Among the favorite plants to decorate our home are geraniums. Although this group contains more than 250 different species, only a few are used for their great ornamental value. However, all of them can suffer from various pathologies that we must know how to recognize in order to treat them in time. For this reason, in this article we are going to talk about the pests and diseases of geraniums.
Our goal here is to create a basic outline that will help us differentiate between the various pests and diseases of geraniums. We will talk about the most common pathologies that affect these plant species. Generally, when we acquire a plant in a garden center, in supermarkets or in nurseries, they are usually healthy. Phytosanitary problems usually appear later, due to poor crop management or invasions of pathogens from neighboring orchards, fields or gardens.
What are the pests and diseases of geraniums?
There are many pests and diseases that can affect geraniums. For this reason, it is important to look at the plants and detect any anomaly as soon as possible in order to start the treatment. Next we will list the most common pests that usually affect geraniums:
- Geranium butterfly: It is also known as the African butterfly or geranium moth. The agent responsible for this so damaging and important plague is the caterpillar Cacyreus marshalli and expands throughout the Mediterranean area and the Iberian Peninsula. If this pest is not controlled, it can kill a very large number of specimens. The Caterpillar Cacyreus marshalli Create small holes in the stems to climb into. As a consequence, both the leaves and the flowers weaken, until the plant finally dies. We can recognize these caterpillars by their green color and their length of about two centimeters.
- Red spider: When temperatures are high and humidity is low, around late spring to early fall, the dreaded Red spider, Also known as Tetranychus urticae. These are very small mites of about 0,5 millimeters in size and of a characteristic red color. They are usually located on the underside of the leaves and cause irreparable damage. As a consequence, the leaves acquire a silvery color because these spiders feed on the juice of the leaves, completely emptying the cells.
- Aphids: There are different types of aphids that can affect geraniums. They are small insects about three millimeters in size. They are generally found in the most tender areas of the plant. They secrete a type of honeydew that causes the leaves to curl and become sticky. The worst thing about this pest is that it adds other pathologies to the crop, since molasses is ideal for the development of the fungus Bold. In addition, aphids can transmit viruses.
- White fly: It is a type of fly called bemisia tobacco. It is very difficult to control once it has established itself in the plant. There, it balds its beak on the leaf and feeds on the sap. In this way, the plant is weakened. It should be noted that, like aphids, the White fly can transmit viruses. It prefers high temperatures and humid environments, which is why it is a fairly common pest from spring to autumn.
- Mealybugs: There are also different types of mealybugs, but what they all have in common is that they are sucking insects. Their modus operandi is the same as that of aphids and whiteflies: they stick their beaks into the stems or the nerves of the leaves to suck the sap. Consequently, the vegetable weakens.
- Caterpillars: Among the caterpillars that most attack geraniums are Pieris cabbage y gamma autographfor example. These devour both the flower buds and the leaves of the plant. As they have chewing mouthparts, we can deduce their presence from the holes they create in the foliage.
- Green mosquito: It is a small, sucking insect called empoasca lybica. It also feeds on the sap of the leaves, causing the leaves to discolor in a similar way to that of the mites.
- Nematodes: It is not very common to see nematodes, not only because of their tiny size, but also because they are found in the substrate. From there they directly attack the roots of plants to feed on their juice. It is quite common to confuse the symptoms they cause with a lack of nutrients or excess water. To identify them, we must uproot the plant and observe if the roots have a type of bulge, which is the result of the plant’s own defense to isolate itself from nematodes.
The most common diseases of geraniums
Regarding the diseases of geraniums, these are the most common:
- Rust: La roya the fungus is caused Puccinia sp.. It is recognized by the appearance of dark pustules that turn orange on the underside of the leaves. Those leaves that are very invaded, end up drying.
- Botrytis: One of the most well-known diseases is botrytis, caused by the Botrytis cinerea. It is more frequent in humid and cool environments. It attacks both flower buds and leaves. Affected areas rot and become covered in dark gray mold.
- Oidium: Powdery mildew It is caused by a fungus called Erysiphe spp.. It is very easy to identify, as it appears on the upper surface of the leaves as an ashy or white powder. Those areas that are affected by this fungus turn yellowish and end up drying out.
- Alternariasis: Another of the most common diseases of geraniums is the alternariasis, caused by the fungus Alternaria spp.. When this pathogen attacks, small brown spots appear on the older leaves of the lower or middle part of the geranium.
- Anthracnose: The fungus responsible for anthracnose is Gloeosporium pelargonii. It causes black or brown spots on the shoots, buds and leaves of the geranium. These spots expand over time and end up withering the affected areas. Another fungus that causes very similar spots is called Ascochyta spp..
- Foot disease: caused by fungus Pythium spp.foot sickness attacks the neck of the vegetable. The affected part ends up rotting, thus causing the death of the plant. It usually appears when the geranium is still young and leads to excess water in the soil. We can also detect it by the darkening that appears on the neck of the trunk at ground level. Sometimes it can be accompanied by a light and clear powder.
How to fight geranium diseases?
Once we are clear about the pest or disease of the geraniums present, We must take action as soon as possible. The treatment that we can carry out will depend on the type of pathogen that is affecting the plants.
In the case of pests, it is different insects that may be damaging plants. Therefore, each one has a specific treatment. We will comment on them below.
- Geranium butterfly: It is best to try to prevent this plague, but once it has appeared it can be combated with systemic insecticide treatments. In addition, it is important to prune the infected stems, that is, those that have the caterpillar inside.
- Red spider: The most effective treatment is through the use of acaricides, wetting the plant it enters.
- Aphids: The way to treat aphids is by using systemic insecticides.
- White fly: Systemic insecticides are also used to combat whitefly.
- Mealybugs: Although it is true that mealybugs are also combated with insecticides, it is more difficult to eliminate them because of the shell that protects them. For this reason, it is advisable to start treatment when they are still in the early stages of invasion, since their shell is not well developed.
- Caterpillars: When it comes to combating caterpillars, we can use contact or systemic insecticides. It is best to apply them as soon as we have seen butterflies on the plants, as they are the ones that lay the caterpillars.
- Green mosquito: It is combated with systemic insecticides.
treatment of diseases
When it comes to treating geranium diseases, fungicides are often used instead, as most are caused by fungi. Even so, the treatment and the type of product will depend on the disease in question. Let’s see how to combat the diseases that we mentioned above:
- Rust: Burn affected plants to destroy their spores.
- Botrytis: Apply specific fungicides, prevent the plant from suffering injuries and place it in a well-ventilated place.
- Oidium: Use antioidios (fungicide) and remove branches and leaves severely affected by the fungus after a few days. Good ventilation is also recommended.
- Alternariasis: Treat with copper-based fungicides.
- Anthracnose: Apply specific fungicides as soon as the first symptoms appear. It is important to wet the entire aerial part of the vegetable.
- Foot disease: Water with a specific fungicide that is dissolved in the water. Keep the substrate moist without flooding it (it can also be done to prevent this disease).
I hope that this information has been useful to you both to detect and to treat the pathologies of your geraniums.