They may look like little fluffy cotton balls with legs, but the damage mealybugs can do in the flower garden is serious. Mealybugs, a cousin to other garden pests like scale and whiteflies, can damage many flowering and ornamental plants by direct feeding and by introducing diseases into the garden. Organic flower gardeners can control this pest in several ways without resorting to toxic pesticides.[图片]Identify Mealybugs and Mealybug Damage Mealybugs are tiny insects, about 1/8 inch in length, but their color and clustering habit make mealybugs easy to find on garden plants. Most common mealybug species are white, and have waxy looking filaments covering their bodies, giving them a fuzzy or hairy appearance. An exception is the hibiscus mealybug, which is pinkish-brown and lacks the fringe. Mealybugs feed on garden plants by inserting their sharp mouthparts into the leaves and stems to suck sap. Damaged leaves look wrinkled or puckered, and the insects can contaminate cut flowers with webby egg sacs and clusters of larvae. The honeydew mealybugs excrete compounds the damage, as it harbors black sooty mold and encourages the growth of plant viruses.[图片]Integrated Pest Management for Mealybugs Several species of parasitic wasps prey on mealybugs, so flower gardeners should attract these predators with nectar rich plantings of yarrow, sweet alyssum, and bee balm. Lacewings and pirate bugs also feed on mealybugs, so gardeners should be aware of the possibility of damaging these pests with insect spray, even if the spray is organic. The honeydew mealybugs exude attracts ants, which aren’t pests themselves, but protect mealybugs from natural predators. Planting common vetch as a cover crop can draw ants away from mealybugs by providing a supplemental nectar source. Gardeners can also discourage ant colonies by tilling the surface of the soil to disrupt nests.[图片]Biological Pest Control for Mealybugs Organic gardeners have at least two commercial options for biological mealybug control. The ladybug species Cryptolaemus montrouzieri, commonly called the mealybug destroyer, feeds voraciously on mealybugs at all stages of development. In fact, gardeners must take care not to mistake this beneficial insect for a pest, as the larvae of this ladybug resemble mealybugs. Gardeners can order adult mealybug destroyers to release during periods of high infestation, and this ladybug will feed on other garden pests like aphids or thrips when the mealybugs are gone. Gardeners can use the OMRI (Organic Materials Review Institute) approved insect-killing fungus marketed under the trade name Mycotrol, which contains spores of Beauveria bassiana. Gardeners can use this product until the day of harvest for cut flowers, as it’s safe for people, animals, and the environment.[图片]Organic Sprays for Mealybugs As soft bodied insect pests, mealybugs are susceptible to insect soap sprays. Gardeners must spray mealybugs directly with the insect soap to disrupt the cell membrane and kill the insects, so this spray doesn’t work as a preventative agent. The biggest drawback of insect soaps is their potential to damage or burn plants. To reduce plant toxicity, spray plants in the evening and spray them with water in the morning, as high temperatures and sunlight increase plant damage from insect soap.[图片]Mealybugs on Houseplants Mealybugs and their nymphs thrive in greenhouses, making this insect pest common on houseplants. Orchids are particularly susceptible to damage and death from mealybug infestations. Isolate new houseplants for one week before placing them around other houseplants. Inspect the plants each day for signs of white mealybugs or their webbing, and kill any insects with a cotton swab dipped in rubbing alcohol.

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There is hardly a gardener out there who hasn’t encountered a Japanese beetle. The adult Japanese beetle is a shiny, metallic green with copper-brown wing covers and it’s about 3/8 of an inch in length. However, not all metallic green or copper beetles are Japanese Beetles. To make sure you're dealing with Japanese beetles check their undersides for five small, white tufts under the wing covers and an additional tuft at the end of the abdomen.[图片]An individual Japanese beetle doesn’t do that much damage while feeding on a plant, but they tend to congregate in large numbers and can easily defoliate shrubs and trees. These bugs are hard to get rid of, but there are steps you can take to control them. Keep in mind that the adult Japanese beetles are only around for a little over a month, so don’t automatically reach for harsh chemicals unless they become a serious problem.[图片]Stages of Development Beetles typically go through 4 stages of development. It’s important to know when they are passing through each stage in your climate because control methods are different for each stage. The life stages for the Japanese Beetle are: Egg: Small, oval, white eggs. These are laid in the soil. If moisture is sufficient, they will absorb it and enlarge, becoming rounder as they do. Larvae: This is the white grub stage that is so familiar in lawns. Japanese beetle larvae have a V-shaped series of bristles on their raster (the underside of the tip of the abdomen.) Grubs will grow in length as they feed and mature. Pupae: The pupae stage is where the grub starts to transform into a beetle. Japanese beetle pupae start out cream colored and age to a reddish brown. Adult Beetle: The adult beetles are about 3/8 inch long, and the shell is a shiny, metallic green with copper-brown wing covers. Adults emerge from the ground between May and June, depending on your area. They live for about 30 to 50 days.[图片]Life Cycle of the Japanese Beetle The first beetles to emerge start to look for suitable plants to eat and start feeding immediately. They also send out an odor known as a congregation pheromone to signal later emerging beetles where to go. Mating starts soon after. The females will feed on your plants for a couple of days and then burrow into the soil to lay their eggs. Shortly after, they will return to feeding and mating and start the cycle all over again. By the end of the season, each female Japanese beetle will have laid about 50 eggs.[图片]Eggs develop at different rates in different soil temperatures, developing most rapidly in warm soils of about 80 to 90 degrees F. Once they develop into larvae, they will move up toward the surface of the soil and start feeding on roots and organic matter. This is why grub control is usually applied in late summer to fall. The pesticide needs to be applied while the grubs are feeding on the grass roots. As the soil cools and the grubs mature, they start moving back down deeper into the soil for winter. They’ll stay there until the soil warms in the spring, at which time they burrow back up toward the surface where they’ll pupate and eventually emerge as adults.[图片]What Plants do Japanese Beetles Eat? There’s a wide smorgasbord of plants for Japanese beetles to feast on, over 300 varieties of trees, shrubs and non-woody plants. Some of their favorites include roses, maples, elms, grapes and crab apples. However, they also feed on weeds like poison ivy and bracken. How to Control Adult Japanese Beetles It’s impossible to get rid of Japanese beetles entirely. More will fly in as the current crop are killed. There aren’t many natural controls for adult Japanese beetles. Birds aren’t partial to them, and although some predatory wasps and flies have been imported, their population isn’t large enough yet to control the Japanese beetle problem.[图片]The most effective natural control is to go into your garden with a jar of soapy water and knock the beetles into it. Japanese beetles feed in groups, starting at the top of plants, so it’s pretty easy to fill a jar with them. Insecticidal soap will kill adult Japanese beetles only if it is sprayed directly on the beetle. It does not have any residual effect, meaning that beetles that aren’t sprayed directly won’t be harmed.[图片]A word of caution about the pheromone beetle traps. They will attract beetles; you’ll probably wind up with more beetles coming into your yard than you would have without the trap. The original intention of the traps was to track when and how many Japanese beetles were in the area, not as a means of eradication. Finally, if you have repeated intense infestations, you should check your soil in late summer to see if you have a large grub population. Lift a 1 square foot section of turf. If there are more than a dozen grubs in this small area, consider treating your lawn with some type of grub control. However, not every garden that has a Japanese beetle problem is associated with a lawn full of grubs. The beetles can hatch in your neighbor's lawn and find your tasty garden with very little effort.[图片]More Toxic Controls (to Be Used With Caution) There are several insecticides labeled for use on adult Japanese beetles. These sprays will kill on contact and also have some residual effect. Keep in mind that these sprays will kill more than just the Japanese beetles, so use them only for extreme infestations. And again, Japanese beetles are only a pest for a little over a month, so don’t overreact. Always read and follow label directions when using any pesticide.

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If you suspect a lace bug problem in your flower garden, get out your magnifying lens, because these garden pests are only about 1/8 of an inch long. Under magnification, you can see where these bugs got their name: their transparent wings form a lacy shield over their square shaped bodies.[图片]Identify Lace Bug Damage In the flower garden, the most likely victims of lace bugs are azalea bushes. Lace bugs especially seek out azaleas growing in sunny spots. Lace bugs and their larvae feed on azaleas and other flowering plants and shrubs throughout the growing season, using their sharp mouthparts to pierce plant foliage and suck the juices from leaves. If your flowers are infested with lace bugs, you might notice: Yellow stippling on leaves White stippling on leaves Evidence of leaf curl Browning of leaves during active growth Premature leaf drop Lace Bug Life Cycle Like many bugs, lace bugs begin their life cycle as larvae. The female lace bug inserts the eggs into the leaves of host plants, so a food source is available to newly hatched larvae. The larvae are very tiny and difficult to see, but they are usually present and feeding under leaves along with their parents. After about six weeks, the larvae mature into adult lace bugs, which can spawn several more generations of pests that season.[图片]Organic Sprays for Lace Bug Control In spite of their imposing shields, lace bugs are susceptible to most organic sprays. The trick is to apply the sprays thoroughly to the undersides of leaves, where lace bugs feed and reproduce. Use these sprays to kill active lace bug adult and larvae populations: Light horticultural oil Insect soap Neem Spinosad Cultural Control of Lace Bugs As with all plants, those under stress make the tastiest meal for insect pests. Ensure your plants can shrug off minor lace bug attacks by keeping them healthy. You may as well hang up a “dine here” neon sign if you allow your azalea, a woodland shrub, to bake in full sun. Dry soil and an absence of mulch also create conditions that pique the interest of lace bugs. Dappled shade or morning sun, regular irrigation, and a 3-inch layer of organic mulch keep plants vigorous and pest-free.[图片]Beneficial Insects That Kill Lace Bugs Many predators feed on lace bugs, reducing your need to spray insecticides on your flowering plants. Natural lace bug enemies include: Assassin bugs Lacewings Ladybugs Pirate bugs Predatory mites Spiders If you want to provide a beneficial bug-friendly habitat to attract these natural predators, eliminate the use of insecticide sprays. Insecticides not only kill beneficial insects, but they eliminate the food source of beneficial bugs, forcing them to seek greener pastures.[图片]Conventional Pesticides to Control Lace Bugs If lace bug swarms are turning your flowering oasis into a withered graveyard, it might be time to break out some conventional chemical pesticides. A benefit of these broad-spectrum sprays is their residual effect, helping to kill multiple generations of lace bugs. Use any of these sprays to kill lace bugs: Carbaryl, sold under the brand name Sevin Imidacloprid, see below Malathion, marketed by Ortho, Hi-Yield, and Spectracide Pyrethroids, including Bonide Eight Vegetable Fruit, & Flower Spray; Monterey Bug Buster; and Ortho Bug-B-Gon[图片]Use any of these sprays to kill lace bugs: Carbaryl, sold under the brand name Sevin Imidacloprid, see below Malathion, marketed by Ortho, Hi-Yield, and Spectracide Pyrethroids, including Bonide Eight Vegetable Fruit, & Flower Spray; Monterey Bug Buster; and Ortho Bug-B-Gon Of these conventional sprays, only the imidacloprid is systemic, meaning the plant takes up the chemical, making it rain proof. Homeowners can shop for imidacloprid under the brand name Merit or Bayer Advanced Garden Tree & Shrub Insect Control.

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相关图片 [图片]#金银花白粉病 分布与危害 金银花Lonicera japonica Thunb.别名山银花，属忍冬科多年生藤状灌木，以蕾或将开的花入药，叶、枝也可入药，具清热解毒之功效，60年代开始由野生转为家种，现在从南到北，许多市县都有种植，一度面积颇大。白粉病是金银花上常见病害，全国各种植区广泛发生，危害严重。 症状 主要危害叶片，有时也为害茎和花。叶上病斑初为白色小点，后扩展为白色粉状 斑，后期整片叶布满白粉层，严重时叶发黄变形甚至落叶；茎上病斑褐色，不规则形，上生有白粉；花扭曲，严重时脱落。 病原 Microsphaera lonicerae (Dc.)Wint.in Rabenh.称忍冬叉丝壳，属于囊菌亚门真菌。子囊果散生，球形，深褐色，大小65-100μm；5-15根附属丝，长55-140μm，是子囊果直径的0.7-2.1倍，无色，无隔或具1隔膜，3-5次双分叉。子囊3-7个，卵形至椭圆形，大小34-58×29-49(μm)。子囊孢子2-5个，椭圆形，大小16.3-25×8.8-16.3(μm)。无性态为Oidium sp.菌丝体，叶两面表生，分生孢子梗直立，大小50-94×7-10(μm)；分生孢子2-3个串生，少数单生，椭圆形、筒形，向基型产生，大小28-49×12-20(μm)。 发生规律 病菌以子囊壳在病残体上越冬，翌年子囊壳释放子囊孢子进行初侵染，发病后病部又产生分生孢子进行再侵染。温暖干燥或株间荫蔽易发病。施用氮肥过多，干湿交替发病重。 防治方法 （1）因地制宜选用抗病品种。 （2）加强栽培管理。 合理密植，注意通风透气；科学施肥，增施磷钾肥，提高植株抗病力；适时灌溉，雨后及时排水，防止湿气滞留。 （3）药剂防治。 发病初期喷洒15％三唑酮可湿性粉剂2000倍液或12.5%国光黑杀2500-3000倍液喷雾防治。 常用药剂：黑杀、三唑酮

相关图片 [图片]#菊花斑枯病 分布与危害 菊花斑枯病又称黑斑病、褐斑病，是药用植物菊花生产上的常见病害，严重影响药菊的产量和药用价值。 症状 主要危害叶片，初于下部叶片上出现褐色小斑点，后扩展成黑褐色圆形或近圆形至不规则形斑，大小5-l0mm，外部有一不明显黄色晕圈。后期病斑边缘呈黑褐色，中央稍褪色，湿度大时出现不大明显的小黑点，即病菌分生孢子器。严重时病斑融合成片，致整个叶片变黄干枯或变黑脱落，有的病叶卷成筒状。 病原 Septoria chrysanthemella Sacc. 称菊壳针孢和S.obesa Syd.称菊粗状壳针孢，均属半知菌亚门真菌。菊壳针孢分生孢子器球形至亚球形，大小51—78μm，褐色或黑褐色，器壁膜质，孔口直径12-17μm；分生孢子针状或丝状，无色，具3-6个隔膜，大小23-43×1.1-1.8(μm)。菊粗状壳针孢分生孢子器直径66-160μm，分生孢子长44-108μm，较菊壳针孢大。菊壳针孢在PDA培养基上生长缓慢，菌落黑褐色半球状，致密。在燕麦培养基上生长较好，菌落直径大，培养63天达13mm，产孢也多。20-24℃产孢所需时间为16天，12℃及28℃分别为37天和21天；分生孢子在清水中不发芽或发芽率很低。分生孢子萌发温限12-32℃，萌发适温26-28℃，55℃经10分钟致死。分生孢子萌发需有水滴或水膜及充足的氧气，否则即使相对湿度接近饱和也不萌发。适应酸碱度范围为pH3-11，其中以pH5-7最适。 发生规律 病菌在病残体上越冬，翌春条件适宜时，病菌借风雨传播，经20-30天潜育发病后又产生分生孢子进行再侵染。高温多雨条件易发病，华南5-10月气候温暖潮湿易发病，北方8-9月发病重。此外，连作、栽植过密 及老根留种的花圃发病重。 防治方法 ①减少侵染来源：开花结束后，彻底清除病残体，集中销毁。 ②培育苗壮，以增强植株的抗病能力。 ③化学防治：可定期喷施国光银泰（80%代森锌可湿性粉剂）600-800倍液+国光思它灵（氨基酸螯合多种微量元素的叶面肥），用于防病前的预防和补充营养，提高观赏性； 发病初期，病初期喷洒25%咪鲜胺乳油（如国光必鲜）500-600倍液，或50%多锰锌可湿性粉剂（如国光英纳）400-600倍液。连用2-3次，间隔7-10天。

相关图片 [图片]#菊花叶斑病 分布与危害 药菊Chrysanthemum morifolium(Ramat.)Tzvel.(Dendranthema morifolium(Ramat.)Tzvel.)属菊科多年生草本植物，是常用中药，以花入药，药用菊花品种较多，如茶菊、黄菊、白菊等，具明目解毒、散风清热之功效，全国各地均有栽培。 症状 主要危害叶片，叶面初生针尖大小褪绿色至浅褐色小斑点，后扩展成圆形至椭圆形或不规则状，中心暗灰色至褐色，边缘有褐色线隆起，直径3-8mm，个别病斑长20mm。 病原 Cercospora chrysanthemi Heald et Wolf称菊尾孢，属半知菌亚门真菌。子座不发达；分生孢子梗生于叶两面，丛生，基部膨大，梗密集或不密集，浅橄榄褐色，在0-2处屈曲，个别膨大，顶端呈亚平截形，生大孢子痕，直立或近直立，大小20-80×3.5-5.0(μm)；分生孢子针状，基部平截无色，顶端尖，直或略弯，具6-33个不大明显的隔膜，大小40-125×2-4(μm)。分生孢子形成后，分生孢子梗尖端继续伸长，再顶生分生孢子。 发生规律 以菌丝体和分生孢子丛在病残体上越冬，以分生孢子进行初侵染和再侵染，借气流及雨水溅射传播蔓延。通常多雨或雾大露重的天气有利发病。植株生长不良，或偏施氮肥长势过旺，会加重发病。 防治方法 （1）农业防治。 适时灌溉，注意清沟排渍，避免偏施氮肥，适时喷施植宝素等，使植株健壮生长，增强抵抗力。结合采摘叶片收集病残体，携出田外烧毁，减少传染源。 （2）药剂防治。 发病前用国光银泰（70%代森锌）500-600倍液，75％百菌清可湿性粉剂1000倍液加70％甲基硫菌灵可湿性粉剂l000倍液提前进行预防， 发病初期可使用国光英纳可湿性粉剂400-600倍与国光必鲜乳油500-600倍交替使用，防止单一用药病菌产生抗性。 常用药剂：多·硫、百菌清、甲基硫菌灵、异菌脲

相关图片 [图片]#夹竹桃褐斑病 分布与危害 夹竹桃Nerium indicum Mill．属夹竹桃科木本植物，以叶、花入药，有毒，具强心利尿、祛痰杀虫之功效，全国大部分省区均有分布。褐斑病是夹竹桃上重要病害，各地普遍发生，危害严重。 症状 主要危害叶片，初在叶尖或叶缘出现紫红色小点，扩展后形成圆形、半圆形至不规则形褐色病斑。病斑上具轮纹。后期中央退为白色，边缘红褐色较宽。湿度大时病斑两面均可长出灰褐色霉层，即病菌的分生孢子梗和分生孢子。 病原 Cercospora neriella Sacc.称欧夹竹桃尾孢，属半知菌亚门真菌。子座深褐色，大小25-125μm。分生孢子梗色浅，粗细不匀，聚集成束状，具隔膜0-3个，不分枝，顶端生有小型孢子痕，大小5-35×3-5(μm)。分生孢子圆筒形，具1-5个隔膜，大小15-50×3-5(μm)。此外，C.nerii-indici Yaman称夹竹桃尾孢，也是该病病原。 发生规律 病菌以菌丝体在病叶上或随落叶留在土表越冬。翌春产生分生孢子，通过风雨传播到夹竹桃上，萌发的孢子从气孔或伤口侵入，引起发病。3-7月发生，苗木生长过密或细弱发病重。 防治方法 （1）农业防治。 合理密植，不宜栽植过密；科学肥水管理，培育壮苗；清除病叶集中烧毁，减少菌源。 （2）药剂防治。 发病前期可定期喷施国光银泰可湿性粉剂600-800倍液，国光多菌灵，百菌清进行预防，发病初期使用国光英纳可湿性粉剂400-600倍液、或国光必鲜乳油500-600倍液叶面喷雾进行防治。 常用药剂：甲霜灵锰锌，咪鲜胺，丙环唑

相关图片 [图片]#菊花根癌病 分布与危害 根癌病是药用植物菊花的主要病害之一，全国各栽培区广泛发生，危害严重。 症状 主要发生在植株根颈处或侧根及枝干上，病部产生大小不等的肿瘤，初期肿瘤为灰褐色，表面光滑，质地不硬，后变为棕褐色，表皮粗糙或龟裂变硬，致地上部失绿或变黄，叶小且早落，病株生长缓慢或枯死。 病原 Agrobacterium tumefaciens (E.F.Smith et Townsend)Conn. 称癌肿野杆菌或根癌土壤杆菌，属细菌。细菌短杆状，单生或成对生长，大小1.2-3×0.4-0.8(μm)，具1-5根周生鞭毛，革兰氏染色阴性，能形成荚膜，无芽孢；在肉汁胨琼脂培养基上生长迅速，菌落白色，圆形，边缘整齐，光亮半透明。在液体培养基上呈淡云状混浊，表面有一层薄膜。生理生化表现：不液化明胶；凝固牛乳但不胨化；还原石蕊牛乳变蓝；对硝酸盐轻微还原；在葡萄糖、果糖、阿拉伯糖、半乳糖、甘露醇、水杨苦酸上微产酸，但不产气；不水解淀粉。细菌生长温限0-37℃，适温25-30℃，致死温度51℃经10分钟。细菌耐酸碱范围pH5.7-9.2，最适pH7.3。 发生规律 根癌细菌在肿瘤组织皮层内或混入土中越冬。细菌可在土壤中存活一年以上，通过雨水和灌溉水传播。此外，地下害虫，如蛴螬、蝼蛄和线虫也能传播细菌。细菌通过虫伤、机械伤及其他根病引起的损伤侵入。侵入后只定植于皮层组织，在寄生过程中分泌B-吲跺乙酸刺激周围细胞加速分裂，体积增大形成癌肿。寄主细胞变成癌瘤后，没有病菌仍能继续扩展。 温湿度是根癌细菌侵染的主要条件，病菌侵染与发病随土壤湿度升高而增加，反之则减轻。癌瘤与温度关系密切，28℃时癌瘤长得快且大，高于3l-32℃不形成，低于26℃形成慢且小。碱性土壤利于发病，酸性土壤对发病不利，pH6.2-8尚能保持病菌致病力，pH6以下发病轻或不发病。土壤粘重，排 水不良发病重；土质疏松、排水良好的砂质土发病轻。耕作不慎或地下害虫为害，造成伤口，均利于病菌侵入，增加发病机会。苗木带菌是远距离传播的主要途径。 防治方法 （1）因地制宜种植抗病品种。 （2）重病区实行2年以上轮作。 （3）药剂防治。 ①对怀疑有病的苗木用72％农用硫酸链霉素1500倍液浸泡半小时或1％的96％硫酸铜浸泡5分钟，冲净后定植。 ②细心栽培，避免各种伤口，发现重病株要及时拔除，轻病株可用抗菌剂402对水300-400倍液浇灌或把瘤切掉用72％农用硫酸链霉素可溶性粉剂3000倍液涂抹，有一定治疗效果。必要时用甲冰碘液，即用甲醇50份、冰醋酸25份、碘片12份混合均匀涂在癌瘤表面及周围3cm处，可杀死肿瘤表层细菌。 （4）生物防治。 国外有报道，在发生癌肿病植株根部分离到一种无致病力的放射野杆菌(Agrobacterium radiobacter)K84株系能放射野杆菌素84(agrocin84)，一种核苷酸杆菌素，能有效抑制癌肿组织形成，利用K84制剂浸种或浸根等处理，对癌肿病有很好的防治效果。 常用药剂：农用硫酸链霉素、抗菌剂402

相关图片 [图片]#菊花枯萎病 分布与危害 枯萎病是药用植物菊花上的重要病害，全国各栽培区广泛分布，造成严重损失。 症状 初发病时叶色变浅发黄，萎蔫下垂，茎基部也变成浅褐色，横剖茎基部可见维管束变为褐色，向上扩展枝条的维管束也逐渐变成淡褐色，向下扩展致根部外皮坏死或变黑腐烂，有的茎基部裂开。湿度大时产生白霉，即病菌菌丝和分生孢子。该病扩展速度较慢，有的植株一侧枝叶变黄萎蔫或烂根。 病原 Fusarium oxysporum Schl.f.sp.chrysanthemi Snyder et Hansen称尖镰孢菌菊花专化型，属半知菌亚门真菌。在PDA培养基上气生菌丝茂盛，絮状，菌丛背面浅紫色至紫色，个别白色。大分生孢子纺锤形或镰刀形，壁薄，两端尖，多具3个隔膜，少数4个或5个，3个隔膜的大小25-36×3.6-4.7(μm)；小分生孢子生于单瓶梗或较短的分生孢子梗上，数量很多，肾形至椭圆形，l-2个细胞，大小6-14×2.7-3.6(μm)；厚壁孢子球形至椭圆形，1-2个细胞，顶生或间生；单生或双生，个别串生。 发生规律 病菌主要以厚垣孢子在土中越冬，或进行较长时间的腐生生活。在田间，主要通过灌溉水传播，也可随病土借风吹往远处。病菌发育适温24-28℃，最高37℃，最低17℃。该菌只为害菊花，遇适宜发病条件病程2周即现死株。潮湿或水渍田易发病，特别雨后积水、高温阴雨、施氮肥过多、土壤偏酸易发病。 防治方法 （1）因地制宜种植抗病品种。 （2）重病田与其他作物实行轮作。 （3）加强栽培管理。 选择宜排水的砂性土壤栽种；科学施肥，提倡施用酵素菌沤制的堆肥或腐熟有机肥，增施磷钾肥，提高植株抗病力；适时灌溉，雨后及时排水，防止田间湿气滞留；及时剪除田间病枝，减少传染源。 （4）药剂防治。 发病初期喷洒国光多菌灵50％可湿性粉剂600-800倍液浇灌，或使用国光三抗（30%噁霉灵）水剂1000-1200倍液，国光根灵（70%敌磺钠）800-1000倍浇灌。

相关图片 [图片]#款冬白绢病 分布与危害 款冬Tussilago farfara L．别名冬花，属菊科多年生草本药用植物，以其花蕾入药，具润肺、止咳、化痰之功效，华北、西北、四川、河南、湖南均有栽培。白绢病是款冬生产上常见病害，各地广泛发生，危害严重。 症状 染病幼苗或成株根茎部出现水渍状病斑，后渐蔓延扩展，在病部及土表长出白色棉絮状菌丝体，其上形成很多白色的小菌核，后随菌核增大至油菜籽大小时，颜色亦变成深褐色，菌核和菌丝缠结在一起覆在植株基部表面。 病原 Sclerotium rolfsii Sacc.称齐整小核菌，属半知菌亚门真菌。有性态为Athelia olfsii(Curzi)Tu.＆Kimbrough．称罗氏阿太菌，属担子菌亚门真菌。在PDA培养基上菌丝体白色，茂盛，呈辐射状扩展；菌丝粗2-8um，分枝不成直角，具隔膜。菌核初为乳白色，后变浅黄色至茶褐色或棕褐色，球形至卵圆形，大小1-2mm，表面光滑有光泽。菌核由3层细胞组成，外层棕褐色，表皮层下为假薄壁组织，中间为疏丝组织。菌核不与菌丝联结，很易脱落。 发生规律 病菌以菌核在地表或含有病残物的肥料中越冬。翌年温湿度适宜时，从菌核中长出菌丝侵染桑苗茎基部，后病部又长出菌丝沿土缝匍匐蔓延至邻近植株或病健株直接接触进行再侵染。发病适温为30-35℃4该病在南方桑树栽培区易发病。生产中用塑料薄膜保温保湿的沙藏预措插条易发病。苗圃地连作的发病重。 防治方法 （1）农业防治。 ①重病田实行轮作。 ②加强栽培管理。 选择高燥地块种植；科学肥水管理，培育壮苗；采用干净的河边沙预措插条能减少或控制其发病。 （2）药剂防治。 栽种前进行插条消毒，可用50％多菌灵可湿性粉剂500倍液或50%甲基硫菌灵可湿粉600倍液，将沙喷湿喷透，再用塑料薄膜盖7-8天进行沙藏预处理插条；也可把沙藏后的插条用上述杀菌剂浸泡20-30分钟，都能减少白绢病的发生。 白绢病发病初期，可用国光三抗（30%恶霉灵）1000倍液或国光根灵（70%敌磺钠）800倍液根部浇灌进行防治。