动态第181页 - 绿手指 - 养花技巧、花生病了怎么办、花园打理和设计

2018年05月29日

Description: This herbaceous wildflower is 5-12" tall, consisting of a single stem and a whorl of 3 spreading leaves at its apex. The central stem is purplish green or maroon, terete, glabrous, and rather stout. Individual leaves are 3-4" long and 2-3½" across; they are ovate or oval, smooth along their margins, sessile, glabrous, and parallel-veined. The upper leaf surface is medium green or mottled green (a mixture of both light green and medium green). The leaf bases are rounded and their tips are usually blunt. On a mature plant, a single sessile flower develops on top of the whorl of leaves. Individual flowers consist of 3 dark maroon petals about ¾-1¼" long (rarely greenish yellow or brown), 3 green or purplish green sepals about ½-1" long, 6 stamens about ½-¾" long, and an angular superior ovary with 3 recurved stigmata at its apex. The erect petals are narrowly elliptic to elliptic in shape. The sepals are narrowly lanceolate and widely spreading to slightly ascending; they lie above the plane of the leaves. The anthers have dark maroon and yellow stripes; they are much longer than the filaments. The blooming period occurs from mid- to late spring, lasting about 3 weeks. The flowers usually have a slight aroma of rotting meat. Each flower is replace by a dry 3-celled fruit that is whitish to purplish green. The fruit splits open to release the seeds. The root system consists of a stout rhizome and secondary fibrous roots. Clonal offsets occasionally develop from the rhizome.Distribution Map Cultivation: The preference is dappled sunlight to light shade during the spring; during the summer, more shade is tolerated. The soil should be moist, rich, and loamy with abundant organic matter (decaying leaves, etc.). This wildflower develops slowly from seed, requiring several years to reach maturity. The seeds should be kept moist and planted as soon as possible; they are often slow to germinate. It is also possible to start plants from clonal offsets. Range & Habitat: The native Sessile Trillium is found primarily in NE and southern Illinois, where it is uncommon. It is more common further to the east. Habitats include rich mesic woodlands, floodplain woodlands in valleys, lower slopes of shady ravines, and swamps. These habitats are dominated by such deciduous canopy trees as Sugar Maple, American Beech, American Basswood, and Green Ash. In Illinois, Sessile Trillium occurs in high quality woodlands where the original ground flora is still intact. Faunal Associations: Robertson (1929) observed a small weevil, Centrinites strigicollis, visiting the flowers for pollen. Because of the malodorous odor and color of the petals, the flowers are probably visited by beetles and flies that are attracted to rotting flesh. The polyphagous caterpillars of two moths, Clepsis melaleucana (Black-Patched Clepsis) and Euplexia benesimilis (American Angle Shades), have been observed to feed on trilliums. The seeds are distributed by ants (and possibly some beetles), which are attracted to their elaisomes (food appendages). White-Tailed Deer readily browse on the foliage of trilliums, although Sessile Trillium may be eaten less often than some trillium species because of its dark-colored and less conspicuous flowers. Photographic Location: A soggy area of Goff Woods Nature Preserve in NW Ohio. This woodlands is a small remnant of what was once called the 'Great Black Swamp,' which covered large areas of NW Ohio and NE Indiana. [图片]Comments: In many ways, Sessile Trillium resembles the more common Prairie Trillium (Trillium recurvatum), which is also found in wooded habitats in Illinois. Sessile Trillium can be distinguished from the latter species by its sessile rounded leaves and widely spreading or ascending sepals, which are held above the leaves. In contrast, the leaves of Prairie Trillium taper gradually into petioles and the sepals of its flowers hang downward below the leaves. Both Sessile Trillium and Prairie Trillium can have flowers with greenish yellow petals, but this is rather uncommon. Other trilliums in Illinois have petals that are never colored dark maroon, or their flowers have conspicuous pedicels (flowering stalks). Other common names of Trillium sessile are Toadshade and Wake Robin.

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Miss Chen

2018年05月29日

Description: This herbaceous perennial plant is about ½–1¼' tall. It consists of a single erect stem that has 3 spreading leaves at its apex. A mature plant produces a single sessile flower above the leaves, while an immature plant produces only leaves. The stem is light green, medium green, or yellowish green; it is terete, glabrous, and fairly stout. The leaves are up to 6" long and 3½" across; they are ovate in shape and smooth along their margins, tapering into distinct petioles. The upper leaf surface is mottled with patches of light and dark green, although sometimes it is solid green. The lower leaf surface is pale green. Both surfaces are glabrous. In addition to parallel primary veins, the leaves also have diagonal secondary veins that crisscross between the primary veins. Each flower consists of 3 yellow petals, 3 green sepals, 6 yellow stamens, and a green ovary with 3 stigmata. The petals are 1–1¼" long, rhombic-elliptic in shape, and erect, curving inward toward their tips. The sepals are ¾-1" long, glabrous, and triangular-lanceolate in shape; they hang downward from the base of the flower. The stamens are about ½" long, curving inward toward their tips; the large anthers of the stamens are narrowly oblongoid in shape and longer than the filaments. The blooming period occurs from mid- to late spring, lasting about 3-4 weeks. There is no noticeable floral scent. Individual flowers are fairly long-lasting. Afterwards, the flowers are replaced by 3-celled fruits (technically berries) that contain many small seeds. These fruits are a little less than ½" in length (about 10 mm.), rhombic-ovoid in shape, 6-angled, and greenish. The seeds are dark brown and partially white from their food appendages. The root system consists of a thickened erect rootstock, secondary fibrous roots, and rhizomes, from which clonal offsets are occasionally produced. [图片]Cultivation: This plant prefers dappled sunlight to medium shade, mesic levels of moisture, and rich loamy soil with decaying leaf litter. Like other Trillium spp. (Trilliums), this species is slow to develop because of the short period of active growth during the spring. The foliage persists until about the middle of summer. Range & Habitat: The native Shay's Trillium is quite rare in Illinois. According to official records, it has been observed in only Jackson County. However, the webmaster encountered it in Champaign County a few years ago, and there has been scattered sitings of Shay's Trillium in northern Illinois (see Distribution Map). Habitats include mesic deciduous woodlands where the original flora has remained little disturbed by modern development. [图片]Faunal Associations: The pollinators of the yellow flowers are unknown. Caterpillars of the polyphagous moths Clepsis melaleucana (Black-patched Clepsis) and Euplexia benesimilis (American Angle Shades) feed on trilliums (Covell, 1984/2005). Because of their food appendages, the seeds are distributed to new locations by ants. White-tailed Deer are very fond of the foliage and flowers of trilliums as a source of food. Their seeds can pass through the digestive tract of these animals and germinate in new locations (Vellend et al., 2003). However, too many deer can cause populations of trilliums to decline because of excessive browsing. Photographic Location: A mesic deciduous woodland at Busey Woods in Urbana, Illinois, and a woodlands in Ogle County, Illinois. The photograph of the Shay's Trillium with mottled leaves was taken by Lisa Culp (Copyright © 2013). [图片]Comments: Shay's Trillium (Trillium recurvatum shayii) is a rare form of the common Prairie Trillium (Trillium recurvatum). The typical form of this species has maroon flowers and black anthers. Another uncommon form of the Prairie Trillium that occurs within the state, Trillium recurvatum lutescens, has yellow flowers like Shay's Trillium, however its anthers are black or purple. In contrast, Shay's Trillium has yellow anthers. All three forms of this trillium usually have leaves that are mottled in different shades of green, however, plants with solid green leaves also occur. Regardless of its form, the Prairie Trillium differs from other trilliums in Illinois by the following set of characteristics: 1) its flowers are sessile, 2) its leaves have petioles, 3) its sepals hang downward, and 4) its petals are yellow or maroon. Other trilliums have flowers on short stalks, or their leaves are sessile, or their sepals are spreading to ascending, or their petals are white.

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Miss Chen

2018年05月29日

Description: This herbaceous perennial plant is ½-1¼' tall and unbranched. The erect central stem is light green to reddish purple, terete, rather stout, and glabrous. At the apex of this stem, there are 3 spreading leaves surrounding a single sessile flower. Immature plants, however, produce only leaves without the flower. The leaves are 3-6" long and 1½-3½" across; they are ovate in shape and smooth along their margins, tapering into distinct petioles. The upper leaf surface is medium green and heavily mottled with patches of light green and dark green; it is glabrous. The lower leaf surface is pale green and unmottled; it is also glabrous. On rare occasions, some plants will have leaves with solid green upper surfaces. Leaf venation is parallel with occasional interconnecting secondary veins. The flower has 3 maroon petals, 3 green sepals, 6 stamens with long black anthers, and an ovary with 3 stigmata. The petals are 1–1¼" long and rhombic-elliptic in shape; they curve inward toward their tips. The sepals are ¾–1" long, lanceolate-triangular in shape, and smooth along their often purplish margins; they hang downward from the base of the flower. The stamens are about ½" long, curving inward toward the other stamens. The blooming period is mid- to late spring, lasting about 3-4 weeks. Individual flowers are relatively long-lived. There is no noticeable floral scent. Afterwards, each flower is replaced by a single fruit (technically a berry). These fruits are a little less than ½" (10 mm.) long, rhomboid-ovoid in shape, 6-angled, and pale green to purplish green. Each fruit contains several small seeds; they are dark brown with white food appendages. The main rootstock is thickened and elongated, with numerous feeder roots. Rhizomes are also produced, causing this plant to form clonal colonies. [图片]Cultivation: The preference is medium shade to dappled sunlight, moist to dry-mesic conditions, and soil containing loam or clay-loam. The foliage is rarely bothered by pests or disease. Trilliums are slow to develop because of the short period of active growth during the spring, and up to 10 years may be required before a plant reaches flowering size in the wild. Range & Habitat: The native Prairie Trillium is a common plant that occurs in every county of Illinois (see Distribution Map). It is found primarily in rich woodlands, open woodlands, and savannas, where deciduous trees are dominant (including oak-hickory woodlands and maple-dominated woodlands). Sometimes this species survives degradation of woodland habitats, and it can be found along fence rows with woody vegetation, overgrown areas near railroads, and miscellaneous waste areas with partial or light shade. [图片]Faunal Associations: The maroon flowers of the Prairie Trillium may attract carrion beetles and flesh flies, although little is known about the insect pollinators of this trillium (Trillium sp.) because floral visitors are rare. Only pollen is available as a floral reward. The caterpillars of two polyphagous moths, Clepsis melaleucana (Black-patched Clepsis) and Euplexia benesimilis (American Angle Shades) feed on trilliums (Covell, 1984/2005). The seeds of these plants are often distributed by ants because of their food appendages. Among mammalian herbivores, White-tailed Deer are especially known to eat the flowers and foliage of trilliums. There is also some evidence that the seeds of trilliums can pass through their digestive tracts and remain viable. Therefore, White-tailed Deer may help to distribute the seeds across long distances (Vellend et al., 2003). Where White-tailed Deer are too abundant, however, they may destroy local populations of these plants. It is possible that the mottled pattern of the foliage of the Prairie Trillium is an adaptation to deer predation as this type of pattern may help to camoflage the plant with the surrounding forest floor. [图片]Photographic Location: A mesic woodland at Busey Woods in Urbana, Illinois, and an upland savanna in McLean County, Illinois. Comments: The common name is misleading because the Prairie Trillium occurs in woodlands like other trilliums (Trillium spp.), rather than prairies. However, it is especially common in Illinois and the surrounding states where prairies occur. This trillium species is relatively easy to identify for the following reasons: 1) its sepals hang downward from the flower, whereas in other Trillium spp. the sepals are usually spreading to ascending; 2) its flowers are sessile against the central stem and leaves, whereas the flowers of some trilliums (e.g., Trillium erectum) are held above the foliage on short stalks; and 3) the leaves taper gradually at their bases into short petioles, whereas the leaves of some trilliums are sessile and quite rounded at their bases. There are different forms of the Prairie Trillium that have yellow or maroon flowers, yellow or black anthers, and mottled or solid green leaves. The form described here, Trillium recurvatum recurvatum, is by far the most common.

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Miss Chen

2018年05月29日

Description: This perennial plant is 2½–6" tall and unbranched. It produces a single glabrous stem that terminates in a whorl of 3 leaves. The stem is light green, sometimes with reddish brown tints. The leaves are up to 2½" long; they are green or olive green, oval to ovate, hairless, and smooth along the margins. Their leaf venation is parallel. The base of each leaf is more rounded than its tip; it has a short petiole. Mature plants produce a single flower on a short peduncle about ½" long that is straight or arching (usually the latter). The flower is up to 2" across, consisting of 3 white petals, 3 green sepals, 6 yellow stamens, and a a tripartite style. The petals are oval-ovate and often slightly undulate along their margins. The recurved sepals are lanceolate and often slightly reddish or yellowish on the outer surface. The blooming period occurs during early to mid-spring and lasts about 2 weeks. Each fertilized flower is replaced by a 3-lobed fruit that is about ½" long. The root system consists of a thickened rootstock, secondary feeder roots, and rhizomes. Snow Trillium can reseed itself, but it more often produces vegetative clones from the rhizomes. At favorable sites, colonies are often formed. [图片]Cultivation: The preference is filtered sunlight during the spring (before the trees leaf out), and light shade during the summer. The soil should be mesic to dry, and loamy or rocky with a shallow layer of decaying leaves. There should not be too much competition from other ground layer plants during the late spring or the summer. The foliage withers away by the end of summer. Range & Habitat: The native Snow Trillium occurs in central and northern Illinois, where it is rather uncommon (see Distribution Map). However, it is locally common at a few high quality sites. Habitats include thinly wooded bluffs, upper slopes of bluffs (especially along rivers), and upper banks of rivers. This is an indicator species of high quality woodlands. It grows where the layer of decaying leaves is not too thick. [图片]Faunal Associations: Very few insects visit the early-blooming flowers for nectar or pollen. Most likely, the flowers are pollinated by Andrenid bees (Andrena spp.), queen bumblebees, and other bees that become active early in the spring. The caterpillars of two polyphagous moths, Clepsis melaleucana (Black-Patched Clepsis) and Euplexia benesimilis (American Angle Shades), feed on trilliums (Trillium spp.) occasionally. The fruits are probably eaten by small mammals and birds, although there is a lack of information regarding the particular species that do this. Such animals can help to introduce the seeds into new areas. Deer are very partial to the foliage of trilliums, although the Snow Trillium may be less vulnerable to their browsing than others because of its small size and strong tendency to grow on inaccessible slopes. [图片]Photographic Location: The slope of a bluff in Vermilion County, Illinois, and a river bank at Allerton Park in Piatt County, Illinois. Comments: This is one of the earliest wildflowers to bloom in woodlands and it is the smallest trillium (Trillium sp.). The Snow Trillium can be distinguished from other white-flowered Trilliums by considering the following features: 1) It is only 2-4" tall while in bloom, 2) it blooms earlier in the spring than other trilliums, 3) it has white flowers on a short stalk that is erect or arching, and 4) each fruit has 3 conspicuous lobes. The common name refers to the fact that snow can be found on the ground when the flowers bloom. This cute little trillium should be protected wherever it is found.

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Miss Chen

2018年05月29日

兰花又名中国兰花、地生兰、兰草，为兰科兰属多年生宿根草本花卉。原产我国其中云、贵、川、藏分布较广，是我国传统名贵花卉，也是世界名花。人们历来把兰花看作是高贵、典雅的的象征，并与梅、兰、竹、菊合称“四君子”。兰以清香淡雅与菊、水仙、菖蒲并称“花草四雅”，而兰花居四雅之首。兰花朴实无华，叶色常绿，叶质柔中有刚，花幽香清远，有极高的观赏价值，是陈列客厅、居室或点缀书房、门厅之珍品，下面为你详细介绍兰花僵蕾的原因与防治方法。 [图片]养兰一年到头也就3个喜悦：春季新苗多多；秋天花苞多多；来年开花多多。但我们却经常会发现有些花苞长着长着就发黑、干缩、脱落了，如何预防兰花僵蕾情况的出现呢？笔者通过多年的养兰实践观察发现，兰花花芽分化是在新苗的成熟期，要持续近1年的时间。一般兰花经过一年的营养积累，花苞出土。各个品种的花期是不一样的，春兰、蕙兰、墨兰、寒兰、春剑、莲瓣兰等花苞出土后，有一个较长时间的生长、孕蕾和春化过程。这一过程短则五六个月，长的甚至要7个月。四季兰、夏寒兰等从花苞出土到开花，时间不长，短的20来天，长的30天至40天。无论有春化期还是没有春化期的品种，在营养生长期和生殖生长期都要注意肥水和光照的管理。花苞发黑、焦枯脱落死亡的原因有很多方面，多数是因为湿度过大、肥过多、不通风等原因造成的。一般花芽分化足以说明营养充足，无需继续灌肥，只需叶面追肥就可以了。所谓的花期要注意肥水管理，促使花芽膨大长足，即注意叶面追肥。同时，这一期间温度偏高，兰花仍在继续生长，要加强杀菌消毒。当花苞出土后，若一味施肥、灌水，加之偶遇高温闷热、不通风等情况，就会发生花苞发黑、焦枯脱落死亡的情况。 [图片]兰花在孕蕾期，立秋至冬至以前，要加强磷钾肥的追肥，促使花苞膨大长足，不管杀菌消毒还是喷洒薄肥，间隔时间为7天至10天，不能过勤、过浓，适当多见阳光，否则会伤害到花苞导致烂心。另外，要注意开花前的控水、控肥。花苞小的时候，要注意扣水一两次，这与以后的开花品质有直接的关系。如果不是赶时间参加兰展，就不要刻意调节温度和湿度，让其自然开放。新苗营养生长期要施用以氮肥为主的多元素肥料，促使植株生长壮实，达到抗病、抗旱的目的，保证花芽生长的条件。所以，花苞能不能正常开花，与前期管理密不可分。

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Miss Chen

2018年05月29日

很多人养花往往是处于一时爱好，并没有根本的养花常识，所以常常面对的是自个的盆栽植物萎蔫等现象束手无策，或是盲目的进行处理，导致植物走向死亡。植物出现萎蔫现象，这也是最使养花者头痛的问题，造成植物萎蔫的原因很多，如缺水、缺肥、缺少光照、温度不适应，对土壤中所含酸碱度不适应、施化肥过量、感染了病毒、遭到了虫害受到空气有毒气体的损害等等，情况十分复杂，不过，大多数是由于水分不够造成的。 [图片]（1）由于空气过于干燥而造成的萎蔫，弥补的办法是对植物周围的地面，叶面每天喷水2?3次；（2）由于盆土缺水，常常是由于养花者每次浇水的量太少，只把锱土表面浇潮了就以为够了，结果是花卉的根部吸收不到水分，这是花卉的浇水的大忌，养花者称之为“浇半截水”，这样时间长了，花卉自然要因为得不着水分而萎蔫。（3）补救的办法，当然是对盆土进行浇水，但这里有一个特别值得注意的问题：这时对盆土浇水只能逐渐增加浇水量，不可猛然一下子浇得太多，这是因为当花卉植株萎蔫时，它的根毛已经萎缩，丧失了吸水的功能，同时，萎蔫已使细胞失水，若供应水分骤然过多，会使细胞壁和原生质发生质壁分离，所以植物在干旱之后，猛然吸入大量的水分时，也会导致死亡。[图片]

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Miss Chen

2018年05月29日

康乃馨是优异的切花品种。矮生品种还可用于盆栽观赏。花朵还可提香精。这种体态玲珑、斑谰雅洁、端庄大方、芳香清幽的鲜花，随着母亲节的兴起，成为全球销量最大的花卉。我国广泛栽培供观赏，有很多园艺品种，耐瓶插，常用作切花，温室培养可四季开花。 [图片]康乃馨的常见病害有叶斑病、灰霉病等；主要虫害是蚜虫、红蜘蛛康乃馨叶斑病。又名茎腐病，是康乃馨的一种严重病害。多发生在叶和茎上，有时也发生在蕾和花上。在叶片上发病多从下部开始，先产生淡绿色水渍状小圆斑，后逐渐变为紫色。随着病斑的扩大，病斑中央发生枯死。边缘褐色，病斑有圆形、椭圆形或不规则形，直径约4-5毫米，中央枯死部分为灰白色至灰色，以后在病斑上产生黑色霉层。植株受害严重时，叶片枯萎下垂，但不脱落，在枝条上，病斑绕茎或分枝一周后，上部枝叶和花蕾即萎缩枯死。此病从4月上旬到初冬均可发生，在温室中栽培全年皆可发病，盛夏雨季发病最为严重。如果栽植过密，则蔓延很快。但此病在北方却发病较少。防治方法：①在南方发病严重的地区栽种，应从健壮的植株上选择无病枝条，以防止病菌初次侵染；也可以引一生中北方抗菌力强的细叶品种栽种。②摘芽、切花后，可选用75%百菌清、70%代森锰锌或80%代森锌可湿性粉剂500倍溶剂化喷洒，也可以喷施1%的波尔多液防治，效果都很好。如生长期发病，应及时摘除病叶或拔除病株，并喷洒上述药剂，防止病情蔓延。康乃馨灰霉病。此病多发生在花瓣和花蕾上，偶有发生在茎叶。花瓣感病后，起初花瓣的边缘出现淡褐色水浸状，逐渐大部分花瓣被灰色真菌侵入繁衍，此时如果气温较高，湿度较大，就易造成腐烂。花蕾上发病时，呈水浸状不规则斑，并逐渐发生腐烂，使整个花蕾不能开放。防治方法：①注意室内通风透光，降低湿度；②发现病株及时清除；每隔15天左右喷一次75%的百菌清可湿粉剂500倍液，连喷2-3次，有效好的防治效果。康乃馨如发生锈病，可喷洒敌锈钠800倍液。康乃馨遭蚜虫、红蜘蛛等危害时，可喷40%乐果乳剂1000倍液或80%敌敌畏乳剂1000倍液防治。 [图片]养护注意事项 1、光照条件。康乃馨属中日照植物，喜阳光充足。除育苗期和盛花期外，无须担心强光为害，且借助辅助光可增加花冠直径和花色鲜艳度。光强与单位面积切花产量有明显的正相关性。 2、温度条件。康乃馨喜凉爽，不耐炎热，可忍受一定程度的低温。若夏季气温高于35℃，冬季低于9℃，生长均十分缓慢甚至停止。在夏季高温时期，应采取相应降温措施，冬季则需盖塑料薄膜或进入温室，以保持适当的温度。 3、水分条件。康乃馨根系为须根系，土壤或介质长期积水或湿度过高、叶片表面长期高温，均不利于其正常生长发育。因此提倡滴灌，另外还应注意水质及水分含盐量的问题。 4、土壤条件。康乃馨喜保肥、通气和排水性能良好的土壤，其中以重壤土为好。适宜其生长的土壤pH值是5.6~6.4。从一些土壤分析实验表明，pH值在5.95~7.9范围内，土壤有机质含量对开花无明显影响，主要决定于土壤质地。

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Miss Chen

2018年05月29日

害虫对杀虫剂抗性发展的历史，也就是杀虫剂发展应用的历史。随着有机合成杀虫剂的出现和推广应用，害虫抗药性发展速度明显加快，由于有机氯和有机磷杀虫剂的大量使用，抗性害虫的种树几乎成直线上升。 [图片]害虫抗药性的特点是害虫几乎对所有合成化学农药都会产生抗药性；害虫抗药性是全球现象，抗性形成有地区性，主要取决于该地用药历史与用药水平。双翅目、鳞翅目昆虫产生抗药性种树做多，农业害虫抗药性虫种树超过卫生害虫，重要农业害虫如蚜虫、棉铃虫、小菜蛾、菜青虫、马铃薯甲虫及螨类的抗药性尤为严重。世界卫生组织对害虫的抗药性下的定义是“昆虫具有忍受杀死正常种群大多数个体的药量的能力在其种群中发展起来的现象”。昆虫抗药性是指种群的特性，而不是昆虫个体改变的结果；抗性是相对于敏感种群而言；抗性有地区性，即抗性的形成与该地的用药历史、药剂的选择压力等有关；抗性是由基因控制的，是可遗传的，杀虫剂起了选择压力的作用。 [图片]第一、轮换用药不要长期单一使用某种农药防治某种害虫，这样就可以切断害虫抗药性种群的形成过程。轮换使用的品种应尽可能选用作用机制不同的农药。如有机磷农药、拟除虫菊酯类农药、氨基甲酸酯类农药、生物制剂类农药等，杀虫原理各不相同，可交替使用。同一类的农药品种轮换使用应慎重，因害虫易获得交互抗性，即对某种农药产生抗性后，对和该种农药同类的其他品种也会产生抗性。第二、混合用药两种作用方式和机制不同的农药混合使用，可减缓害虫抗药性的发生速度，即使抗药性已经形成，混合用药也能对抗药性起抑制作用。以前，混合用药较成功的方案有：敌百虫、敌敌畏与马拉硫磷混用；菊酯类杀虫剂与有机磷类杀虫剂混用；敌百虫与辛硫磷混合使用；机油乳剂与有机磷杀虫剂混用等。必须注意的是，混配农药也不能长期单一使用，要轮换用药，否则，同样有引起抗药性的危险，甚至引发害虫产生多种抗药性。第三、农药的间断使用或停用当一种农药已经引发了某种害虫的抗药性以后，如在一段时间内停止使用该农药，则害虫的抗药性会逐渐减退甚至消失。如某些有机磷农药引起红蜘蛛的抗药性，经过若干年停用后，红蜘蛛的抗药性可基本消失。这样，药剂的作用仍可恢复。第四、添加增效剂在农药中加入增效剂，可明显起到活化农药、提高药效、延缓和抑制害虫产生抗药性的作用。如在氧化乐果中加入少量柴油防治蚧壳虫，可溶蚀蚧壳，使农药进入害虫体内，克服了蚧壳虫对氧化乐果的抗药性。除油类物质外，常用的增效剂还有中性洗衣粉、豆浆、植物油等。第五、多样化的施药方法农药的使用方法除了常规的喷雾外，还可采用其他方法，如拌毒土、制毒饵、土壤施药、涂药、滴药、烟熏等，不同的用药方法交替进行，有助于预防和克服害虫产生抗药性。第六、开发使用土农药土农药原料来源广，制作简单，对害虫不会诱发抗药性。目前，有待开发的土农药主要是植物性农药，如烟草、蓖麻、大蒜、辣椒水、韭菜等。此外洗衣粉、油类、生石灰、烧碱、松香等，这些都是配置土农药的好原料。

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Miss Chen

2018年05月29日

蛀心虫，又称食心虫。蛀心虫的种类很多，包括天牛幼虫、粉蛾幼虫和其他昆虫的幼虫等，一般钻入枝梢内啃食木质进行为害，受其影响的果树，轻者生长不良、树势衰弱黄化，重者甚至整棵树死亡。蛀心虫种类很多，有天牛幼虫、粉蛾幼虫和其他昆虫的幼虫等。蛀心虫最初蛀入嫩枝，然后再向枝干部蛀入。樱花、梅花、无花果、蔷薇等最易受害。现总结出防治蛀心虫的方法如下： [图片]一、用铁丝伸入蛀孔，刺死蛀虫。也可把铁丝的尖端回弯成钩形，将虫体钩出。二、在蛀孔中塞入一团浸透了敌敌畏溶液的棉花球，把蛀孔口用黏土或凡士林等封闭，则蛀虫可被杀死。三、在蛀孔内注射纯酒精，使之渗入枝干，将虫杀死。四、蛀心虫的卵一般产在幼茎上，孵化后的幼虫沿着幼茎爬动，可及早撒布驱虫的药剂。五、已有蛀心虫蛀入的枝干，可从蛀孔下70厘米左右连同虫体一起剪去。 [图片]

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Miss Chen

2018年05月28日

Description: This perennial wildflower is 2-6' tall and usually unbranched, except toward the apex where the flowerheads occur. The glabrous central stem is light green to purple. The alternate leaves are up to 8" long and 6" across (excluding the petioles), becoming gradually smaller as they ascend the central stem. They are quite variable in shape; the lower leaves are often divided palmately into 3 lobes (or less often 5 lobes), while the upper leaves often lack lobes (ovate or deltoid). The margins of the leaves are undulate, dentate, or entire (smooth). The upper surface of each leaf is medium to dark green and hairless, becoming yellowish green with age. The petioles are as long as the leaf blades or somewhat shorter. The foliage of this plant contains a white latex. The central stem terminates in a panicle of flowerheads that is about as wide as it is tall; smaller panicles often develop from the axils of the upper leaves. The typical panicle will have 2-4 widely spreading branches at the apex of a central stalk (peduncle); from each of these branches, several flowerheads and their buds hang downward from shorter branches (pedicels). These branches are hairless or slightly pubescent and light green to pale purple. Each flowerhead is up to ¾" long and ½" across when it is fully open; it has 5-6 outer ray florets and no disk florets. The ray florets are greenish white, cream-colored, or greenish yellow. The cylindrical base of each flowerhead has about 5 primary bracts (phyllaries) that are light green and hairless; each of these bracts is linear in shape and about ½" in length. At the very bottom of each flowerhead, there are also several secondary bracts that are much shorter than the primary bracts. The blooming period occurs from late summer into the fall and lasts about a month. Each ray floret is replaced by an achene with a small tuft of hair; these hairs are either light tan (var. altissima) or orange-brown (var. cinnamomea). The achenes are distributed by the wind. The root system is tuberous. Sometimes this species forms small colonies of plants. [图片]Cultivation: Preferred growing conditions consist of light shade to dappled sunlight and fertile loamy soil that is moist to slightly dry. Rocky or sandy soil is also tolerated. The size of individual plants can be highly variable depending on soil fertility, moisture conditions, and light levels. Range & Habitat: The native Tall White Lettuce is occasional in southern and extreme eastern Illinois, otherwise it is rare or absent (see Distribution Map). This species is more common further to the east. Habitats include rich mesic woodlands, rocky upland woodlands, sandy woodlands, bluffs and shaded ravines, woodland borders, swamps and seeps, and shaded to partially shaded riverbanks. This species is found in deciduous woodlands where Sugar Maple, American Basswood, and/or American Beech are often present as canopy trees. Faunal Associations: Information about floral-faunal relationships for this species is limited. Bumblebees suck nectar from the flowerheads and cross-pollinate them; Halictid bees, beetles, and other insects may feed on the pollen, but they are not effective pollinators. Even though it has a bitter taste, White-Tailed Deer occasionally browse on the foliage. [图片]Photographic Location: A deciduous woodland at Turkey Run State Park in west-central Indiana. Comments: Two major groups of woodland lettuce can be found in Illinois and neighboring states: species of Wild Lettuce (Lactuca spp.) and species of White Lettuce (Prenanthes spp.). Species in the former group have flowerheads that are erect or hang sideways, while species in the latter group have flowerheads that droop downward. Tall White Lettuce can be easily distinguished from other species of White Lettuce in Illinois by examining the primary bracts (or phyllaries) of the flowerheads: each flowerhead has 5 primary bracts (phyllaries) that are light green and hairless (less often there are 4 or 6 bracts). Other species of White Lettuce in Illinois have 8 or more primary bracts; depending on the species, these bracts may be hairy or pale purple. As a general rule, leaf shape is unreliable as a guide to identification because it is highly variable within each species of White Lettuce. Other common names that are sometimes applied to Prenanthes altissima and similar species include Lion's Foot and Rattlesnake Root.

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