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Miss Chen
2018年05月26日
Miss Chen
美人蕉正如它的名字一样，它是一种很美的观花植物，叶似芭蕉、花朵儿似蝴蝶甚是娇艳而且花期还不短。 近几年各地庭园、路旁栽植的杂种美人蕉、株型矮壮、叶色墨绿，花色丰富，色彩鲜艳，深为人们喜爱。可是1998年深圳绿地大片发生毁灭性青枯病。各地每年损失近10万株，病区发病率20~30%，严重的成片死亡，影响景观。
病菌侵染植株的茎干和根系，流行期植株从染病到枯死一般10~15天。大多从根部感病，也有从茎干处侵入，病株地上部叶片失水变黄，萎蔫下垂，逐渐茎基或茎干出现黑色条斑，绕茎一周后整株枯死。横切坏死根或茎，几分钟后切面上有乳白色或黄褐色细菌粘液溢出，此即为病原细菌，是室外诊断青枯病的重要依据。若纵切茎干还可见条状黑褐色斑带。 发生规律： 病菌可存活于土壤、植株残体和垃圾混合物中，凡是种过花生、番茄、茄子、烟草、木麻黄、桉树、菊花、大丽花等染病植物的土壤，以及这些罹病植物的花、茎、根和叶的病残体接触过的土肥、水源都有可能存在和繁殖青枯病原细菌，若使用这些土壤、水肥培育美人蕉就会发生青枯病。病菌在土壤中可存活1年以上，干燥或水淹时仅能存活30天和90天。病菌主要从寄主伤口侵入，风雨损伤、昆虫蛀食、人为活动都会为病菌侵入创造机会。地表迳流，株间连根是小区间主要的传播途径。远距离传播靠带病的块茎繁殖材料。一般每年3月开始发病，6~10月发病严重，7~9月为高峰期。台风雨后，当大气温度在33~35℃，相对湿度80%以上时，若绿地积水，青枯病最易流行。
防治方法： 1.不要在病区取块茎作繁殖材料，严格检疫，发现批量带病种苗，应成批淘汰。 2.不要在发生过青枯病的土壤上种植美人蕉。若要施用土杂肥应先堆沤，充分腐熟，或每平方米用40％福尔马林50倍液6公斤淋洒后复盖薄膜消毒。 3.病害流行期不要中耕除草，避免损伤植株。发现病株立即拔除，挖去病土并在四周撒淋25%青枯灵400~600倍液或90%土、链霉素3000~4000倍液或硫磺粉剂。在病区台风过后最好淋撒上述药剂1次。 养殖注意事项： 充足的日照，美人蕉喜欢阳光的照射，每天要给予最少6个小时的日光照射，如果缺少阳光将导致花期延后，页面变黄等。 合适的温度，美人蕉喜欢温暖的天气，在10度以下将停止生长，零度时就会出现冻害，最适宜的温度在20-26度之间。在冬天时记得防止因天气过冷造成的冻害。 及时浇水，美人蕉喜湿润，所以平时要多浇水，特别是夏天天气较热，水分蒸发较快的情况下。但是在冬天和刚栽培的时候要少浇水。移栽第一次浇水时要浇透，平时保持盆图湿润即可，随着植株根茎生长，浇水量可逐步增加。 土壤及施肥，美人蕉对土壤不是很挑剔，但最好是疏松、排水良好的土质，另外还要土壤深厚。在种植之前要施足基肥，刚生长的前两个月适合每15天施一次肥料，之后每一个月施肥一次即可。
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文章
Miss Chen
2018年05月26日
Miss Chen
柑橘是一种常见的水果，几乎人人都吃过，柑橘树自生活中也比较常见。柑橘树是一种常绿小乔木，四季常青，枝叶整齐茂密，远远看去非常漂亮。春天香花满树开放，秋天黄果挂满枝头，让人垂涎欲滴。柑橘也是我国南方地区的重要经济水果之一，每年柑橘病虫害的发生，都会造成柑橘大幅度减产，果实的品质下降，给果农带来很大的经济损失。
1柑橘病害的综合防治 1.1农业防治农业防治是最基本、最经济、最安全的病虫害防治措施，是果树无公害病虫综合治理的基础。主要措施有：选用优良的抗病虫品种的脱毒苗木；合理密植和间作，保护天敌，保持生态平衡。及时清除病虫残体，中耕除草，摘除病虫果和虫苞，减少果园内外的病虫初次和再次侵染来源。加强栽培管理，合理施肥，采取果实套袋技术，提高果树对病虫害的抵抗能力。 1.2生物防治许多害虫有其自然的天敌，如食蚜蝇、草蛉、七星瓢虫等以蚜虫为食；赤眼蜂可控制卷叶虫、吹绵蚧；利用大红瓢虫可有效控制柑橘吹绵蚧。通过果园合理间作作物、种植绿肥及有益植物、改善果园生态环境，招引天敌，或人工饲养释放、引进天敌，增加天敌种群数量，恢复其自然控制力，充分利用天敌来杀灭柑橘病虫害。 1.3物理防治即根据果树害虫的习性，采取机械方法防治害虫。常用措施有： 1.3.1捕杀法。在害虫的某一个发育时期，对于有群居性又容易捕杀的害虫，抓住时机进行捕杀。 1.3.2阻隔法。设置屏障，防止幼虫和不善于飞行的成虫扩散、迁移。 1.3.3诱杀法。根据害虫的趋性，采取性引诱剂诱杀、糖醋液诱杀、频振式杀虫灯诱杀，降低虫口密度，减少化学防治次数。 1.4化学防治化学防治虽然具有作用迅速、效果显著、使用方便等优点，但长期广泛使用会使许多病虫产生抗药性，杀伤天敌，污染果品及其环境，对人们的健康和可持续发展造成威胁。因此，必须注意选择农药品种，改进技术。达到经济、有效、安全的目的。在使用化学方法防治柑橘病虫害时应注意：①严格执行农药品种的使用准则，禁用高毒、高残留、高致病农药，有节制地使用中毒低残留农药，优先采用低毒低残留或无污染农药。②科学使用农药。严格执行安全用药标准，通过对症下药、选择作用机理不同的几种农药，交替使用来提高防治效果。 2柑橘病害防治技术 2.1柑橘疮痂病病状：柑橘疮痂病又称“疥疮疤”、“癞头疤”、“麻壳”等，主要为害叶片、新梢和果实，尤其易侵染幼嫩组织。叶片染病，开始产生蜡黄色油渍状小斑点，然后病斑渐扩大、木栓化，形成灰白色至暗褐色圆锥状疮痂，病斑一面突出，一面凹陷。严重时病斑连片，导致叶片扭曲畸形。幼叶染病常干枯脱落；幼果染病，果面密生茶褐色疮痂，常早期脱落。 防治方法：对外来苗木实行严格检疫或将新苗木用50%多菌灵可湿性粉剂800倍液浸泡30min。当春芽长1～2mm时喷40%多菌灵胶悬剂600倍液或70%甲基硫菌灵超微可湿性粉剂1000倍液，等有2/3左右的花落掉后再喷上述杀菌剂，温带桔区于5月下旬至6月上旬补喷1次。 2.2柑橘溃疡病病状：主要为害叶片、果实和枝梢。叶片染病，初期在叶背产生黄色或暗黄绿色油渍状小斑点，然后叶面隆起，出现米黄色海绵状物。果实染病，与叶片上症状相似。高感品种枝梢也染病，初生圆形水渍状小点，后扩大，病斑木栓化，形成大而深的裂口。最后数个病斑融合形成黄褐色不规则形大斑，边缘明显。 防治方法：在无病区设置苗圃，对所用的苗木和接穗用72%农用链霉素可溶性粉剂1000倍液加1%酒精浸30～60min，或用0.3%硫酸亚铁浸泡10min进行消毒。落花后开始喷洒1∶1∶200倍式波尔多液或70%甲基硫菌灵超微可湿性粉剂1000倍液，幼龄树在春梢、夏梢、秋梢萌发后20d各再喷1次。 2.3柑橘炭疽病病状：柑橘炭疽病俗称爆皮病，叶片染病多发生在叶缘或叶端，病斑浅灰色，边缘褐色，呈不规则形或近圆形，直径0.2～1.4cm。枝梢染病始于叶柄基部腋芽处，病斑开始呈淡褐色，椭圆形至长梭形，病部环枝一周时，病部以上变成灰白色枯死并散生小黑点。大枝或主干染病，病斑长椭圆形或条状，果实染病上面常出现干斑或果腐。 防治方法：冬季清园时喷1次波美0.8～1度石硫合剂，在春梢、夏梢、秋梢及嫩叶期、幼果期喷0.5∶1∶100倍式波尔多液或80%炭疽福美可湿性粉剂800倍液。 2.4柑橘树脂病病状：柑橘树脂病又称砂皮病、蒂腐病。桔树染病后致枝叶凋萎或整株枯死。枝干染病时，表现流胶和干枯两种类型。 流胶型：病部初呈灰褐色水渍状，组织松软，皮层具细小裂缝，后流有褐色胶液，边缘皮层干枯或坏死翅起，使木质部裸露。 干枯型：皮层初呈红褐色、干枯稍凹陷，有裂缝、皮层不易脱落，发病部位和健康部位相接处有明显隆起界线，流胶不明显。发病树皮下有黑色小粒点。叶片染病，表面散生黑褐色硬质突起小点，有的很多密集成片，呈砂皮状。成熟果实染病，果蒂附近最初出现水渍状，并变软，后变深褐色波及到脐部，最终导致全果腐烂。 防治方法：剪除病枝，收集落叶，集中烧毁或深埋，刮除病枝或病干上病皮，病部伤口涂36%甲基硫菌灵悬浮剂100倍液，施药后再用无色透明的乙烯薄膜包扎伤口，结合防治炭疽病、疮痂病喷洒70%甲基硫菌灵超微可湿性粉剂1000倍液或60%防霉宝可湿性粉剂800倍液。
2.5柑橘脚腐病病状：柑橘脚腐病俗称“烂蔸巴”。主要为害根颈部，地上部也可受害。根颈部染病初期，病部褐色，有酒糟气味，流有胶液。严重的环绕整个树干，使柑橘树死亡。 防治方法：发现病树，及时将腐烂皮层刮除，并刮掉病部周围健全组织0.5～1cm，然后在切口处涂抹10%等量式波尔多液或2%～3%硫酸铜液。 2.6柑橘煤污病病状：柑橘煤污病又称煤烟病，主要为害叶片、枝梢及果实，初期仅在病部生一层暗褐色小霉点，然后逐渐扩大，直至形成绒毛状黑色或暗褐色霉层，并散生黑色小点。 防治方法：及时防治介壳虫、粉虱、蚜虫等刺吸式口器害虫，发病初期喷40%克菌丹可湿性粉剂400倍液或0.5∶1∶100倍式波尔多液。 2.7柑橘立枯病病状：柑橘立枯病有两种，一种是丝核菌引起的真菌病害，另一种是由拟细菌引起的立枯病。 丝核菌立枯病：茎部及根茎近地面处，一开始出现褐色水渍状斑块，后逐渐扩大，使病部缢缩或叶片自上向下萎蔫死亡，病部可见白色菌丝休，后期可见灰白色油菜籽状小菌核。 拟细菌立枯病：叶脉先黄化，后叶肉萎黄，病叶硬化向外卷，叶脉隆起或破坏，逐渐木栓化，造成落叶或枯梢，，新生叶细小，色淡萎黄，病株开花提前，但易落。果实小或畸形，树势弱，2～4年后枯萎死亡。 防治方法：合理轮作，避免连作，每平方米苗床施用25%甲霜灵可湿性粉剂9g＋70%代森锰锌可湿性粉剂1g对细土4～5kg拌匀，施药前打透底水，取1/3拌好的药土撒于地下，其余2/3药土覆在种子上面。发病初期喷20%甲基立枯磷乳油1200倍液或75%百菌清可湿性粉剂600倍液。对拟细菌引起的立枯病从两方面入手，一是喷洒25%扑虱灵可湿性粉剂1500倍液或50%抗蚜威超微可湿性粉剂3000倍液防治柑橘木虱。二是喷盐酸土霉素500～1000mg/L溶液。 2.8柑橘黑星病柑橘黑星病又称黑斑病。主要为害果实，也可为害叶片、枝梢。果实染病分为黑星型和黑斑型两种类型。 黑星型病状：病斑红褐色，圆形，直径1～6mm，后期病斑变成黑褐色，边缘隆起，中部凹陷，上面着生黑色小粒点，贮藏期继续扩展，发病部位易被腐生菌侵染引起腐烂。 黑斑型病状：病斑大，淡黄色或橙黄色，后渐变成暗褐色至黑褐色，圆形或不规则形，严重时病斑连片覆盖大部分果面。贮藏期，果肉变黑，腐烂。 防治方法：秋末冬初结合修剪，剪除病枝、病叶，并清除地上落叶、落果，集中销毁。同时喷洒1～2波美度石硫合剂，柑橘落花后喷洒0.5∶1∶100倍式波尔多液或50%多霉灵可湿性粉剂1500倍液，每隔15d喷1次，连续防治3～4次。 2.9柑橘黑腐病病状：主要为害果实。症状常因品种而稍有不同。温州蜜柑染病，果面近脐部变黄，看上去类似于成熟果，后发病部位变褐，呈水渍状，不断扩大，呈不规则形，四周紫褐色，中央色淡。宽皮桔类，病菌主要从脐部小孔或伤口侵入，致病部果皮呈水渍状，失去光泽，后变黄褐色，果心变墨绿色，具有霉状物。 防治方法：剪除过密枝条和枯枝，及时防虫，减少人为伤口和虫伤。发病初期喷洒75%百菌清可湿性粉剂600～800倍液或70%代森锰锌干悬粉500倍液。
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文章
Miss Chen
2018年05月26日
Miss Chen
榕树生长迅速，且寿命长，树冠大易成型，且虫害少，是良好的绿化树种。晋人嵇含在《南方草木》中写道：榕树……叶如木麻，实如冬青，树干攀曲，其阴十亩，故人以息焉；而又枝条目口繁、叶又茂细，软条如藤，垂下渐渐入地，藤稍人工，便生根节，或一大株，有根四五条，而横枝及邻树连理。可见榕树易栽，易活，易培养。 在300多种各类园林绿化、行道树中，榕树是人们常见与熟悉的树种，约占30%左右。近十年来，榕树更成为园林绿化的宠儿，随处都可看见它的倩影。
但榕树害虫却给您带来不愉快的心情。当您漫步在行人道上，抬头一望，榕树的叶片斑白缺刻、扭曲畸形，悬吊的毛虫更令您毛骨悚然。这都是榕树害虫所为。下面介绍几种榕树主要害虫的形态及防治方法： 一、灰白蚕蛾，属鳞翅目家蚕蛾科 形态与习性：成虫、幼虫外表与家蚕相似，但体形较小，成虫体灰褐色，前翅有4条暗褐色线纹，翅中央有半月形黑纹。幼虫体灰白色。卵扁园形，初呈黄色，后变淡黑色。蛹淡黄色，肾披白色丝织状物，以蛹越冬。广州1月底至2月初可见羽化成虫，卵产于枝干上或叶面和叶背上，呈双行排列，初孵幼虫在叶片上取食叶肉残留表皮，随着虫龄增大，幼虫沿叶缘取食，好似家蚕取食一样，幼虫有叶丝悬挂习性。 防治方法：由于行道树人流量大，应采用高效低毒、少污染、低臭味的药剂喷杀，掌握初孵幼虫用含100亿以上孢子/克的生物制剂杀螟杆菌1000倍液；或在幼虫孵化盛期用80%敌敌畏乳油1000倍液、90%敌百虫1000倍液喷杀，效果可达90%以上。
二、榕紫蝶，属鳞翅目斑蝶科 形态与习性：成虫翅长75mm体翅暗褐色，反光时呈现紫蓝色光彩，前翅外缘和亚外缘有两列白色斑点，翅反面的前后翅中室各有一白园斑点，环绕后翅中室也有5个白色斑点。卵为顶端球状的园柱形，表面具六边形的图案纹，黄色，近孵化时褐色。老熟幼虫头黑褐色，体背面具褐、白相间的环节，中、后胸和第2、8腹节各有1对紫色内质丝。蛹呈椭园状、光滑，表面具银色金属光彩并有褐色斑纹。该虫在广州4?11月均有发生为害。成虫多在白天活动，卵散产于叶面或叶背，初孵幼虫常将卵壳当第一餐，随后蚕食叶表皮，高龄幼虫沿叶缘咬食成缺刻，严重时把叶片吃光，除为害榕树外，还为害夹竹桃花卉。 防治方法：蛹悬挂于枝叶上易发现，可人工摘除集中消灭；低龄幼虫期及时用90%敌百虫1000倍液或80%敌敌畏乳油800倍液喷杀亦可用生物制剂，每克含活孢子100亿以上的青虫菌或苏云金杆菌兑水500?1000倍喷杀，每隔10?15天喷杀一次，连续三次。 三、透翅毒蛾，属鳞翅目、毒蛾科 形态与习性：雄成虫触角棕色，前翅透明，翅脉黑棕色，翅基黑褐色，后翅黑褐色，顶角透明；雌成虫触角淡黄色，前后翅淡黄色，前翅中室后缘散布褐色鳞片。卵赤色。幼虫暗色，第1?2腹节背面有茶褐色大毛丝，各节皆有3对赤色肉质隆起，丛生长毛，背线黄色，老熟幼虫水青色，雄背线为暗黑色。蛹略呈纺锤形，有红褐色斑。该虫在广州5?10月间发生，以5?6月最为普遍，为害最烈。幼虫咬食叶片，造成叶片残缺不全，严重影响生长。 防治方法：幼虫期喷90%敌百虫800倍液或兴棉宝3000倍液，亦可采用生物制剂苏云金杆菌和核型多角病毒以毒杀幼虫。 发生少量时可采用人工捕杀幼虫和蛹。 四、榕管蓟马，属缨翅目，管蓟马科 形态与习性：虫体黑褐色，头顶单眼区有锥状突起和六角形网纹，前翅透明，前后翅缘呈平行状，前足胫节黄色，中、后足胫节为褐色，腹部尾端管状，卵呈肾形乳白色。该虫在广州全年发生，最为普遍，为害严重。成虫、若虫均为害嫩叶和幼芽，受害叶子形成虫瘿，出现叶片、嫩梢卷缩畸形，害虫藏匿其中，受害部位颜色变为深紫红色。除为害榕树之外，亦为害杜鹃、龙船花等。 防治方法：发生高峰期喷2.5%鱼藤精300倍液；80%敌敌畏800倍或2.5%敌杀死乳油剂3000倍液喷杀，每隔7?10天一次，连续3次防效显著。
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Miss Chen
2018年05月26日
Miss Chen
听到发财树这个名字，男女老少都喜欢养，特别是做生意的人喜欢，还有很多公司开业的时候，都喜欢送发财树，毕竟发财树寓意是发财。发财树属于盆栽植物，其实不是很好养，随处可见被养死了的发财树，只有把发财树茂盛，才能够体现出发财树的价值和含义，下面来看看发财树在养殖过程中常见的病害都有哪些，该如何防治。
发财树常见的病害有根（茎）腐病与叶枯病。 一、根（茎）腐病这是一种严重危害发财树的常见病害，又称为腐烂病。 防治方法： （1）保持栽培环境的干爽，重视栽培介质及场地的消毒； （2）半成品出柜卸至操作棚后，即用速克灵喷洒发财树头部，以预防灰霉病菌的危害； （3）栽种前用利刀剪除主根顶部扭伤及腐烂组织，然后再用速克灵喷洒伤口，晾干后即栽植； （4）栽植一周后，盆中的介质渐干，愈合组织已形成，新根已开始长出，用普力克、安克或锌锰灭达乐（雷多米尔-锰锌）喷洒发财树光杆，以药液沿杆部流入盆土为宜。此后的杀菌剂以安克、土菌灵、雷多米尔或疫霜灵每周一次轮用； （5）若腐霉病菌活跃，则用普力克、土菌灵、雷多米尔或疫霜灵喷施，一般药效在两周左右。若天气仍然不好，须再用不同的药剂喷施，以防抗药性的产生。期间若发现有溃烂植株，应立即丢弃。
二、叶枯病防治方法： （1）发现病叶及时摘除，并销毁； （2）在发财树的栽培过程中应加强养护管理，适时浇水施肥，每个生长季节可追施肥2-3次叶面肥，如0.5%的氮磷酸二氢钾或双效微肥的200倍液； （3）苗木从南方向北方调运之前，叶面喷施保护性杀菌剂，如70%百菌清800倍液，或者18%多菌铜乳粉200倍液，或50%退菌特600倍液，运到北方后，应及时定植，加强肥水管理，防止脱水和脱肥。南方地区栽培发财树可从雨季开始，每隔10-15天喷施50%多菌灵800倍液，或70%百菌清800倍液，75%甲基托布津1500倍液。 另外，虫害主要有蔗扁蛾，该虫在我国是新纪录，主要是幼虫危害发财树，还可对一品红、福禄桐、鹅掌木、夏威夷椰子进行危害。
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Miss Chen
2018年05月25日
Miss Chen
Description: This perennial plant is 1-3' tall, branching occasionally in the upper half. The light green to reddish brown stems are usually glabrous; sometimes the central stem has sparse lines of hairs. The alternate leaves are up to 5" long and 3" across (excluding the petioles), becoming smaller as they ascend the stems; they are medium to dark green above and light to medium green below. The lower leaves are cordate, while the upper leaves are cordate-ovate or ovate; their margins are coarsely serrated. Leaf upper surfaces are glabrous, while their lower surfaces are either glabrous or there are hairs along the major veins. The narrow petioles of the leaves are about one-half to almost as long as their blades (up to 3½" in length); they are either unwinged or slightly winged, becoming shorter among the upper leaves. The upper stem terminates in a panicle of flowerheads about ½-1½' long. This panicle is longer than it is wide and it is more broad toward the bottom than the apex. When upper lateral stems are present, much smaller panicles may be produced. The central stalk, lateral branches, and peduncles of each panicle are light to medium green, terete, and glabrous to short-pubescent. Each small flowerhead is about ½" across, consisting of 7-15 ray florets that surround a similar number of disk florets. The petaloid rays of these flowerheads are lavender, light blue-violet, or less often white; they are linear-oblong in shape. The corollas of the disk florets are short-tubular in shape; these corollas are initially cream-colored or pale yellow, but they later become pale purple to reddish purple with age. The apices of these corollas are 5-lobed; these lobes are short and erect. The base of each flowerhead is surrounded by slender floral bracts (phyllaries) that overlap each other in several series. These scaly bracts are light green, except for diamond-shaped patches of dark green toward their tips; they are linear-lanceolate to narrowly lanceolate in shape and about 3-5 mm. in length. The peduncles of the flowerheads are short (less than ½" in length). Among the branches of each panicle, there are leafy bracts up to 1" long; they are elliptic or linear-oblong in shape. The blooming period occurs from late summer into the fall and lasts about 1-2 months. Afterwards, the florets are replaced by achenes with small tufts of white hair. Individual achenes are 2-3 mm. long and oblongoid-oblanceoloid in shape. The root system is fibrous and short-rhizomatous. This aster reproduces by reseeding itself and vegetatively through its rhizomes.
Cultivation: The preference is light shade or partial sun, moist to dry-mesic conditions, and soil that contains loam, clay-loam, or some rocky material. Occasionally the foliage is affected by powdery mildew and other kinds of disease organisms during the fall. During hot dry weather, the lower leaves may wilt and fall off. Plant size is variable depending on the fertility of the soil and moisture conditions. Plants that are grown in shade will produce smaller panicles of flowers than those that are grown in more sunlight. Range & Habitat: The native Blue Wood Aster occurs occasionally in scattered counties across Illinois (see Distribution Map). It is more common in the northern half of the state than in the southern half. Habitats include moist to dry deciduous woodlands, woodland borders, areas adjacent to woodland paths, thinly wooded bluffs, shaded areas along streambanks, and rocky wooded slopes. Some disturbance is beneficial in heavily wooded areas if it reduces excessive shade from overhead canopy trees or excessive competition from shrubs.
Faunal Associations: The nectar and pollen of the flowerheads attract many kinds of insects, including long-tongued bees, short-tongued bees, wasps, flies, butterflies, skippers, and beetles. Bees are particularly important pollinators of the flowers. Caterpillars of the butterflies Chlosyne nycteis (Silvery Checkerspot) and Phyciodes tharos (Pearl Crescent) feed on the foliage of asters (Symphyotrichum spp.), as do the caterpillars of many moth species (see Moth Table). Some moth caterpillars also feed on the flowers, developing seeds, stems, and roots. Other insects that feed on these plants include leaf beetles, the larvae of leaf-mining flies and fruit flies, plant bugs, stink bugs, lace bugs, aphids, and leafhoppers (see the Insect Table for a more complete listing of these species). Mammalian herbivores, including rabbits, groundhogs, deer, and livestock, browse on the foliage of asters occasionally. The Wild Turkey and Ruffed Grouse eat both the foliage and seeds to some extent. Photographic Location: A rocky woodland in west-central Indiana. The inflorescence is small because the photographed plant was growing in a dry upland area of a shady woodland.
Comments: In Illinois, the Blue Wood Aster (Symphyotrichum cordifolium) often hybridizes with Arrow-Leaved Aster (Symphyotrichum sagittifolium) and Drummond's Aster (Symphyotrichum drummondii), which can make the identification of some field specimens from this aster complex very difficult. The Blue Wood Aster can be distinguished from both Arrow-Leaved Aster and Drummond's Aster by its narrow petioles; the petioles of the latter two species are conspicuously winged with narrow green margins. Unlike Drummond's Aster, the Blue Wood Aster has stems and leaf undersides that are hairless or they have lines of hair; the stems and leaf undersides of Drummond's Aster are evenly pubescent. Some authorities consider the preceding species of asters to be varieties of each other, in which case the Blue Wood Aster is the typical variety, Symphyotrichum cordifolium cordifolium. Another woodland species, Short's Aster (Symphyotrichum shortii), is also similar to Blue Wood Aster in appearance, but Short's Aster has larger flowerheads (¾–1" across) and its leaves are smooth to slightly serrated along their margins. Another common name of Symphyotrichum cordifolium is Heart-Leaved Aster. A scientific synonym of this aster is Aster cordifolius.
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Miss Chen
2018年05月25日
Miss Chen
Description: This herbaceous perennial plant is 1-1½' tall, consisting of both basal leaves and a flowering stem with a pair of opposite leaves. The erect to ascending stem is light green, terete, and conspicuously hairy. Both types of leaves are up to 6" long and 4" across (excluding the petioles); they are bipinnatifid, consisting of 1-3 pairs of primary lateral lobes and a primary terminal lobe. The primary lateral lobes are up to 2" long and 1" across, while the primary terminal lobe is up to 2" long and 2" across. Both types of lobes have shallow to moderately deep secondary lobes with rounded tips. For mature leaves, the upper leaf surface is yellowish green to dark green and glabrous, while the lower leaf surface is pale green and pubescent to hairy. Immature leaves may have short appressed hairs on their upper surfaces. The petioles of the leaves are up to 4" long and sparsely hairy. There is little difference in the appearance of the basal and opposite leaves, although the latter have shorter petioles. The foliage contains a yellow-orange sap. The upper stem terminates in either an individual flower or an umbel of 2-4 flowers. Each flower is about 1¼-2¼" across, consisting of 4 yellow petals, 2 early-deciduous sepals, numerous stamens with golden yellow anthers, and a pistil with a single stout style and knobby stigma. The petals are orbicular-obovate in shape, while the sepals are light green and very hairy. The ovary of the pistil is ¼-½" in length, narrowly ovoid in shape, more or less yellow, and finely hairy. The pedicels are ¼-2" long, light green, hairy, and terete; they are ascending to erect while the flowers are in bloom. The blooming period occurs from mid- to late spring, lasting about 2-3 weeks. In the absence of insect pollination, the flowers can self-pollinate. Shortly afterward, the flowers are replaced by ovoid seed capsules about ¾-1" long that nod from their pedicels; these capsules are 4-segmented and densely hairy. Numerous seeds are released after each capsule splits apart. They are dark brown and about 1.5 mm. in diameter; there is a white fringe of oil bodies (elaisomes) along one side of each seed. The root system consists of a woody caudex with coarse fibrous roots.
Cultivation: The Celandine Poppy should be grown in dappled sunlight underneath a tree, or along the foundation of a building in partial shade. It adapts best to rich loamy soil and moist to mesic conditions. Most vegetative growth and development occurs during the spring before the trees fully leaf out. This plant adapts to flower gardens readily. Range & Habitat: The native Celandine Poppy is an uncommon plant that occurs primarily in southern Illinois; it has also been observed in Vermilion and Cook counties further to the north (see Distribution Map). Habitats include mesic deciduous woodlands, lower slopes of ravines, bases and lower slopes of bluffs, and rocky banks of streams. The Celandine Poppy is found in high quality woodlands; it is one of the woodland wildflowers that is threatened by the invasion of Alliaria petiolata (Garlic Mustard) and Microstegium vimineum (Japanese Stiltgrass).
Faunal Associations: Little is known about the floral-faunal relationships for this species. The flowers provide only pollen as a reward to floral visitors. MacRae (1991) has observed adults of some metallic wood-boring beetles (Acmaeodera spp.) visiting the flowers. It is also likely that the flowers are visited by various bees and flies. The seeds are distributed to new locations by ants, which are attracted to their oily appendages (elaisomes). Woodland mice eat the seeds. The toxic foliage is avoided by mammalian herbivores. Photographic Location: A flower garden in Urbana, Illinois.
Comments: The Celandine Poppy has attractive flowers and foliage. It resembles another species of the Poppy family, Celandine (Chelidonium majus), but the latter has yellow flowers that are smaller in size (¾" across or less) and its seed capsules are hairless, narrowly cylindrical, and erect. Celandine is a somewhat weedy species that was introduced from Europe; it is a biennial that blooms during the summer. Other species of the Poppy family in Illinois have flowers that are white, pink, orange-red, or purplish red. Most of these species have been introduced from Eurasia, although one of them, Bloodroot (Sanguinaria canadensis) is native to Illinois. Another common name of Stylophorum diphyllum is the Wood Poppy.
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Miss Chen
2018年05月25日
Miss Chen
Description: This perennial wildflower is about 6-12" tall and unbranched, or sparingly so. Both fertile and infertile shoots are produced; the latter develop later in the year and don't produce flowers. The central stem is light green to pale purplish green and glabrous to moderately pubescent. The opposite leaves are up to 3" long and 1¼" across; they are ovate, lanceolate, oblanceolate, elliptic, or broadly oblong. The upper surface of these leaves is medium to dark green and finely pubescent (sometimes sparsely); their margins are smooth (entire) and ciliate. The leaf bases are sessile or nearly sessile, while their tips are either acute or blunt; lower leaves are more likely to have short petioles and blunt tips than upper leaves. The central stem of each fertile shoot produces a terminal cyme of flowers; occasional individual flowers may develop from the axils of the upper leaves. Each flower is about ½" across, consisting of 5 green sepals, 5 white petals (looking like 10 petals, because each petal is deeply bifurcated), a white ovary with 3 styles at its apex, and 10 stamens with reddish brown anthers. The petals are about the same length or a little longer than the sepals. Each sepal is lanceolate to ovate and pubescent. The pedicel of each flower is up to 1" long and pubescent. The blooming period occurs from mid- to late spring and lasts about a month. Each flower is replaced by an ovoid capsule that is open at its apex; it has 6 curved teeth around its upper rim. Each capsule contains many small seeds that are globoid, somewhat flattened, and minutely warty. Each seed is often slightly notched on one side. The root system consists of a taproot with slender fibrous roots. Small colonies of plants are occasionally formed.
Cultivation: The preference is dappled sunlight to light shade during the spring, followed by light to medium shade. The soil should be well-drained but consistently moist, with an abundance of organic matter and a layer of decaying leaves. It should also be somewhat acidic. Shallow rocky ground and slopes help to reduce competition from taller plants. Range & Habitat: The native Star Chickweed is a rare plant in Illinois, where it is state-listed as 'endangered.' It has been found in Pope County of southern Illinois, and a few counties in NE Illinois (see Distribution Map). Illinois lies at the NW corner of the range for this species. It is more common in the southern half of Indiana and other states. Habitats include edges of rocky meadows, rocky wooded slopes, wooded bluffs, and the upper slopes of sandstone ravines. Outside of Illinois, another typical habitat is rich mesic woodlands. This conservative species is found in high quality woodlands, especially where sandstone is close to the ground surface.
Faunal Associations: The flowers of Star Chickweed attract cuckoo bees (Nomada spp.), mason bees (Osmia spp.), Halictid bees (Augochlorella spp., Lasioglossum spp.), Andrenid bees (Andrena spp.), the Giant Bee Fly (Bombylius major), Syrphid flies, and other miscellaneous flies. Butterflies and skippers are rare visitors of the flowers. These insects are attracted primarily to the nectar of the flowers, although some of the bees collect pollen for their larvae and some of the flies feed on pollen as adults. Insects that feed on Stellaria spp., including possibly this chickweed, are the aphid Abstrusomyzus phloxae, the Pale Tortoise Beetle (Cassida flaveola), and caterpillars of a moth, Lobocleta ossularia (Drab Brown Wave). Information about this chickweed's ecological relationships with vertebrate animals is currently unavailable. Photographic Location: The edge of a rocky meadow and the wooded upper slope of a sandstone ravine at Shades State Park in west-central Indiana.
Comments: Of all the chickweeds (whether native or introduced), Star Chickweed is arguably the most attractive. It's a pity that this species isn't more common in Illinois. The only other chickweed in Illinois that resembles it is Myosoton aquaticum (Water Chickweed), which is native to Eurasia. This latter species can become larger in size than Star Chickweed, and its leaves are usually more broad toward their bases. Even more importantly, the flowers of Water Chickweed have 5 styles and its seed capsules have 5 teeth. In contrast, Star Chickweed has flowers with 3 styles and seed capsules with 6 teeth. Water Chickweed, as its common name suggests, also prefers damp water-logged habitats, such as roadside ditches and low areas along rivers. Other common names of Stellaria pubera are Giant Chickweed and Great Chickweed; these names sometimes refer to Myosoton aquaticum as well.
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Miss Chen
2018年05月25日
Miss Chen
Spike of FlowersDescription: This perennial wildflower is 3-12" tall, consisting of an unbranched flowering stalk, 1-2 basal leaves, and a few alternate leaves. Usually, individual plants are less than 7" tall. The basal leaves are 1-6" long and ¼-¾" across; they are lanceolate, oblanceolate, or elliptic in shape, while their margins are smooth. The alternate leaves are located along the lower half of the flowering stalk; they are often bladeless and sheath-like, but sometimes there are blades ¾-2½" long and about ¼" across. When alternate blades are present, they are narrowly lanceolate, oblanceolate, or elliptic, and their margins are smooth. Both basal and alternate leaves are medium to dark green and glabrous. The erect central stalk is medium to dark green, terete, and relatively narrow; it is glabrous below, becoming short-pubescent and glandular above. This stalk terminates in a spike of flowers about ¾-4" long. The flowers of each spike are densely arranged into 3-ranks (a double spiral). Each flower has 6 white tepals, a green ovary, and other reproductive organs. The tepals form a tubular corolla about 4-5 mm. long that is slightly curved and nodding. The corolla has an upper hood consisting of 3 fused tepals, a lower lip consisting of a single tepal, and 2 lateral tepals. As each flower develops, the lateral tepals become free toward the base and extend along the sides of the corolla. The lower lip extends to about the same length, or slightly beyond the hood. This lip is somewhat recurved, narrowly oval in shape, and its margins are slightly undulate and crisped. At the base of the lip, there is a pair of slender curved callosities (resembling minute claw-like extensions). The interior of the corolla is usually white, otherwise it is pale cream. The ovary is medium green, ovoid-oblongoid in shape, usually short-pubescent, and about 4-5 mm. long (although it becomes larger after the blooming period). Partially obscuring the ovary, there is a green bract (about 5-8 mm. in length) that is lanceolate-elliptic, short-pubescent, and glandular. The blooming period occurs during the early fall, sometimes extending into mid-fall. The flowers bloom from the bottom to the top of the raceme. Afterwards, the seed capsules develop, becoming about the same length as the bracts; they are sessile and ovoid-oblongoid in shape. Eventually, these capsules release numerous minute seeds that are carried aloft by air currents. The root system consists of a few roots that are fleshy and fibrous. Cultivation: The preference is dappled sunlight to light shade, moist to mesic conditions that are well-drained, and soil containing loam or clay-loam with some decaying organic matter. In addition to these requirements, appropriate strains of a fungus or fungi should be present in the soil that can form a symbiotic association with the root system.
Range & Habitat: The native Lesser Ladies' Tresses has been found mostly in southern and central Illinois, where it is uncommon (see Distribution Map). However, this species appears to be slowly spreading into other parts of the state. Habitats include moist to mesic woodlands, rocky upland woodlands, open woodlands, areas along paths in woodlands, edges of swamps, and semi-shaded areas along abandoned fields. Lesser Ladies' Tresses appears to flourish when disturbance reduces competition from shrubs, trees, and tall vegetation. Such disturbance may be related to fire, wind storms, or human actions. In the wooded habitats where this wildflower occurs, the dominant trees are deciduous. Faunal Associations: Various kinds of bees visit the flowers of Spiranthes spp. (Ladies' Tresses Orchids) for nectar, including bumblebees, Halictid bees, leaf-cutter bees (Megachile spp.), and little carpenter bees (Ceratina spp.). The foliage and flowers are browsed occasionally by mammalian herbivores, including the White-Tailed Deer, Cottontail Rabbit, and Groundhog. Because of its small size and inconspicuous nature, Lesser Ladies' Tresses can be overlooked by these herbivores, however. Photographic Location: In a wooded area of a park in Champaign County, Illinois. Comments: There are two varieties of Lesser Ladies' Tresses. The typical variety requires cross-pollination by insects to produce fertile seeds; it is found in several southern states. The other variety, Spiranthes ovalis erostella, has a more northern distribution that includes Illinois. This latter variety lacks some of the reproductive structures (specifically, the rostellum and viscidium) that prevent self-pollination. Therefore, in the absence of cross-pollination by insects, this variety of Lesser Ladies' Tresses is capable of self-pollination, increasing the likelihood that seeds will be produced. Lesser Ladies' Tresses can be distinguished from other Spiranthes spp. (Lady Tresses' Orchids) by its small size (typically 3-6" tall), small flowers (tepals less than 6 mm. long), and narrow flowering stalks. In particular, the base of the lower lip of each flower has a pair of slender curved callosities (resembling minute claw-like extensions) that are distinct for this species. In contrast, the callosities of a more common species, Spiranthes cernua (Nodding Ladies' Tresses), resemble a pair of wart-like protuberances at the base of the lower lip of each flower. This distinction usually requires a 10x hand lens to see.
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Miss Chen
2018年05月25日
Miss Chen
Description: This perennial wildflower is about 1-2¼' tall, consisting of loose clumps of unbranched leafy stems that are more or less erect. The central stem of each plant is medium green, slender, terete, and glabrous; it has a pair of longitudinal wings (about 0.5 mm. in length). At intervals, pairs of opposite sessile leaves occur at intervals along each stem. These leaves are 2-4" long and 1-2½" across; they are ovate-cordate, ovate, or lanceolate in shape and their margins are smooth (entire). The upper leaf surface is dark green and glabrous, while the lower leaf surface is medium green and either glabrous or pubescent along the veins. Leaf venation is pinnate; the lateral veins are curved, rather than straight. Above the uppermost pair of leaves, there occurs a spike-like raceme of flowers on a peduncle about 2" long. This raceme is about 1-4" long and curves to one side; about 2-10 flowers occur along the upper side of the raceme, where they are ascending to erect. Each flower is about 1½" long, consisting of a scarlet tubular corolla with 5 upper yellow lobes, a short green calyx with 5 narrow teeth, 5 slightly exerted stamens, and a pistil with a strongly exerted style. The tubular corolla is more narrow toward the bottom than the top; its upper lobes are slightly recurved, widely spreading to ascending, triangular in shape, and about 8-12 mm. in length. The teeth of the calyx are 5-8 mm. long and narrowly linear-lanceolate in shape. The base of the calyx is tubular and very short. The short pedicels of the flowers are up to 2.0 mm. in length. The blooming period occurs from late spring to early summer (rarely later), lasting about 1 month. There is no noticeable floral scent. Afterwards, the flowers are replaced by 2-celled seed capsules that are 4-6 mm. tall and 6-10 mm. across at maturity. Each cell of the capsule contains a few seeds. Later in the summer, these capsules split open to discharge their seeds explosively. The root system is fibrous and rhizomatous. Clonal offsets often develop from the rhizomes. Cultivation: The preference is partial sun to light shade, moist conditions, and a fertile loam with abundant organic matter. This plant can be propagated from stem cuttings (dipped in growth hormone) or by division of the root system. Seeds should be planted in the ground as soon as possible. Insect pests and disease organisms rarely bother the foliage. Indian Pink can be cultivated in areas that are north of its natural range (in Zones 4 or 5). Range & Habitat: The native Indian Pink is occasional in southern Illinois, while in the rest of the state it is absent (see Distribution Map). Illinois lies along the northern range-limit of this species. Habitats include bottomland woodlands, wooded areas along streams, and edges of swamps. This wildflower is found in high quality natural areas.
Faunal Associations: Ruby-throated Hummingbirds cross-pollinate the flowers, from which they receive nectar. Aside from this, little is known about floral-faunal relationships for this species. The foliage and roots of Indian Pink are usually avoided by mammalian herbivores because of their toxicity from alkaloids and calcium oxalate crystals. However, White-tailed Deer may browse on the foliage sparingly in some areas. Photographic Location: A bottomland woodland in southern Illinois. Comments: Indian Pink has attractive flowers with striking colors. It is the only member of the Logania family (Loganiaceae) that is native to Illinois. Once the distinctive flowers are in bloom, it is very easy to identify this plant. In the past, the roots of Indian Pink were used as a vermifuge (to expel intestinal worms), however this practice has been largely discontinued because of the potentially dangerous side-effects. Other common names of this plant are Pinkroot and Worm-Grass.
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Miss Chen
2018年05月25日
Miss Chen
叶斑病菌在病残体或随之到地表层越冬，翌年发病期随风、雨传播侵染寄主。鸡冠 花褐斑病夏秋（8-9月）病重，鱼尾葵叶斑病夏季高温病重，君子兰叶斑病春、秋发生， 但温室中四季均可发生。连作、过度密植、通风不良、湿度过大均有利于发病。今天要为大家介绍的是芭蕉叶斑病。
芭蕉叶斑病常见的有两种，即黄条叶斑病和黑条叶斑病。近两年来，时有发生，芭蕉叶片受害面积常占叶片总面积的20％～40％，严重时达80％以上，病株的大多数叶片干枯死亡。 　 一、病症 黄条叶斑病发病初期是在植株顶部第三或第四片嫩叶上表面出现细小的黄绿色病纹，病纹与叶脉平行纵向扩展，形成黄绿色或黄色条纹，之后条纹再扩展形成暗色斑块，出现水渍状，中央变褐色或锈红色，边缘有黄色晕圈环绕，以后斑块或条纹的中央组织干枯。发病严重时，多个病斑或条纹相互融合，周围组织坏死，叶片大面积变黑干枯和迅速死亡。 黑条叶斑病初时出现在完全展开的第三或第四片嫩叶下表面的叶脉间，有细小的褪绿色斑点。斑点扩展成锈褐色条纹，随后颜色加深，变成暗红色、褐色或黑色。严重受害叶片，病斑或条纹融合，造成大面积叶肉组织毁坏，变成黑色和水渍状，最后病叶迅速死亡、干枯、下垂，倒挂在假茎上。 叶斑病属真菌性病害，在高温高湿的天气条件下易发生流行，尤其是台风暴雨后，叶片造成伤口多，发病更为严重。以密植、不除吸芽、土壤排水不良、蕉园四周杂草丛生、管理不周、偏施氮肥、通风条件差的蕉园发病最为常见。
二、防治方法 1、加强肥水管理：增施有机肥和磷钾肥，避免偏施氮肥，促使植株生长健壮。同时在香蕉新叶抽出展开时，用核苷酸、高美施、喷施宝或磷酸二氢钾进行根外喷施，增强树势，提高其抗病能力。 2、注重蕉园护理：及时挖通蕉田排灌沟，做到能排能灌；清除园内杂草，挖除多余吸芽，降低蕉园湿度，保持畦面干爽湿润，以利生长，减少发病。 3、清理病叶枯叶：对发病较重的植株，及时剪除植株上的重病叶片和枯死叶片，清除地面的病残叶，搬出园外烧毁，减少菌源，使果园通风透光，降低湿度，减轻危害。 4、适时喷药防治：在发病初期、清除病叶后以及大风暴雨后及时用药防治，每隔7～10天喷1次，连续喷3次。防治药剂可选64％杀毒矾800倍液、70％代森锰锌700倍液、77％可杀得1000倍液、25％必扑尔1000倍液等，以上药剂要交替使用，避色产生抗药性，提高防效。
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