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Dummer. ゛☀
2017年09月19日
Dummer. ゛☀
Unlike other blights, chestnut blight is not just associated with shoot dieback; it can kill twigs and branches of any size. It is actually a canker disease caused by a fungus, Cryphonectria parasitica, formerly known as Endothia parasitica. The significance of chestnut blight is tied to the species it decimated- the American chestnut, Castanea dentata. In 1900 the American chestnut was not only the dominant species of eastern hardwood forests in the U.S., it was the most important tree commercially, because of its beautiful, rot resistant lumber, because of the quantities of edible nuts it produced, and because of the rapidity with which it could repopulate clear-cut areas of the forest.[图片]Chestnut blight was first identified in the United States in New York City in 1904, but it probably entered the country earlier, in the late 1800s on imported Asian chestnuts. By 1950, 99.9% of American chestnuts were reduced to either dead stumps or stumps with adventitious sprouts arising from the roots surrounding them. Many of these stumps persist today and are still sending up diseased sprouts that are as susceptible to chestnut canker as the parent plant. Other species that are highly susceptible to chestnut blight are the Allegheny chestnut (C. pumila), the bush chinkapin chestnut (C. alnifolia) and the European chestnut (C. sativa). The last species, Castanea sativa, is not native to the U.S. and is restricted here. Some oaks are host to the disease; these include live, post, scarlet and white oaks. It is also occasionally found on shagbark hickory, red maple and staghorn sumac.[图片]Chinese and Japanese chestnuts have shown some resistance to chestnut blight; for these Cryphonectria parasitica is a stress pathogen only. No other species of chestnut, however, has the characteristics necessary to replace the American chestnut as a forest tree or as an ornamental. The European chestnut, Castanea sativa, does share some of these characteristics, but it is also susceptible to chestnut blight and its importation into this country is restricted.[图片]Symptoms and Diagnosis Obvious symptoms on the American chestnut include flagging (the yellowing and dying of individual branches) and dead leaves that hang onto branches over the first winter. On young trees and on juvenile branches of mature trees, cankers appear as yellowish to reddish areas in the bark around branch crotches; these cankers can girdle and kill a branch within a few weeks. On mature trees, cankers are initially imperceptible unless the bark is stripped off. Later, as the canker expands, the bark swells and cracks, eventually falling off. Yellowish brown fruiting bodies may be visible on the surface of the bark around the canker or in the cracks in the bark. In American chestnuts, the trunk is eventually girdled which can occur within a few weeks for young trees and within a few years for mature trees. Few last longer than four years. Suckers usually shoot up from the surrounding roots of American chestnuts providing a constant supply of susceptible tissue for the pathogen’s continued existence; this suckering does not occur in other species.[图片]Live oaks decline slowly. Foliage at the crown is chlorotic and sparse with dead branches. Cankers are difficult to discern. Severe dieback can occur on post oaks and scarlet oaks, but smaller cankers or superficial cankers are more common. Cankers on post oak are more pronounced than on live oaks and the bark will usually slough off, while on scarlet oaks the cankers appear swollen and remain covered with bark. Swelling can also indicate cankers on white oak. Infected Chinese and Japanese chestnuts are usually stressed trees. Chinese chestnuts display twig or branch dieback or targetlike cankers, and bark will eventually slough off. Buff to orangish flat, mycelial fans in the diseased bark are characteristic of chestnut blight although positive diagnosis of the disease requires a laboratory test to culture the fungal pathogen.[图片]Life Cycle The success of this disease must be attributed, as least in part, to its ability to spread in so many different ways. Vectors include insects, birds, other animals, wind, and rain. Ascospores or conidia enter fresh wounds, probably caused by insects, usually in bark surrounding branches and twigs. Buff to orange mycelial fans then spread into living bark and cambium tissue. As cell death occurs, the fungus spreads into living tissue. Thus, as branches and twigs are girdled, the canker moves toward living tissue–ultimately to the main trunk of the tree. It does not, however, invade the crown. The environmental conditions necessary to the survival of the chestnut blight pathogen seem virtually unlimited. No condition in which a chestnut can live discourages or suppresses the pathogen. It can live anywhere chestnuts live and can reproduce at any time of the year.[图片]Integrated Pest Management Strategies 1 There is no cure for chestnut blight. Once the pathogen is present in an area, and it is already present in most areas, any American chestnut is at extreme risk; therefore, do not plant them. Other species should only be planted in preferred growing conditions; stressed sites will place them at risk. 2. Choose resistant species. Although the search for a blight resistant American chestnut has been ongoing for nearly a century, no blight resistant American chestnuts are currently on the market. Specimens sold as "blight free" have not been exposed to the disease (i.e., blight-free does not mean blight resistant).
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Dummer. ゛☀
2017年09月19日
Dummer. ゛☀
Bacterial wetwood, also known as slime flux, is caused by an infection of one or more of several bacteria. It results in a water-soaked, oozing or bleeding condition of wood, which occurs in the trunk, branches and roots of shade and ornamental trees. It is normally not serious in most trees but is a chronic disease, which causes concern and can contribute to a general decline in tree vigor over time. Trees most susceptible to the disease include: elms, apple, crabapple, London plane, redbud, aspen, dogwood, magnolia, Russian olive, beech, fir, maple, sour gum, birches, hemlock, mountain ash, sycamore, boxelder, hickory, mulberry, sweet gum, butternut, horse chestnut, oaks, tulip tree, cottonwood, linden, pines, black locust, poplar, willow and walnut.[图片]Symptoms and Diagnosis Symptoms vary with geographical location suggesting that the environment influences disease development. Trees in the western United States show more variability in internal disease development with much less bleeding and symptom expression than trees in the East and Midwest. Wetwood appears internally in the trunk and large limbs as a dark brown-black water-soaked area when the area is sectioned. The first external sign of wetwood is usually bubbling and seepage from wounded tissue in V-shaped branch crotches, wounds made by removal of branches, injection holes and trunk cracks. Insects are often attracted to the ooze on which they feed but there is not any evidence that these insects cause damage or transmit the bacteria but it is believed that some wood boring insects such as beetles may transmit the disease.[图片]Life Cycle Organisms, most commonly bacteria, infect the tree deep in the tissue and start a process of fermentation. The resulting pressure (up to 60 psi) forces the bacterial ooze out cracks, branch stubs and pruning cuts. This ooze discolors bark, kills the cambium near the cut preventing proper callusing of wounds and kills grass and other plants on which it drips. Bacterial wetwood is noticed externally when it exudes slime and leaves a stain on the bark. Wilting of foliage is common in young trees; old trees are more likely to develop a general decline in vigor or branch dieback in the upper crown.[图片]Integrated Pest Management Strategies 1. There is no cure or preventive treatment to avoid infection and development of bacterial wetwood. The following strategies may help. 2. Fertilization. Fertilize stressed trees to stimulate vigorous growth and lessen the severity of the disease but refrain from over fertilizing healthy vigorous trees as this may increase their susceptibility to the disorder.[图片]3. Pruning. Remove any dead and weak branches. Promptly remove any loose or diseased bark around the area and make a clean cut arround wounds to facilitate healing. It is advided to disinfect tools with 70% rubbing alcohol before pruning a tree. Inserting a drainage tube to drain the area is not recommended. Insertion of a drainage tube can spread the disease and result in more harm than good.
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Dummer. ゛☀
2017年09月19日
Dummer. ゛☀
Bacterial leaf scorch (BLS) is a systemic disease caused by the bacterium Xylella fastidiosa, which invades the xylem (water and nutrient conducting tissues) of susceptible trees. It is most commonly seen in pin, red, shingle, bur, and white oaks, but can also affect elm, oak, sycamore, mulberry, sweetgum, sugar maple, and red maple. Xylem-feeding leafhoppers and spittlebugs spread the bacterium from tree to tree. Transmission between trees through root grafts has also been reported. There is no cure for this disease; it is chronic and potentially fatal.[图片]Symptoms and Diagnosis The first noticeable symptom is premature browning of leaves in mid-summer. Symptoms worsen throughout late summer and fall. Leaf margins turn brown, beginning with the older leaves and moving outward, spreading to leaves toward the branch tip. In most, but not all infected trees, browned, dead areas of the leaf are separated from green tissue by a narrow yellow border. The browned leaves may drop from the tree. Infected trees leaf-out normally the following year, with leaves on a few more branches turning prematurely brown in late summer. Symptoms become progressively worse over a period of 3 to 8 years, until the entire tree turns brown prematurely. The lack of green, chlorophyll producing leaves year after year leads to twig, branch, and limb death due to continual defoliation.[图片]Bacterial leaf scorch can easily be mistaken for oak wilt or Dutch elm disease, except for the following: The cycle of bacterial leaf scorch repeats and becomes worse over a long period of time. Oak wilt and Dutch elm disease are both capable of killing susceptible trees within a matter of months. There is no streaking of the sapwood with bacterial leaf scorch. In bacterial leaf scorch, the leaf browning develops from the leaf edges and works toward the mid-vein, whereas browning tends to happen in a more overall, uniform manner with oak wilt and Dutch elm disease.[图片]Bacterial leaf scorch can also be mistaken for drought and heat stress. However, damage by bacterial leaf scorch begins in old leaves and spreads to the branch tips, with browning around the leaf edges. Damage due to environmental stresses tends to cause overall browning to the canopy and to individual leaves. Trees tend to react to environmental stress soon after damaging conditions occur whereas bacterial leaf scorch is unique in its timing. Leaf browning is generally not noticed until mid-summer and intensifies through late summer and fall. The only way to confirm the diagnosis of bacterial leaf scorch is through laboratory analysis. This can be done by sending a sample to the MU Extension Plant Diagnostic Clinic. The best time to test for the presence of this disease is in late summer or early fall, when the bacteria count is at its highest.[图片]Life Cycle Infected leafhoppers and spittlebugs feed on the succulent, terminal shoots of susceptible host trees, transmitting the bacteria. Xylem vessels become clogged with bacterium as it travels within, multiplying and infecting other parts of the tree. There are no viable control options for the insect vectors. The cold-sensitive bacteria overwinter in protected areas within the xylem of the tree, and their populations begin to climb again as the next growing season progresses.[图片]Integrated Pest Management Strategies 1. Maintain plant vigor. There is no cure for the disease. Keeping susceptible trees healthy and thriving can help them resist infection and survive longer once they are infected. 2. Practice good sanitation. Branches that have died due to bacterial leaf scorch should be routinely removed. Infected trees that are in a severe state of decline should also be removed. Disinfect pruning tools with a 10% bleach solution between pruning cuts.[图片]3. Plant resistant species. In areas where bacterial leaf scorch has occurred, avoid planting highly susceptible trees. 4. Antibiotic injections. Oxytetracycline root flare injections applied in spring can reduce bacterium levels and delay symptoms by a couple of weeks. They are expensive, need to be reapplied each year, and possible damage resulting from long-term use is unknown. A certified arborist should be contacted if you are considering injections.
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Dummer. ゛☀
2017年09月19日
Dummer. ゛☀
Ash yellows is a disease caused by Candidatus fraxinii, which affects the tree's vascular system or its’ phloem sieve tubes. It is presently only found in North America. Ash yellows disease cycle is still a mystery. Experts think it is transmitted by insect vectors such as leaf hoppers which also transmit viruses. Symptoms seem to appear most widely on white ash (Fraxinus americana) than green ash (F. pennsylvanica.) It can also affect at least ten other ashes including black ash (F. nigra) and blue ash (F. quadrangulata.) The ash yellows phytoplasma can also cause symptoms of witches broom in lilacs often called lilac witches broom.[图片]Ash decline is the rapid decline of ash trees including sparse crown growth and dieback. It may be caused by many factors including environmental factors like weather stresses or poor soil conditions and other pathogens like ash yellows. Symptoms and Diagnosis Symptoms of ash yellows and decline can vary depending upon ash species and environment conditions. White ash shows the most prominent of symptoms for ash yellows and can result in substantial dieback which leads to premature death of the trees. Trees may show slow twig growth and short internodes among the twigs causing a tufted appearance of foliage and thinning of the overall crown. The symptomatic leaves can be stunted, chlorotic (yellow coloring,) have upturned margins, and premature autumn color. When the branches are slow growing laterally, another symptom is deliquescent branches which lose their apical dominance. Additionally, the branches can have severe dieback. The tree may develop witches broom at the trunk collar and occasionally in major branches as well.[图片]Green ash can have similar symptoms as white ash but usually less severe. Green ashes can develop witches broom at the base of the tree without the other symptoms. Green ash appears to tolerate ash yellows better than white ash. Observation of the trees’ conditions is very important since adverse environmental conditions can cause similar decline in ash trees as ash yellows. Some environmental factors to look out for are mechanical damage, drought stresses, insect infestations, and parasitic fungi. The witches broom can be diagnostic of the ash yellows but this symptom is not always present with infected ash trees.[图片]Ash decline can be caused by both ash yellows and other environmental factors, mentioned above. Ash decline is typified by growth reduction and crown dieback. Both ash yellows and environmental factors can work together to cause the premature death of the ash tree in as little as 2 years or as many as 10 years once symptoms occur. Molecular method tests such as polymerase chain reaction (PCR) are available in diagnostic labs for the ash yellows phytoplasma. At this point, the presence of witches broom is the most reliable diagnostic symptom in the field but not all infected trees have them. Integrated Pest Management Strategies 1. Remove the tree. There is no cure for ash yellows. Remove any trees that have severe dieback over 30 to 50% of the crown and decline since the tree will not recover. 2. Improve the vigor of the tree. Although there is no known cure for ash yellows or decline, improving the growing conditions of your tree by watering during drought or fertilizing the tree in the fall can help the tree to live longer and look better.[图片]3. Choose trees suited to the growing conditions. Do not plant ash trees in drought prone areas and reduce competitive plants. Plant a diverse group of trees including other types of trees besides ash trees. 4. Plant more resistant trees. Plant other ash trees besides white and green ash. Some cultivars that have shown to be more resistant to ash yellows are Fraxinus pennsylvanica ‘Bergeson,’ ‘Dakota Centennial®’, ‘Patmore,’ and Fraxinus americana ‘Autumn Applause.’
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玲儿
2017年09月19日
玲儿
ベゴニア・センパフローレンスの育て方・栽培方法 育て方のポイント 栽培環境・日当たり・置き場 日当たりと風通しのよい場所で育てます。春から日ざしに慣らしてきた株は夏の強い直射日光にも耐えますが、急に強い日ざしにさらすと葉焼けを起こすので、夏は建物の東側などで管理します。 また、梅雨明けの前後で環境ががらりと変わると、一時的に見苦しくなりますが、軽く切り戻しておけば、秋には回復します。 耐寒性はないので、晩秋まで楽しんだら処分するか、あるいは霜が降りる前に室内に取り込み、日当たりのよい窓辺で管理すると冬越しします。 水やり 庭植えの場合は、植えつけ後にたっぷりと与え、その後は雨にまかせます。ただし、真夏は表土がよく乾いたら、早朝にたっぷりと水やりします。 鉢植えの場合は、表土が乾いたら鉢底から流れ出るくらいたっぷりと水やりします。真夏と冬の水やりは過湿にならないよう注意します。 [图片]肥料 用土にはあらかじめ緩効性化成肥料を元肥として混ぜておきます。夏と冬を除き、生育旺盛な株には緩効性化成肥料を置き肥するか、液体肥料を施します。生育が衰えている株には肥料は施しません。 病気と害虫 病気：灰色かび病、うどんこ病 長雨の時期には灰色かび病が、春と秋にはうどんこ病が発生しやすいので、株が蒸れないように注意し、湿度が高いときには葉にかからないように水やりします。 害虫：アブラムシ 春と秋にアブラムシが発生しやすいので注意します。 用土（鉢植え） 水はけがよく、通気性に富み、適度な保水性のある土が適しています。市販の草花用培養土6、腐葉土3、牛ふん堆肥1の割合で配合するとよいでしょう。 [图片]植えつけ、 植え替え 春から初夏、または秋に行います。鉢植えで、土が古くなって水はけが悪くなった株や、根がよく張っている株は、根鉢のまわりの硬くなった土を落とし、新しい用土で同じ大きさの鉢、もしくは二回り大きな鉢に植え替えます。根腐れ気味の株は、古い土と腐った根を落とし、新しい用土を用いて一回り小さな鉢、もしくは同じ大きさの鉢に植え替えます。 ふやし方 春から初夏、または秋にさし木でふやします。株の先端部でも、途中の部分でもさし木ができますが、開花した節には葉芽がないので、必ず葉芽のある節を選んでさし穂をつくります。 [图片]主な作業 花がら摘み：雄花は自然に落ちるのにまかせればよいですが、葉の上に落ちると病気の原因になるので取り除きます。雌花が終わったら花柄のつけ根から折り取ります。 切り戻し：草姿が乱れたときに切り戻しますが、夏前に深く切り戻すと暑さで株が弱るので、軽く切り戻す程度にとどめます。9月になれば株元からわき芽が吹いているので、それを残すように枝を整理します。
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Dummer. ゛☀
2017年09月19日
Dummer. ゛☀
Anthracnose is a group of related fungal leaf and stem diseases that infect shade trees. Maple anthracnose is not the same disease as oak anthracnose, although the symptoms of these diseases may be quite similar. Anthracnose diseases generally infect the leaf veins and cause death of the vein and surrounding tissue. Control of anthracnose diseases follows the same procedure for all shade trees affected. The disease does not cause the death of the host but may reduce growth over successive seasons of complete defoliation.[图片]Symptoms and Diagnosis Irregular, light brown spots of dead tissue develop along the veins of the leaves. Affected plants may have the appearance of being sun-scorched. Sunken cankers containing fungal spores develop on infected twigs of some trees, such as sycamore. Life Cycle Anthracnose fungi overwinter on fallen leaves and twigs that were infected the proceeding year. Infection is favored by cool, moist weather in the spring of the year. Infection can occur on the vulnerable young leaves when there is a film of water on the leaf surface. Infection is typically more severe on the lower third of the tree, where the humidity is the highest.[图片]Integrated Pest Management Strategies 1. Collect and destroy infected leaves as they fall. Infected leaves and twigs that remain in the vicinity are a source of spores for new infections in the spring. 2. Prune out dead branches. Be sure to clean all garden tools to avoid the spread of the disease. A 1–part bleach to 9–part water solution can be used to dip tools into between cuts. 3. Promote air circulation. Thin out excessive twig and branch growth. This will reduce the period of time that leaves are wet and vulnerable to inoculation.[图片]4. Keep trees growing vigorously. Supply 1–2 inches of water weekly only during dry periods. Fertilize early in the spring or in late fall. 5. Spray with a fungicide when leaves are beginning to enlarge from the buds. Reapply at 7–10 day intervals for two or three more times. Fungicide sprays are most appropriate for younger, newly transplanted trees that may not be able to withstand defoliation. The available fungicides are preventive, not curative, and therefore, must be applied before spotting occurs. Commonly used products include copper, chlorothalonil (Daconil), captan, ferbam, mancozeb, maneb, and thiram. Your pesticide choice should be based on the particular problem you are seeking to control. Consult an arborist for difficult situations and where power equipment is required.
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玲儿
2017年09月19日
玲儿
ベゴニア・センパフローレンスの基本情報 学名：Begonia Semperflorens-cultorum Group 和名：四季咲きベゴニア　　 科名 / 属名：シュウカイドウ科 / シュウカイドウ属（ベゴニア属） 特徴 ベゴニア・センパフローレンスはベゴニア属のなかでも最もなじみのある種類です。開花期間が長く、春から霜が降りる晩秋まで咲き続けます。さらに暖地であれば、軒下などで冬越しすることもあります。 街角や公園で花壇苗として多く利用され、小柄な草姿に鮮やかな花色がメリハリのある模様をつくり出します。コンテナの寄せ植えにも使いやすい植物です。 春を中心に、花のついたポット苗が手ごろな価格で園芸店に並ぶので、それを5月に植えつけます。市販のタネを春にまいても夏から開花します。 なお、普及種のセンパフローレンスとは異なりますが、‘ドラゴン・ウィング’や‘ビッグ’といった草丈50cm以上に伸びる大柄なタイプもあり、性質がほぼ同じなので、ここではセンパフローレンスの仲間としています。 [图片]種類（原種、園芸品種） 「ダブレット」シリーズ Begonia Semperflorens-cultorum Doublet Series つやのある銅葉と、花色とのコントラストが美しい。八重の小輪花をやや下向きに咲かせる。コンパクトにまとまるので、鉢植えで楽しむ。 [图片]‘ルルカ’ Begonia Semperflorens-cultorum ‘Luluca’ 緑葉に白い斑が涼しげ。成長が緩慢なので、形がくずれることが少なく、鉢植えで楽しむとよい。 ‘ココナッツ・アイス’ Begonia Semperflorens-cultorum ‘Coconut Ice’ 八重咲きでは珍しい覆輪花。大株になるので、夏の前後に切り戻しを行うとよい。 ‘ドラゴン・ウィング’ Begonia Semperflorens-cultorum ‘Dragon Wing’ 節間が大きく、草丈が50cm以上に伸び、大きめの花が5〜8輪房になって咲く。暑さに強く、真夏も元気に咲き続ける。庭植えまたは大鉢で育てると豪華。 [图片]
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Dummer. ゛☀
2017年09月19日
Dummer. ゛☀
Algal leaf spot is a foliar disease most commonly seen in warm humid climates or in greenhouses. The causal organism is Cephaleuros virescens, a green parasitic alga whose usual hosts are plants with leathery leaves such as cotoneasters, magnolias, hollies, rhododendrons and viburnums. Algal leaf spot is sometimes called green scurf because the spots may have a crusty, fuzzy or flaky appearance.[图片]Symptoms and Diagnosis Algal leaf spot is characterized by grayish, green, brown or orange cushion-like blotches on the leaf surface. Some hosts may also have diseased twigs and branches that are girdled and stunted with reddish brown fruiting bodies. The spots are generally 1/2 inch or less in diameter although they may coalesce to form larger colonies. Leaf tissue may die beneath the spots and the leaves may yellow and drop prematurely.[图片]Life Cycle During wet weather, the algae produce spores that are spread by wind and splashing rain. The spores infect leaf tissue causing small, greenish circular spots that may age to light brown or reddish brown. The spots may appear raised and velvety. The algae will overwinter or survive other unfavorable environmental conditions in leaf spots including those on fallen leaves.[图片]Integrated Pest Management Strategies 1. Encourage healthy plants with good cultural techniques. This disease is most damaging on plants that are already slow-growing or weakened. 2. Clean up fallen leaves and remove diseased leaves from the plant. Good sanitation practices will help control this disease. 3. Promote dry leaves by improving air circulation and drainage. If necessary, selectively prune overcrowded vegetation. Avoid spraying water on the leaves. 4. Use fungicidal sprays containing copper if chemical control is necessary
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Dummer. ゛☀
2017年09月19日
Dummer. ゛☀
The spruce spider mite (Olibonhychus ununguis) is a cool season mite unlike the two-spotted and red spider mite, which are most prevalent during hot, dry weather. It is native to North America and is one of the most destructive spider mites in the US. Its preferred host is spruce (Colorado blue, Norway, Dwarf Alberta, and white) but it will also feed on arborvitae, cedar (Cedrus), dawn redwood, Douglas fir, hemlock, juniper, larch, and pine. It can cause considerable damage early in the season before many gardeners are even thinking about spider mites and again in the fall.[图片]Symptoms and Diagnosis The first indication of spruce spider mite damage is an off-green color, mottling or stippling of the needles; which may not be very noticeable until early or mid summer. Usually older, inner needles are attacked first. Damaged needles turn yellow then bronze in June and fall prematurely. Fine webbing may also be present. In severe infestations, twigs and branches can drop all their needles and die leaving dead areas on the plant. Stressed trees may be killed.[图片]Life Cycle Small reddish-orange, oval or circular eggs overwinter in bud scales, on the bark and on needles. The young hatch in mid March to late April. Feeding begins and continues through the cool, moist days of spring. When hot, dry conditions begin and daytime temperatures reach 80-90 degrees F., activity slows and resting eggs are laid. The young hatch when the cooler days of fall resume. Spruce spider mites are small, 0.5 mm (1/50 inch), but can be seen with a hand lens. The young are pale green when they first hatch but become very dark green to dark brown as they age. Adults have salmon-pink body-spines and legs. The young have only 6 legs but adults have 8. The spruce spider mite overwinters as eggs in bud scales or on the needles and bark of the host plant. There are 7-10 generations a year. Each can be completed in only 3-4 weeks.[图片]Integrated Pest Management Strategies 1. Monitor plants in early spring and again in early fall. Remember, this spider mite is a cool-season mite. Monitoring for the mites and eggs can be done by tapping the branch over a sheet of white paper. Also check for beneficial mites and insects that may be feeding on the spruce spider mites. If beneficial insects are present, let them do the control. Applying a pesticide will kill the beneficial insects and the population of the problem spruce mite can actually increase. Beneficial mites are usually faster moving, are reddish in color, and leave a red stain when crushed. Adult spruce spider mites are green to brown and leave a green stain when crushed. Ten or more mites per sample with few if any beneficials present, usually warrants application of a miticide.[图片]2. Wash the mites and eggs off the foliage with a strong stream of water. A weekly or bi-weekly “washing” of the foliage in spring and fall can help prevent a population build-up. 3. Use insecticidal soaps or horticultural oil. These pesticides are less harmful to beneficial insects that help keep mite populations in check. Needles of blue-needled evergreens sprayed with an oil spray will turn green. The new unsprayed needles, however, will be blue. Soaps do not have this effect on needle color. 4. Apply Neem or a pyrethroid-based pesticide late in the season to kill adults before they lay eggs that will overwinter. 5. If a fall infestation was severe, apply a dormant oil spray in mid winter to kill overwintering eggs.[图片]6. Have the tree sprayed by a certified arborist or tree care professional. Most pesticides available to homeowners are very weak miticides and will not control spruce spider mites well. Stronger miticides are restricted use pesticides and require application by a certified applicator.
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玲儿
2017年09月19日
玲儿
フロックスの育て方・栽培方法 育て方のポイント 栽培環境・日当たり・置き場 鉢植えの場合、パニキュラタ種は、日なたから半日陰、ストロ二フェラ種は日陰、スブラタ種、ドラモンディ種は日なたに置きましょう。特にドラモンディ種は、強く凍らせないように注意したいので、冬は防寒するか、南向きの日だまりに移動させましょう。 庭植えでは、パニキュラタ種は日なたから半日陰の肥沃な場所、ストロニフェラ種は半日陰で、少し湿り気のある場所、スブラタ種は、日なたでかつ過湿にならないように斜面やロックガーデンに植えつけましょう。ドラモンディ種は、日当たりがよく、肥沃で水はけのよい花壇を好みます。 [图片]水やり 鉢植えは、土の表面が乾いてきたら、たっぷり水を与えましょう。スブラタ種は過湿を嫌うので、水を頻繁に与えすぎないようにしましょう。 庭植えは、特にストロニフェラ種は乾燥を嫌うので、真夏に乾燥が続いたらたっぷり水を与えましょう。ほかの種は、ほとんど水を与える必要がありません。 肥料 鉢植えは、3月から6月、9月から10月に、緩効性化成肥料（チッ素N-リン酸P-カリK=10-10-10）を施します。特にドラモンディ種とその交配種は多肥を好むので、定期的に肥料を施して肥料切れを避けましょう。 庭植えへの肥料は、特に必要ありません。 [图片]病気と害虫 病気：うどんこ病、灰色かび病 うどんこ病にかかると4月から6月、9月から10月、葉や茎が小麦粉をかけられたように白くなります。肥料不足や日照不足、風通しが悪いと発生が多くなります。 灰色かび病は6月から7月、9月から10月、雨が続くと発生しやすくなります。風通しをよくし、花がら摘みをこまめにすると発生が少なくなります。 害虫：アブラムシ、ナメクジ、アオバハゴロモ 5月から10月、特に新芽にアブラムシが発生しやすいので、よく観察し、発生したら防除しましょう。 ナメクジは6月から7月、梅雨どきにナメクジの発生が多くなります。昼間は鉢の底や石の下などに潜んでいて、夜に這い出して植物を食害するので、夜に見回ると見つけやすいです。 アオバハゴロモは6月から10月、茎葉に綿がついたようになり、刺激すると素早く飛んで逃げる虫です。風通しをよくすると、発生が少なくなります。 用土（鉢植え） 水はけと水もちのよい土を好みます。特にスブラタ種は、素焼きの鉢に植えたり、鉢底石を入れて水はけと鉢内の通気を図りましょう。赤玉土中粒5、腐葉土3、酸度調整済みピートモス2の配合土に、適量のリン酸分を含む緩効性化成肥料を混ぜて使用します。 [图片]植えつけ、 植え替え それぞれの種類に合った場所に植えつければ、あまり手をかけなくてもよく育つ丈夫な植物です（「栽培環境」参照）。 ふやし方 株分け：パニキュラタ種は、植えつけて2～3年すると株が混み合ってくるので、3月から4月に株を掘り上げて植え替えを兼ねて株分けし、ふやすことができます。ほかに、ストロニフェラ種も5月から6月に、株分けできます。 タネまき：ドラモンディ種は3月から4月、9月から10月に、パニキュラタ種は10月から11月にタネまきをしてふやせます。 根伏せ：パニキュラタ種は、3月から4月に根伏せでふやせます。 さし芽：ストロニフェラ種は5月から6月、スブラタ種は5月から6月と9月に、さし芽でふやせます。 主な作業 切り戻し：6月から8月、梅雨どきに切り戻して茎を短くすることで、風通しを促し、蒸れによる病気の発生を防ぎましょう。また、パニキュラタ種は花が少なくなったら切り戻すと、二番花が咲きやすくなります。 花がら摘み：花後、花びらは自然に落ちますが、あとに萼や花がらが長く残ります。放置すると病気の発生源になるので、特に3月から10月はこまめに取り除きましょう。
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