How to grow China asters? Growth characteristics and key maintenance and care points explained
China asters are common flowers in our daily life, with many varieties divided into dwarf, medium and tall types; China asters with diverse flower shapes have the characteristics of rich flower colors, a long flowering period and good ornamental effect.
At present, dwarf China asters are mostly grown in pots, courtyards and gardens, while tall varieties are used as cut flowers for ornamental display. During the flowering period, some can be gathered and placed in a vase on a windowsill or tea table, and the spherical China aster placed in a study looks super cute.
Growth characteristics of China asters:
China aster belongs to the Asteraceae family and is an annual or biennial herbaceous plant. China asters have dwarf, medium and tall varieties. Height (15) 30-100 cm. The stem is upright, the leaves are ovate or oblong, and the inflorescence is a capitulum. Petals come in colors such as pale white, pale red, yellow and blue-purple. The corolla of the bisexual flowers is yellow. The achene is oblong-obovate-lanceolate, slightly flattened, and the flowering and fruiting period is from May to October.
Maintenance and care of China asters:
1. China asters love sunlight, but they are not tolerant of cold or heat. They like humid air, but fear waterlogging in the soil. Therefore, during care, light and water must be well controlled and must not be excessive.
2. China asters are shallow-rooted plants, so in dry seasons special attention must be paid to the timeliness of water supply.
3. Potted China asters should be repotted with new soil once a year. During the growing period, keep the potting soil moist, but do not let it become waterlogged, and drain promptly in the rainy season. They like fertilizer; apply a nitrogen-phosphorus-potassium water-soluble fertilizer every half a month, and stop nitrogen fertilizer after flower buds appear. A phosphorus and potassium water-soluble fertilizer can be applied to promote more and brighter flowers. Also frequently loosen the soil around China asters to help the roots absorb water and fertilizer and grow strong!
The above are the key maintenance and care points for China asters compiled by the editors of Huinong Network. It is worth noting that China asters are prone to pest and disease damage under high temperature and high humidity, which can occur from the seedling stage to the flowering stage, so flower lovers should pay attention to prevention.
Key points for autumn care of courtyard flowers
Key points for autumn care of courtyard flowers
(1) Characteristics of autumn climate. According to traditional customs in our country, around August 8 on the Gregorian calendar is the day of "Start of Autumn" in the Chinese lunar calendar, which means that from this day until before "Start of Winter" in early November is "autumn."
In East China, the average daily temperature in autumn is generally between 10 and 22 degrees Celsius, which is favorable for plant growth. But autumn is also a transitional season from summer to winter, and the temperature changes greatly. In early autumn, the highest temperature is still above 30 degrees Celsius, and can even reach 35 degrees Celsius; while in late autumn, the lowest temperature can be below 0 degrees Celsius.
In this season, the warm and humid southeast wind from the Pacific Ocean will gradually be replaced by the cold and dry northwest wind from the northwestern plateau. When the northwest wind forms and breaks out southward, the surface atmosphere is controlled by cold air, while the upper layer is controlled by subtropical airflow, creating the clear and crisp autumn weather.
Autumn is also an important turning point in plant growth. Many herbaceous flowers have already passed their flowering period, their seeds have matured, and their life cycle has ended, so seeds need to be collected and sown to prepare for the next round of the life cycle. The growth of perennial flowers and trees begins to slow or stop, and some trees begin to shed leaves and will enter dormancy to get through the cold winter. Meanwhile, another group of winter flowers that go dormant in summer, such as cyclamen, primrose and calla lily, begin to wake up and enter a new peak growth period, so water and fertilizer must keep up.
(2) Daily management of autumn flowers
① Management methods: In autumn, for flower growers, in addition to continuing summer daily management such as watering and fertilizing, there are also many "special" tasks to do as the climate changes.
Early autumn: At this time, the high temperatures of summer have not completely retreated, especially the midday heat, which is still a threat to flowers and trees. Therefore, the summer shade curtains should not be removed in a hurry; just open the curtains in the morning and evening to let in light and air, and keep shading at other times. Some flowers should receive even more special attention.
For orchids, keep a humid and cool environment, and it is best to spray water 2 to 3 times a day, with the spray in mist form, until the leaf surface is moist. More water should be sprinkled on the balcony, ground or sand bed to help lower the temperature and prevent the threat of the "autumn tiger."
For lotus planted in vats in summer, although the flowers have completely faded, sufficient water and light should still be ensured. Once the seed pods mature, they can be picked off so the lotus rhizomes can continue to grow, ensuring lush blooms the following year.
For kumquat, an excellent plant for winter fruit display, when it blooms for the third time, do not let rain fall directly on the flowers, so as to ensure the fruit-setting rate.
The flower buds of rhododendrons are differentiating, so reduce watering and apply more phosphorus fertilizer to ensure vigorous blooming next spring.
Cyclamen and mature clivia can be repotted and given fresh soil to ensure the potting soil is loose and nutrient-rich, and to prevent blind flowers or flower buds stuck between the leaves.
Geraniums, the darlings of the balcony, after a summer of continuous growth and flowering, also need repotting and fresh soil, as well as branch pruning and shaping. Branch pruning means cutting off the flowering branches, leaving only stubs about 10 cm high at the base to encourage new branches to sprout and keep the plant shape strong and beautiful. Within 1 week after pruning, do not water or fertilize to prevent infection of the cut surfaces.
Chrysanthemums should be pinched for the last time, and more topdressing should be applied at the same time, until flower bud differentiation.
Mid-autumn: At this time sunlight gradually weakens, the summer heat has dissipated, and the temperature drops noticeably. Flowers and trees that were shaded in summer should gradually have their shading time reduced or the curtains removed.
As the temperature decreases and sunlight weakens, the water and fertilizer consumption of ordinary flowers and trees also decreases accordingly. The frequency of watering can be changed from twice daily in summer to once every 1 to 2 days or once every 2 to 3 days, and the frequency of fertilizing can also be changed from 1 to 2 times per week to once every 1 to 2 weeks.
At the same time, special attention should also be paid to the following matters:
First, after camellias form buds, apply phosphorus fertilizer once to ensure bright flowering the following year.
Second, after calla lilies go dormant, new leaves are just emerging, so watering requires special care; do not pour water into the leaf sheaths to prevent rot.
Third, for kumquat, the "good fruit of the New Year," fertilize frequently, preferably with fermented soybean cake water and bone water or a mixture of turtle belly and intestines, to ensure sufficient water and fertilizer and achieve abundant fruit.
Fourth, early September is the suitable time for artificial hybridization of dahlias, so artificial pollination should be carried out promptly.
Fifth, for stump bonsai such as plum, elm and hackberry, this is an important time for shaping and styling. Leaves can be picked and branches wired, and thin fertilizer applied to encourage new leaves. After the leaves are uniform, prune again into a flat shape.
Late autumn: Around October 8 is Cold Dew, and around the 24th is Frost's Descent. Sunshine gradually shortens, autumn colors fully appear, and the average daily temperature is generally below 10 degrees Celsius. Once a cold wave arrives, nighttime temperatures can drop below 0 degrees Celsius, with frost or frost damage. At this time, be sure to always pay attention to weather forecasts and promptly do the work of moving flowers and trees indoors and protecting them from the cold.
In late autumn, it is necessary to get the timing right for moving plants indoors, moving flowers and trees placed on balconies or in the open to indoor winter quarters, commonly called "moving indoors." Whether the timing of moving indoors is accurate or not has a great bearing on whether flowers and trees overwinter safely. If moved indoors too early, the indoor temperature is too high; if moved indoors too late, the flowers and trees will suffer cold damage and may even freeze to death. Therefore, for flower growers, "moving indoors" is also a major matter that cannot be handled carelessly. Moving indoors should be carried out in batches according to the different temperature requirements of different types of flowers and trees.
Tropical flowers and trees such as Aglaia odorata, lucky bamboo, Brazil wood, cordyline and croton, commonly called high-temperature-type flowers and trees, have the poorest cold resistance. Generally, once the normal temperature is below 10 degrees Celsius, they are prone to cold damage, ranging from leaf drop, flower drop, fruit drop and shoot tip damage to death in severe cases. Therefore, such flowers and trees are best sent to a greenhouse for foster care before winter arrives. If foster care is not possible, they should be moved indoors before the temperature falls below 10 degrees Celsius and placed in a warm, sunny spot. Open windows for ventilation at noon on sunny days, and when a cold wave comes, use insulation measures such as double potting and plastic bags. In the coldest weather, heating measures are needed.
Carnations, clivia, asparagus fern, jasmine and cacti, commonly called medium-temperature-type flowers and trees, are difficult to keep safe below 5 degrees Celsius. Therefore, when the nighttime minimum temperature is 5 degrees Celsius, they should be moved indoors. When the weather is too cold, bagging protection is also needed.
Camellias, rhododendrons, orchids, sago palms and banana shrubs have relatively good cold tolerance, so if there is no frost or rain or snow, there is no need to rush to move them indoors. However, if the low temperature is below 0 degrees Celsius, they should be moved indoors and placed in a south-facing room, where they can generally overwinter safely.
Five-needle pines, Buddhist pines, crabapples and Chinese roses, commonly called low-temperature-type flowers and trees, have relatively good cold tolerance and generally do not need to be moved indoors; they only need to be placed in a warm, sunny spot outdoors. Once severe frost or rain or snow occurs, temporary covering with straw curtains is enough for protection.
Management after flowers and trees are moved indoors is also very important. After being moved indoors, water consumption decreases. Generally, small pots should be watered once a week, and larger pots once every 1 to 2 weeks. If the potting soil is not very dry, the watering interval can be extended further. Apart from winter-blooming flowers and trees such as bird of paradise, cyclamen and clivia, which need sufficient water and fertilizer plus extra phosphorus fertilizer, autumn-sown herbaceous flowers that bloom in early spring the following year also need frequent fertilizer and ample water. For ordinary flowers and trees moved indoors to avoid the cold, it is enough to fertilize once every 1 to 2 months or simply stop fertilizing, so as to avoid excessive fertilizer causing leggy growth and reducing cold resistance.
October is the best time to transplant or divide spring orchids, and orchid growers must not miss this opportunity. At this time, the growth vigor of orchids is relatively reduced, and if the flower buds are not damaged during operation, flowering the following year will not be affected. To make division convenient, watering can be controlled several days before division to let the potting soil dry appropriately, making the roots whitish and softer, so that during transplanting or division the roots are less likely to break. But do not let them become too dry; excessive dryness is also bad for orchid growth.
② Autumn harvest and autumn sowing: Autumn is also the season for propagating nursery plants. As the saying goes, spring flowers are sown in autumn. A large number of spring flowers such as cineraria, cyclamen, pansy and corn poppy need to be sown at this time, and seedling-stage management must be done well.
As the saying goes, good seed makes good seedlings, and sowing must begin with seed collection. How can the best seeds be collected? Generally speaking, during the full flowering period of flowers and trees, the climate is suitable and nutrients are sufficient, so the seeds produced are naturally of better quality. Therefore, grasping the accurate seed collection time is the first rule. Of course, even among the same batch of seeds, there will be individual differences. For home flower growing, the amount of seed used is not large, so the method of selecting seed by seed can be used, keeping those seeds that are well developed, regular in shape and plump and full.
According to the different maturity times of different seeds, we can collect the following seeds in each season.
Seed collection: In early autumn, seeds that can be collected include peony, large-flowered purslane, zinnia, iris, redbud, bridal wreath spirea, cypress vine, lily, mimosa, centella, water lily, coreopsis and lotus. In mid-autumn, seeds that can be collected include cypress vine, morning glory, balloon flower, zinnia, spider flower, iris, petunia, Chinese peony, mallow, amaranthus tricolor, okra, Emilia sonchifolia, strawflower, periwinkle, cockscomb, mimosa, canna, Lilium concolor and Lychnis senno. In late autumn, seeds that can be collected include morning glory, cosmos, okra, hosta, marigold, scarlet sage, four o'clock flower, magnolia, forsythia, wisteria, weigela, camellia, crape myrtle, Cucurbita pepo, ornamental pepper, China aster, lycoris, torch lily, autumn anemone, Sinojackia xylocarpa, dogwood and goji.
Different seeds vary greatly in lifespan. Some need to be stored for a period and undergo full dormancy before they can germinate, such as Sinojackia xylocarpa. Some need to be sown immediately after collection, otherwise their germination rate will decrease, such as the seeds of peony and Chinese peony, which must be sown immediately after collection or stored in sand. For example, water lily seeds must be stored in water. Generally, seeds of flowers and trees, after being collected and dried, are placed separately in small paper bags or cloth bags and stored on top of cabinets or in drawers, and can be taken out and used when it is time to sow.
Sowing: In early autumn, flowers and trees suitable for sowing include peony, primrose, cineraria, hollyhock, dianthus, pot marigold, pansy, daisy, snapdragon, campanula, stock and wallflower. In mid-autumn, flowers and trees suitable for sowing include hosta, balloon flower, China aster, cornflower, pot marigold, hollyhock, mallow, stock, petunia, snapdragon, primrose, nasturtium, verbena, pansy, cineraria and cyclamen. In late autumn, sowing of biennial herbaceous flowers should already be finished, and a small number of perennial woody or bulbous flowers and trees, such as cyclamen and nandina, can be sown in pots.
Autumn sowing can be divided into two methods: open-field sowing and indoor sowing. For herbaceous flowers with strong cold tolerance such as daisy, corn poppy, pot marigold and pansy, open-field sowing is generally suitable, and the method is the same as spring sowing. For flowers with poorer cold tolerance such as primrose, cyclamen and clivia, indoor sowing is used. The containers for indoor sowing can be sowing boxes or sowing pans. Generally, a dedicated sowing box is nailed together from wooden strips, about 10 cm high and 40 to 60 cm long and wide. If there is a suitable-sized packaging box at home, it can also be used instead. A sowing pan is a clay pan with a mouth diameter of 30 cm, a height of 10 cm and many round holes in the bottom (available at flower markets). The specific operation steps for sowing are as follows:
Step 1: First cover the round holes in the bottom of the pan with broken tile pieces, and spread a layer of broken tile granules at the bottom (break a broken clay pan into bean-sized granules) or cinders and charcoal crumbs, 3 to 4 cm thick, to facilitate drainage.
Step 2: Fill the upper part with sterilized potting soil (usually mixed from 3 parts humus soil, 1 part garden soil and 1 part sand), filling to a height 1 cm from the pan mouth, and pat level gently with a pressing board.
Step 3: Sow the seeds evenly. The sowing method can depend on the size of the seeds. For tiny seeds such as primrose, mix in some potting soil, mix evenly, and sprinkle evenly on top. For larger seeds such as clivia and cyclamen, place them one by one at a spacing of 1 to 2 cm, pressing slightly when placing so that half of each seed enters the soil and half is exposed, then use a fine sieve (a discarded window screen can be used at home) to sift a layer of quartz sand to cover the seeds.
Step 4: Take an ordinary plastic basin, fill it half full with water, put the sowing pan into the water, and let the water slowly seep into the pan from the bottom holes until the surface is entirely moist, then take it out and place it in a shaded, ventilated spot on the balcony. Cover with glass to keep warm and moist. Be careful to turn the covering glass every day so that the condensed water on its surface evaporates, and leave a small gap to let the potting soil breathe. If the potting soil dries out, spray a little water. After the seedlings emerge, gradually remove the covering glass, then gradually move them to a sunny spot (note: gradually, not all at once into strong sunlight, otherwise they will be scorched). According to whether the potting soil is dry or wet, water promptly with a fine watering can. After the seedlings produce true leaves, use a fine bamboo stick to gently remove the overly dense and poorly growing seedlings, leaving strong, uniform good seedlings. When the seedlings have 3 to 4 true leaves, they should be transplanted into pots.
Methods for sterilizing potting soil include using a dedicated oven. At home, sterilized bagged potting soil can be purchased; the soil can also be spread flat on rooftop concrete on a sunny day and exposed to the sun for 1 to 2 days; or placed in an iron wok and stir-fried over high heat for half an hour; or sprayed with 0.5% potassium permanganate water, then tightly covered with plastic film and left to sit for half a day, then the plastic film removed and the soil used after 1 week. When sowing, to prevent dust from flying, a small amount of water can first be sprayed into the potting soil to make it slightly moist, but the water must not be too much, otherwise the soil becomes sticky and difficult to work with.
Most herbaceous flower seeds do not need any treatment before sowing and can be sown directly. However, some seeds have thick, hard seed coats or are waxy, such as cyclamen, and are best treated before sowing to promote germination and sterilize them. The treatment method is soaking in water. For seeds with thicker seed coats, warm water can be used for soaking (water temperature around 60 degrees Celsius). The soaking time is generally 24 hours as a standard, and after sowing more water should be sprayed to keep them moist. In addition, for seeds with hard seed coats such as lotus, one end of the seed coat can be filed open with a file, then soaked. For seeds purchased from other places, in order to prevent diseases infecting the seeds from spreading locally, soak them in 0.5% potassium permanganate or 0.3% copper sulfate solution for 5 minutes, then take them out, rinse clean with clear water and sow.
Some herbaceous flowers, such as primrose, pocketbook plant and cineraria, need transplanting after sowing. Others are not suitable for transplanting, such as corn poppy and California poppy. These flowers and trees have overly delicate root systems and tend to grow poorly after transplanting, so when the seedlings first put out true leaves, they must be potted into small pots 13 cm in diameter, and after they grow a little larger, removed from the pots and planted in place, or the direct sowing method can be used.
(3) Prevention and control of autumn flower pests and diseases. In autumn, high temperature and dryness make it a peak season for flower leaf spot disease and powdery mildew.
Leaf spot disease is caused by fungi and includes black spot, brown spot and red spot, often occurring on leaves and fruits. In the early stage of the disease, round spots of varying sizes can be seen on leaves or fruits, fading green and turning yellow, with a clear outline around the outer edge. Mold layers or small black grains often appear on the spots, and in the later stage the diseased part necroses.
Powdery mildew is also caused by powdery mildew fungi and mostly occurs on leaves, young fruits and tender branches. The spots are nearly round, with a thin layer of white powder appearing on them. In the later stage, many yellow-brown particles the size of pinheads are scattered on the white powder layer. Removing the white powder layer reveals yellow spots on the affected plant tissue. Chinese roses and dahlias are prone to this disease.
The fundamental method for preventing and controlling the above diseases is to pay attention to hygiene, thoroughly eliminate the source of disease, and promptly clean up dead branches and fallen leaves inside and outside flower pots and on balconies and courtyards. If a large number of flowers are grown, 50% carbendazim wettable powder at 500 to 1,000 times dilution can be sprayed for disinfection. Those growing Chinese peony, peony, chrysanthemum and carnation can also spray 120 to 160 times equal-strength Bordeaux mixture once every 10 days, which can prevent peony red spot disease, carnation leaf spot disease and chrysanthemum brown spot disease.
In addition, applying more phosphorus and potassium fertilizer to flowers and trees to enhance disease resistance is also an effective method. At the same time, pests such as aphids, red spiders and whiteflies are also prone to occur at this time, so plants should be checked one by one. Once found, catch them carefully by hand immediately. When the number is large, spray dimethoate and omethoate to kill them.
Before flowers and trees are moved indoors in late autumn, check pot by pot and branch by branch. If there are scale insect eggs on the branches and trunks, immediately scrape them clean with a bamboo strip. Aphids are relatively large and easy to find, while red spiders are extremely small and mostly on the undersides of leaves, making them hard to notice. Therefore, check the undersides of leaves plant by plant. If small white spots are found, immediately spray with a dimethoate preparation to kill them, or wash with a tobacco infusion (soak about 20 cigarette butts in a bowl of water for 24 hours, then add some soapy water or laundry detergent and mix) and rinse clean with clear water after washing.
If fertilizer, water and everything else are normal but the plant seems to be growing poorly, you should suspect whether there are pests harming it in the soil. The simplest and most effective method is to repot and inspect, checking whether there are cutworms, ants, earthworms, etc. in the soil. If there are, remove them promptly. When repotting, mix some carbofuran into the soil (for a flower pot 20 cm in diameter, about one small plastic spoon is used), or use 2 tablets of "Baihualing" sold in stores, crush them and mix into the soil, which also has a very good sterilizing and insect-killing effect.
What needs special mention here is that in home flower growing, pests and diseases should be checked frequently, discovered early and controlled promptly, using manual capture or water rinsing as much as possible. When pesticides must be used, non-toxic and low-toxicity pesticides should be used as much as possible, and spraying pesticides indoors is absolutely prohibited.
Key points for spring care of courtyard flowers
Key points for spring care of courtyard flowers
(1) Characteristics of spring climate. In early spring, temperatures begin to rise, but very slowly. Although a "little Indian summer" may appear in early March, cold waves still often invade, causing cold and overcast weather. Generally, only by mid-to-late April can the temperature stabilize above 10 degrees Celsius without major fluctuations. In some years, spring rain is continuous and light is insufficient, which increases the difficulty of spring care for potted flowers and requires doubly careful management.
(2) Do a good job of protecting flowers from the cold. Spring flower care must not be taken lightly. If there is slight negligence, flowers carefully tended all winter can be ruined in an instant. Take the spring snow on March 20, 1998 as an example. From March 17 to 18, the temperature rose noticeably, but on the 19th a strong cold air mass from the north moved south fiercely, with north winds of force 7 to 9, lasting for 20 hours. Then came a moderate snow, with the maximum snow depth along the river area reaching 22 cm. Within 3 days, the temperature dropped by 20 degrees Celsius, and the minimum temperature reached -1.8 degrees Celsius, setting a record for the lowest temperature in mid-March along the river area in nearly 40 years, causing many households' flower growing to suffer losses to varying degrees.
(3) Potted flowers in spring should not be moved out early. Some subtropical flowers, such as jasmine and white orchid, and some imported flowers, such as Belgian azalea and tulip, although they can certainly be moved outdoors when the weather is clear and normal, may inevitably suffer freezing damage when the weather changes strongly, or even lose their leaves and dry to death. In addition, early spring is cold and rainy, and outdoors the soil moisture content is too high, which is not conducive to the sprouting and absorption of new roots and affects germination and leaf expansion. Therefore, potted flowers in early spring should generally not be moved outdoors until after a period when the temperature has stabilized at 10 to 15 degrees Celsius. Do not be fooled by the temporary false climate of a "little Indian summer."
(4) Matters to note before and after potted flowers leave the room. Potted flowers on balconies or indoors grow throughout the winter. In recent years, due to rising living standards, many households have air conditioners or electric heaters indoors, and indoor temperature, humidity, sunlight and air are obviously different from outdoors. Relatively speaking, indoor potted flowers are more delicate. If they are moved outdoors immediately when the weather warms in spring, the plants often cannot adapt to the new environment and wilt. Therefore, when moving them outdoors, they must first be hardened off to enhance resistance and gradually adapt to the changed environment. The specific method is to first gradually move them to a cooler place indoors, open doors and windows more for ventilation and light, gradually increase the spacing between pots, reduce watering, and make the branches and leaves firm, thereby enhancing resistance to sudden changes in the external environment. In short, the plants should gradually adapt to the new environment.
(5) Care after repotting
① Gradually restore light: Because repotting damages the root hairs, to ensure survival, first place the plant in a cool place, and after it grows and develops normally, gradually move it from partial light to full light, except for shade-loving flowers and trees.
② Water at the right time: Water as appropriate according to how dry or wet the potting soil is, and by all means avoid watering every day, to prevent the potting soil from being too wet and causing root rot or triggering pests and diseases.
③ Fertilize according to leaf condition: When leaves turn yellow and shrink, apply an appropriate amount of a dilute, fully fermented mixed liquid of vegetable leaves, fish bones, meat bones and human urine.
④ Pest and disease control: Check frequently and treat promptly.
(6) Prevention and control of spring pests and diseases. Common pests and diseases of spring flowers include powdery mildew, rust disease, black spot disease, leaf curl disease and chlorosis, as well as pests such as longhorn beetles, aphids, scale insects and scarab beetles.
① Powdery mildew: Commonly seen on flowers such as impatiens, cineraria, dahlia, Chinese rose and Hall crabapple, mainly occurring on leaves, and also harming tender stems, flowers and fruits. At the initial stage, multiple faded spots first appear on the leaves, but without obvious edges around them, and later the small spots merge into large spots. As the disease develops, the spots become covered with white powder, the leaves shrink, damaged flowers cannot bloom normally, and damaged fruits stop developing. The disease can occur from early spring and extend through summer until autumn. The control method is: at the initial stage, remove diseased leaves early to prevent spread; when the disease is severe, spray lime sulfur mixture, or 1,000 times 70% thiophanate-methyl liquid.
② Rust disease: Flowers and trees prone to this disease are mostly Rosaceae plants such as Chaenomeles speciosa, including roses and Hall crabapple. In addition, Chinese peony and dianthus are also prone to it. The onset period is early spring. Initially, spots appear on young leaves with loss of green, then small black dots densely grow on them. The spots become orange-yellow round patches, and grayish-white woolly material emerges from the underside. By August to September, yellow-brown powdery material is produced and spreads with the wind to juniper trees. The following early spring it spreads again with rain and harms the above flowers again. Therefore, this disease can continue only by parasitizing these 2 types of plants, and in pest and disease theory it is called a "heteroecious disease." When severe, it causes leaf drop; when mild, it causes spots that affect appearance and photosynthesis. The control method is: try to avoid planting alternate hosts such as juniper nearby; in early spring, around mid-March in the Nanjing area, begin spraying 400 times 20% carboxin emulsifiable concentrate or 50% Tuzet wettable powder, and spray again about half a month later until early April. If spring is dry with little rain, one fewer spray can be used; if juniper is planted nearby, the landscaping department should spray lime sulfur mixture on the juniper trees in mid-March to eliminate the pathogen on the juniper.
③ Leaf curl disease: Mainly occurs on the leaves of Rosaceae plants such as plum and peach. When leaves first unfold in early spring, affected leaves are deformed and swollen, turning red. As the leaves grow, they curl toward the underside, and the spots gradually turn grayish-white, with powdery material appearing on them. Because the leaves are damaged, tender shoots cannot grow normally and may even die. When leaf damage is severe, they fall off, affecting growth vigor and reducing flower quantity. The control method is: at the initial stage, promptly remove diseased leaves showing early symptoms to reduce the spread of the pathogen; before budbreak in early spring, spray lime sulfur mixture to eliminate the pathogen overwintering inside and outside the bud scales and on diseased shoots. If this is done continuously for two or three years, the disease can be controlled fairly thoroughly. For potted flowers with severe disease, apply more fertilizer and strengthen management to restore growth vigor and produce more flowers.
④ Aphids: Also called honey bugs. Many potted flowers are harmed by aphids, such as peach, Chinese rose, elm-leaved spirea, plum blossom and cherry blossom. Aphids mostly gather on the undersides of leaves and live by sucking leaf sap. Because they reproduce quickly, as early spring temperatures rise, damaged leaves cannot unfold normally, new shoots cannot grow, and in severe cases leaves fall off, affecting flowering. In summer high temperatures, some aphids migrate to other plants such as vegetables, and fly back to trees in early winter to lay eggs and overwinter. Control methods include: after budbreak and before leaf unfolding, spray 1,000 times 40% dimethoate emulsifiable concentrate to kill newly hatched young aphids; alternatively, do not spray pesticide first, to protect natural enemies such as ladybugs and let them eliminate aphids, and only consider using pesticide when the predator-prey balance is lost and natural enemies cannot control the aphids. When using this method, manual removal or crushing of aphids should still be used as an auxiliary method.
⑤ Scale insects: There are many kinds of scale insects, many varieties harm flowers and trees, and the damage is relatively serious. Tortoise wax scale is white and waxy, round. White peach scale is white and pointed. Oyster shell scale is dark brown, with males elongated and females round. Gray armored scale is dark brown, round, shaped like armor. Plants susceptible to scale insect damage include camellia, pomegranate, oleander, lilac, rhododendron, hibiscus, cherry blossom, plum, peach, crabapple, Chinese rose, magnolia, banana shrub and Chinese evergreen. The larvae first suck sap on leaves, causing leaves to lose green, and as adults they mostly suck sap on branches and trunks, seriously weakening tree vigor and affecting flowering. Control methods include: crush them by hand or scrape them off leaves and branches with a small knife, and spray 1,000 times 40% dimethoate emulsifiable concentrate 1 to 2 times during the larval stage, with 7 to 10 days between sprays.
⑥ Red spiders: Mites. The bodies are small and difficult to distinguish with the naked eye, mostly gather in groups, and reproduce extremely quickly. Many plants are susceptible, such as Chinese rose, rose, multiflora rose, cherry blossom, rhododendron and lilac. The mites gather on the undersides of leaves and suck sap, first causing leaves to lose green, ultimately causing leaf drop and death of new shoots, and in severe cases weakening plant growth or even causing death. The control method is: at the initial stage, spray 1,000 times 40% dimethoate emulsifiable concentrate, or 1,000 to 1,500 times 40% dicofol emulsifiable concentrate, spraying thoroughly. In summer high temperatures, the mites reproduce faster and control is often too late, so pesticide should be sprayed early and continuously 3 to 4 times, with an interval of about 7 days, and the same pesticide should not be used alone to avoid resistance.
Plants include orchid, carnation, Chinese peony, China aster, gladiolus, narcissus, cyclamen and peony. When pest damage is light, it is often hard to notice. When severe, plants grow poorly and bloom weakly. Because there are many kinds of nematodes in the soil and the bodies are small and almost invisible to the naked eye, prevention should be the main approach. For every kilogram of planting soil, add 20 to 30 granules of 3% carbofuran granule, which dissolves through the soil and releases slowly to eliminate nematodes.
⑧ Caterpillars: Including tent caterpillars and walnut caterpillars. They have very mixed feeding habits and harm almost all plants, and outbreaks occur explosively, so early control is needed. Manual capture can mainly be used, and when necessary spray 1,000 times 40% dimethoate emulsifiable concentrate.
⑨ Carpenter moths: The larvae bore and feed inside branches and trunks, commonly seen in peach, plum and cherry blossom. In severe cases they can bore through and break 2-year-old to 3-year-old large branches, affecting tree shape. The control method is: usually observe carefully. When there are bore holes on branches or trunks and small granular frass is excreted from the holes, use an iron wire to dig and poke along the tunnel from the hole, or cut off the branch to kill the pest. The insect body is reddish-brown, with hair on the head and each segment of the body, clearly different from the milky white of longhorn beetles. This method is also used to control longhorn beetles. In addition, 150 times 80% dichlorvos emulsifiable concentrate can be injected into the frass opening of the tunnel with a syringe, then the tunnel sealed with wet mud to kill the pest.
⑩ Scarab beetles or beetle types: Omnivorous pests that feed on leaves or flowers in early spring. Chinese roses and roses are easily damaged, and manual capture is the main control method.
⑪ Underground pests: White grubs, that is, scarab larvae, white. Cutworms, green-black. They live in the soil by feeding on plant roots or root crowns and often cause plant death. The control method is to dig them out promptly from their entry holes in the soil.
⑪ Underground pests: white grubs, the larvae of scarab beetles, are white. Cutworms are green-black. They live in the soil by feeding on plant roots or root crowns, often causing plant death. The control method is to dig them out promptly from their soil entry holes.