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Miss Chen
2017年09月18日
Miss Chen
Uno de las claves del buen funcionamiento del ajo en nuestro macetohuerto es el riego. Su cultivo es sencillo, pero muchas veces nuestras plantitas de ajo mueren por exceso de riego. [图片]Es una planta bianual, con un ciclo de vida de dos años. Tiene unas raíces muy numerosas y cortas, lo que hace que sea una planta muy bien adaptada al cultivo en el macetohuerto. Se cree que su origen se encuentra en el sureste de Asia o en el sur de Europa. Ha sido cultivada desde muy antiguo por los antiguos egipcios y los griegos ya la usaban como planta medicinal. Actualmente se cultiva en todo el mundo y el ajo es muy apreciado por sus propiedades medicinales.Es una planta bastante rústica, que se adapta bien a diferentes climas y tolera bien el frío del invierno. Para la formación del bulbo necesita temperaturas suaves y no le gustan las temperaturas excesivamente cálidas del verano. Por lo tanto, suele cultivarse para que forme el bulbo en primavera. Sin embargo, en macetas, puede plantarse durante todo el año. En macetas de 12 x 12 x 12 cm. funciona muy bien. La plantación se realiza a partir de los dientes de ajo, plantándolos a unos 5 cm. de la superficie con la parte más puntiaguda hacia arriba. Debemos tener en cuenta que el ajo presenta una cierta latencia, o sea, que el ajo recién cosechado puede tardar un cierto tiempo antes de germinar. De cada diente de ajo saldrá una cabeza completa. Diez días después del primer riego, se recomienda aplicar otro riego ligero, con el fin de favorecer la germinación de las semillas que no lo hayan hecho en el primer riego. Con esto, se logra la emergencia de un buen porcentaje de plántulas. A partir de ahí, los siguientes seis o siete riegos se deben aplicar cada 15 a 25 días. La etapa más corta (15 días) o más larga (25) dependerá de las condiciones climáticas del lugar, los requerimientos de humedad de la planta en sus diferentes etapas de desarrollo y la textura del suelo. Cuando las temperaturas comienzan a elevarse, los riegos deben ser más frecuentes, con intervalos entre ocho y diez días. [图片]El último riego se debe aplicar a los 15 o 20 días antes de la cosecha. Respecto a sus enfermedades, el ajo suele plantear pocos problemas, pero algunas de sus patologías o plagas más comunes son: la mosca de la cebolla (insecto), la tiña del puerro (insecto), la roya del ajo (hongo) y el mildiu (hongo).
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Miss Chen
2017年09月18日
Miss Chen
Las variedades de achicoria roja o radicchio (Chicorium intybus) las podemos comer en las ensaladas como una lechuga y tienen unos tonos muy intensos que llaman la atención. Tiene unas hojas violetas con nervios blancos que nos recuerdan a las endibias (son de la misma familia). Es una hortaliza muy apreciada por ser nutritiva y polivalente en la gastronomía. Su sabor es amargo e incluso ligeramente picante, por lo que combina muy bien en ensaladas y otros platos cocinados. Principalmente podemos encontrar dos variedades, la Verona que es redondeada y se parece a una lombarda y la Treviso que es alargada y se parece más a una endibia. [图片]Cómo sembrar achicoria (Chicorium intybus): Podemos sembrar la achicoria tanto a pleno sol como incluso en lugares con semisombra, aunque si tenemos la opción, preferentemente las sembraremos a pleno sol. No les gustan los suelos arenosos o arcillosos. Necesitan suelos profundos, con buen drenaje y ricos en materia orgánica. Antes de sembrar debemos airear un poco la tierra y aportar humus de lombriz o compost. A partir de Marzo ya se siembran al aire libre, si se prevén heladas o temperaturas muy bajas optaremos por la siembra protegida. Cuando sembramos las semillas debemos dejar un marco de plantación de 30×30 como mínimo. La podemos sembrar directamente en el suelo o preparar semilleros y trasplantar posteriormente. Es necesario que las semillas tengan una temperatura de alrededor de 25ºC para poder germinar, aunque a los 6 ó 7 días ya se va adaptando a temperaturas de unos 15ºC [图片]La achicoria necesita mucha agua, por lo que los riegos deberán ser regulares e incluso deberemos incrementarlos a medida que el tiempo va siendo más caluroso y la planta va creciendo y desarrollándose. En todo momento la tierra necesita tener un poco de humedad. Para conseguirlo es importante poner el acolchado o mulching, y así ahorramos agua. En cuanto a las plagas, el mayor enemigo de la achicoria es la babosa (puedes ver aquí como combatirlas de forma ecológica). Por lo demás es un cultivo muy sencillo que no suele dar problemas de plagas o enfermedades. La achicoria la podemos cultivar tanto en el suelo como en macetas y mesas de cultivo. Es un cultivo resistente al frío y al viento. Los cogollos se pueden empezar a cosechar cuando han alcanzado los 12 ó 15 cm de altura. Normalmente se cosecha unas 10 semanas después de la siembra.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Conifer sawflies are a unique group of defoliating insects. The various species (see "Pine Sawfly – Species") are distributed throughout the area where their preferred hosts grow. The larvae are hostspecific and feed on old and current year foliage at some point in their development. Some species have one generation per year with defoliation occurring in the spring and others produce three or more generations with defoliation occurring on into fall. Fall defoliation has a greater impact on trees and it is for this reason that sawflies having multiple generations are considered more devastating.[图片]Sawfly adults resemble large houseflies but are actually primitive broad-waisted wasps. While true flies have one pair of wings, the sawfly has two pairs of wings. The females are equipped with an ovipositor that is serrated, which enables them to saw little slits in the needles where eggs are laid, thus the name "sawflies". Defoliation by sawflies is sporadic, occurring in localized or region-wide outbreaks lasting one or more years. Growth loss the year following a severe defoliation (greater than 75%) can average over 50% and mortality increases due to secondary invasion by bark beetles and pine sawyers.[图片]European pine sawfly is the most common sawfly in Missouri. Symptoms and Diagnosis Sawfly larvae have the curious habit of raising their heads and tails in a threatening manner when disturbed. Overwintering eggs that have been deposited in the needles can be easily located after a heavy frost turns the egg-laying scar yellow. (See "Pine Sawfly – Species" for a detailed description of larvae.) Life Cycle - European Pine Sawfly In August to September, the adult European pine sawflies emerge from their cocoons to mate and lay eggs. Female sawflies emit a sex pheromone that helps the male locate females for mating purposes. Using her saw-like ovipositor to cut through the tough outer skin of the needle, the female sawfly deposits overwintering eggs in slits she makes in the needles. Each female may lay six to eight eggs in each of 10 to 12 needles, but this will vary by sawfly species. European pine sawflies overwinter in the egg stage.[图片]The eggs hatch in April through May and the larvae may feed until mid-June. The larvae feed in groups or colonies, often with three or four larvae feeding on a single needle. Being small and having small mouth parts, they merely rasp off the epidermal cells from the needles, which removes the protective barrier against desiccation. Thus, needles become twisted and brown as they dry out and die. Dead needles are easily detectable when contrasted against the green or surrounding "healthy" needles. As the larvae grow, they remain together and feed from the tip of a needle to the base. The larvae feed on older foliage and move from branch to branch as they strip the needles. Mature larvae drop to the ground and spin tough, brown cocoons in the duff. A few larvae may pupate on the tree. The above life cycle is for the European pine sawfly that only has one generation per year. The life cycle of those with more than one generation per year may vary slightly as some may overwinter in the ground in the pupae stage. Climate and latitude have a great bearing on the number of generations per year.[图片]Integrated Pest Management Strategies 1. Maintain plant vigor. Dry weather and poor soil conditions encourage damage by sawflies, therefore, water during times of drought. Keep plants vigorous with a fertilizing program. 2. Natural controls. Several parasites have been introduced to control this pest. Native birds feed on the larvae. Rodents often eat the pupae in the soil. These agents are usually not adequate in urban settings.[图片]3. Mechanical control —egg removal. If the needles containing overwintered eggs can be found before they hatch, they can be pulled off the plant and destroyed. Do not simply throw on the ground since young could still hatch from the eggs. 4. Mechanical control. Colonies of larvae can be easily removed by clipping off the infested branch. Place these branches in a plastic bag and destroy. Colonies can also be knocked off by sharply striking the infested branch. Crush the larvae or knock into a pail of soapy water. If few colonies are present, they can be controlled using these methods, but large infestations are better controlled by general spraying.[图片]5.Insecticide. Several horticultural oils and insecticidal soaps are labeled for control of sawflies on ornamentals. These usually work well when the sawfly larvae are small, and thorough coverage of the colony can be achieved. Pesticides registered for use include acephate (Orthene), azadirachtin (Bio-Neem, Margosan-O), or carbaryl (Sevin).
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Miss Chen
2017年09月18日
Miss Chen
Dejamos a remojo las semillas de la acelga durante uno o dos días antes de plantarla. Después se siembran a unos 2,5 cm de profundidad del suelo. Cabe recordar dejar al menos 8 cm de distancia entre una y la otra (las acelgas necesitan mucho espacio para las raíces) por eso dependiendo del tamaño de la maceta lo ideal sería poner una planta por macetero. [图片]Requerimientos de la acelga: -Temperatura: la acelga es una planta de clima templado, que vegeta bien con temperaturas medias; le perjudica bastante los cambios bruscos de temperatura. Las variaciones bruscas de temperatura, cuando las bajas siguen a las elevadas, pueden hacer que se inicie el segundo periodo de desarrollo, subiéndose a flor la planta. La planta se hiela cuando las temperaturas son menores de -5ºC y detiene su desarrollo cuando las temperaturas bajan de 5ºC. En el desarrollo vegetativo las temperaturas están comprendidas entre un mínimo de 6ºC y un máximo de 27 a 33º C, con un medio óptimo entre 15 y 25º C. Las temperaturas de germinación están entre 5ºC de mínima y 30 a 35ºC de máxima, con un óptimo entre 18 y 22ºC. -Luminosidad: no requiere excesiva luz, perjudicándole cuando ésta es elevada, si va acompañada de un aumento de la temperatura. La humedad relativa está comprendida entre el 60 y 90% en cultivos en invernadero. En algunas regiones tropicales y subtropicales se desarrolla bien, siempre y cuando esté en zonas altas y puede comportarse como perenne debido a la ausencia de invierno marcado en estas regiones. -Suelo: la acelga necesita suelos de consistencia media; vegeta mejor cuando la textura tiende a arcillosa que cuando es arenosa. Requiere suelos profundos, permeables, con gran poder de absorción y ricos en materia orgánica en estado de humificación. Es un cultivo que soporta muy bien la salinidad del suelo, resistiendo bien a cloruros y sulfatos, pero no tanto al carbonato sódico. Requiere suelos algo alcalinos, con un ph óptimo de 7,2; vegetando en buenas condiciones en los comprendidos entre 5,5 y 8; no tolerando los suelos ácidos. En maceta ésta debe tener como mínimo 25 cm de profundidad y unos 8 cm de distancia con otra planta y debe tener muy buen drenaje. Recolección [图片]La recolección de la acelga puede hacerse de dos formas, bien recolectando la planta entera cuando tenga un tamaño de entre 0,75 y 1 Kg de peso, o bien recolectando manualmente las hojas a medida que estas van teniendo un tamaño óptimo. La longitud de las hojas es un indicador visual del momento de la cosecha (25 cm), siendo el tiempo otro parámetro, 60-70 días el primer corte y después cada 12 a 15 días. Es recomendable cortar las hojas con cuchillos o navajas bien afilados, evitando dañar el cogollo o punto de crecimiento, ya que podría provocarse la muerte de la planta.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Pine needle scale, Chionaspis pinifoliae, is a common insect pest of pines in Missouri. It is most frequently found on Mugo, Scotch (Scots), and Ponderosa pine but will also infest Austrian, red, or white pine and most spruces. Light infestations often go unnoticed and cause little damage. As the population increases, needles become covered with the white scale insects, which suck juices from the needles. A heavy infestation can cause whole branches to die, or in severe cases, kill the plants.[图片]Symptoms and Diagnosis The scales are whitish and only 1/10 of an inch long with a yellow spot at one end. As numbers increase, the whole needle may be covered with scale. When pried off, the scales are hollow, and depending on the time of year, they may contain eggs or feeding insects. Life Cycle Reddish-colored eggs overwinter beneath the female scales. In May to June, young, called nymphs hatch and the migrate to new locations by crawling or being blown by the wind. The nymphs settle, begin feeding, and produce a waxy, scale covering. During late July and early August, mating takes place, and eggs are laid under the scale for next year's generation. (In some locations, a second generation may occur in early fall.)[图片]Integrated Pest Management Strategies 1. Prune and maintain vigor. Mild infestations caught early can be controlled by pruning out infested branches. Water and fertilize plant to maintain plant vigor. Use of chemical pesticides will adversely affect populations of beneficial insects that help to control the pest. 2. Properly timed dormant oil spray. A very effective control is to use a dormant oil spray in late March or early April, before new growth begins. The oil coats the scales, preventing oxygen intake so the insects suffocate. Dormant oil sprays are nontoxic to humans, birds, and pets, but must be applied at the right time to be effective and prevent damage to the plant.[图片]3. Properly timed insecticidal sprays. Pine needle scales are very resistant to pesticides when they are protected by their scales. However, they are very vulnerable when they are in the crawler state. In St. Louis, this is around the beginning of May. Examine infested plants with a magnifying glass for the crawlers. At the presence of crawlers, spray with an insecticidal soap, a summer oil spray, acephate (Orthene) or Neem oil. A fall application may also be made around the middle of August if a fall brood of crawlers is evident.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
There are approximately 140 North American species of lace bugs. Most have a specific host preference, which aids in identification. Some of the important species of lace bugs are for the azalea - Stephanitis pyrioides, hawthorn - Corythucha cydoniae, lantana - Teleonemia scrupulosa, and hackberry - C. celtidis. Lace bugs also feed on oak, elm, basswood, fringetree, and pyracantha among others.[图片]The different species of adults vary from 1/8 to 3/8 inch in length but all have wings and thorax beautifully sculptured with an intricate pattern of veins that resembles lace. The nymphs are dark and are pointed at both ends. Lace bugs, both immature and adults, are most often found on the underside of leaves. The London plane tree, Platanus acerifolia, is more susceptible to the lace bug than the sycamore, Plantanus occidentalis; both are hosts to the same species of lace bug.[图片]Symptoms and Diagnosis If heavily infested, the leaves may turn yellow and fall from trees and shrubs. The lace bug feeding mechanism is one that pierces and sucks the plant juices from leaves. This leaves tiny chlorotic flecks on the upper leaf surface. The underside of the leaves will have adults and spiny, dark-colored nymphs. The underside of leaves will look dirty with dark-brown spots and stains. When disturbed, lace bugs exhibit a peculiar bouncing movement. Life Cycle Female lace bugs lay groups of eggs on the underside of leaves most often along the midrib. These eggs are partially inserted into the leaf tissue and are pale and almost completely hidden inside the leaf. Many species secrete a brownish substance that hardens over the eggs and secures them to the leaf. Dark spiny nymphs hatch from the eggs and go through 5 to 6 nymphal instars before reaching adulthood. A complete life cycle takes only 30 to 40 days; several generations may occur each year. Lace bugs are more prevalent in late summer and fall. In late summer, both adults and nymphs will be feeding at the same time. Some species overwinter as eggs in the leaf or bark crevices or similar protected areas while other species overwinter in the adult stage.[图片]Integrated Pest Management Strategies 1. Live with the insects but maintain plant vigor. In many cases, the damage occurs late enough in the season or is minor enough not to require action. Keeping plants healthy by watering during periods of drought will limit any damage caused by the insects. 2. Select planting areas carefully. Plant susceptible species away from sidewalks and lawns as dropping leaves, twigs, and lace bug excrement can be bad enough to be considered unpleasant.[图片]3. Spray with water. Nymphs can be dislodged by forceful sprays of water and are vulnerable to control by contact with insecticidal soaps. 4. Sanitation. Prompt removal of leaves and twigs under plants can remove overwintering pests and limit the chances of reinfestation. 5. Control. Natural enemies are usually effective in maintaining populations at a low level and bringing outbreaks under control. Chemical controls are usually only used on shade and ornamental trees. Control of the azalea lace bug on evergreen azaleas is often required as the loss of leaves on these plants can have a more serious impact on plant health.[图片]6. Use insecticides. Pesticides registered for use include acephate (Orthene), bendiocarb (Turcam, Closure), capsaicin, carbaryl (Sevin), disulfoton (Di-syston), malathion, permethrin, pyrethrins, and horticultural oils. Spray as soon as eggs hatch on leaves in early spring. Some control is possible with a dormant spray applied just before growth in spring.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Two leafminers are most prevalent. The native holly leafminer, Phytomyza ilicicola, is a common pest of American holly. The holly leafminer, P. ilicis, feeds only on English hollies. The adult of both is a small black fly only about 1/8 inch long; the larva, a maggot, tunnels in the leaves causing yellowish or brown winding trails or blotches. Leaves may also become distorted and flecked with tiny brown dots. Leaves eventually yellow and drop. This should not be confused with the natural yellowing and shedding of older leaves which occurs annually in late spring or when the plant is under stress.[图片]Symptoms and Diagnosis Early signs are small raised bumps on the leaf where the egg has been inserted in the leaf by the female. The females also make small pinpoint holes in the leaves, called feeding punctures, through which they and adult males feed on the tender juice inside the leaf. This damage may be confused with damage caused by leaf spines, which can also cause punctures in leaves. When the young maggots hatch from the eggs, their feeding results in light green serpentine tunnels that become progressively wider as the maggot grows. In later stages, the maggot may have mined an area that looks like a spot or blotch. When scraped with a knife or pin, the upper leaf tissue will peel off revealing a mined area below. The maggot or frass (insect droppings) may be evident. In later stages, the leaves yellow and drop. Examining the leaves for tunnels will confirm the presence of leaf miner.[图片]Life Cycle Only one generation occurs each year. The larvae overwinter in the leaves on the tree or leaves which have fallen. Adults emerge in mid-May to late June and begin laying eggs in about 10 days. The females make a slit in the leaf and deposit an egg inside the leaf. The larva hatches and the young begin feeding on the leaf tissue. Integrated Pest Management Strategies 1. Pick up and destroy infested leaves. If damage is noticed after mid-May, most insecticidal sprays will not control the pest. To limit future infestations or control a minor problem, collect and dispose of the infested leaves on the ground and on the tree in fall or winter. Do not compost the leaves. For minor problems, limit the use of insecticidal sprays used on the plants or in the area, which could kill beneficial insects, such as the small beneficial wasps that parasitize leafminer maggots.[图片]2. Keep plants healthy. A healthy plant is better able to withstand occasional defoliation caused by leaf miners. Water during dry periods and mulch to help retain moisture. 3. Crush the small eggs or tunneling miners. Inspect small plants for early signs of damage and squeeze the eggs or young maggots. 4. If necessary, use insecticidal sprays. For severe cases, spray the new young foliage with an insecticide beginning in mid-May when the adults begin to emerge and lay eggs. Usually two follow-up sprays 7-10 days apart are needed. Check pesticide labels for directions and be sure to spray both the upper and lower sides of the leaf well. Insecticides include acephate (Orthene), spinosad and imidacloprid (Merit). Imidacloprid may also be applied to the soil in early spring.[图片]
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
The boxwood psyllid (Psylla buxi) is the most common insect pest of Buxus sempervirens but all boxwoods are susceptible. They are found most often in the temperate parts of the United States but occur wherever boxwoods are grown in this country. It causes damage by piercing and sucking sap from buds and young leaves resulting in a conspicuous cupping of the foliage. These leaves are weakened and will usually fall off after about one year. The terminal growth will be affected for about two years.[图片]Symptoms and Diagnosis The symptoms of a psyllid infestation are cupping of the young terminal leaves as they begin growth in spring. The psyllid nymphs will be visible inside the cupped leaves although the most obvious sign is the waxy filaments and secretions they produce. Life Cycle Boxwood psyllids have one generation per year. They overwinter as eggs in small orange spindle-shaped eggs that have been laid in between bud scales. Emerging as the new growth begins in April to May and feeding on the buds and young leaves, the nymphs are light green and may have dark markings. They produce and are partly covered with waxy filamentous secretions. The sucking damage causes the leaves to cup and creates a protected area for the developing nymphs. They mature into light green, 1/16 inch long adults that look like miniature cicadas in late May to early June. The adults lay eggs in the bud scales in June and July.[图片]Integrated Pest Management Strategies 1. If the infestation is small, do nothing. The damage caused by boxwood psyllids is only aesthetic and rarely affects the long term health of the plant. 2. Prune out and destroy the affected tips. If done before the nymphs mature to adults, this will decrease the number of eggs for next year. The damage caused by psyllids is complete by early summer and the shrub will outgrow the injury.[图片]3. Spray horticultural oil or insecticidal soap. Apply in early May when new growth occurs. Pesticides sprayed before or after that time will not be effective as the eggs are protected by the bud scales and the nymphs are protected by the cupped leaves. 4. Chemical controls are also available, but should only be used when the infestation is severe. Several pesticides are labeled for use against boxwood psyllids. Always be careful to read the label directions fully before applying any pesticide, and follow directions completely. Systemic insecticides may be necessary during certain stages of the psyllid’s life cycle. Pesticides that are absorbed into the foliage, such as acephate, will control adults in June.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
This pest is the most serious pest of this evergreen plant. It occurs everywhere in the USA from the East to the West coast. All varieties of boxwood are susceptible but the slower-growing English varieties are less susceptible than the American cultivars. The leafminer feeds between the upper and lower sides of the leaf.[图片]Symptoms and Diagnosis The larvae feeding between the upper and lower parts of the leaf causes blisters on the underside of the leaf. The leaves infested by this pest become yellow and smaller than a normal leaf. When the plant is severely infested, it appears completely unhealthy.[图片]Life Cycle Boxwood leafminers over-winter as partially-grown larvae in the leaf blisters. When the days warm in spring, the larvae become active and grow rapidly feeding between the upper and lower leaves for the balance of the summer. In May the adults force the pupal skin out of the mine, where it hangs for a few days after the fly, a gall midge, emerges. The adult leafminer is a yellow to orange-red fly that looks like a mosquito. Adult flies swarm around boxwoods about the time that the Weigelas bloom. When the boxwood’s new growth appears in spring, the females mate, then insert their eggs into the underside of the leaves. The adult fly dies soon after. The eggs hatch in about 14-21 days into the larval stage ( a maggot) that grows and feeds for the rest of the summer. The leaves develop the characteristic blisters as the larvae feed. The larvae then develop into orange pupae which darken before the adults emerge. One generation of the pest occurs each year.[图片]Integrated Pest Management Strategies 1. Select resistant cultivars. Culltivars of English boxwood such as Buxus sempervirens 'Pendula,' '‘Suffruticosa,' 'Handworthiensis,' 'Pyramidalis,' 'Argenteo-varigata' and 'Varder Valley' are more resistant. 2. Natural controls. Encourage natural predators such as green lacewings and spiders. Maintain plant vigor since healthy plants are more tolerant of insect damage. 3. Mechanical controls. Prune the foliage before adults emerge or right after adult flies lay their eggs in May. This reduces the overall population of the leafminer. Pinch leaves hard enough to kill maggots in the infested leaves when practical.[图片]4. Chemical insecticide control. If you choose to use a pesticide, apply when the new leaves are fully formed, around May 1st when the Weigela is in bloom. Make a second application between mid-June and mid-July. Use carbaryl (Sevin) or malathion to control adult flies. Acephate (Orthene) applied in mid-May (about 3-4 weeks after the adults emerge.) can be applied to control the larvae developing in the new leaves. In February to early April, the systemic insecticide imidacloprid (Merit) can be applied around the base of the shrub.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Bagworms, Thyridopteryx ephemeraeformis, produce conspicuous spindle-shaped cocoons on trees and shrubs throughout the United States. Bagworms feed on over 128 plant species. The most commonly attacked plants are arborvitae, red cedar, and other juniper species. They will also feed on fir, maple, juneberry, buckeye, persimmon, ginkgo, honeylocust, larch, sweet gum, spruce, pine, sycamore, poplar, oak, locust, willow, and hemlock.[图片]Symptoms and Diagnosis The principle harm done by the insect is the destruction of foliage by the caterpillars. Plants usually are partially defoliated, weakened, and rendered unsightly. Complete defoliation can occur. The most notable sign of bagworm infestation is the presence of protective bags attached to a branch. The bags incorporate bits of twigs and leaves from the host plant. They are approximately 1 to 2 inches long and resemble Christmas tree ornaments hanging from the limbs.[图片]Life Cycle The adult female bagworm does not look like a moth and never leaves her bag. She is maggot-like in appearance, soft-bodied, and yellowish-white. A mated female lays between 500 and 1000 eggs within the bag, after which she dies. The eggs remain inside the bag throughout the winter until they hatch the following spring. There is one generation a year. From late May to mid-June, bagworm larvae (caterpillars) begin emerging from the bags. Almost immediately after emerging, a larva starts to produce its own protective bag. The bag is constructed such that the larva's head and legs are free. This construction allows the larvae to move about the plant as it feeds on the foliage. As the larva grows, it increases the size of its bag. The full-grown larvae are about one inch long.[图片]When a host plant becomes defoliated, the larvae will crawl off it with their bags and search for a new plant to feed upon. In mid-August, the mature larvae stop feeding and attach their bags to a twig. They close up the bag and pupate. By mid-September, the bagworm has completed its development, and adult males begin emerging from their bags. The male moth has a black, furry body and feathery antennae. The wings are almost transparent and have a span of about one inch. Integrated Pest Management Strategies 1. Handpick the bags. The most economical method of controlling bagworms is to handpick the bags and destroy them. Some birds and insect predators feed on larvae, so light infestations on large, healthy plants are usually controlled by natural means. On large plants, monitor infestations before resorting to chemical sprays. If the problem doesn't get worse, spraying is not required.[图片]2. Use biological controls. In spring, as soon as eggs hatch and the young emerge, spray with Bacillus thuringiensis (Bt). Bt is a bacterium that causes the larvae to become sick, stop feeding, and later die. In St. Louis, the eggs hatch in late May to mid-June, or about the time the cigar tree, Catalpa speciosa, is in full bloom. 3. Use chemical controls. Because bagworms form protective bags very early, contact insecticides, while useful, are less effective than stomach poisons. For best control, spray when insects are young. Chemical controls become less effective as the bagworm matures. Chemical controls include acephate (Orthene), cyfluthrin and spinosad.
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