What are the diseases and pests of potted flowers

Disease 1: Late spring cold

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This is a non-infectious disease that mainly occurs in parts of the south of the Yangtze River and between the Yangtze River and the Huai River. By the end of March, the daytime temperature has reached above 20°C, and many people are eager to move their potted ornamental plants outdoors for conditioning and maintenance. However, at this time, cold air often moves south, and reversal weather of "late spring cold" occurs. The minimum temperature in the early morning often drops below 4°C, causing the new shoots and tender leaves of some flowers originating from the tropics to be "frozen".

Common ones such as white orchid, Milan, jasmine, Clivia, Defen leaf, Syngonium, Fuchsia, Arrowroot, Anthurium, Poinsettia, etc. will seriously affect the normal growth in the spring of that year.

Workaround

Keep abreast of the weather forecast from the local meteorological station. If you encounter special weather conditions such as "late spring cold", a small number of potted plants that have been moved outdoors can be moved back to the greenhouse or indoors. If there are many potted plants moved outdoors, you can gather them together and cover them with a double layer of plastic film.

In the Yangtze River Basin and areas to its north, you generally have to wait until after Qingming or the end of the "last frost period" before moving outdoors. You can cool down by opening doors and windows, adding electric fans and other measures, and then close the doors and windows at night to allow the house to gradually adapt to the outdoor environment.

Disease 2: Powdery mildew

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It mainly harms ornamental plants such as rose, crape myrtle, Mahonia, large-leaf boxwood, and bamboo knotweed. It mainly harms leaves, petioles, pedicels, 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 die, deformed flowers appear, and the tender shoots bend and shorten.

Workaround

Sulfur powder fumigation: In March, an electric fumigator with built-in sulfur powder is used in the greenhouse for sealed fumigation, which has a good prevention and control effect.

Disease 3: Anthracnose

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It mainly harms camellia, sasanqua, Yemen iron, hydrangea, Clivia, dieffenbachia, orchid, spider spore, epiphyllum, rubber tree, cyclamen and other plants in the greenhouse. It mainly harms leaves, young shoots and fruits. The lesions are nearly circular and gray-brown in color. Later, the lesions turn into gray-white with obvious concentric rings and whorled (or scattered) small black spots.

Workaround

The density of flower pots and the spacing of plants and rows can improve ventilation conditions. When the soil in the pot becomes dry, water it appropriately to increase the resistance of the plant.

In the early stage of the disease, use 500 times diluted 80% anthrax thimerosal wettable powder or 800 times diluted 50% polysulfide suspension, spray alternately once every 10 days for 2-3 times in a row.

Disease 4: Botrytis cinerea

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As the temperature rises, excessive humidity and poor ventilation will still cause gray mold to become one of the main diseases of indoor flowers. It harms potted flowers such as gerbera, rubber tree, cineraria, cyclamen, poinsettia, geranium, begonia, green ivy, Ixora, hibiscus, and anthurium, especially the leaves and petals, which are seriously susceptible to the disease.

Workaround

After March, you need to increase ventilation and light transmission, reduce indoor air humidity, and avoid spraying water on the leaves in the evening to prevent moisture from remaining on the leaves for a long time.

For plants in the early stage of the disease, use 500 times diluted 65% mancozeb wettable powder or 1000 times diluted 50% carbendazim wettable powder around noon, spray alternately once every 10 days, for 2-3 times in a row.

Disease 5: Sooty disease

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In March, due to poor indoor ventilation and high humidity, piercing-sucking pests such as scale insects, aphids, and whiteflies cannot be completely eliminated. Sooty mold disease will still occur on the leaves, flowers, and fruits of plants such as citrus, Milan, hibiscus, white orchid, Michelia, fishtail palm, banyan, camellia, bamboo palm, azalea, gardenia, holly, and camellia.

Workaround

Improve indoor ventilation and kill aphids, scale insects, whiteflies and other insect vectors that cause sooty mold disease in a timely manner.

A small number of leaves on some plants are infected with sooty mold. You can use a damp cloth dipped in low-concentration detergent water to wipe off the sooty mold layer.

In the early stage of the disease, you can use 500 times diluted 50% methyl sulfur suspension or 500 times diluted 75% benomyl wettable powder to spray the branches and leaves of the infected plants once every 15 days for 2-3 times.

Pest 6: Scale insects

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For potted ornamental plants placed in the greenhouse, scale insects are still the main type of pest due to restricted ventilation, insufficient light and high humidity.

Such as the green cottony scale on kumquat, the gray mealyscale on yew, the mealyscale on hibiscus, the bran mealyscale on Clivia, the tortoise wax scale and red wax scale on camellia, the horned wax scale on holly, the black helmet scale and oyster shield scale on cycads, the wheel shield scale on roses, the white shield scale of Michelia and white orchid, the bran shield scale on bergamot, the giant tumor oyster scale on orchid, the white shield scale on bamboo palm, the round shield scale on ivy, the coconut round shield scale on Areca palm, and the arrow-pointed shield scale on Osmanthus fragrans, etc. The types of scale insects on each flower are very different.

Prevention and treatment methods

If scale insects appear on a small number of plants in the home, you can use cotton swabs dipped in 75% of alcohol to wipe off the living insects, or use cotton swabs dipped in laundry detergent to wipe off the insects. For smaller scale insects, such as the Sharp-nosed Scale and the White-shielded Scale, you can use transparent tape to remove the living insects.

Alternatively, you can spray with 2000 times diluted 25% cypermethrin wettable powder once every 15 days for 2 times in a row.

Pest 7: Aphids

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As the temperature rises and the amount of watering increases, the damage caused by aphids on indoor ornamental plants will become more serious. Aphids suck the sap from new branches and leaves, which will affect the normal growth of the plant after spring.

Prevention and treatment methods

For a small number of aphids on plants, you can first sprinkle cigarette butts, wood ash or slag ash on the insect bodies and leaves. After about 1-2 hours, rinse them with clean water to kill most of the aphids.

Pest 8: Whiteflies

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The main one is the greenhouse whitefly, which harms cineraria, hibiscus, rose, nasturtium, and lantern flower; the second is the citrus whitefly, which harms kumquat, golden bean, daisy, bergamot, rose, white orchid, and Milan, etc. Their harmfulness cannot be underestimated.