The genus Hibiscus of the family Malvaceae includes many species, mainly ornamental, but some of economic value. There are shrubs and herbs, annuals or perennials, deciduous or evergreen. Both are plants native to tropical Asia and the Pacific Islands, where they can reach considerable sizes, while in temperate climates they remain more closed. There are many hibiscus diseases that can affect crops.
For this reason, we will devote this article to telling you about the diseases of hibiscus and the features of caring for this plant.
Although there are many varieties, they all have one characteristic in common, which is that the flowers which open in the leaf axils or at the end of the branches are trumpet-shaped and may have one, two or several petals. The most diverse colors. : Pink, red, blue, yellow, white and sometimes corolla of only one color and stamens of contrasting color. The cup consists of five sepals and the corolla consists of 5 petals in a single flower. The column of stamens protrudes from the center of the flower, in which the stamens are aligned, generally longer than the corolla. The column of stamens bears five pistils along its length. With the exception of a few species (Hibiscus arnottianus and Hibiscus waimae, which are lightly scented), the flowers are odorless.
It is grown as a small tree or hedge and is often found in almost any city in Mediterranean climates due to its resistance to oxidants, pollutants such as nitrogen and sulfur dioxide, and harsh weather conditions. .
Cultivation of hibiscus
Hibiscus is a versatile plant that can be grown successfully in the ground or outdoors, weather permitting, it’s obviously the latter. In fact, due to their origin, they cannot stand the cold of winter, as they only grow well outdoors in areas with a temperate climate and full sun.
Planted in pots, if they are sunny and facing south, they can also decorate terraces, especially in winter, and even better when temperatures drop below 13°C, they are brought indoors.
If your climatic conditions do not allow you to grow outdoors all year round, but only in spring and summer, we remind you that the hibiscus must gradually get used to the outdoors. At first, it should be placed in a cool, sheltered place for several days. After that, for about 10 days, it was placed in direct sunlight only in the morning, reorienting it to shade during peak hours. Then you can leave it quietly in the sun without fertilizing for about a month to give it time to adjust to the change in character. Don’t be alarmed if you see leaves turning yellow and dying at first, this is normal.
This plant can also grow in our house. In this case, it should be placed in a very bright place, avoiding drafts in any case. It is best to ventilate the place where it is in summer to prevent the temperature from exceeding 25°C.
There are annual hibiscus and perennial hibiscus. It is remembered that annual hibiscus flowers die after flowering.
Associated problems and pests
Hibiscus can exhibit certain types of problems without becoming pests or diseases that can alter the appearance of the plant. Most hibiscus diseases are fungal and are caused by excessive watering or ambient humidity. The most common pests are insects that feed on them.
Here are the most common hibiscus problems:
- Its flowers fall before opening: This usually happens due to lack of lighting, cold weather, or lack of irrigation.
- Rare flowers: usually due to a lack of light. Move to a location with lots of natural light.
Among the pests we found that the most affected hibiscus:
- Red Spider: It appears in hot, dry climates, weaving a kind of spider’s web under the leaves. It feeds on the sap and the leaves turn yellow and dry. Prevent and solve it by spraying the leaves in front and behind.
- aphids: read more here: “Insects harmful to plants”
- Whitefly: Their larvae attach themselves to the leaves, where they feed, weakening the plant. To find out if your hibiscus is affected by this insect, gently shake the leaves, if you notice a cloud of white powder, it’s a small whitefly.
- Woodlouse: It lives under leaves and feeds by sucking sap from leaves and new shoots.
Most diseases are caused by fungi.
- Alternate: It appears in conditions of excessive heat and humidity. Concentric spots with a yellow center and a brown or black exterior. This fungus is difficult to eradicate, but not impossible. To avoid its appearance, it is essential to maintain “a clean pruning and maintenance” to eliminate leaves, branches and dry or rotten flowers and avoid unnecessary watering and fumigation.
- botrytis: This fungus manifests as a gray mold on leaves and flowers, and benefits from very high humidity and very dense mats on bushes. Correct by thinning foliage, pruning, removing dead leaves and flowers, and dead branches.
- iron whorlHibiscus – Although common on many plants, this is one of the main problems with hibiscus. Its main symptoms are yellowing of the leaves and excessive irrigation due to alkaline substrates or lack of nutrients. It is corrected by reducing irrigation and adding compost or organic matter containing iron (Fe) to the substrate. See here: “Why do plant leaves turn yellow?”
- Rust: This fungus attacks the leaves and stems mainly on hot, very humid days. It appears on the underside of leaves as small raised yellow, orange, brown or red dots. The affected part should be excised and removed.
- Root rot: It is usually caused by water stains on the substrate. It is solved by correcting drainage and preventing future flooding. Pythium is the fungus responsible for this disease.
- stem rot: Rhizoctonia can affect the roots and the crown of the stem, quickly leading to the death of the plant.
It should be noted that fungal diseases can be prevented by avoiding excessive moisture or flooding of the substrate. Spray the foliage and clean the pruning only in hot weather to clean the bushes and provide air and light to the whole plant.
Hopefully with this information you can learn more about hibiscus diseases and their characteristics.