What are the flower pests and diseases in autumn? Recognize the commonly occurring types

Autumn is a season when flower pests and diseases occur frequently. The main diseases include leaf spot, black spot, anthracnose, fusarium wilt, and powdery mildew, etc. The main insect pests include scale insects, aphids, thrips, longhorn beetles, carpenter moths, whiteflies, leaf miners, mites (red spider mites, tarsonemid mites), and nematodes, etc. So how should flower pests and diseases be prevented and controlled in autumn?

I. What are the main flower pests and diseases in autumn?

1. Leaf spot

Leaf spot mainly damages camellia, osmanthus, elm, orchid, bromeliad, Buddhist pine, areca palm, etc. The general diseased leaf rate is 15%-30%, and in severe cases it reaches more than 50%.

2. Black spot

Black spot mainly damages Chinese rose, rose, chrysanthemum and other flowers, and the damage is relatively common, with a damage rate of 20%-40%.

3. Anthracnose

Anthracnose damages many kinds of flowers. Common affected flowers include orchid, lucky bamboo, camellia, orchid tree, orange jasmine, rubber tree, white magnolia, clivia, calathea, palm family flowers, etc. The damaged leaf rate of flowers is 10%-30%, and in severe cases more than 90%.

4. Fusarium wilt

Fusarium wilt damages palm family flowers (seedling stage), chrysanthemum, etc.

5. Powdery mildew

Powdery mildew damages crape myrtle, Chinese peony, etc.

6. Scale insects

Scale insects are a relatively common insect pest, often damaging sago palm, areca palm, white magnolia, osmanthus, camellia, banana shrub, orange jasmine, banyan, elm, Fukien tea, palm bamboo, etc.

Under conditions of high planting density or high shade, insect pests occur severely, and if prevention and control are not timely, they may very likely cause leaf drop, dead branches, and even plant death.

7. Mites

There are many kinds of flowers damaged by mites, and common ones include citrus, elm, marigold, Chinese rose, rose, sago palm, bamboo, etc.

Autumn is the peak period of mite damage, and targeted pesticides must be used for timely prevention and control.

8. Thrips

Thrips often damage small-leaved banyan, etc. After transplanting, banyan, heteropanax, sago palm, etc. are susceptible to boring damage by longhorn beetles and carpenter moths, with a general damaged plant rate of 10%-40%.

Whiteflies, aphids, leaf miners and other pests and diseases mainly damage chrysanthemum, Chinese peony, azalea and other flowers.

Nematodes occur relatively commonly in plants and are not easy to detect. The main targets of damage include lucky bamboo, palm family plants, chrysanthemum, etc.

II. Tips for preventing and controlling flower pests and diseases

The prevention and control of flower pests and diseases should focus on prevention, with special attention to avoiding water source pollution that leads to disease outbreaks. After pests and diseases occur, timely targeted treatment must be carried out.

1. Timely clean up diseased and residual branches and leaves in the flower field, use clean and unpolluted water sources to irrigate flowers, and reasonably arrange the layout of various flower varieties in the field to reduce the mutual spread of pest and disease sources and the occurrence of repeated infection.

2. Apply pesticides timely and according to the symptoms.

Disease control: For leaf spot and black spot, pesticides such as thiophanate-methyl, carbendazim, mancozeb, and copper oxychloride can be sprayed for control. For anthracnose, prochloraz, imazalil, or zineb can be used for control. For powdery mildew, dinocap, suspension concentrate, or triadimefon can be used for control.

Insect pest control: For scale insects, methidathion is preferable for control; for mites, pyridaben, propargite, amitraz, etc. are preferable for control; for thrips and whiteflies, imidacloprid, methomyl, etc. can be used for control; for leaf miners, dimehypo, cartap, etc. can be used for control; for nematodes, Miral is used for control. If boring pests occur, in addition to surface spraying of pesticides, methods such as pesticide pouring and mixing with mud for smearing can also be used for control.

Prevention and control of flower pests and diseases in spring

Common flower pests and diseases in spring include powdery mildew, rust, black spot, leaf curl, and chlorosis, as well as pests such as longhorn beetles, aphids, scale insects, and scarab beetles.

Prevention and control methods

<1> Powdery mildew: commonly seen on garden balsam, cineraria, dahlia, Chinese rose, hall crabapple and other flowers. It mainly occurs on leaves, and also damages tender stems, flowers, and fruits. At the initial stage, multiple faded diseased spots first appear on the leaves, but there is no obvious edge around them, and later the small spots merge into large spots. As the disease develops, the diseased spots become covered with white powder, the leaves shrink, affected flowers cannot bloom normally, and affected fruits stop developing. The disease occurrence period can extend from early spring through summer until autumn. Its prevention and control methods include: at the initial stage, remove diseased leaves as early as possible to prevent spread; when the disease is severe, spray 0.2 degree to 0.3 degree lime sulfur mixture, or 1000 times 70% thiophanate-methyl solution.

<2> Rust: Flowers and trees prone to this disease are mostly Rosaceae plants such as Chaenomeles speciosa, including roses, hall crabapple, etc. In addition, Chinese peony and dianthus are also susceptible to this disease. The disease occurs in early spring. Initially, spotted chlorosis appears on tender leaves, then dense small black spots grow on them. Initially, yellow round patches appear on tender leaves, and grayish-white wool-like matter extends from the underside. From August to September, yellow-brown powdery matter is produced and spreads with the wind to sabina chinensis trees. In early spring of the following year, it spreads again with rain and damages the above flowers. Therefore, this disease can continue only through parasitic damage on these two types of plants. In pest and disease theory, it is called "alternate host disease." When the damage is severe, it causes leaf drop; when lighter, it causes spots, affecting appearance and photosynthesis. Its prevention and control methods are: try to avoid planting alternate host plants such as sabina chinensis nearby; in early spring, around mid-March, begin spraying 400 times 20% carboxin emulsifiable concentrate or 50% thiram wettable powder, and spray once more after about half a month until early April. If spring has little rain or is dry, one fewer spray may be applied.

<3> Leaf curl: 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, and the color turns red. As the leaves grow, they curl toward the underside, the diseased spots gradually turn white, and powdery matter appears on them. Because the leaves are damaged, tender shoots cannot grow normally and may even die. If leaf damage is severe, they fall off, affecting tree vigor and reducing flower quantity. Its prevention and control methods include: at the initial stage, timely remove diseased leaves showing early symptoms to reduce the spread of the disease source; before bud break in early spring, spray 3 degrees to 5 degrees lime sulfur mixture to eliminate the disease source overwintering inside and outside bud scales and on diseased shoots. If this can be done for two or three consecutive years, the disease can be controlled relatively thoroughly. For potted flowers with severe disease, increase fertilizer application and strengthen management so that tree vigor can recover and more flowers can bloom.

<4> Aphids: also known as honey insects. Many potted flowers are damaged by aphids, such as peach, Chinese rose, flowering almond, plum blossom, cherry blossom, etc. Aphids mostly gather on the underside of leaves and live by sucking leaf sap. Because they reproduce quickly, as early spring temperatures rise, affected leaves cannot unfold normally, new shoots cannot grow, and in severe cases leaves fall off, affecting flowering. In hot summer, some aphids migrate to other plants such as vegetables, and only in early winter do they fly back to trees to lay eggs and overwinter. Its prevention and control methods include: after bud break and before leaf unfolding, spray 1000 times 40% dimethoate emulsifiable concentrate to kill newly hatched young aphids; alternatively, do not spray pesticide first in order to protect natural enemies such as ladybugs and let them eliminate aphids, and only consider using pesticides when the imbalance in population dynamics means natural enemies cannot control aphids. When using this method, it must still be combined with the auxiliary method of manually picking and crushing aphids.

<5> Scale insects: The scale insects are the most numerous among pests in terms of species and the number of flowers and trees they damage. Tortoise wax scale: white waxy, round. White peach scale: white, pointed. Oyster shell scale: dark brown, males elongated, females round. Armored scale: dark brown, round, resembling armor. Plants susceptible to scale insect damage include camellia, pomegranate, oleander, azalea, rose of Sharon, cherry blossom, plum, peach, crabapple, Chinese rose, etc. The larvae first suck sap on the leaves, causing chlorosis, and by the adult stage they mostly suck sap on branches and trunks, severely weakening tree vigor and affecting flowering. Its prevention and control methods include: crush them by hand or scrape off pests on leaves and branches with a small knife, and spray 1000 times 40% dimethoate emulsifiable concentrate 1 to 2 times during the larval stage, with an interval of 7 to 10 days between sprays.

<6> Red spider mite: a type of mite. The body is small and almost impossible to distinguish with the naked eye. They mostly gather in groups and reproduce extremely quickly. Many plants are susceptible to damage, such as Chinese rose, rose, flowering peach, cherry blossom, azalea, etc. The mites gather on the underside of leaves and suck sap, first causing chlorosis, and ultimately causing leaf drop and death of new shoots. In severe cases, small trees weaken in growth and even die. Its prevention and control methods include: at the initial stage, spray 1000 times 40% dimethoate emulsifiable concentrate, or 1000 times to 1500 times 40% trichlorfon acaricide emulsifiable concentrate. When spraying to kill them, it must be thorough and dense. In hot summer, this pest reproduces quickly, and control is often too late, so pesticides should be sprayed early, continuously 3 to 4 times, with an interval of about 7 days between applications, and a single pesticide should not be used alone to avoid resistance.

<7> Nematodes: Nematodes damage plant roots and cause abnormal plant development. Affected plants include orchid, carnation, narcissus, tree peony, etc. When the pest damage is light, it is often hard to notice. When the pest damage is severe, plants grow poorly and bloom poorly. Because there are many kinds of nematodes in soil and the bodies are tiny and almost invisible to the naked eye, prevention should be the main approach. For each kilogram of planting soil, add 20 to 30 granules of 3% furadan granules, which dissolve in the soil and are slowly released to eliminate nematodes.

<8> Caterpillars: including tent caterpillars, oriental moth caterpillars, etc. They have very mixed feeding habits and damage almost all plants, appearing in outbreaks. They should be controlled early. Manual capture can mainly be used, and when necessary, 1000 times 40% dimethoate emulsifiable concentrate can be sprayed.

<9> Carpenter moths: The larvae bore and feed inside branches and trunks, commonly seen on peach, plum, and cherry blossom. In severe cases, they can bore through 2- to 3-year-old large branches, affecting tree shape. Its prevention and control methods are: usually observe carefully; when there are boreholes on branches or trunks and small granular frass is excreted from the boreholes, use an iron wire to dig out from the borehole along the insect tunnel, or cut off the branch to kill the pest. The insect body is reddish-brown, with hairs 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 insect tunnel from the frass opening with a syringe, and then the insect tunnel can be blocked with wet mud to kill the pest.

<10> Scarab beetles or beetles: omnivorous pests of leaves or flowers. Roses and others are susceptible. Manual capture is the main prevention and control method.

<11> Underground pests: white grubs, namely scarab beetle larvae, white. Cutworms, green-black. In the soil, they live by feeding on plant roots or root crowns and often cause plant death. The prevention and control method is to dig them out promptly from the holes where they enter the soil.

Prevention and control of flower pests and diseases in spring

      Common flower pests and diseases in spring include powdery mildew, rust, black spot, leaf curl, and chlorosis, as well as pests such as longhorn beetles, aphids, scale insects, and scarab beetles.

Prevention and control methods

<1> Powdery mildew: commonly seen on garden balsam, cineraria, dahlia, Chinese rose, hall crabapple and other flowers. It mainly occurs on leaves, and also damages tender stems, flowers, and fruits. At the initial stage, multiple faded diseased spots first appear on the leaves, but there is no obvious edge around them, and later the small spots merge into large spots. As the disease develops, the diseased spots become covered with white powder, the leaves shrink, affected flowers cannot bloom normally, and affected fruits stop developing. The disease occurrence period can extend from early spring through summer until autumn. Its prevention and control methods include: at the initial stage, remove diseased leaves as early as possible to prevent spread; when the disease is severe, spray 0.2 degree to 0.3 degree lime sulfur mixture, or 1000 times 70% thiophanate-methyl solution.

<2> Rust: Flowers and trees prone to this disease are mostly Rosaceae plants such as Chaenomeles speciosa, including roses, hall crabapple, etc. In addition, Chinese peony and dianthus are also susceptible to this disease. The disease occurs in early spring. Initially, spotted chlorosis appears on tender leaves, then dense small black spots grow on them. Initially, yellow round patches appear on tender leaves, and grayish-white wool-like matter extends from the underside. From August to September, yellow-brown powdery matter is produced and spreads with the wind to sabina chinensis trees. In early spring of the following year, it spreads again with rain and damages the above flowers. Therefore, this disease can continue only through parasitic damage on these two types of plants. In pest and disease theory, it is called "alternate host disease." When the damage is severe, it causes leaf drop; when lighter, it causes spots, affecting appearance and photosynthesis. Its prevention and control methods are: try to avoid planting alternate host plants such as sabina chinensis nearby; in early spring, around mid-March, begin spraying 400 times 20% carboxin emulsifiable concentrate or 50% thiram wettable powder, and spray once more after about half a month until early April. If spring has little rain or is dry, one fewer spray may be applied.

<3> Leaf curl: 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, and the color turns red. As the leaves grow, they curl toward the underside, the diseased spots gradually turn white, and powdery matter appears on them. Because the leaves are damaged, tender shoots cannot grow normally and may even die. If leaf damage is severe, they fall off, affecting tree vigor and reducing flower quantity. Its prevention and control methods include: at the initial stage, timely remove diseased leaves showing early symptoms to reduce the spread of the disease source; before bud break in early spring, spray 3 degrees to 5 degrees lime sulfur mixture to eliminate the disease source overwintering inside and outside bud scales and on diseased shoots. If this can be done for two or three consecutive years, the disease can be controlled relatively thoroughly. For potted flowers with severe disease, increase fertilizer application and strengthen management so that tree vigor can recover and more flowers can bloom.

<4> Aphids: also known as honey insects. Many potted flowers are damaged by aphids, such as peach, Chinese rose, flowering almond, plum blossom, cherry blossom, etc. Aphids mostly gather on the underside of leaves and live by sucking leaf sap. Because they reproduce quickly, as early spring temperatures rise, affected leaves cannot unfold normally, new shoots cannot grow, and in severe cases leaves fall off, affecting flowering. In hot summer, some aphids migrate to other plants such as vegetables, and only in early winter do they fly back to trees to lay eggs and overwinter. Its prevention and control methods include: after bud break and before leaf unfolding, spray 1000 times 40% dimethoate emulsifiable concentrate to kill newly hatched young aphids; alternatively, do not spray pesticide first in order to protect natural enemies such as ladybugs and let them eliminate aphids, and only consider using pesticides when the imbalance in population dynamics means natural enemies cannot control aphids. When using this method, it must still be combined with the auxiliary method of manually picking and crushing aphids.

<5> Scale insects: The scale insects are the most numerous among pests in terms of species and the number of flowers and trees they damage. Tortoise wax scale: white waxy, round. White peach scale: white, pointed. Oyster shell scale: dark brown, males elongated, females round. Armored scale: dark brown, round, resembling armor. Plants susceptible to scale insect damage include camellia, pomegranate, oleander, azalea, rose of Sharon, cherry blossom, plum, peach, crabapple, Chinese rose, etc. The larvae first suck sap on the leaves, causing chlorosis, and by the adult stage they mostly suck sap on branches and trunks, severely weakening tree vigor and affecting flowering. Its prevention and control methods include: crush them by hand or scrape off pests on leaves and branches with a small knife, and spray 1000 times 40% dimethoate emulsifiable concentrate 1 to 2 times during the larval stage, with an interval of 7 to 10 days between sprays.

<6> Red spider mite: a type of mite. The body is small and almost impossible to distinguish with the naked eye. They mostly gather in groups and reproduce extremely quickly. Many plants are susceptible to damage, such as Chinese rose, rose, flowering peach, cherry blossom, azalea, etc. The mites gather on the underside of leaves and suck sap, first causing chlorosis, and ultimately causing leaf drop and death of new shoots. In severe cases, small trees weaken in growth and even die. Its prevention and control methods include: at the initial stage, spray 1000 times 40% dimethoate emulsifiable concentrate, or 1000 times to 1500 times 40% trichlorfon acaricide emulsifiable concentrate. When spraying to kill them, it must be thorough and dense. In hot summer, this pest reproduces quickly, and control is often too late, so pesticides should be sprayed early, continuously 3 to 4 times, with an interval of about 7 days between applications, and a single pesticide should not be used alone to avoid resistance.

<7> Nematodes: Nematodes damage plant roots and cause abnormal plant development. Affected plants include orchid, carnation, narcissus, tree peony, etc. When the pest damage is light, it is often hard to notice. When the pest damage is severe, plants grow poorly and bloom poorly. Because there are many kinds of nematodes in soil and the bodies are tiny and almost invisible to the naked eye, prevention should be the main approach. For each kilogram of planting soil, add 20 to 30 granules of 3% furadan granules, which dissolve in the soil and are slowly released to eliminate nematodes.

<8> Caterpillars: including tent caterpillars, oriental moth caterpillars, etc. They have very mixed feeding habits and damage almost all plants, appearing in outbreaks. They should be controlled early. Manual capture can mainly be used, and when necessary, 1000 times 40% dimethoate emulsifiable concentrate can be sprayed.

<9> Carpenter moths: The larvae bore and feed inside branches and trunks, commonly seen on peach, plum, and cherry blossom. In severe cases, they can bore through 2- to 3-year-old large branches, affecting tree shape. Its prevention and control methods are: usually observe carefully; when there are boreholes on branches or trunks and small granular frass is excreted from the boreholes, use an iron wire to dig out from the borehole along the insect tunnel, or cut off the branch to kill the pest. The insect body is reddish-brown, with hairs 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 insect tunnel from the frass opening with a syringe, and then the insect tunnel can be blocked with wet mud to kill the pest.

<10> Scarab beetles or beetles: omnivorous pests of leaves or flowers. Roses and others are susceptible. Manual capture is the main prevention and control method.

<11> Underground pests: white grubs, namely scarab beetle larvae, white. Cutworms, green-black. In the soil, they live by feeding on plant roots or root crowns and often cause plant death. The prevention and control method is to dig them out promptly from the holes where they enter the soil.