If you want to learn how to keep your geraniums safe from pests and diseases that may affect them, keep reading this article from Grow your Patch, where we explain how to tackle the pests and diseases of geraniums.
Pests of Geraniums
Among all the pests that can affect plants, we will highlight the following ones that particularly target geraniums.
Geranium Moth
The geranium moth, also known as the geranium borer, is one of the most damaging pests that affects geraniums, especially in Spain along the Mediterranean coast. This pest requires close attention and control because it can easily spread from one plant to another, causing multiple plants to die off rapidly and dramatically.
Fortunately, it’s quite easy to identify. Just check if the stems of your geranium are holed. If they are, the caterpillar is likely already inside. This pest causes internal damage by feeding on the plant from the inside, weakening its leaves and flowers.
Aphids
Aphids measure about 3 millimeters and position themselves on all the tender areas of the plant. Symptoms include curled and sticky leaves due to the honeydew secreted by these tiny insects. This honeydew serves as an ideal breeding ground for sooty mold or increases the transmission of virosis among nearby plants.
Spider Mites
This pest affects geraniums during the warm temperatures in spring and summer. They measure about 0.5 millimeters, are reddish in color, and settle on the undersides of leaves. They are not visible to the naked eye, so you will need a magnifying glass to see them.
However, the symptoms caused by this pest on geraniums are very recognizable. You may notice a silvery color starting to appear on the leaves or small webs in cases of severe infestation.
Whiteflies
No larger than 3 millimeters, the whitefly is a pest that prefers high temperatures and excess humidity for reproduction. Luckily, they’re easy to identify; you just need to gently shake the plant to see a cloud of insects around it. They feed on the sap, which can severely weaken the plant in no time. Typically, they lay their eggs and larvae on the undersides of leaves.
Scale Insects
Brown in color and resembling warts, scale insects appear on the stems and leaves of the geranium. Inside are the eggs and larvae of the scale insect, which, as adults, develop a distinctive silvery color. They adhere to the stem or leaves to feed on the plant and excrete honeydew, contributing to the growth of fungi just like aphids.
Leaf Caterpillars
There are several species, aside from the geranium moth caterpillar, capable of affecting these plants. The best way to combat them is to remove them by hand and ensure that the undersides of the leaves are free from eggs.
Greenflies
These tiny sucking insects pierce the leaves of geraniums to extract sap. The clearest symptoms include loss of color in leaves or the appearance of reddish hues on leaves before they fall off.
Nematodes
Nematodes enter the root system to feed on the plant. This makes it very difficult to detect their presence. However, some of their symptoms are easy to recognize, such as the loss of color in the leaves or yellowing before wilting occurs.
Diseases of Geraniums
Now that we have seen the pests of geraniums, let’s detail the diseases that can affect this plant.
Rust
Rust is one of the most common diseases in geraniums. It is characterized by dark pustules that turn orange and are located on the underside of the leaves, causing them to wilt and dry out.
Botrytis
This disease primarily affects leaves and flowers, forming a dark gray mold that can cause them to rot quickly.
Powdery Mildew
This fungus is easily identified by the appearance of a whitish powder on the leaf surfaces that gradually yellows the leaves until they completely dry out.
Alternaria Leaf Spot
Small brown spots appear on the older parts of the plant, specifically on its leaves, leading to general weakness.
Anthracnose
Small dark brown spots can be found on the leaves, shoots, and buds of the geranium, which expand until wilting occurs in the affected area.
Foot Rot
This fungus produces spots similar to those of anthracnose, making it easy to confuse them, but it can also be treated using the appropriate fungicide.
Bacterial Infections
These bacteria appear as necrotic spots on the leaves, leading them to dry and eventually fall off. There is no cure for these infections, so it’s necessary to isolate the affected plant to prevent contagion.
Mosaic Virus
Geraniums can also be infected by plant viruses, such as the mosaic virus. Its most representative symptoms include the appearance of variegated yellowish spots on the leaves and malformations in their flowers.
How to Prevent Pests and Diseases of Geraniums
Preventive treatments, as is common in such cases, are usually more advisable in the long run. Regarding pests, it’s beneficial to plant aromatic plants in the garden or near access points of your home such as doors and windows to help deter unwanted insects, such as lavender, basil, mint, rosemary, or citronella.
In terms of fungi and diseases, the best practices include:
- Keeping the garden and plants well-aired.
- Always immediately remove any damaged plant parts.
- Avoid allowing fallen leaves and other organic material to accumulate.
When temperatures are warm and there are rainy conditions, it’s advisable to apply natural fungicides, such as those made with milk, as these are ideal conditions for fungi to develop.
