动态第745页 - 绿手指 - 养花技巧、花生病了怎么办、花园打理和设计

2017年09月17日

There are over 1200 known species of whiteflies, most of which feed on only one or a few species of plants each. Some are pests on valuable crops such as the sweet potato whitefly (Bemisia tabaci). Others, like the greenhouse whitefly (Trialeurodes vaporariorum), feed on a broad range of herbaceous plants both inside the greenhouse and outside in the garden. Some of the host plants that the greenhouse whitefly attacks are the tomato, fuchsia, lantana, and coleus.[图片]The silverleaf whitefly (Bemisia argentifolii) has been found on as many as 500 hosts such as canna lilies, bearded iris, crepe myrtle, lantana, petunia, and rose. Whiteflies are one of the most difficult insect pests to control. They are not true flies but are more closely related to aphids, mealybugs, and scale, which are also sap-sucking insects. In some parts of the country, some species of whitefly can transmit several plant viruses.[图片]Symptoms and Diagnosis Identification of the whitefly is easy as a white cloud of insects rise from foliage when disturbed. The adults are about 1/16 to 1/10 inch in length, wedgeshaped, and appear powdery. Infested leaves may show little if any symptoms or may be mottled and yellow. Leaves will also become coated with a sticky substance called honeydew, which is secreted by feeding whitefly nymphs and adults. A black, sooty mold may sometimes grow on the honeydew. Sooty mold does not damage the leaf. The feeding, however, removes nutrients from the plant, which results in stunting, poor growth, defoliation, reduced yields, and sometimes death. On certain plants the silverleaf whitefly causes specific damage symptoms such as silvering of leaves on squash, irregular ripening in tomato, whitestalk in broccoli and cauliflower, light root in carrots, and white stem in poinsettia.[图片]Life Cycle The whitefly spends its winters in weeds and ornamental plants, migrating to crops and gardens in spring and summer. Once temperatures warm up in the summer, populations can build rapidly with the highest populations probably occurring in late summer. They lay their tiny eggs on the undersides of leaves. Adult females usually lay between 200 to 400 eggs. Sometimes the eggs are deposited in a circular pattern (not true in all species) in groups of 30 to 40 as the female will often keep her mouth part in the plant to feed while moving in a circle to deposit eggs. Within about a week the eggs hatch into flattened nymphs, called crawlers that wander about the plant. Soon, they insert their mouth part and begin to feed. The first stage has legs and antennae, but these are lost after the first molt and the flattened, oval-shaped larvae stay fixed at one feeding site. The last part of the fourth instar is the pupa. Adults emerge from the pupa through a Tshaped slit and soon mate and reproduce. The adults live about one month. Within a population, all life stages are present and generations often overlap.[图片]Integrated Pest Management Strategies 1. Inspection. Inspect all new plants planted in the garden for whiteflies. Inspect regularly and remove by hand older leaves that are heavily infested with whiteflies in a non-mobile nymphal stage. 2. Biological control. Whiteflies have many natural enemies in the garden setting including spiders, lady beetles, and lacewings. However, these predators are not effective if there is a frequent use of insecticides.[图片]3. Mechanical control. The use of traps can be very helpful in controlling light infestations. Make yellow sticky traps about 12 x 6 inches and coat them with a sticky substance such as Tanglefoot, petroleum jelly, or heavy grade motor oil. Hang the traps vertically near the affected plants. The adults are attracted to yellow. Traps are also commercially available. Use one trap per plant. 4. Chemical control. Whiteflies have developed resistance to some chemicals. Because of this resistance, a certain product may work well in one area but not in another. Resistance may be delayed by alternating the types of chemicals used. In addition, the egg and non-feeding pupa stages are generally not as susceptible to insecticides as are the adults and nymphs. Consequently, eradication of a whitefly population usually requires four to five applications of a registered insecticide at five to seven day intervals. Be sure the applications are made to the lower leaf surface, and apply as soon as whiteflies are detected. Do not wait until populations become severe.[图片]Before using any insecticide for whitefly control, make sure that the site and target plant are both listed on the label. Follow label directions carefully. 5. Chemicals. Some of the over-the-counter chemicals which could be used are malathion, imidacloprid, permethrin, or pyrethrins. Insecticidal soap, petroleum oil, and insect growth regulators can also be effective.

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2017年09月17日

Thrips are minute, slender-bodied insects less than 1/16 inch to about 3/16 inch in length. With magnification, you can identify the adults that range in color from yellow to black and have four long, narrow, fringed wings. The young nymphs are smaller, wingless, and range in color from yellow to white. Many thrips are plant feeders attacking flowers, leaves, fruit, twigs, or buds.[图片]Symptoms and Diagnosis Thrips congregate by the hundreds and leave black, varnish-like fecal deposits on the underside of leaves. To feed, they puncture the epidermal layer of the host plant with their single large mandible, then slurp the cell sap as it flows into the wound. As a result of their feeding, the foliage appears dusty or silver and dull. Some species may burrow between the upper and lower leaf surfaces to feed. Blossoms can become streaked with brown and can wither prematurely. Injured leaves are twisted or discolored and scarred. The fruit of host plants is often pitted. A few species are beneficial predators of mites and small insects including other thrips, and some feed on fungal spores. Several species may bite people. Some species act as vectors of plant disease. Thrips are poor fliers, so that damage may first appear in one location and then slowly spread over the plant. Thrips will be most apparent on flowers, especially white, yellow, and other light-colored blooms.[图片]Life Cycle Eggs are inserted into leaves, fruit, stems, or the bark of trees and shrubs. One to two weeks later, pale, wingless nymphs emerge and feed actively until they pupate. Some species enclose the pupa in a cocoon on the ground or on the host plant. The winged adult thrips emerge from the cocoon or pupal stage. Generations may occur every two to three weeks, but the largest populations are present from late spring to midsummer. Thrips overwinter in the egg stage.[图片]Integrated Pest Management Strategies 1. Knock off thrips with a forceful spray of cold water in small gardens, preferably early in the morning. Use a nozzle that produces a fine spray of water, and thoroughly wash off the undersides of affected leaves. The control is most effective when repeated at least 3 times, either daily or every other day. 2. Keep plants well irrigated and adequately misted since thrips prefer a dry environment. 3. Prune and destroy injured and infested plants. Do not compost them. 4. Predacious spiders, mites, and pirate bugs help control thrips. Conserving naturally occurring populations of beneficial insects by avoiding persistent pesticides is important to biologically controlling thrips.[图片]5. Aluminum foil and other disorienting mulches have been used with some success to reduce thrips infestations. 6. Two applications of pyrethrum applied 3 to 4 days apart will treat serious infestations. 7. Insecticidal soaps are effective for temporary reduction of thrips populations. Spray every 3 days for 2 weeks. To control iris thrips, spray insecticidal soap at the base of each plant every 5 to 7 days until the infestation has been controlled. To prevent thrips problems, soak iris divisions and gladiolus corms for 30 minutes in a hot water bath (110–125 degrees F). Dig up gladiolus bulbs early in the fall and let them cure in open trays in a shady location with good air flow such as a garage for a few weeks before soaking them. Then allow the bulbs to dry thoroughly before storing.[图片]8. Spray infested plants with a systemic insecticide such as imidacloprid (Merit) since thrips frequently burrow inside the plant tissue. 9. If necessary, use chemical insecticides such as acephate (Orthene), bifenthrin, imidacloprid, or spinosad. Spray 2 or more times at intervals of 7-10 days to control thrips as they hatch.

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2017年09月17日

Two of the most damaging insects on perennial plants are the tarnished plant bug, Lygus lineolaris, and the four-lined plant bug, Poecilocapsus lineatus. These two plant bugs can cause serious problems because they have such a wide variety of host plants. The four-lined plant bug feeds on 250 plant species which are mostly herbaceous. The tarnished plant bug is a problem on a wide variety of ornamental flowers.[图片]Symptoms and Diagnosis Damage varies slightly from the two plant bugs. The four-lined plant bugs cause small (1/16 inch), discolored areas on leaves where they suck out cell juices. Injured areas will turn black or become translucent, and after several weeks, the dead tissue may drop out, leaving small holes. The adults feed on the upper surfaces of leaves and are voracious feeders. The topmost leaves will generally be the first to be injured.[图片]Damage from the tarnished plant bug is in the form of distorted foliage or disbudded plants. This damage is caused by the overwintered adults which attack swollen and opening buds in the early spring. The disbudding will cause the plant to be short and bushy. If the attack takes place after shoot elongation begins, the tip will often turn black and die, or it will be so damaged that shoot stunting or distortion occurs. Stems frequently break at the injured area.[图片]Life Cycle The four-lined plant bug overwinters as eggs inserted into a slit near the top of tender shoots. Nymphs emerge from the eggs in May. Nymphal coloring varies from bright red to yellow. The species requires about 30 days to complete nymphal development. Forewings of adults are yellow, but may turn bright green. However, the four black stripes that give the insect its name remain distinct. This species normally has one generation a year. Adults of the tarnished plant bug overwinter as adults in leaf litter. Beginning in the spring, they lay eggs mainly in the stems and flowers of herbaceous plants. After hatching, the young nymphs usually remain to feed on the same plant until they mature. The nymph is green or pale yellow and grows rapidly. Adults are capable flyers and readily move from place to place. There may be two to five generations per year. In midsummer, a life cycle may be completed in about 25 days. By late summer, populations can become very abundant.[图片]Integrated Pest Management Strategies 1. Live with the damage. Since damage is often cosmetic, some damage can be tolerated. Often, natural predators will keep the insects under control. 2. Remove leaf litter. To limit problems in coming years, clean up leaf litter to avoid overwintering sites for tarnished plant bugs. 3. Prune out egg masses. Learn to identify the egg masses of four-lined plant bugs and prune them out in winter.[图片]4. Use insecticidal soaps. If populations are high enough, spraying with an insecticidal soap may be necessary. Because the tarnished plant bug can go through many generations in a single year and cause great damage to a plant, it is best to initiate control when it first appears. 5. If necessary, use chemical insecticides. Plant bugs can be controlled with malathion, and carbaryl (Sevin).

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2017年09月17日

Stink bugs are attractive and distinctive insects that are generally easy to identify. Ranging in size from 1/4 to 1 inch long and about half as broad, they are shield-shaped with a triangle-like horny scale on their back. Also, as the name indicates, many stink bugs do produce an offensive odor when disturbed. The most common pest species are green, brown, gray, or yellow and some have red or yellow markings. Their host plants include blackberry, cabbage and other members of the mustard family, corn, tomato, eggplant, bean, soybean, and trees such as apple, peach, pecan, and cherry. Stink bugs may also be found on ornamental plants including columbine, snapdragon, and sunflower. The harlequin bug, Murgantia histrionica, a red and black-spotted species of stink bug, is an important pest of crops in the mustard family in the southern United States. The green stink bug, Acrosternum hilare, and brown stink bugs, Euschistus spp., can be of economic importance in soybean fields primarily by reducing seed quality and quantity. A few species of stink bugs are predatory on other insects.[图片]Symptoms and Diagnosis In the "true bug" group, stink bugs feed by inserting their mouth parts into the leaves, flowers, buds, fruit, and seeds of host plants and sucking plant sap. Large infestations of stink bugs may cause plants, especially small plants and young tender growth, to wilt, become stunted and misshapen, or die. Other damage includes yellow or white blotches on leaves; misshapen or aborted fruits, seeds, and buds; calluses, blemishes or depressions; and black pits on nuts. Tomatoes exhibit pale yellow spots and a white pithy area just under the skin at the puncture site. Peaches and other fruits may develop scarring and dimpling resulting in cat-facing or a pitted appearance. The seeds in soybean pods may be deformed, small, discolored, or shriveled.[图片]Life Cycle The stink bug overwinters as an adult in protected areas such as under dead weeds, leaf litter, or the bark of trees. In early summer, the female lays clusters of eggs on the underside of leaves. These eggs are barrel or keg-shaped with a circular lid. In one to three weeks, the young hatch into wingless nymphs that resemble small adult stink bugs, although the coloration may differ from that of the adult. The nymphs will molt several times before developing wings and becoming an adult. The number of generations per year depends on the species.[图片]Integrated Pest Management Strategies 1. Sanitation. Control weeds in susceptible crops and in areas adjacent to gardens to decrease breeding and overwintering habitat. It is important to remove weeds early in the growing season before stink bug populations increase or the loss of habitat may force pests to move into the garden. 2. Collect insects. Hand pick and destroy eggs and bugs. 3. Use natural controls. Encourage other natural predators such as parasitic wasps and flies by growing small-flowered plants. The unpleasant odor produced by stink bugs deters many predators but several bird species do consume these pests.[图片]4. Use trap crops. Plant trap crops of mustard and treat that area with an appropriate pesticide. 5. Use insecticides. If damage is severe, use insecticidal soap, sabadilla, pyrethrin or permethrin (Eight).

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2017年09月17日

Spider mites are very common pests of outdoor plants. The mites suck juices from the plants, causing the plants to look dull and unhealthy. Mites also cause plants to lose vigor so that they may be unable to overcome a severe infestation, resulting in the plant's death. In Missouri, the most common outdoor spider mite is the two-spotted spider mite. The spruce spider mite infects conifers such as spruce, juniper, and arborvitae. They are less than 1/60th inch in size and difficult to see without a magnifying lens. They are not insects but rather a member of the spider family in which all members have eight legs.[图片]Symptoms and Diagnosis Spider mites are among the most ubiquitous of pests, attacking a wide variety of field, garden, greenhouse, nursery, and ornamental plants, as well as several weed species. Infestations of two-spotted spider mites result in the bleaching and stippling of leaves. Severe infestations may cause entire leaves to become bronzed, curled, and completely enveloped in sheets of webbing. Damage to the foliage may result in leaf drop and reduction in the overall vitality of the plant. When a leaf or branch is tapped over a white sheet of paper, the mites appear as small specks that resemble dust or pepper and may be seen to move.[图片]Life Cycle Adult female spider mites overwinter under loose bark, in cracks in the soil, in leaf litter, and in other protected places. In the spring, adults emerge and begin laying eggs. Each female typically deposits 70 eggs and lives for only 30 days. Eggs hatch in 5–7 days. As many as 10 generations may occur each year. The young look similar to the adults, but newly hatched young have only six legs and do not possess the characteristic dark spots on the back. Reproduction of the two-spotted spider mite is favored by hot, dry conditions, so serious damage is likely to occur in mid-July to September. The spruce spider mite is most active durng cooler weather in Spring and Fall.[图片]Integrated Pest Management Strategies 1. Knock mites off plants with water. Spraying with a strong stream of water (particularly the undersides of leaves) will provide some control. Spray plants frequently to control future buildups. For severe infestations, affected plants or plant parts can be removed and destroyed. There are several natural predators that feed on spider mites. The use of chemical insecticides to control other garden pests can result in the death of these beneficial insects and a subsequent increase in the population of spider mites. 2. Use insecticidal soap. Insecticidal soaps specially formulated to kill insects and not damage plants are effective if used frequently until the problem is under control.[图片]3. Use superior horticultural oil sprays. Highly refined oils sold as superior or horticultural oils are also very effective in controlling spider mites. The oil suffocates the mites. Unlike dormant oils, these oils are highly refined and under proper conditions, can be applied to plant foliage without damage. Follow label directions to avoid damage to some plants that may be sensitive. Superior oils are considered nontoxic and are less likely to kill beneficial insects. 4. Use chemical insecticides or miticides. A very safe product made from the seeds of a tropical tree is called Neem. It is commercially available under the name Margosan-O. Other chemical controls include malathion, bifenthrin, cyfluthrin, and kelthane. Be sure to follow all label directions when using pesticides. Many pesticides are very harmful to bees and fish when used improperly.

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2017年09月17日

The phlox plant bug, Lopidea davisi, is an eye catching true bug. It is reddish orange and black. It is a piercing sucking insect with a long proboscis. It feeds mainly on phlox and can cause serious damage to phlox.[图片]Symptoms and Diagnosis The phlox bug’s feeding causes white or light green spots on the leaves and buds that later show yellow stippling. The leaves then turn brown, curl, dry out and drop. The plant may become stunted and die. The bug feeds on leaves, stem terminals, flowers and seeds. It may be hard to see because it hides on the underside of leaves.[图片]Life Cycle The phlox bug overwinters in the egg stage in dead phlox stems. It has two generations per year. The first generation appears in late spring, the second in mid to late summer. It undergoes incomplete metamorphosis. Integrated Pest Management Strategies 1. Practice good sanitation. Cut back and dispose of badly infested stems and leaves. Clean up stem and leaf litter of phlox and neighboring plants in winter before early spring.[图片]2. Scout for nymphs and treat. Apply insecticidal soap to both the upper and underside of the leaves. Use a light horticultural oil. 3. Use chemical controls if warranted. Products listed for use include pyrethrins, permethrin or acephate (orthene), a systemic.

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2017年09月17日

The large milkweed bug, Oncopeltus fasciatus, is colored orange-red and black. It has a long proboscis and is a piercing sucking insect. It feeds on the seeds, leaves and stems of milkweed (Asclepias). It is found in small groups on milkweed often on the stems, leaves and on the seed pods. The bodies of milkweed bugs contain toxic compounds derived from the sap which they suck from milkweed. Milkweed bugs are true bugs (Hemiptera) . They are used as research insects because they are easy to use in the laboratory, have a short life cycle and are easy to manipulate.[图片]Symptoms and Diagnosis Milkweed bugs are more of a nuisance than a threat to milkweed plants. They feed on the seeds by piercing the seed pod and can be found in all stages of growth on the plants in mid to late summer. Life Cycle The milkweed bug undergoes incomplete metamorphosis. The nymphs look like adults but do not have full wings and their color pattern is different. They have five instars before they reach adulthood. Black wing pads appear early in their development. Eggs are a light lemon yellow changing to a reddish color. Incubation period is about four to five days. Each molt lasts five to six days. An adult will live for about one month. The insect overwinters as an adult.[图片]Integrated Pest Management Strategies 1. Live with the damage. Milkweed bugs do little damage and are only present for a short period of time. Just living with the insects may be the most prudent thing to do. 2. Sanitation. Remove leaf litter and spent stalks in the fall to eliminate overwintering sites.[图片]3. Use insecticidal soap. For quick control of an infestation insecticidal soaps are very effective and safe. Good coverage of the insects with the spray is necessary for it to be effective. 4. Use chemical insecticides. If necessary use chemical insecticides such as malathion or carbaryl.

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2017年09月17日

Mealybugs get their common name from white waxy secretions that cover their bodies. They are in the order Homoptera, which includes scales, whiteflies, and aphids, some species of which also cover their bodies with white waxy secretions, making field identification confusing. In warmer climates, mealybugs are serious pests on many citrus and ornamental plants. In this area, a wide variety of indoor and tropical plants summered outdoors or maintained in greenhouses can be attacked, as can many outdoor woody trees and shrubs, perennials, and summer annuals (e.g. begonia and coleus).[图片]Some mealybug species can overwinter as nymphs and eggs. However, outside resurgences in the spring often come from introduction of mealybuginfested plants, with young nymphs from the infested plant colonizing nearby plants. Ants may also transport mealybugs from one plant to another. Symptoms and Diagnosis The typical female mealybug is 1/16 to 1/8 inch long with a white, waxy, oval body and functional legs. Some species are up to1/4 inch long. Males are much smaller, usually winged, and seldom seen.[图片]Mealybugs infest all plant parts; feeder roots, root crowns, stems, twigs, leaves, flowers, and fruit. Here, mealybug infestations usually involve leaves (mostly undersides), stems, branches, and joints. They pierce and suck sap, excreting a sticky honeydew over leaves and stems that provides an excellent growth medium for a sooty-colored mold, giving the plant a dirty, sooty appearance. Ants are likely to be found feeding on the honeydew. Heavily infested plants will experience irregular or no growth, yellowed leaves, and significant leaf drop. Left untreated, plants can die.[图片]Life Cycle Most species are egg layers, though some, especially under greenhouse-like conditions, give live birth. Normally, females lay about 500 eggs in a cottony mass. Hatching in 1 to 2 weeks, nymphs resemble adult females, but male and females then develop differently. Female nymphs increase in size with each molt, reaching adulthood in about a month. In contrast, male mealybugs go through two or so molts and then enter a pupal state in a flimsy cocoon before hatching as a tiny, fly-like, twowinged adult, incapable of feeding and soon to die. Outdoors, two generations a year are common. Eight generations a year are possible in optimal greenhouse-like conditions. Several developmental stages can usually be found simultaneously.[图片]Integrated Pest Management Strategies 1. Prevent new infestations. Examine, quarantine for 2 or 3 weeks, and treat as necessary (see below) all new plants before placing them near mealybug-free plants. Examine all plants frequently for pests. 2. Conserve natural enemies. Predatory insects, such as lacewings, syrphid flies, ladybugs, and several small parasitic wasps, prey on outdoor mealybugs and can often keep their population within bounds. An introduced beetle, Cryptolaemus montrouzieri, the mealybug destroyer, is available commercially for release in greenhouses. Avoid unnecessary insecticide use to minimize damage to these beneficial insects.[图片]3. Remove mealybugs manually. Depending on host plant size and scope of infestation, remove mealybugs with alcohol-dipped cotton swabs or physically knock them off plants with a forceful water spray and repeat as necessary. While unlikely to eliminate mealybugs, this approach can often keep the infestation within tolerable limits and will have no negative impact on beneficial insects. 4. Control ants. Ants are known to transport mealybugs from one plant to another, so physical barriers or chemical controls that do not adversely impact beneficial insects can be part of a prevention and control program. 5. Use insecticidal soap or superior horticulture oil sprays. If above methods fail to reduce mealybug populations to acceptable levels, use insecticidal soap sprays or superior horticultural oil spray following label directions carefully to avoid damage to sensitive plants and beneficial insects. If possible, treat when crawlers are present. Mealybugs hide under leaves and in crotches, so be sure spraying is thorough. Repeat application as necessary in accordance with label instructions.[图片]6. Use chemical insecticides. Acephate (Orthene), bifenthrin, and pyrethrins are effective against mealybugs. Follow label directions carefully.

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2017年09月16日

Numerous species of leafhoppers and planthoppers are found in Missouri, and many of them have a broad host list (for example, the potato leafhopper, Empoasca fabae, has over 100 host plants). They feed on foliage and shoots of many different plant species by piercing the plant cells and sucking out the contents. The damage that results from feeding depends on the host plant and the specific hopper. Only a few species of hoppers transmit pathogens such as those that cause curly top virus and aster yellows. Adult hoppers are excellent short-distance jumpers when disturbed, and they can be pests when found in high numbers.[图片]Symptoms and Diagnosis Hoppers are agile insects that can move with equal ease either forwards, backwards, or sideways like a crab. The crab-like motion distinguishes hoppers from most other insects. In addition, they can hop to escape danger or to move to another host plant. Feeding damage from some species causes small white spots (stippling) to appear on the upper leaf surface, usually beginning near the leaf midrib. Stippled areas can unite into larger whitish blotches on mature leaves. With some plants, feeding damage causes a drying and yellowing (or browning) of leaf margins, and possibly the whole leaf. Some leafhopper species cause curling or stunting of terminal leaves with their feeding. Another sign of feeding is the presence of tiny varnish-like spots of excrement on the underside of leaves. Also, check under leaves for white, papery cast skins that remain from the molting process.[图片]The lacebug is another insect that causes stippling from feeding and leaves dark droplets of varnish-like excrement on the underside of leaves. Distinguishing lacebugs from leafhoppers is easy: Lacebugs have a lacy pattern on their upper side, they don't jump or run sideways, and they are about half as broad as they are long. Yet another pest that can cause stippling is the spider mite. Check under leaves for the webbing left by spider mites (leafhoppers don't leave webbing).[图片]Life Cycle Adults of most species of leafhopper range between 1/8 to 1/4 inch long. They are slender and frequently have an angular, pointed head. Coloration depends on species, but generally leafhoppers are shades of green, brown, or yellow and are often mottled. Nymphs (immatures) look similar to the adults except that the nymphs are smaller and don't have wings. Nymphs typically feed on the underside of leaves, where the humidity is higher and they are more protected from predators. Leafhoppers have several generations each year. Some species migrate south in winter and return north with late spring weather.[图片]Integrated Pest Management Strategies 1. Live with the pests. Because of their mobility and abundance, leafhoppers are not easy to control. However, leafhoppers are seldom present in large enough numbers to seriously injure plants. In addition, leafhoppers have many natural enemies, including lady beetles, lacewings, damsel bugs, and spiders. They are also subject to diseases and parasites that help keep their numbers down under most conditions. 2. Use row covers. Floating row covers or netting can be placed over plants early in summer to exclude leafhoppers. Remove row covers when the plants begin to flower. 3. Monitor with sticky traps. Many leafhoppers are attracted to yellow sticky traps which should be placed close to the foliage of the crop. Populations can be monitored with sticky traps and low populations can be managed using these traps.[图片]4. Apply insecticidal soap. Insecticidal soap can control leafhoppers if applied when the insects are small. The immature leafhoppers are usually found on the underside of leaves so be sure to spray there also. 5. Apply insecticides. Other insecticides available for leafhopper control include botanical pyrethrins, carbaryl (Sevin), malathion, bifenthrin, cyfluthrin, bendiocarb (Turcam, Closure), disulfoton (Disyston), and acephate (Orthene). In general, these are most effective on the immature leafhoppers because they can't escape as well as the adults and are typically more susceptible to chemicals.

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Dummer. ゛☀

2017年09月16日

Leaf cutter bees (Megachile rotundata) are small native bees about ¼ inch long, robust and dark grey with a pollen brush on the underside of the abdomen. They are beneficial for the most part and only cause minor damage to ornamentals such as rose and ash by cutting half moon-shaped disks from the leaves. They are not aggressive but can give a mild sting if handled. They are important plant pollinators.[图片]Symptoms and Diagnosis The most characteristic symptom of leaf cutter bees are the half-moon shaped holes they make on the edges of leaves as they remove disks of leaf tissue to take back to form nest cells. A leaf may have a single disk removed or several.[图片]Life cycle Leafcutter bees are solitary bees. They do not form colonies. Females emerge in late spring, mate and form new nests in soft, rotten wood, the pith area of plants, or other existing holes of the correct size. They line the nest with the leaf fragments they collect, provision each cell with a mixture of nectar and pollen, lay an egg and seal the cell. Finished nests may contain a dozen cells or more. The young bees develop and remain in the cell overwintering as a full-grown larvae. There is only one generation a year.[图片]Integrated Pest Management Strategies 1. Prevention. Eliminate breeding sites. Look for rotting boards with sawdust pushed out of excavated tunnels or thick stemmed plants with hollowed openings. 2. Mechanical control. Cover susceptible plants with cheesecloth or other loose netting during periods when leafcutter bees are most active (in late summer). To prevent leafcutter bees from tunneling into rose canes, seal exposed pith as canes are pruned. Place a thumb tack, bit of sealing wax or white glue on the opening.[图片]3. Chemical controls. Insecticides are ineffective for preventing leaf cutting. Remember, leafcutter bees are native, beneficial bees, important as pollinators.

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