Solutions to Common Diseases and Pests of Flowering Plants (Part 1)
People sometimes get sick, and plants are the same. If temperature, humidity, ventilation and other factors are not managed well, plants are very likely to suffer from diseases. So flower lovers should promptly understand and master the common diseases of plants, so as to better grow plants. Below, the editor has compiled common plant diseases and their solutions. Let's learn together.
1. Late spring cold
Late spring cold refers to when daytime temperatures have already reached above 20°C by the end of March, and many friends are eager to move their flowers outdoors for care. But in this season, cold air often moves south from time to time, causing a reversal weather pattern known as "late spring cold." At this time, our flowers are very prone to frost damage and similar problems due to the excessive temperature difference.
Solution
When facing weather like late spring cold, we need to pay close attention to weather forecasts and should not rush to move plants outside, or cover the plants with plastic film to prevent frost damage.
2. Powdery mildew
Powdery mildew mainly harms leaves, petioles, flower stalks, flower buds and tender shoots. The affected parts will be covered with a layer of white powdery substance. In severe cases, it will cause leaves to turn yellow, flower buds to wither and die, and deformed flowers to appear.
Solution
Sulfur powder fumigation: In March, use an electric heating fumigator in the greenhouse, place sulfur powder inside, and carry out sealed fumigation, which has a relatively good control effect.
3. Anthracnose
Anthracnose mainly harms the leaves, tender shoots, fruits and other parts of the plant. The lesions are round and grayish-brown in color. In the later stage of the disease, the lesions turn grayish-white, accompanied by obvious concentric rings and small black spots.
Solution
Improve the ventilation and air permeability of the plant and keep the potting soil moist to increase the plant's resistance. If the disease is in its early stage, spray with 500 times dilution of 80% carbendazim-thiram wettable powder, once every 10 days, for 2-3 consecutive times.
4. Gray mold
When the temperature rises, humidity is too high and ventilation is poor, gray mold is very likely to appear. Gray mold has the most serious impact on leaves and petals.
Solution
After the beginning of spring, we should pay attention to ventilation and light transmission in the plant's growing environment, reduce indoor air humidity, and stop spraying water on the plants at night to prevent moisture from remaining on the leaf surface for a long time. For plants in the early stage of disease, around noon, spray alternately with 500 times dilution of 65% zineb wettable powder, or 1000 times dilution of 50% hymexazol wettable powder, once every 10 days, for 2-3 consecutive times.
The above is compiled by the editor of Huinong Network regarding common plant diseases and solutions. The above pesticide plans are for reference only, and we hope they are helpful to everyone.
Common Diseases and Pests of Flowers and Their Treatment Methods
Common Flower Disease 1: Late spring cold
Harm
This is a non-infectious disease, mainly occurring in areas south of the Yangtze River and parts of the region between the Yangtze and Huai Rivers. By the end of March, daytime temperatures have already reached above 20°C, and many people are eager to move potted ornamental plants from indoors to the outdoors for conditioning and care. At this time, cold air often moves south, causing a reversal weather pattern known as "late spring cold." The lowest temperature in the early morning often drops below 4°C, causing the newly sprouted tender leaves of some tropical-origin flowers to be "frozen" and damaged.
Common examples include Michelia alba, Aglaia odorata, jasmine, clivia, Dieffenbachia, Syngonium, fuchsia, Calathea, Anthurium, poinsettia, etc., which can seriously affect normal growth in that spring.
Solution
Keep abreast of the weather forecast from the local meteorological station. When encountering the special weather of "late spring cold," for a small number of potted plants already moved outdoors, they can be moved back into the greenhouse or indoors; if there are many potted plants moved outdoors, they can be gathered together and covered with a double layer of plastic film.
In the Yangtze River basin and areas to its north, generally one must wait until after Qingming or after the "final frost period" ends before moving them outdoors. You can lower the temperature by opening doors and windows and adding electric fans, then close the doors and windows well at night, so that they have a process of gradually adapting to the outdoor environment.
Common Flower Disease 2: Powdery mildew
Harm
It mainly harms ornamental plants such as Chinese rose, crape myrtle, Mahonia fortunei, large-leaf boxwood, and Polygonum virginianum. It mainly harms leaves, petioles, flower stalks, flower buds and tender shoots. The affected parts are covered with a layer of white powdery substance. In severe cases, the leaves turn yellow, the tender leaves curl, shrink and thicken, the flower buds wither and die, deformed flowers appear, and the tender shoots bend and shorten.
Solution
Sulfur powder fumigation: In March, use an electric heating fumigator in the greenhouse, place sulfur powder inside, and carry out sealed fumigation, which has a relatively good control effect.
Common Flower Disease 3: Anthracnose
Harm
It mainly harms camellia, tea plum, Dracaena fragrans, hydrangea, clivia, Rohdea japonica, orchids, Aspidistra, Epiphyllum, rubber tree, cyclamen, etc. in the greenhouse. It mainly harms leaves, tender shoots and fruits. The lesions are nearly round and grayish-brown. In the later stage, the lesions turn grayish-white, with obvious concentric rings and whorled (or scattered) small black spots.
Solution
Adjust the placement density of potted flowers and the plant and row spacing of ground-planted plants to improve ventilation and air permeability. Water appropriately when the potting soil becomes dry to increase the plant's resistance.
In the early stage of disease, spray alternately with 500 times dilution of 80% carbendazim-thiram wettable powder, or 800 times dilution of 50% carbendazim-sulfur suspension concentrate, once every 10 days, for 2-3 consecutive times.
Common Flower Disease 4: Gray mold
Harm
As temperatures rise, with excessive humidity and poor ventilation, gray mold is still one of the main diseases of indoor flowers. It harms potted flowers such as African daisy, rubber tree, cineraria, cyclamen, poinsettia, geranium, Rieger begonia, pothos, Ixora, hibiscus, and Anthurium, especially causing severe infection of leaves and petals.
Solution
After March, strengthen ventilation and light transmission, reduce indoor air humidity, and prohibit spraying water on the leaf surface in the evening to prevent moisture from remaining on the leaf surface for a long time.
For plants in the early stage of disease, around noon, spray alternately with 500 times dilution of 65% zineb wettable powder, or 1000 times dilution of 50% hymexazol wettable powder, once every 10 days, for 2-3 consecutive times.
Common Flower Disease 5: Sooty mold
Harm
In March, due to poor indoor ventilation and air permeability and high humidity, piercing-sucking pests such as scale insects, aphids and whiteflies cannot be completely eliminated. Sooty mold can still occur on the leaves, flowers and fruits of plants such as citrus, Aglaia odorata, hibiscus, Michelia alba, Michelia figo, fish-tail palm, banyan, camellia, Rhapis, azalea, gardenia, Ilex cornuta, and Fujian tea.
Solution
Strengthen indoor ventilation and air permeability, and promptly kill aphids, scale insects, whiteflies and other insect vectors that induce sooty mold.
If a small number of leaves on an individual plant are infected with sooty mold, you can use a wet cloth dipped in low-concentration laundry detergent water to wipe away the sooty mold layer.
In the early stage of disease, spray the branches and leaves of the infected plant with 500 times dilution of 50% carbendazim-sulfur suspension concentrate, or 500 times dilution of 75% chlorothalonil wettable powder, once every 15 days, for 2-3 consecutive times.
Common Flower Pest 6: Scale insects
Harm
For potted ornamental plants placed in greenhouses, due to limited ventilation, insufficient light and relatively high humidity, scale insects are still the main pest type.
For example, green mealybug on kumquat, gray mealybug on yew, manmealybug on hibiscus, chaff scale on clivia, tortoise wax scale and red wax scale on camellia, horn wax scale on holly, black helmet scale and oyster shell scale on cycad, wheel scale on Chinese rose, Pseudaulacaspis cockerelli on Michelia figo and Michelia alba, chaff scale on Buddha's hand, giant tuberculate oyster shell scale on orchids, white scale on Rhapis, round scale on ivy, coconut round scale on areca palm, arrowhead scale on Osmanthus fragrans, etc. The species of scale insects on each type of flower are greatly different.
Control methods
For scale insects appearing on a small number of household plants, you can use medicinal cotton dipped in 75% alcohol to wipe off the live insects, or dip it in laundry detergent solution to wipe off the insects. For smaller scale insects, such as arrowhead scale and Pseudaulacaspis cockerelli, you can use transparent adhesive tape to stick off the live insects.
Or spray to kill with 2000 times dilution of 25% buprofezin wettable powder, once every 15 days, for 2 consecutive times.
Common Flower Pest 7: Aphids
Harm
As temperatures rise and watering increases, aphid damage on indoor ornamental plants will also become more serious. Aphids pierce and suck the sap of newly sprouted branches and leaves, which will affect the normal growth of the plant after the beginning of spring.
Control methods
For aphids on a small number of plants, you can first sprinkle tobacco powder, plant ash or furnace slag ash on the insects and leaves. After about 1-2 hours, rinse thoroughly with clean water, and most of the aphids can be killed.
Common Flower Pest 8: Whiteflies
Harm
The main one is greenhouse whitefly, which harms cineraria, hibiscus, Chinese rose, nasturtium, lantern flower, etc.; the next is citrus spiny whitefly, which harms kumquat, golden bean, bitter orange, Buddha's hand, Chinese rose, Michelia alba, Aglaia odorata, etc. Their harmfulness should not be underestimated.
Control methods
When the outbreak is severe, use 2000 times dilution of 10% imidacloprid wettable powder, or 2500 times dilution of 25% buprofezin wettable powder.
Control Methods for Diseases and Pests of Household Flowers and Plants
Household flower pests are divided into three types: piercing-sucking pests, leaf-eating pests and root pests. Piercing-sucking pests use their mouthparts to pierce into plant tissues and suck plant sap, such as aphids, scale insects and spider mites (red spiders).
Leaf-eating pests gnaw on plant leaves, causing notches and holes, such as various moths, butterflies, borers and inchworms. Root pests lurk in the soil and harm plant roots, or come to the surface at night to bite through the root and stem parts of plants, causing plant death, such as white grubs, cutworms and mole crickets.
Common pests and harmful animals: aphids (Chinese rose, chrysanthemum, flowering peach, etc.), red spiders (azalea, roses, dahlia, Michelia alba, Osmanthus fragrans, etc.), scale insects (jasmine, orchids, Rohdea japonica, kumquat, camellia, Michelia figo, cycad, Michelia alba, etc.), lace bugs (azalea, cherry blossoms, etc.), slugs, snails, sow bugs (in damp places, under and around flower pots, etc.), etc.
Common diseases: leaf spot (such as chrysanthemum, Chinese rose, Michelia alba, azalea, camellia, orchids, etc.), anthracnose (orchids, Michelia figo, chrysanthemum, camellia, Michelia alba, Rohdea japonica, Osmanthus fragrans, etc.), powdery mildew (chrysanthemum, Chinese rose, dahlia, crape myrtle, etc.), downy mildew (Chinese rose, cineraria, wax begonia, cyclamen, etc.), damping-off (generally seedlings are susceptible to this disease), chlorosis (yellowing due to dry conditions from lack of water, yellowing due to waterlogging from too much water, yellowing due to lack of fertilizer, yellowing due to iron deficiency, etc.).
Household flower growing emphasizes "prevention first, integrated control." First, do not bring diseased or pest-infested plants home, and when propagating, choose disease- and pest-free plant materials; second, improve and strengthen cultivation management and improve the environmental conditions in which the plants are placed, such as improving ventilation and light conditions, loosening the soil, and controlling moisture, so that the plants grow robustly and their ability to resist diseases and pests is improved; third, once disease or pests are found, deal with them as early as possible. Use manual methods as much as possible to remove them or apply self-made "preparations," such as using a soft brush to brush off scale insects; using tobacco leaf water or very dilute soapy water to wash off aphids and spider mites; cutting off and removing withered or diseased branches and leaves; fourth, since it is inconvenient to use pesticides at home, you can use some methods that are harmless to people, do not pollute the environment, and are simple and effective.
Prevention and control of diseases: Use fungicides to control diseases. For example, garlic liquid can control rust and root-knot nematode disease in flowers, and preserve cut flowers against decay. In addition, you can also use small-packaged pesticides, such as chlorothalonil, thiophanate-methyl, amobam, carbendazim, etc.