动态第759页 - 绿手指 - 养花技巧、花生病了怎么办、花园打理和设计

2017年09月15日

Slugs and snails feed at night and are easy to spot. They leave behind unmistakeable silvery slime trails and decimated young plants, leaves and flower buds. During the day they tend to gravitate to dark, moist areas of the garden and greenhouse, or hide on the undersides of large leaves and under pots.[图片]Plants affected They feed on a wide range of plants and cause severe damage as they rasp or chew away on leaves, stems, roots, bulbs, tubers, buds, flowers and fruit with their toothed tongue. About Slugs/Snails Slugs and snails are collectively known as garden molluscs. Slugs and snails have many similarities since slugs have actually evolved from snails. Their external shell has been replaced by an internal plate that protects their lungs.[图片]Both are soft-bodied and move using a large muscular foot that slides over a slimy secretion. They have two pairs of tentacles, the lower for smelling and the upper for seeing. Noted for elaborate courtship and mating rituals, they can lay up to 500 eggs during adulthood. Snails can often be seen joined together whilst mating. The field slug, Deroceras reticulatum, this is generally the most damaging slug. It's 3cm to 4cm in length and can be various colours from grey to fawn. It feeds mainly above ground.[图片]The garden slug, Arion hortensis, a dark grey to black slug, up to 4cm long. It feeds above and below ground. Keeled slugs, Milax spp, there are many different species, all are dark grey, brown or black and up to 10cm long and with a distinct ridge or keel running down the back. They live in soil but also feed above ground. Common snail, Helix aspersa, these have a grey-brown shell with darker bands. They are often found near walls, in rockeries and in overgrown herbaceous borders. Snails can live for several years, hibernating in clusters, in dry holes in walls and so on. Round-backed black or brown slugs, Arion ater, these feed on rotting vegetation and therefore don't require controlling.[图片]Treatment Chemical Products containing the following chemical ingredients are all effective on Slugs/Snails Metaldehyde Methiocarb Copper sulphate Ferrous phosphate Aluminium sulphate Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments. Organic Attract slugs and snails by leaving out decaying organic matter, such as lettuce leaves or grapefruit skins. Inspect these after dark then collect and kill molluscs by dropping them into a bucket of salty water. Use copper rings around the base of susceptible plants - these repel molluscs by generating a small electric current. Sink shallow dishes (or purpose-built slug and snail traps) filled with beer to soil level. Slugs and snails are attracted to the beer, become intoxicated and drown.[图片]Sprinkle ashes, soot, sharp sand, crushed nut or eggshells around plants to provide a physical barrier that slugs and snails don't like to cross. You can buy live nematodes, Phasmarhabditis hermaphrodita, commercially. Drench infested areas with this tiny worm which burrows into the body of the slug and infects it with bacteria which kill it. These nematodes aren't effective against snails. Grow plants with rough or hairy leaves which are less palatable or use some young plants as sacrificial specimens in order to discourage the slugs and snails from your favourites. Products containing Ferrous phosphate are acceptable for Organic gardeners as they do not harm other wildlife or contaminate the soil.[图片]Prevention Cultivate growing areas frequently to expose eggs, young and adults to predators such as birds, frogs and hedgehogs. Limit the use of organic composts and mulches around plants, because they're particularly attractive to slugs. Remove objects from growing areas that molluscs can use as daytime refuges, such as logs and large stones.[图片]Encourage natural enemies such as beetles and centipedes by providing overwintering refuges in the autumn. Check your flower beds, pots and lawns at night using a torch and collect the slugs and snails that will be searching around for food.

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2017年09月15日

Small black flies around 2mm long run over the soil surface or fly slowly around houseplants, pot plants and borders. Larvae are small translucent worms, up to 1cm long. They are harder to see but can be found in the immediate area under the soil around the roots. When infestations are heavy, there may be shiny silken threads on the top of the soil.[图片]Plants affected Fungus gnats attack the roots of virtually all houseplants, pot and border plants including vegetables, ornamentals, fruits, fungi and even weeds. About Black fungus gnats Fungus gnats are small flies around 2mm long, which are usually black in colour. They are extremely common pests, usually present around most house and greenhouse plants. There will be many overlapping generations all year round on indoor plants. Each female fungus gnat can lay up to two hundred microscopic eggs after mating.[图片]Eggs are laid into soil around the base of the plant, and hatch after five to seven days. The larvae are no more than 1mm long when they first emerge, but can grow to ten times that before pupating. The larvae are difficult to see with the naked eye due to their small size and translucent bodies. They will hide beneath the soil surface where it is moist, and feed mostly on dead organic matter but can damage seedlings and the base of soft cuttings. Larvae can also survive on patches of mould on greenhouse floors and benches. At room temperature, newly hatched larvae will develop into adults in 20 to 25 days. During hotter times of the year in greenhouses, the lifecycle can be as short as one to two weeks.[图片]Treatment Chemical Products containing the following chemical ingredients are all effective on Black fungus gnats Pyrethroids and Pyrethrin Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments. Organic Place sticky traps between and around the base of plants to catch adults. For indoor plants, the predatory mite Hypoaspis can be applied to the soil. The mites inhabit the just area under the soil surface where fungus gnats pupate.[图片]Water the parasitic nematodes Steinernema feltiae into infested soil. These naturally occurring parasites will infect fungus gnat larvae with bacteria and kill them. Letting the soil dry out partially may help to reduce the larval population in pots. Prevention Practice good plant hygiene by removing any old, dead leaves and fungal growth from the top of pots.[图片]Water plants only when required to prevent the build up of fungal growths. Cover the surface of pots with sand as a barrier against egg laying females.

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2017年09月15日

Leaves, stems, flowers and buds will blacken, shrivel, wilt and possibly die. Fruits can become discoloured, and plants may be covered in a white, shiny frost. Stem and trunk bark may split, and develop cankers as a result of the damage.[图片]Plants affected Potentially all non-hardy plants. About Frost damage can occur anytime between late September to mid May. Regular freezing and thawing of plants weakens cell walls. Ice crystals form inside the plant removing water from the cells, or causing them swell and rupture.[图片]Younger, tender plants are generally more susceptible, although hardier plants can be damaged during severe frosts. Gardens sometimes have areas where cold air collects, commonly called “frost pockets”. Plants infected with viral diseases are often more susceptible to frost damage. When soil freezes, young plants may be squeezed out from beneath the surface. The length of exposure to cold temperatures is often as important and the actual temperature.[图片]Preventing further damage Covering plants with horticultural fleece will reduce exposure to frost. Removing any affected plant material will reduce the spread of disease from the damaged areas. Avoid planting seeds in “frost pockets” in your garden. Choose hardy plant varieties to grow. A south facing wall will provide a warmer micro-climate for tender plants.

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2017年09月15日

When attacks are severe, foliage will be peppered with small holes and pits, and growth may be reduced. The tissue around damaged areas will become dry and discoloured.[图片]Plants affected Many plants from the Brassica family are attacked, as well as a small number of ornamentals. About Adult beetles are up to 3mm long, usually shiny black in colour and may have light coloured stripes down their wing casing. Larvae are small white coloured grubs with brown heads and pairs of fleshy legs. Eggs are tiny opaque yellow elliptical forms, and are laid around plant roots. Adults usually have long, hinged hind legs that enable them to jump like fleas.[图片]Over-wintering takes place as adults, either beneath the soil surface or amongst plant debris around the base of the plant. Adults re-emerge in early spring to feed and mate. During dry periods in April/May, feeding can be severe and may result in plants dying. During this time adults can be seen jumping on and around infested plants. Eggs are laid towards the end of May/ early June, and will hatch a few days later. The larvae will begin to feed immediately after hatching. Mainly on plant roots, although some larvae feed on leaves. Pupation occurs in late summer, with second generation adults emerging during autumn.[图片]Treatment Chemical Rotenone Pyrethrins Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments. Organic Fleeces can be used to protect new seedlings from infestation. Encourage insectivorous birds by hanging boxes and feeders. Use yellow sticky traps to catch adults.[图片]Prevention Flea beetles prefer dry conditions, so keep plants well watered. Remove all plant debris from the base of your plants, to reduce over-wintering sites. Try “trap planting” by growing more susceptible hosts between your primary plants.

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2017年09月15日

Leaves will become a dark brown colour and drop. Blossoms will die back. Fruits will become discoloured and wrinkled. A white slimy substance may excrete from infected areas. [图片]Plants affected Pears, apples, hawthorn, rose About Fireblight Fireblight is a disease caused by a bacteria. It gets its name from the scorched look of infected leaves. The first recorded outbreak in Britain was in 1957. In Northern Ireland, the Channel Islands and the Isle of Man it is a notifiable disease, and any potential or confirmed outbreaks must be reported to DEFRA. [图片]The slime contains the bacteria, which spreads to other plants on insects, birds and other small animals. The bacteria can also be transmitted with garden tools, from water splashes during rainfall or by any other mechanical means. The infection will spread quickly spread throughout a plant, which may die in only a few months. Treatment Chemical There is currently no chemical control commercially available for fire blight. [图片]Organic Remove any infected leaves, flowers and branches and burn them. Sterilise any tools used for removing infected material with a household bleach solution after each cut and always prune or saw into undamaged healthy wood. Avoid planting more trees from susceptible species.

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2017年09月15日

Holes in the leaves giving a lace-work look as caterpillars feed on the soft tissue between the veins. Once the caterpillars are feeding leaf discolouration and rapid defoliation often results as they decimate the crop. Check for adult moths, caterpillars and their frass, or droppings.[图片]Plants affected The whole cabbage family, for example cauliflowers, turnips, kale, rape, Brussels sprouts, broccoli, watercress, but the main host plants are cabbages. Sometimes mustard plants and ornamental cultivated plants can be infested, such as sweet alyssum, wallflower, candytuft and stocks. About Diamondback moth Adult moths are nocturnal, 8mm in length, grey/brown, long and thin in shape with diamond markings on their backs. They often migrate to this country in large numbers from mainland Europe. The green caterpillars grow to 12mm in length and are thicker in the middle of their bodies.[图片]This moth goes through four larval stages before pupating and becoming an adult, over a 15-30 day period. Plant damage is only caused by the caterpillars, with the last stage causing the worst damage. Plants are often stripped bare by heavy infestations. Caterpillars pupate in loosely spun silken cocoons attached to the undersides of leaves. It is the pupal stages that overwinter, although up to six generations can occur each year. Adult moths emerge in May to mate and lay shiny, yellow eggs. Eggs are 1mm in width and are laid on leaves singly or in pairs. If threatened, caterpillars drop off the leaves and hang by a thread.[图片]Treatment Chemical Products containing the following chemical ingredients are all effective on Diamondback moth Pyrethroids and Pyrethrin Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments. Organic Encourage natural predators and parasites. Regular observation of crops to check for damage or infestation. Crop containment, for example, grow in polytunnels, greenhouses or under fleece. Companion planting with marigolds or onions.[图片]Avoid sowing crop at peak breeding times. Water foliage regularly as larvae can be easily drowned. Prevention Thoroughly check, and remove infested plants. Use sticky traps to monitor the first appearance of adult moths.

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2017年09月15日

Dead and wilting young plants, softening and decaying of mature plants. Also the larvae are often found within the root tubers and they are 8-10mm long white coloured maggots.[图片]Plants affected Mainly Onions but other members of the Allium family can also be attacked. About Onion fly Adult Onion Flies emerge from pupae that have over-wintered within the soil. Pupal cases are brown, oval shaped and about 10mm long. Onion flies have several generations a year, the first generation usually emerges about May/June time. The first generation of adults to emerge are able to reproduce within a few days and females then lay batches of eggs onto or nearby onion seedlings. The eggs laid are small, white and elongated, with darker stripes that run longitudinally.[图片]Second and third generations attack the onion sets which will have developed from the seedlings. The damage is caused not by adult flies but by their grey, legless maggot-like larvae (8mm long) feeding on the onion sets and moving from one to another in the soil. Adult onion flies are similar in appearance to house flies however they are grey, slightly smaller and have longer legs. Larvae can often cause secondary damage such as rotting when they bore in and out of the roots. Treatment Chemical Products containing the following chemical ingredients are all effective on Cutworms There are no approved insecticides currently available to amateur gardeners.[图片]Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments. Organic Regular observation of crops to check for damage or infestation and remove any affected plants immediately and incinerate. Keep weeds under control that could be alternative host plants e.g. dandelions. Crop containment e.g. Fleece barrier to stop flying adults, or grow in poly- tunnels. Avoid planting in soils that have un-rotted organic matter present. Plant sets instead of seeds and avoid planting in rows if possible to stop maggots moving from plant to plant. Avoid sowing at peak Onion Fly breeding times.[图片]Prevention Very efficient checks of the crop for any signs of infestation, any prompt removal of any plants affected, use sticky traps to monitor numbers of adults using white and yellow traps. Use biological pest control species to control numbers, such as Predatory Flies – Coenosia tigrina, Wasp sp. – Aphaerata pallipes, Beetle sp. – Aleochara bilineata or the Fungus – Entomopthora muscae.

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2017年09月15日

Clusters of eggs on leaves, small caterpillars feeding inside pea pods, or evidence of the caterpillars entrances into the peapods to feed.[图片]Plants affected Primarily vegetable peas, but also sweet peas, tares, vetches, clover and sometimes cabbage. About Pea moth Adult pea moths are plain grey/ brown in colour with small pale yellow markings on their sides. They are tent-shaped, have a 15mm wingspan and long antennae. Females usually lay their eggs on leaves or flowers during May/ June. Eggs are small and flat and are usually laid in groups over a period of 2-3 weeks. Larvae are small yellow/ white, dark headed caterpillars up to 6mm long, and emerge after about 3 weeks.[图片]Caterpillars wander the host plant for a day before entering a developing seed pod in which they feed for up to a month. Caterpillars emerge from the pods by eating their way out and over-winter in the soil as pupae in silken cocoons. Pea moth larvae are most destructive during July/ August time. There is usually only one generation per year. Treatment Chemical There are currently no chemical controls commercially available for the home garden to control pea moths. Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.[图片]Organic In small outbreaks remove affected Pods by hand and burn. Try to sow peas before or after pea moths have become active and are breeding. Remove any other plants or weeds nearby that are host plants for pea moths.[图片]Preventing further problems Plant peas within netting or under fleece to keep adults out. Try using pheromone traps to dispatch of adults. Encourage natural predators such as birds with feeders.

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2017年09月15日

Stems will be damaged at the base and may be completely severed. Plants will wilt and may die. There may also be damage to leaves, roots and tubers.[图片]Plants affected Many garden fruit, vegetable, and ornamental plants are affected. About Cutworms Cutworms are the larvae of certain species of nocturnal moths. They are widespread throughout the UK. In June and July the moths lay eggs in batches of 30-50 on leaves and stems. The eggs hatch two weeks later. Larvae range from dull grey or brown in colour to green or white. They can reach 2-4cm in length when fully grown. Larvae can be found feeding at night on the soil surface. They cause severe damage by chewing the base of stems, roots, leaves and tubers. After one to two months of feeding they pupate in the soil. A second generation hatches in August and September.[图片]Second generation larvae will over-winter in the soil, coming to the surface to feed when environmental conditions are favourable. Treatment Chemical Products containing the following chemical ingredients are all effective on Cutworms There are no approved insecticides currently available to amateur gardeners. Note: It is important to read manufacturer's instructions for use and the associated safety data information before applying chemical treatments.[图片]Organic Regularly cultivate soil in winter to expose over-wintering larvae to predators. Encourage insectivorous birds by hanging bird boxes and feeders. In greenhouses drench potted plants to bring larvae to the surface, then pick them off by hand. Prevention Use pheromone traps to monitor the presence of moths during June and July.[图片]Avoid planting in known areas of infestation. Keep gardens free from weeds and plant debris as they can be used for egg laying.

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Dummer. ゛☀

2017年09月15日

Wilting plants and yellow/brown patches on lawns. Plants affected Leatherjackets mainly attack grass roots. They will also feed on cereal crops and burrow into potato tubers.[图片]About Leatherjackets Leatherjackets are the larval stage of crane flies. Crane flies, also known as daddy-long-legs, have long thin legs, one pair of wings and a small thin body around 2.5cm long. Males and females can be identified by comparing the tip of their abdomens: males - are blunt whilst females - are pointed. Adults are commonly seen flying from late August to October. Since adults do not feed they cause no plant damage. Mating and egg laying takes place within 24 hours of adults emerging. Females lay their eggs by 'hopping' on the soil surface. Each time they land they insert their pointed abdomen into the soil and deposit an egg. The larvae emerge as small brown grubs. They will begin feeding on root structures of grasses.[图片]During the day the larvae remain under the soil, but on wet nights may appear above the surface and feed on plant stems. Larvae overwinter in the soil until spring, when they begin feeding again. There are four stages of larval development. When they reach full size larvae they can be up to 4cm in length. They pupate in August. The pupae have rows of spines along their sides which enable them to move up and down within the soil during wet and dry periods. Treatment Organic Regular and thorough observation of lawns and plants is essential when wishing to control leatherjackets organically.[图片]Remove by covering small areas of lawn with black polythene overnight after heavy rain or irrigation. The grubs will come up onto the grass and can be removed in the morning. Natural enemies can be released onto the affected plants. The parasitic nematode Steinernema feltiae can be watered into the ground around affected areas. These parasites infect the grubs with bacteria to kill them. Compacting the soil using a heavy roller will make it harder for the grubs to move through it.[图片]Prevention Regularly check lawns and plants for signs of leatherjacket infestation and deal with them as soon as they appear. Encourage insect-eating birds by hanging feeders in the winter months and nest boxes in the spring.

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