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Miss Chen
2018年05月23日
Miss Chen
贴梗海棠也叫皱皮木瓜，是一种集观赏与药用价值于一体的植物。既可以作为盆栽装饰家庭，又可以用于园林建设；既可以赏花，果实又可以入药，非常实用。 贴梗海棠是一种很高大的落叶灌木，春天花开，红的、粉的、粉白的争相斗艳，花团锦绣，煞是好看。花瓣有两种，一种是重瓣，一种是半重瓣，淡雅娇艳非常好看。作为独特的观赏植物，贴梗海棠多用于园林建设，门房花厅，绿色中一团红色、粉色、粉白色，有诗情画意之感，让人赏心悦目。
下面要为大家介绍一下日常养殖中贴梗海棠常见的虫害及其防治方法。 危害贴梗海棠的主要虫害有： 1. 萍实巢蛾。主要以幼虫蛀食植物的花和果，9月下旬至10月，幼虫老熟吐丝结薄茧，在浅土层或树皮的裂逢内化蛹越冬。防治方法： ⑴冬季清除破碎的树桩和开裂的树皮，并杀死越冬的幼虫。 ⑵在7月用10厘米长的皱折纸板绕在树上诱杀老熟幼虫。 ⑶幼虫孵化盛期，用杀螟松1000倍液或二氯苯醚菊酯2000倍液喷洒。
2. 舞毒蛾。主要是幼虫的危害，初孵幼虫一般群集在叶片的背面，夜间吃食叶片，严重时可将全株的叶片吃光；2龄幼虫白天在树皮缝隙、树杈、树下杂草以及石块下潜伏。防治方法： ⑴在羽化盛期的晚上，用黑光灯诱杀成虫。 ⑵幼虫大量发生时，用菊酯类杀虫剂或50%辛硫磷乳油1500倍液，或2.5%臭氰菊酯乳油3000倍液喷洒。 ⑶在树干的基部涂70厘米宽的90%敌百虫原药100倍的药环，触杀幼虫。 ⑷摘除卵块并烧毁。
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Miss Chen
2018年05月23日
Miss Chen
植物其实与人是一样的，缺乏某种元素时，都会出现不同程度的病症。不同的微量元素，给人体带来不同的益处。植物亦是如此。 植物对一些元素需要量较大，如氮、磷、钾等大量元素；对另一些元素需要量相对较小，如镁、锌、锰、铁、铜、硫、硼、钼等微量元素。植物所需的微量元素，其功能各不相同，如果某种微量元素缺乏，就会引起植物生理机能的紊乱，导致植物出现各种症状，影响叶色和花姿，甚至使植株衰弱以至死亡。下面介绍植物缺乏微量元素的症状及矫正方法，供参考。
一、缺铁症。 新叶叶肉变黄，但叶脉仍绿，一般不会很快枯萎。但时间长了，叶缘会逐渐枯萎。矫正方法：及时进行叶面喷洒0.3-0.5%的硫酸亚铁溶液，每隔10-15天喷一次，连喷2-3次。 二、缺锌症。 一般表现植株矮小，新叶缺绿，叶脉绿色，叶肉黄色，叶片狭小。矫正方法：用0.05-0.1%的硫酸锌溶液进行叶面喷洒每株用硫酸锌1克与适量的腐熟肥混合追施均有较好效果。 三、缺镁症。 先从老叶的叶缘两侧开始向内黄化，随着缺镁程度的加剧，叶片呈黄色条斑，叶片皱缩，根群少，叶小、花小、花色淡，植株的生长受到抑制，矫正方法：叶片喷洒0.2-0.4%的硫酸镁溶液2-3次，或每株施钙镁磷肥2-3克。 四、缺锰症。 叶片失绿，出现杂色斑点；但叶脉仍为绿色，花的色泽低劣。矫正方法：用0.1-0.2%的硫酸锰溶液进行叶面喷洒，为了防止药害，可加入0.5%的生石灰制成的混合液喷雾。
五、缺硫症。 植物缺硫一般多为幼叶先呈黄绿色(不是象缺氮那样通常老叶先变黄)，植株矮小，茎干细弱，生长缓慢，植株的发育受到抑制。矫正方法：每株施硫酸钾2-3克。 六、缺钙症状。 顶芽易受伤，叶尖、叶缘枯死，叶尖常弯曲成钩状，根系也会坏死，严重时则全株枯死。矫正方法：可用0.2-0.4%的石灰水溶液进行浇灌，连浇2-3次，每次每株20-30毫升。 实践证明，微量元素缺乏症，一般多是长期不换土，或长期单一施用氮素化肥的结果。如能采用肥沃的盆土并定期换盆添土，注意施有机肥料，一般植物是不会缺少微量元素的。 所以爱护植物，就要像爱护一个婴儿一样，营养齐全它才会健康的生长。
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Miss Chen
2018年05月23日
Miss Chen
别看扶桑花外表大大咧咧的透着一股热情劲儿，其实它的花心非常纤细，《本草纲目》中曾形容它“枝柯柔弱”，可见要养好这“枝柯柔弱”的扶桑花，不下一番功夫是不行的。今天小编主要说的是扶桑的主要病虫害及其防治方法。
1)扶桑叶斑病 叶斑病是一种真茼性病害。多发生在秋末天气转冷时期，尤其北方地区入窖不及时更易发生。最初的症状是叶片出现淡黄色及红黄色斑点，病斑扩大后呈圆形或椭圆形，在比较潮湿的条件下，病斑上可出现黑色的粒状物，即病原菌的分生孢子器，后期叶片干枯脱落。该病害的防治关键是做好防寒工作，秋后大风降温时采取保护措施，在此基础上及时喷布500～800倍液的代森锌或1500倍％铵都可以起到很好的防治效果。 2)扶桑茎腐病 茎腐病是一种为害严重并日发生范围较广的真菌病害。该病多发生在雨季，高温多雨条件下发病严重。病原菌多从植株的根茎交结处侵染，初期病状不十分明显，只是受害部位的皮层皱缩，稍显暗褐色，但皮下组织却已开始腐烂，变成褐色，病斑绕茎一周后，植株干枯死亡。从叶面上看，发病初期时，叶片萎蔫，边缘出现黄褐色枯斑，逐渐向里扩展，后期叶片干枯脱落。该病防治的关键是防止暴雨长期冲刷植株，并在雨季前后每隔10天左右用200～500倍液托布津涂干。试验表明，这种方法有很好的防治效果。
3)扶桑根结线虫病 也是一种分布广、为害严重的病害。该病从地上部分观察，初期叶片生长衰弱，边缘出现红褐色的枯斑。并向内扩展，后期叶片干枯脱落。从地下部分观察，则发现在植株根系间出现大大小小的瘤状物，初期光滑肉色，后期粗糙褐色，内藏针尖大小的梨形雌线虫。 该病的防治较困难。如果株数少可换土，土壤一定要经过较长时间的暴晒，旧土不要再用。较多植株也可施入涕灭威颗粒剂，可按5寸盆埋入0.5克左右计划。
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Miss Chen
2018年05月23日
Miss Chen
想要家里有热带风情的感觉，栽种一盆鹤望兰就足够了，它有着厚而宽的革质叶子，最亮丽的要数它的艳丽花朵，像是一只仰头瞭望的小鸟一般的花朵。 鹤望兰是一种原产南非的植物，养护需要常年温暖的环境，最低养护要保持在10度以上，在室内养护是非常容易生长的。今天要跟大家分享的是此植物的斑枯病。
鹤望兰斑枯病是由枇杷茎点霉（属半知菌类真菌）引起。病菌以菌丝体和分生孢子器在寄主上或随病残体在土壤中越冬，第2年春天条件适宜时，从分生孢子器中逸出分生孢子进行初侵染和再侵染，使病害不断扩展，植株生长衰弱和盆土偏碱易发病。该病为害叶片，开始在叶上生灰白色枯斑，边缘生褐紫色线圈，较灰斑病宽明显，其上生许多黑色小粒点，即病原菌的分生孢子器。
防治措施： ⑴精心养护，使植株健壮。该花喜温暖潮湿，不耐寒，生长适温为18-24℃，夏季畏强光暴晒，冬季需阳光充足，要求疏松肥沃的土壤。生长开花期要充分浇水，15-20天追一次肥，花期应增施磷肥，盆栽的二年换一次盆。 ⑵叶片剪去后用30%碱式硫酸铜悬浮剂300倍液涂抹伤口或剪口。 ⑶发病初期喷洒30%碱式硫酸铜悬浮剂400倍或47%加瑞农可湿性粉剂800倍液、70%代森锰锌可湿性粉剂500倍液，隔10天喷洒1次，连用2-3次。
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Miss Chen
2018年05月22日
Miss Chen
Description: This perennial plant is ¾–2½' tall and unbranched, except toward the apex where the flowers occur. The central stem is green to purple, 4-angled, and hairy to glandular-hairy. Often, the margins of the stem along its angles are shaded purple. The hairs of the stem are widely spreading. Pairs of opposite leaves occur along the entire length of the stem. These leaves are 1½–3" long and ¾–1¾" across; they are lanceolate-oblong to oval-ovate in shape, while their margins are crenate to crenate-serrate and ciliate. Generally, upper leaves are more narrow in shape than the leaves below. Leaf bases are truncate, rounded, or broadly wedge-shaped, while leaf tips are blunt. The upper leaf surface is medium to dark green and mostly glabrous, while the lower leaf surface is pale green and pubescent or hairy (especially along the major veins). The petioles are up to ¾" long with grooved upper surfaces; they are more or less hairy. The central stem terminates in a spike-like raceme of flowers up to 4" long. In addition to this raceme, secondary racemes are sometimes produced from the axils of the upper leaves. The central stalk of each raceme is 4-angled, green to purplish green, and glandular-hairy; the hairs are widely spreading. Individual flowers along the raceme are ½-¾" long; their 2-lipped corollas are strongly ascending, but their mouths open laterally. Each flower consists of a pale to dark blue-violet corolla, a short green calyx, 4 inserted stamens, and a 4-lobed ovary with a single style. The corolla has a hood-like upper lip and a descending lower lip; the back and apex of the hood are more or less finely pubescent. The lower lip has irregular blotches of white (usually in pairs along the sides of a central blue-violet vein). In addition to these lips, there are also a pair of small lateral lobes. The lateral lobes are attached to the upper lip; they are often whitish and recurved. The calyx is glandular-hairy and shallowly divided into two lobes; there is a conspicuous protuberance on the back of the calyx.
The pedicels of the flowers are short (about 4 mm. in length), relatively stout, and pubescent. At the pedicel bases, there are pubescent leafy bracts up to 1¼" long and ½" across; they are lanceolate-oblong or elliptic-oblong in shape. The margins of these leafy bracts are ciliate and either toothless (entire) or sparingly crenate-serrate. The blooming period occurs from late spring to mid-summer, lasting about 3-4 weeks. Afterwards, the corollas become detached and wither away, while the persistent calyces become swollen and enclose the developing nutlets. There are 1-4 nutlets per calyx (often only 1 or 2). The small nutlets are minutely tuberculate. The calyces eventually split open to eject the nutlets; this may be caused in part by raindrop logistics. The root system is fibrous and short-rhizomatous. Cultivation: The preference is light shade to partial sun, mesic to dry-mesic conditions, and an acidic soil containing some organic material.
Range & Habitat: The native Hairy Skullcap is occasional in southern Illinois, while in the rest of the state it is largely absent (see Distribution Map). Illinois lies along the northern range-limit of this species. However, a northern outlier population occurs in SE Michigan and NW Indiana. Habitats include rocky woodlands, bluffs, wooded slopes, rocky areas along streams, and well-drained bottoms of sandstone canyons. Hairy Skullcap is found in higher quality natural areas. In some areas of southern Illinois, it is currently threatened by the spread of an invasive species, Japanese Stilt Grass (Microstegium vimineum). Faunal Associations: The nectar and pollen of the flowers attract various bees. Butterflies and skippers may also visit the flowers, but they are less effective at cross-pollination. The leaves of Hairy Skullcap and other Scutellaria spp. (Skullcaps) are attacked by several skeletonizing leaf beetles (Phyllobrotica spp.) and the Shining Flea Beetle (Asphaera lustrans). In particular, Phyllobrotica circumdata has been observed on Hairy Skullcap. The larvae of two micro-moths also feed on the foliage of Scutellaria spp. (Skullcaps): Caloptilia scutellariella and Prochoreutis inflatella. Larvae of the former moth are blotch leaf-miners, while larvae of the latter moth skeletonize the leaves. The bitter foliage is not eaten by mammalian herbivores.
Photographic Location: A wooded sandstone canyon in southern Illinois. Comments: This is another native species of Scutellaria (Skullcap) that could be cultivated in shaded gardens. Both the foliage and flowers are reasonably attractive. The bitter foliage does not have a mint fragrance. It is possible to confuse Hairy Skullcap (Scutellaria elliptica) with some of the other woodland Scutellaria spp. in Illinois. It differs from Heart-Leaved Skullcap (Scutellaria ovata) by having less wide leaves that lack cordate bases (with the possible exception of the lowermost leaves). It also differs from Downy Skullcap (Scutellaria incana) by having spreading glandular hairs on its stems, flowering stalks, and calyces. The foliage and calyces of Downy Skullcap are more short-pubescent or canescent and they lack glandular hairs. Another woodland species, Showy Skullcap (Scutellaria serrata), has glabrous foliage and larger flowers (1" in length or more). Across its range, Hairy Skullcap varies somewhat in the extent of its hairiness: the typical variety is less hairy than var. hirsuta.
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Miss Chen
2018年05月22日
Miss Chen
Description: This herbaceous perennial plant is about 3½-8' tall, branching occasionally. The stems are often 4-angled and furrowed; they are slightly hairy or glabrous. The opposite leaves are up to 7" long and 3½" across (excluding the petioles), becoming somewhat smaller as they ascend the stems. These leaves are medium to dark green, cordate-ovate to ovate in shape, serrated along their margins, thin-textured, and largely hairless, except for some short pubescence along the undersides of their veins. The slender petioles are up to 2½" long; they are light green to red and glabrous to slightly hairy. The upper stems terminate in elongated panicles of flowers up to 1' long. Each panicle is somewhat cylindrical in shape, consisting of an erect central stalk (rachis) with short lateral branches that are widely spreading to ascending. Both the central stalk and lateral branches are light green; the latter also have short glandular pubescence, and they are slender and wiry. There are individual bracts (green, linear in shape, and up to 1" in length) that become progressively smaller as the panicle branches. Individual flowers are about 8 mm. (1/3") long and short-cylindrical in shape; each flower has a short-tubular green calyx with 5 blunt teeth and a corolla with 5 rounded lobes. The exterior of the corolla is dull green, while its interior is predominantly reddish brown. Each corolla has a pair of upper lobes that function as a hood, 2 short lateral lobes, and a lower lobe that curves downward. All of these lobes are reddish brown on the inside, except the lower lobe, which is greenish yellow. Appressed against the upper interior of this corolla, there is an infertile stamen that is reddish brown or purple. The 4 fertile stamens have yellow anthers; they are located toward the bottom of the corolla. The slender pedicels are a little longer than the flowers. The blooming period occurs from mid-summer to early fall, lasting about a month; only a few flowers are in bloom at the same time. Each flower is replaced by a 2-celled capsule that contains numerous tiny seeds. The root system is rhizomatous and knotty-tuberous.
Cultivation: The preference is medium shade to partial sun, moist to mesic conditions, and soil that is loose and loamy. The size of this plant can be highly variable, depending on its age, location, and environmental conditions. Range & Habitat: Late Figwort (Scrophularia marilandica) is a fairly common plant that has been observed in most counties of Illinois (see Distribution Map), where it is native. Habitats include mesic deciduous woodlands, sandy woodlands, savannas, edges of shaded hillside seeps, woodland borders, thickets, and fence rows that are overgrown with trees. This species tolerates minor to moderate levels of disturbance.
Faunal Associations: The small flowers contain abundant nectar, which attracts the Ruby-throated Hummingbird, honeybees, bumblebees, leaf-cutting bees (Megachile spp.), a long-horned bee (Melissodes bimaculata), Halictid bees (Halictus spp., Lasioglossum spp., etc.), Vespid wasps (Polites spp., Vespula spp.), and various Eumenine wasps (Robertson, 1929). Halictid bees also collect pollen from the flowers. Insects that feed destructively on the leaves, plant juices, and other parts of Late Figwort and other figworts (Scrophularia spp.) include larvae of the gall fly Lestodiplosis scrophulariae, the stink bug Cosmopepla lintneriana, the aphid Myzus scrophulariae, the flea beetle Capraita thyamoides, and caterpillars of the moth Elaphria chalcedonia (Chalcedony Midget). Because the foliage is bitter and acrid, it is rarely browsed by mammalian herbivores.
Photographic Location: Busey Woods in Urbana, Illinois. A small colony of Late Figwort (Scrophularia marilandica) was growing in a mesic area of this deciduous woodlands. Comments: The figworts (Scrophularia spp.) have weird little flowers that attract many wasps and bees. They are not grown in gardens very often because their flowers are not very showy (by human standards). The only other figwort that occurs in Illinois is Early Figwort (Scrophularia lanceolata). This species is less common than Late Figwort (Scrophularia marilandica); in Illinois, it is found only in the northern section of the state. Early Figwort blooms a little earlier than Late Figwort (hence their common names), although their respective blooming periods overlap to some extent. The flowers of Early Figwort have sterile stamens that are yellow, rather than reddish brown or purple (the sterile stamens of both species are located along the upper interior of their corollas).
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Miss Chen
2018年05月22日
Miss Chen
Description: This wildflower consists of a rosette of basal leaves and a flowering stalk about 1-3' tall. Individual basal leaves are up to 9" long and 3" across; they are oblong to ovate-oblong, crenate or smooth along their margins, and medium green. Basal leaves are glabrous to sparsely hairy on their upper surfaces, while their lower surfaces are sparsely to moderately hairy. Generally, young leaves are more hairy than older leaves. The inflorescence consists of a panicle of flowers, which develops from an erect central stalk. This stalk is fairly stout, terete, and densely covered with spreading hairs. The panicle is ellipsoid in shape, ½–1½' long, and about 1/3 as much across when it is fully extended. The branches of the panicle are ascending to spreading and usually pubescent. There is a single linear-lanceolate bract at each major fork of the branches. Depending on the size of the inflorescence, the flowers vary in abundance; they usually bloom at about the same time. Each flower is ¼" across, consisting of 5 narrow white petals, 5 green sepals that are joined together at the base, 10 stamens with white to orange-brown anthers, and 2 prominent pistils that are green and joined together. The sepals are triangular in shape and become recurved when the flowers bloom. The petals are longer than the sepals. The blooming period occurs during the late spring for 2-3 weeks. Each flower is replaced by a pair of beaked follicles; each follicle splits open along one side to release its seeds. The root system consists of a crown of fleshy fibrous roots and rhizomes. Clonal offsets from the rhizomes are often formed. Cultivation: The preference is light shade to partial sun, consistently moist conditions, high humidity, and thin rocky soil containing sandstone. The site should be protected from prevailing winds. Range & Habitat: The native Forbe's Saxifrage is found in southern Illinois (where it is uncommon) and 3 counties in northern Illinois, where it is rare; it is absent from the remaining areas of the state (see Distribution Map). This map excludes the distribution of the more common typical variety, Saxifraga pensylvanica pensylvanica (Swamp Saxifrage). Habitats are largely restricted to the lower slopes of rocky bluffs (usually north-facing), moist ledges along sandstone ravines, and the lower slopes of sandstone canyons, particularly where some seepage of moisture occurs. These habitats are always found in wooded areas with varying amounts of shade. Forbe's Saxifrage is restricted to high quality natural areas. Faunal Associations: The flowers are cross-pollinated primarily by small bees, wasps, and various flies. Less common visitors include sawflies and beetles. These insects usually suck nectar, although some of the bees also collect pollen, while some flies and beetles prefer to feed on the pollen. These observations are from Graenicher.
Photographic Location: Lower slope of a sandstone canyon at the Portland Arch in west-central Indiana. Comments: I have selected Vasey's taxonomic classification of Forbe's Saxifrage. This is something of a compromise. Some botanists in Illinois and Indiana (e.g., Mohlenbrock, 2002) classify Forbe's Saxifrage as a separate species, Saxifraga forbesii, rather than a variety of Saxifraga pensylvanica (Swamp Saxifrage). Other botanists don't recognize Forbe's Saxifrage at even the varietal level. Generally, Forbe's Saxifrage is supposed to have hairier basal leaves than Swamp Saxifrage, and the petals of its flowers are longer than the sepals. Swamp Saxifrage is supposed to have slightly smaller flowers, where the petals are about the same length as the sepals. Swamp Saxifrage is found primarily in the northern half of Illinois, where it is found in both sunny and shaded wetlands. The only other Saxifrage in Illinois is Saxifraga virginiensis (Early Saxifrage), which has been found only in Hardin County. This latter species is much smaller in size; it prefers drier upland areas and can bloom as early as mid-spring.
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Miss Chen
2018年05月22日
Miss Chen
Description: This herbaceous perennial plant is 1–2½' tall, branching occasionally. The stems are light green to pale red or purple, glabrous, and veined. The leaves are alternate, opposite, or basal. The basal and lower leaves are palmately divided into 5 leaflets; these compound leaves span up to 5" long and across, and their petioles are up to 6" long. The middle to upper leaves are trifoliate with 3 leaflets; they are smaller in size and usually sessile. The leaflets are up to 2½" long and 1" across; they are oblanceolate, elliptic, obovate, or ovate in shape. Each leaflet is shallowly cleft and coarsely serrated along the margins; the bottom of each leaflet is wedge-shaped and sessile. Both the leaves and their petioles (if any) are glabrous. Each upper stem terminates in 1-5 umbels of flowers. Each umbel is globoid or semi-globoid and spans up to ½" across; it consists of 20-60 tiny flowers and their pedicels. The stalk (or ray) of each umbel is up to 1" long. Each umbel has 1-3 perfect flowers (male & female reproductive organs), while the remaining flowers are staminate (male only). Whether perfect or staminate, each flower has a short green calyx with 5 ovate teeth, 5 greenish yellow petals that are obcordate in shape, and 5 exerted stamens with conspicuous anthers. The anthers are initially yellow, but they later become brown. In addition, each perfect flower has a bristly globoid ovary and a pair of long recurved styles. These styles are longer than the bristles of the ovary. The blooming period occurs from late spring to mid-summer and lasts about 2-3 weeks. Each bur-like fruit contains a pair of seeds. The root system is fibrous. Colonies often develop in favorable habitats. Cultivation: This plant is typically found in partial sun to medium shade, moist to slightly dry conditions, and fertile loamy soil. While the flowers are not very showy, it can be used as a ground cover in shaded areas. Range & Habitat: Common Black Snakeroot is occasional to common in most areas of Illinois (see Distribution Map), where it is native. Habitats include deciduous woodlands, areas along woodland paths, thickets, shaded seeps, and fence rows that are overgrown with woody vegetation. Sometimes this species invades shaded areas of gardens. Tolerance to degradation of woodland habitat is above average.
Faunal Associations: The nectar and pollen of the flowers attract small bees (Halictid & Andrenid) and various flies. White-Tailed Deer and other mammalian herbivores avoid consumption of the foliage because of its bitter taste. The small prickly fruits can cling to the fur of mammals, feathers of birds, and clothing of humans; this helps to distribute the seeds to new locations. Photographic Location: A mesic area of Busey Woods in Urbana, Illinois. Comments: Common Black Snakeroot can be distinguished from other Sanicula spp. (Black Snakeroots) by its greenish yellow flowers. Other Black Snakeroots have greenish white flowers. The recurved styles of Common Black Snakeroot are longer than the prickles of the ovary, while other Black Snakeroots have more erect styles that are shorter or the same length as the prickles of their ovaries. The common name (Black Snakeroot) probably refers to the pioneer belief that the bitter roots were useful in treating snake bites, although this is highly doubtful. Another scientific name of Common Black Snakeroot is Sanicula gregaria, which resulted in the common name, 'Clustered Black Snakeroot.'
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Miss Chen
2018年05月22日
Miss Chen
Description: This herbaceous plant is a biennial or short-lived perennial; it is about 1-2' tall, branching occasionally. The stems are glabrous and light green; they are terete or somewhat angular. The alternate leaves are usually trifoliate, although some of the smaller upper leaves are simple. The lower leaves often appear to be palmate with 5 leaflets, but this is because each lateral leaflet has been deeply divided into 2 large lobes. In outline, the lower compound leaves are nearly orbicular in outline (up to 5" wide and 5" across, excluding the petioles) while the upper compound leaves are more narrow. The leaflets and large lobes are obovate, ovate, or broadly elliptic in shape, while their margins are coarsely double-serrated and sometimes cleft along their margins. Leaf venation within each leaflet and lobe is pinnate. The upper leaf surface is yellowish green (in bright sunlight) to dark green (in shade) and glabrous. The lower leaves have long petioles, while those of the upper leaves are much shorter. These petioles are light green, glabrous, and slightly sheathed at their bases; they are grooved above and convex below. The upper stems terminate in small umbels or compound umbels of greenish white flowers. Each umbel consists of 1-4 umbellets and spans up to 2½" across. Each umbellet has 2-3 pistillate or perfect flowers and about 2-6 staminate flowers (less often, there will be 7-15 staminate flowers); these flowers form a tight cluster that is irregularly globular in shape. The perfect and pistillate flowers are more conspicous because of their bur-like ovaries. These ovaries are about 3-5 mm. in length, globoid-ovoid in shape, and green; their outer surfaces are covered with hooked prickles (about 1 mm. in length). Each flower has 5 greenish white petals and a green calyx with 5 linear-lanceolate lobes; these lobes are shorter than the prickles of the ovaries. The styles of perfect and pistillate flowers (less than 1 mm. in length) are also shorter than the prickles of the ovaries. Each staminate or perfect flower has 5 short stamens.
The blooming period occurs from late spring to mid-summer and lasts about 3 weeks for a colony of plants. There is no noticeable floral scent. Each bur-like fruit contains 2 seeds. The root system is fibrous. This plant spreads by reseeding itself and it occasionally forms colonies. Cultivation: The preference is light to medium shade, moist to slightly dry conditions, and a loamy soil with an abundance of organic matter. Range & Habitat: Canadian Black Snakeroot is a common plant that occurs in nearly all counties of Illinois (see Distribution Map), where it is native. Habitats include mesic deciduous woodlands, north-facing bluffs, areas along woodland paths, edges of shaded seeps, fence rows with woody vegetation, edges of yards underneath trees, and flower gardens in shady areas. This plant occurs in both natural habitats of varying quality and disturbed areas.
Faunal Associations: The flowers attract few insect pollinators, although occasionally they are visited by Halictid bees (Lasioglossum spp.), masked bees (Hylaeus spp.), and Syrphid flies, which suck nectar. An aphid, Aphis clydesmithi, sucks plant juices at the stem base and root collar, while another aphid, Aphis saniculae, sucks plant juices from the undersides of the leaves. Canadian Black Snakeroot is the preferred host plant of the latter aphid. The bitter foliage is avoided by grazing livestock and probably other mammalian herbivores as well. The small burry fruits cling readily to the feathers of birds, fur of mammals, and clothing of humans; this helps to distribute the seeds far and wide. Photographic Location: Underneath a lawn tree in Urbana, Illinois.
Comments: Canadian Black Snakeroot is not very showy, in part because it does not bloom until after the deciduous trees in woodlands have developed their leaves. Except for the bur-like ovaries, the flowers are inconspicuous. This species is well-adapted to the shady conditions that exist underneath trees during the summer, and it can become a minor weed along the edges of yards and in flower gardens. Except for Sanicula gregaria (Clustered Black Snakeroot), which has greenish yellow flowers, the various Sanicula spp. in Illinois have small greenish white flowers. The species of this latter group are rather difficult to distinguish. Canadian Black Snakeroot differs from Sanicula marilandica (Maryland Black Snakeroot) by its short styles, which are no longer than the prickles of its ovaries; the latter species has pairs of curved styles that are much longer than the prickles of its ovaries. Canadian Black Snakeroot differs from Sanicula trifoliata (Large-Fruited Black Snakeroot) by the size and shape of its burry fruits: The fruits of the former species are 3-5 mm. long and ovoid-globoid in shape, while the fruits of the latter species are at least 5.5 mm. in length and ovoid in shape. Furthermore, the calyx lobes of the latter species are as long or longer than the surrounding prickles, and its stamens are longer and more conspicuous than those Canadian Black Snakeroot.
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Miss Chen
2018年05月22日
Miss Chen
现在人们对植物的喜爱程度越来越高，几乎家家中都会摆放几盆，既可以装点环境，又可以净化空气。但在养殖过程中总会遇到各种病害。各类病害根据症状、发生发展规律的不同，防治的方法也有不同，现介绍花卉一些病害的识别及防治措施。
一、生理性病害 造成生理性病害的原因主要有：温度不适宜，光照不适宜，水分失调，营养条件不适宜，土壤盐分过多，有害气体和物质的危害，土壤酸碱度不适宜等都会影响花卉的正常生长发育，导致病害发生，因此，这类病害又叫非侵染性病害。它靠喷药是不能有效防治的。它在田间发病较普遍，没有发病中心，发病时间和部位也较一致，不具有传染性。生理性病害有个共性：即往往首先表现在嫩叶、新枝上，如叶片黄化、枯萎、凋落，根部腐烂、出现茎叶柔细易折断、倒伏等等生长不良的现象。 二、细菌性病害 由细菌引起的花卉病害。如防治不及时，常会造成毁灭性灾害。细菌性病害主要有条斑、斑点、渍斑、萎蔫及腐烂等类型。细菌性叶斑病一般表现为急性坏死斑，呈水渍状，病斑周围有一个黄色晕圈，如菊花、秋海棠的细菌性叶斑病。细菌性腐烂病有一种腥臭味，且腐烂组织带有黄色的菌脓，如百合软腐病，马蹄莲的腐烂病、软腐病。细菌性萎蔫病往往造成青枯（而真菌性萎蔫常伴有黄化），如菊花、大丽花的青枯病，香石竹的细菌性枯萎病，菊花的细菌性枯萎病，报春花的细菌性萎蔫病。　　　　　　　　　　　　　　　　　　
三、真菌性病害 花卉的绝大部分病害均是由真菌引起的。如菊花的霜霉病、天竺葵灰霉病、橡皮树炭疽病、桂花炭疽病、马蹄莲黑斑病、玫瑰霜霉病、鸡冠花褐斑病、郁金香疫病及各种花卉苗木的立枯病、猝倒病。真菌的菌丝体为营养体，无性和有性孢子为繁殖体，借助风、雨、昆虫或种苗、杂草传播，也可由土壤继代传播，通过花卉植物表皮的气孔、水孔、皮孔等自然孔口和各种伤口侵入植株体内。真菌病害常常造成植株腐烂、萎蔫、变色等症状，病症特别明显，用肉眼即可观察到病原体或其变态形式，如白粉、灰霉、黑霉、霜霉、小黑点、菌核等症状，真菌性坏死是真菌性病害最主要的症状之一。 四、病毒性病害 主要由病毒引起。花卉的病毒病多为全株性的慢性病，外部表现的症状常为花或叶褪缘、环斑、起泡、黄化、枯斑、丛斑、或叶片变细、皱缩及枝叶、花和果实畸形等。病毒病只有病状，没有病征，这与真菌性和细菌性病害不同。有些病毒病表现的症状易与非侵染性病害相混淆，区别之处在于，病毒病的发生具有明显的由点到面逐渐扩展的蔓延性，病株上出现的病状常从顶端开始，然后扩展到植株的其他部位。如菊科花卉的病毒病、金边瑞香病毒病、香石竹病毒病等。病毒病主要通过刺吸式口器的害虫如蚜虫、叶蝉、飞虱、木虱、蓟马等传播，也会通过土壤中的线虫和真菌、种苗和花粉传播；同时在花卉苗木的嫁接、管理过程中，病株与健株的接触，无性繁殖的穗、块茎、球茎、鳞茎等都可能是病毒病传播的机会，甚至在剪枝、切花时，人的手和工具都是传播的条件。 五、线虫病害 根结线虫病可危害多种花卉，如各种观赏番茄、观赏辣椒的根结线虫病、鸡冠花及菊科花卉的根结线虫病等。该病仅侵害植株根部，以侧根受害较重，在侧根上形成许多根结，互相连结成念珠状，根结常成球形或圆锥形，大小不等，表面生有许多须根，形成团状须根，剖开根结，可见到许多半透明的白色针尖大小的洋梨状的线虫，根结初期色浅，表面光滑较坚实，逐渐变为淡褐色、褐色、深褐色腐烂。线虫在瘤内吸食汁液，感病植株呈现营养不良、矮化、叶片小而皱、丛生，以后逐渐枯萎、根系坏死，造成叶枯、花落等后果。　　　　　　　　　　　　　　　　　 六、防治措施 防治花卉病害，主要应做好以下关键措施： 1.严格执行国家有关检疫法规，属于检疫对象的病害要严加防范，不能从有这种病害发生的区域（或国外）引进种、苗；购进种、苗时应仔细检查，如发现有检疫对象应坚决拒收、拒进，并作销毁处置，如烧毁、深埋等。 2.选用抗病品种。 比如同样的菊科花卉品种，也要作小面积的引种试验，有的应作接种鉴定和自然诱发鉴定，筛选出抗病性强的品种。 3.加强土壤和种苗的消毒处理。 特别是许多名贵花卉，不论是本土栽种，还是作盆栽，都要对土壤进行消毒处理，如喷洒高锰酸钾拌撒生石灰粉等处理措施。有条件的还应用多菌灵、五氯硝基苯进行消毒灭菌，前者按每平方米拌1.5克，也可按1：20的比例配成药土撒在苗床上；后者按每平方米圃地用五氯硝基苯4克、代森锌5克，混合后再与12千克细土拌匀。播种时下垫上盖对炭疽病、立枯病、猝倒病、菌核病有特效。种苗播种时可以用0.3％至0.5％的高锰酸钾溶液浸种0.5至1小时；也可用0.5％至1％的硫酸铜溶液浸种1至2小时后，冲洗沥干水后播种。 4.加强栽培管理。 一是大棚花卉要注意通风透光，即使严寒的冬季，每天中午也要揭侧膜或开窗，以降低棚内湿度，否则会诱发灰霉病、叶斑病、霜霉病、白粉病的大发生。光照强度应控制在适宜植株生长发育的程度。二是合理灌溉、滴灌、沟灌或给土面给水，防止灌溉水飞溅，将病原孢子或细菌带到健株上，可有效控制病害发生。不可让水分滞留在花瓣或叶面上，为病菌萌发侵入植株提供条件。土壤湿度太高则会造成各种根腐病原菌对根的危害。三是在移栽、整枝、摘心时尽量不造成伤口，为病菌提供侵入点。最好选晴天操作，以利伤口愈合，防止病原菌的侵入。在扦插时，应进行消毒，尽量避免通过手指及工具传播病菌。四是合理施肥。不偏施氮肥，适当增施磷钾肥，过多施用肥料反而会对植株造成肥害，甚至会造成植株黄化、生长不良。五是注意田间卫生。将病株、病叶、杂草摘除，并带离栽培场所销毁，可降低甚至完全清除场内病原菌密度，减轻发病，尤其是对防治细菌性病害、病毒性病害或枯萎病等系统性病害十分有效。 5.适时、适度进行药剂防治。可视病害种类、轻重等用保护剂、铲除剂、治疗剂等。 真菌性病害一般可以选用72.5％普力克水剂、15％粉锈宁可湿性粉剂、50％速克灵粉剂、64％杀毒矾可湿性粉剂、50％多菌灵可湿性粉剂等防治。细菌性病害一般可选用72％农用链霉素可湿性粉剂、77％可杀得可湿性粉剂、25％络氨铜水剂等防治。病毒性病害一般可用1.5％植病灵乳剂、20％病毒A可湿性粉剂、83增抗剂等药剂防治。防治根结线虫病可选择克线灵乳剂，或发病后用80％敌敌畏1000倍液浇灌花卉根际土壤，以杀死线虫。生理性病害不具有传染性，通过改善造成病害的环境条件，实施对症治疗，植株一般较易康复。
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