Geraniums are a common and popular garden flower. Also known as cranesbills, they are perennial flowers that are also often cultivated as annuals. Geraniums generally have vibrant red blossoms, but also can come in other shades. They are capable of growing well in a vast array of different soils. As with the majority of plants, there are several diseases that can affect geraniums.
Bacterial blight is also sometimes referred to as bacterial stem rot, bacterial leaf spot and bacterial wilt. This geranium disease results from the bacterial pathogen known as Xanthomonas campestris pv. Pelargonii. One primary symptom of bacterial blight is the appearance brown, tiny and water-soaked spots on the under-surfaces. They generally are V-shaped. Other symptoms include darkened veins on the leaves and the leaf margins start to wilt and droop. In cases of systemic infection, the whole geranium can become flaccid and the branches can wilt back and die. The stems can dry up and rot. This disease can be managed by pulling out the weeds and eliminating plant debris and using soil amendments to make sure the soil is well-draining.
In times of high humidity or moisture, plant tissues or debris that are infected with botrytis blight start to develop fuzzy and gray growths from botrytis cinerea, which is a type of fungus. The leaves can develop small lesions or spots, or even larger dead areas with rings. Lesions with V-shapes may appear. The flowers can turn entirely brown and prematurely wilt in times of extreme humidity or moisture. This geranium disease can be handled by maintaining proper sanitation and getting rid of plant debris and taking out weeds.
Leaf rust is caused by a fungal pathogen known as Puccinia pelargonii-zonalis. The disease manifests itself with yellow, tiny spots on the leaves' upper surfaces. Pustules that have a rust color might also appear on the leaves' undersides. The pustules can also develop on the petioles, stems and stipules of the geranium. Leaf rust can be eliminated by getting rid of plant debris and pulling out weeds, as well as abstaining from overhead irrigation. Fungicides may also be used.