Several fungal diseases attack lawn grasses. Following is a short description of the most common diseases to help you sort out which one may be causing your problem. The diseases have been categorized as patches (cause dead spots or patches in the lawn), rings (cause rings of dead or affected grass), or leaf blight (affect individual blades of grass, often over a wide area and no distinct patch or ring pattern may be noticeable). Since most grass diseases affect leaves, patches and rings describe certain diseases in more advanced stages of development.[图片]Result in Dead Spots or Patches BROWN PATCH (Rhizoctonia solani) Round patches of turf up to several feet in diameter appear watersoaked and eventually turn brown. Dark gray smoke ring is sometimes visible on lower mowed turf. DOLLAR SPOT (Moellerodiscus spp. & Lanzia spp. or Sclerotinia homeocarpa) Rounded, straw-colored, slightly sunken patches up to 2 inches in diameter on bentgrass greens, 4–6 inches in diameter on other lawns. Spots have a reddish margin and expand until they girdle the leaf blade. Cottony mycelium may be evident in the morning growing over dead tissue.[图片]RED THREAD (Laetisaria fuciformis) Pinkish patches from 3 to 15 inches in diameter develop during rainy weather. The grass in the patches is pink and dead and contains coral-red masses of mycelium. The disease is more common in fescues and grows best from 60 to 70 degrees F. SNOW MOLD (Gerlachia nivalis and Typhula spp.) Grayish white patches up to 3 feet in diameter. Grass blades are collapsed and matted. Several different fungi are responsible for snow mold disease. Dead areas appear in the turf after the snow has melted. PYTHIUM (Pythium spp.) Rounded sunken patches up to 1 foot in diameter. Leaves appear water-soaked and shiny at first, turning tan when dry. White mycelium grows over all leaf tissue, not just dead tissue as in dollar spot.[图片]Result in a Ring in the Lawn FAIRY RING (Marasmius oreades and others) Dark green ring with lighter green center, 2 ft to 100 ft in diameter. A mycelium starts in one spot and spreads in all directions. At certain times of the year, the fruiting bodies, mushrooms, may develop near the outer borders of the year’s growth of mycelium. The grass within the ring may appear to be healthy but later may collapse and die. NECROTIC RING SPOT (Leptosphaeria korrae) 1–3 patches of red or purple leaves that bleach with water stress. Many patches grow greater than 12 inches in diameter with weeds or resistant grasses forming frog-eyes in the center of the ring.[图片]SUMMER PATCH (Magnaporthe poae) Small tan or straw-colored spots appear on the leaves in early summer. These spots enlarge and coalesce until large areas of the lawn are killed. This disease is active only during the warmest part of the summer. Affects Scattered Leaves POWDERY MILDEW (Erysiphe graminis) Powdery mildew appears as dirty spots or blotches on the leaf sheaths, varying in color from light gray to brownish. It is especially prone to develop in wet weather and on poorly drained lawns. The infection spreads by the numerous white spores, which form on infected leaves.[图片]LEAF SPOTS (also called Melting out, various organisms) Many grasses are affected by leaf spot diseases. General symptoms include tan or strawcolored spots on leaves usually bordered by a darker color. Black spore-producing structures may be seen in the center of the spots of some diseases. RUST (Puccinia graminis var. agrostis) The disease appears as small, reddish spots on the leaves. Merion bluegrass, a special strain of Kentucky bluegrass, is very susceptible to this disease.[图片]ANTHRACNOSE (Colletotrichum graminicola). This disease is common on creeping bentgrass and annual bluegrass. The fungus causes individual grass blades and/or plants to yellow and die when it invades crown and root tissue. Black, hairy, and spiny fruiting bodies are abundantly produced on dead tissue but may also be seen on green leaves as well.

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#菊潜叶蝇 分布与危害 菊潜叶蝇学名Phytomyza syngenesiae Hardy属于双翅目，潜叶蝇科。在我国南方、北方均有发生。主要为害菊花及菊科杂草等。该虫食性杂。 主要以幼虫潜入叶肉钻蛀为害，潜道纵横交错。造成叶肉被吃光，引起叶片枯萎。雌虫用产卵器刺破叶组织产卵，及雌雄成虫吸食叶片汁液，使叶片造成许多白点。 形态特征 成虫形似小苍蝇，雌成虫体长约2-3毫米，翅展6.3-7.0毫米。雄虫略小，体灰色至灰黑色，复眼红褐色。翅一对，透明，有紫色闪光。足黑色，腿节端部黄色。雌虫有漆黑色粗壮产卵器；雄虫腹末有1对抱握器。 卵长约0.3毫米，椭圆形，灰白色，略透明。 幼虫长圆筒形，长3.2-3.5毫米，蛆状；老龄幼虫体黄白色或鲜黄色。 蛹长约2毫米，纺锤形，羽化前黑褐色。 发生规律 该虫在南方年发生10代，在北方是以蛹越冬，江、浙一代越冬虫态不固定。在浙江杭州3月下旬可见成虫，4-5月为发生盛期，为害严重。夏季发生较少，秋季虫口回升，数量不多。成虫羽化后1-2天交尾产卵。一般江卵产在叶背近边缘处，幼虫孵化后即可取食。幼虫期共3龄，在气温为20度下，完成一代需14天。 防治方法 (1)加强栽培管理，在菊花凋谢后，将植株上部剪除并烧毁，发现受害叶及时摘除。附近有豆科、十字花科、菊科杂草要及时清除，减少虫源。 (2)保护和利用天敌。 (3)化学防治 在幼虫潜叶为害初期及时喷洒10％吡虫啉可湿性粉剂（ 毙克）1000倍液、5.7%甲维盐（乐克）乳油2500-3000倍液 ,40%啶虫.毒（必治）1500-2000倍液 可连用1-2次，间隔7-10天 。

#金盏菊中金弧夜蛾 相关图片 [图片]分布与危害 在我国河南及华东等地有均有分布。寄主有金盏菊、菊花、翠菊、大丽菊、蓟等。 该虫主要是以幼虫吸食叶片为害，影响植株的生长发育。进而影响经济发展。 形态特征 成虫体长17毫米，翅展37—42毫米。头、前中胸部红褐色，后胸褐色。腹部黄白色。前翅紫褐色，有大的金色近三角形斑。 老熟幼虫长40毫米。头部小，胴部黄绿色。腹部第五至八节较粗，逐渐向前方缩小。步曲行走。 发生规律 该虫1年生2—3代。以蛹在寄主上越冬。4-5月羽化为成虫。成虫有趋光性。6-11月均可见到幼虫虫为害，以7-8月为害最烈。幼虫老熟卷叶筑一薄茧化蛹其中。 防治方法 （1）根据成虫有趋光性，可用黑光灯诱杀。 （2）在幼虫少量发生时，可用人工捕捉；也可用800~1000倍液50%杀螟松消灭虫害。 （3）化学防治 在低龄幼虫期，可喷雾50%丙溴辛硫磷乳油（如国光依它）1000-1500倍液，或20%氰戊菊酯乳油（如国光乙刻）2000倍液，40%啶虫毒乳油（如国光必治）1500-2000倍液进行防治，重点喷淋害虫危害部位 ，喷药时药液尽量接触虫体，连用2次，间隔5-7天。

#菊姬尽管蚜 分布与危害 菊姬长管蚜又名菊小长管蚜，是菊花生产中的一种重要害虫。 危害症状：以若蚜、成蚜危害菊花，群集危害幼茎嫩叶，有的在叶背为害，使叶片卷缩，影响茎叶正常生长发育。开花前，还可群集为害花梗，影响开花。到秋后第二次盛发期群集危害花梗、花蕾，开花后还危害花蕊，并进入管状花瓣，严重影响花的质量和观赏价值。该虫分泌物还易诱发煤污病的发生。严重为害时，植株矮化或死亡。 形态特征 无翅胎生雌蚜体深红褐色，长2.0-2.5毫米；触角、腹管和尾片暗褐色；腹管圆筒形，末端渐细，表面呈网眼状。尾片圆锥形，表面有齿状颗粒，并长有11-15根毛。 有翅胎生雌蚜体暗红褐色，具翅一对。腹部斑纹较无翅型显著；腹管、尾片形状同无翅型，尾片毛9-12根。 若蚜体赤褐色。体态似无翅成蚜。 发生规律 菊小长管蚜每年发生10~20代，以无翅胎生雌蚜在留种菊花的叶腋和芽旁越冬。在温暖地区不发生有性蚜，北方寒冷地区冬季在温室或暖房中越冬。到三月初即开始活动繁殖。4月中旬至5月中旬为繁殖盛期，5月上旬有翅蚜开始上升，5月中旬至为有翅蚜盛发期，6月下旬至7月下旬田间的虫口密度较低，8月初开始回升。9月中旬到10月下旬为第二次繁殖盛期，虫口密度出现第二个峰值。从11月中旬起以无翅孤生雌蚜集中向留种株或菊茬上越冬。当平均温度为20℃、相对湿度65%-70%时，完成一代历时约为10天。 防治方法 蚜虫繁殖快，世代多，用药易产生抗性。选药时建议用复配药剂或轮换用药，可用50%啶虫咪水分散粒剂（国光崇刻）3000倍液，10%吡虫啉可湿性粉剂（如国光毙克）1000倍液，40%啶虫.毒乳油（如国光必治）1500-2000倍液，或啶虫咪水分散粒剂（国光崇刻）3000倍液+5.7%甲维盐乳油（国光乐克）2000倍混合液喷雾均可针对性防治 ，防治时建议在常规用药基础上缩短用药间隔期，连用2-3次。

#木槿蚜虫 分布与危害 春、夏、秋季节，木槿常受蚜虫危害。使其叶片发黄，皱缩畸形，严重时植株枯死。蚜虫排泄物还能诱发煤污病。危害木槿的蚜虫主要是棉蚜。棉蚜分布广泛，寄主繁多。 形态特征 有翅胎生雌蚜体长1.2～1.9毫米，体色黄或深绿色，前胸背板黑色，腹部两侧有3～4对黑斑，腹管圆筒形，黑色，尾片青色乳头状。无翅胎生雌蚜1.5～1.9毫米，体色夏季较浅为黄绿色，春秋季较深为绿色至棕黑色，体外被有蜡粉，腹管与有翅型相同。 发生规律 棉蚜1年发生20多代，以卵在木楼等木本花卉茎的基部越冬。越冬卵第2年3～4月间孵化，寄生于越冬寄主的新芽上，繁殖2～3代后产生有翅蚜，4～5月飞到菊花、百合等草本花卉或棉花上危害。繁殖10～20代后，到10月间又迁飞回本槿等木本植物上产卵越冬。 防治方法 1.保护七星瓢虫、食蚜蝇、草岭等天敌，也是有效的防治方法。 2.在蚜虫大量发生时，选用必治（40%啶虫毒）1500-2000倍液、毙克（10%吡虫啉）1000-1500倍液、崇刻（50%啶虫脒）3000-5000倍液喷杀。

#黄山贡菊斜纹夜蛾 分布与危害 黄山贡菊即徽菊，为我国四大名菊之一。其集色、香、味、型于一身，用途广泛，具观赏、保健、医疗功能，性寒，味甘，能散风清热，平肝明目。菊花含有菊苷、胆硷、腺嘌呤等多种成份，长期饮服可避暑除烦，明目醒脑，清静五脏，排毒健身，益智延年，预防多种疾病。斜纹夜蛾是黄山贡菊上的重要害虫，近年发生有逐渐加重趋势，严重影响贡菊的产量和品质。 形态特征 1、成虫：体长14-26毫米，体深褐色。前翅灰褐色，斑纹复杂，内、外横线灰白色，波浪形，有白色条纹，在环状纹与竖状纹间，自前缘向后缘外方有3条白色斜线。后翅白色，呈紫红色或水红色闪光。 2、卵：半球形，卵粒不规则重叠2-3层，卵块上覆黄白色 绒毛。初产黄白色，孵化前紫黑色。 3、幼虫：成长幼虫体长38-51毫米。头部黑褐色，胸腹颜色变化较大，有黑色、土黄色或暗绿色等。虫口密度大时，体色较深。中胸至第9腹节在亚背线内侧有三角形黑斑1对。 4、蛹：长18-23毫米，褐色至暗褐色。第4-7节背面近前缘密布小刻点，腹末有臀棘1对。 发生规律 斜纹夜蛾一般1年发生5-6代。近几年，菊花地里的该虫始发于6月下旬，止于11月中下旬，基本上每月1代，第2、3、4代为害重。成虫昼伏夜出，对糖醋酒液及发酵的胡萝卜、豆饼、麦芽、牛粪等有很强的趋性。卵多产于高大、茂密、浓绿的菊花上，尤以植株中部叶片背面叶脉分叉处最多。初孵幼虫群集卵块附近叶背啃食，留上表皮和叶脉，出现筛网状花叶，有时咬食花蕾和花瓣，造成残破。2龄后分散为害，4龄后进入暴食期，表现为背光性，傍晚开始取食，黎明即躲藏，阴雨天可少量取食，一般以晚上9-12时取食最烈。食叶成缺刻或孔洞，严重时可将全田菊花叶片吃光，仅留下光杆，并迁移其他田继续危害。幼虫6龄，老熟后在3-6厘米表土内造一卵圆形土室化蛹，土壤板结时可在枯叶下化蛹。斜纹夜蛾为喜温性害虫，抗寒力弱。水肥条件好、生长茂密的田块虫口密度大，发生重。土壤干燥对化蛹、羽化不利，大雨、暴雨对低龄幼虫和蛹不利。 防治方法 1、农业防治 （1）诱杀成虫。斜纹夜蛾成虫具有较强的趋光性、趋化性，在成虫发生期用黑光灯诱杀成虫，或用糖6份:醋3份:白酒1份:水10份和90%敌百虫1份的糖醋液诱杀成虫，效果均好。 （2）清除田间及其周围的杂草，减少成虫产卵及栖息场所；适时深中耕，消灭土中的老熟幼虫和蛹；在管理过程中，结合田间其他农事活动及时摘除虫卵叶和初孵幼虫叶，集中深埋或销毁。 2、药剂防治 （1）用药原则。选用高效、低毒、低残留农药品种，少用拟除虫菊酯类药剂；选用几种不同类农药品种进行交替使用，避免长期使用单一农药品种，以延缓斜纹夜蛾抗药性的产生；喷施药液时要均匀周到，植株根际附近地面要喷到、喷细致；注意严格遵守用药安全，注意收获的间隔期，确保贡菊产品安全。 （2）用药时期。宜在卵孵盛期至3龄前用药防治，4龄后施药应在傍晚进行。 （3）化学防治：尽量选择在低龄幼虫期防治。此时虫口密度小，危害小，且虫的抗药性相对较弱。防治时用45%丙溴辛硫磷（国光依它）1000倍液，或国光乙刻（20%氰戊菊酯）1500倍液+乐克（5.7%甲维盐）2000倍混合液,40%啶虫.毒（必治）1500-2000倍液喷杀幼虫，可连用1-2次，间隔7-10天。可轮换用药，以延缓抗性的产生。

#日本蜡蚧 分布与危害 全国各地均有发生。主要危害山茶花、腊梅、紫荆、紫藤、紫薇、夹竹桃、含笑、石榴、栀子花、桂花、月季、贴梗海棠、火棘、荷花玉兰、白玉兰、梅花、牡丹等多种花卉。 危害特点：以成、若虫在枝梢和叶片背面主脉上危害。严重时常诱发煤污病。 形态特征 雌成虫短椭圆形，淡棕色，长2.5～3.5毫米，背部覆盖一层厚的蜡壳，蜡壳灰白色，有的虫壳略有微红。蜡壳划分成块状，背面中央隆起，有白色柔软的蜡眼，周缘有弧状突起8个，体背有龟甲状凹纹，长4毫米左右，随寄主不同变化较大。雄成虫体长1.5毫米，体紫褐色，胸背板棕红色。卵长椭圆形，长0.28毫米，产时乳黄色，后变为紫色。若虫初龄扁椭圆形，长0.5毫米，橙黄色，腹末有长、短尾毛各1对。雌雄分化后，雌性蜡壳似龟甲，雄性蜡壳长椭圆形，背中央有隆起的蜡板，体周边缘呈星芒状13条蜡角。蛹长椭圆形，紫褐色，体长约1毫米。 发生规律 每年发生1代，以受精雌虫于枝上越冬，少数也能在常绿树种叶片上越冬。第2年3月下旬开始孕卵，产卵从4月底至5月上旬开始，产卵盛期在5月中旬。卵产于母体下，每雌产卵1600粒，卵期15～20天～5月下旬至6月底陆续孵化，孵化盛期在6月上、中旬。初孵若虫爬行很快，多爬行至叶面近叶脉两侧或嫩枝固定下来，固定后6小时开始分泌蜡，15天后形成星芒状。雌蚧7月底开始向枝条上转移，以一二年生枝上为多，雄蚧仍在叶片上。9月上旬开始出现雌、雄成虫，雄虫交配后很快死去。 防治方法 （1）园艺防治：发生初期量少时，人工剔除；合理疏枝，通风透光。 （2）生物防治：保护利用天敌，如红蜡蚧扁角跳小蜂、红点唇瓢虫等。 （3）药剂防治：在若虫孵化期喷药，药剂可选用25％西维因可湿性粉剂2000倍液，50％辛硫磷乳油1500倍液，50％杀螟松乳油1500倍液。以上药剂隔7天喷1次，连续喷3次。

Brown patch (Rhizoctonia solani) is a fungus which attacks most commonly cultivated grasses: bent grass, perennial ryegrass, tall fescue and annual bluegrass, but especially tall fescue. There are various species of Rhizoctonia which can attack grass plants from seedling stage too mature plants and are pathogenic over a wide range of environmental conditions. It is common in dense, highly fertilized turf.[图片]Brown patch may also be referred to as Rhizoctonia blight. Large brown patch is used to describe the disease in zoysiagrass. Large Patch in Zoysia Lawns Symptoms and Diagnosis Symptoms vary depending on the turfgrass species and mowing height. Susceptibility of the cultivar, management practices and weather conditions determine the degree of injury. More than one fungi may also be present in the lawn. As the name suggests, symptoms include small circular patches of brown, lifeless grass. These patches often enlarge and join together, reaching diameters of six feet or more. Newly established lawns may be more severely damaged than established lawns.[图片]In cool-season grasses water soaked circular patches that range from a few inches to several feet in diameter appear. The affected leaves wilt and turn light brown, but remain upright. A dark, grayish-black ring (smoke ring) of wilted grass often is present around the perimeter of the diseased areas in the early morning. Life Cycle Disease development requires the presence of an active fungus, vigorous growth of a susceptible grass, daytime temperatures ranges between 75 degrees and 85 degrees F, the presence of free moisture on the foliage and night temperatures below 68 degrees F. This fungus feeds on dead organic matter in the soil, but will attack grass when the right environmental conditions arise. Hot, humid conditions promote spread of the fungi.[图片]Integrated Pest Management Strategies 1. Fertilizer. Avoid heavy, early spring and summer fertilization, particularly with soluble nitrogen. Avoid over fertilization of turfgrasses growing in shaded areas. Use slow-release nitrogen fertilizers. Fertilize to maintain adequate but not lush growth during the growing season. Properly fertilized turf will recover quicker from disease injury than will under-fertilized turf. 2. Collect waste. Remove and dispose of clippings from infected areas or when conditions are conducive to disease development. Mulching mowers that chop clippings to 1/4 inch or less do not contribute to brown patch development. Mow only when the grass is dry, being sure to remove no more than one third of the top growth.[图片]3. Prune. Prune trees and shrubs to allow air movement and light penetration to reach the turfgrass. 4. Watering. Water to a depth of about 6 inches no more than once a week. More frequent watering provides an ideal environment for disease development. 5. Drainage. Provide good surface and subsurface water drainage to reduce humidity in the turf canopy.[图片]6. Fungicide. Use a preventive fungicide program with recommended fungicides. Read labels for proper fungicides and their use. 7. Replant dead areas. The disease can occur quickly, spread rapidly and then stop abruptly as environmental conditions change. Frequently, the best and only recourse is to replant dead areas at the proper time of year—early fall or spring.

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Anthracnose is usually associated with turf suffering from heat injury in midsummer, but it can also develop in spring and fall. Anthracnose may occur in conjunction with other diseases such as summer patch and Rhizoctonia brown patch. It is a common disease of bentgrass and annual bluegrass.[图片]The most severe damage is when the anthracnose fungus (Colletotrichum) infects and colonizes the lower crown of the turfgrass plant. This is sometimes referred to as basal crown rot. Plants with a crown rot are killed, resulting in a thinning of the turfgrass stand. Spore-producing acervuli and small, black resting structures called sclerotia form on the decaying crown. The scattered structures are visible with a hand lens and appear as small pepper-like dots.[图片]Symptoms and Diagnosis From a distance, affected bentgrass and/or annual bluegrass appear unthrifty and have a yellow or bronze cast. Affected turf may wilt rapidly during midday and require frequent watering . Individual plants affected with anthracnose first turn yellow and then die. Distinct leaf spots are not commonly formed by the anthracnose fungus. Instead, individual leaf blades fade from dark green to light green and then to yellow. There is no distinct region between healthy and diseased tissue as commonly observed with other leaf spotting fungi. The fungus produces conspicuous black fruiting structures called acervuli in the leaves. The acervuli are abundant in dead tissue and may also form in green, apparently healthy leaves. The black hairy or spiny fruiting bodies are easily visible with a 10X hand lens. Spines associated with ascervuli are diagnostic for Colletotrichum fungi .[图片]Life Cycle Anthracnose may develop throughout the growing season, although it is more common in midsummer when cool-season turf is experiencing heat or drought stress. The anthracnose fungus, Colletotrichum graminicolum, overwinters on living plant material. Stressed turfgrass is most susceptible to infection. The fungus penetrates the root, crown and/or leaf tissue during high humidity and wet weather conditions.[图片]Integrated Pest Management Strategies 1. Fertilizer. Get a soil test and correct fertilizer deficiencies, especially phosphorus and potassium. Very light fertilization with a balanced fertilizer during the summer may help the turf withstand stresses and recover quickly. 2. Mowing. Low frequent mowings enhance disease development. Consider raising mowing height to three inches during midsummer. 3. Watering. Use proper watering practices. Water in early morning with approximately 1 inch of water per week or to a depth of 6 inches. Avoid dry spots and frequent, light waterings.[图片]4. Fungicides. Fungicides are continually being developed for use against fungi. Select one for your disease and read the label before applying any fungicide or pesticide. Pesticides registered for use include: azoxystrobin (Heritage), chlorothalonil (Daconil), Neem extract, copper, mancozeb, maneb, thiophanate methyl (Cleary 3336), and triadimefon.

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Whiteflies are common on houseplants and in greenhouses. They are piercing-sucking insects found on the underside of leaves. When disturbed on a heavily infested plant, a white cloud of adults will fly into the air. A large infestation can cause plant damage and loss of leaves. In most cases, it is more of a nuisance than a threat to the plant. Since homes and greenhouses are always warm, they can reproduce throughout the year.[图片]When purchasing new plants, always check under the leaves making sure pests are not present. Also, check branching areas for pests. In the home make a habit of checking the underside of leaves when you water. They are easiest to remove at an early stage. In most cases, the pest will not be spotted until there are adults flying around the plant when they are disturbed.[图片]Symptoms and Diagnosis Identification of the whitefly is easy as an apparent white cloud of small snowflakes rises from foliage when disturbed. The adults are about 1/10 to 1/16 inch in length, wedge shaped, and moth-like with white, powdery wings. Symptoms vary—infested leaves may show little, if any, symptoms or may be mottled and yellow. Leaves will also become coated with a sticky substance called honeydew that is secreted by feeding whitefly nymphs and adults. A black, sooty mold may sometimes grow on the honeydew. Sooty mold does not damage the leaf. The feeding, however, removes nutrients from the plant, resulting in stunting, poor growth, defoliation, reduced yields, and sometimes death.[图片]Life Cycle Whiteflies are closely related to scales, mealybugs, and aphids. They undergo complete metamorphosis with all life stages present at any time. Eggs are laid on the underside of the leaves. One female can lay about 200 to 400 eggs. They are usually laid in cigar- or circle-shaped clusters of 30 to 40 eggs. The eggs hatch in about a week into nymphs or crawlers. The crawlers wander about the plant and insert their mouth parts to feed on plant sap. When they molt, they lose their antennae and attach themselves to the underside of the leaves where they continue to feed until they pupate. Adults emerge and are about 1/10 to 1/16 inch long and look like a small white moth. The adult has four wings that are covered with a white, powdery, waxy substance. Within a population, all life stages are present, and generations often overlap. The life cycle takes only 18 days.[图片]Integrated Pest Management Strategies 1. Inspection. Inspect all new plants brought indoors for whitefly. Inspect regularly, and remove by hand older leaves that are heavily infested with whiteflies in a non-mobile nymphal stage. Isolate new plants for a few days before placing them among other plants. 2. Mechanical control. The use of traps can be very helpful in controlling light infestations. Make yellow sticky traps about 12 x 6 inches and coat them with a sticky substance such as Tanglefoot, petroleum jelly, or heavy grade motor oil. Hang the traps vertically near the affected plants. The adults are attracted to yellow. Traps are also commercially available. One trap for every couple plants is recommended.[图片]3. Chemical control. Whiteflies have developed resistance to some chemicals. Because of this resistance, a certain product may work well in one area but not in another. Resistance may be delayed by alternating the types of chemicals used. In addition, the egg and non-feeding pupa stages are generally not as susceptible to insecticides as are the adults and nymphs. Consequently, eradication of a whitefly population usually requires four to five applications of a registered insecticide at five to seven day intervals. Be sure the applications are made to the lower leaf surface, and apply as soon as whiteflies are detected. Do not wait until populations become severe.[图片]Some of the over-the-counter chemicals that could be used contain permethrin or pyrethrins. Insecticidal soap, petroleum oil, and insect growth regulators can also be effective. Before using any insecticide for whitefly control, make sure that the target plant is listed on the label and that the chemical is approved for use indoors. Follow label directions carefully.

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