of annual and perennial ornamentals. The great variety of ornamental species, soil types, slopes, and mulches creates the need for a variety of weed management options. Because of the many variables, weeds in landscape plantings are usually controlled by a combination of nonchemical and chemical methods.
Weeds occur in every lawn, but they seldom become problems in well-managed, vigorously growing turfgrass. Most weed invasions can be prevented with proper lawn maintenance and good preventative practices or remedied with overseeding.
Large populations of whiteflies can cause leaves to turn yellow, appear dry, or fall off. Like aphids, whiteflies excrete honeydew, so leaves may be covered with black sooty mold. The honeydew attracts ants, which interfere with the activities of natural enemies.
Most species of wild blackberry, also called brambles, provide important sources of food and cover for many birds and mammals. Four species, however, are considered weeds. Two of these are non-natives, cutleaf blackberry (Rubus laciniatus) and Himalaya blackberry (Rubus discolor [=R. procerus]). In addition, two native species can also be weeds under certain conditions, thimbleberry (Rubus parviflorus) and California blackberry (Rubus ursinus [=R. vitifolius]). Of these weedy species, the most common, vigorous, and troublesome is Himalaya blackberry.
The windscorpion is a predatory creature related to spiders. Other names used for it include camel spider and sunspider, but it is neither a spider nor a scorpion. It is common from the arid southwest to California’s San Joaquin Valley.
Several fungal diseases, sometimes called heart or sap rots, cause the wood in the center of trunks and limbs to decay. Almost all species of woody plants are subject to trunk and limb decay.
The common names "wood wasp" and "horntail" are used to describe several kinds of wood-boring insects (families Siricidae, Xiphydriidae, Anaxyelidae, and Orussidea). Of greatest public interest are the large, nonstinging wasps that normally are attracted to and complete their life cycles in recently dead or dying conifer trees.
Many species of wood-boring beetles, especially flatheaded or metallic wood borers, long-horned beetles and roundheaded wood borers feed on live trees that are old, weakened or fire- or insect-killed trees. They will not attack wood structures or furniture. Three families of beetles have species of wood borers that invade and damage structural and decorative wood and furniture. These families are the powderpost beetles, deathwatch beetles, and false powderpost beetles.
Woodpeckers (Melanerpes spp.), including sapsuckers (Sphyrapucys spp.), and flickers (Colaptes spp.) belong to an interesting and well-known group of birds in the family Picidae. There are 17 species found in California, two of which are California-listed endangered species. Woodpeckers come into conflict with people when they use human dwellings in their search of food, or as a surface for territorial/social drumming, or for nest construction. Such activities not only create disturbing noises but, more significantly, may cause structural damage.
Invasive woody plants and large perennial grasses such as bamboo can be very hard to control or eliminate from your garden. In this publication, you will get basic information on a variety of chemical and nonchemical methods that can get the job done.
Yellow starthistle, Centaurea solstitialis, is common in open areas on roadsides, rangeland, wildlands, hay fields, pastures, and waste areas. Recent reports indicate that yellow starthistle infests between 10 and 15 million acres in California. It forms dense infestations and rapidly depletes soil moisture, thus preventing the establishment of other species. It is also poisonous to horses, causing a fatal nervous disorder called "chewing disease," (nigropallidal encephalomalacia).
Wasps become a problem only when they threaten to sting humans. One of the most troublesome of the social wasps is the yellowjacket. Yellowjackets, especially ground- and cavity-nesting ones such as the western yellowjacket, tend to defend their nests vigorously when disturbed. In fall, foraging yellowjackets are primarily scavengers and they start to show up at picnics, barbecues, around garbage cans, at dishes of dog or cat food placed outside, and where ripe or overripe fruit are accessible.
Full title: Zoropsis spinimana, A Mediterranean Spider in California: Pest Notes for Home and Garden. Zoropsis spiders have been in the San Francisco Bay Area since the mid-1990s. With a body up to 5/8 inch long and a leg span of up to 1 1/4 inches, this harmless hunting spider can be confused with the wolf spider. Learn to know the difference.