Gladioli: diseases and pests, treatment and prevention

Gladioli, like all bulbous plants, are susceptible to various diseases and pests. But simply spraying and watering is insufficient and even improper. Addressing these flower problems requires understanding the underlying causes. Pests spoil the plant's appearance, killing the planting material, and even the plant itself. The most dangerous gladioli pests are:

Gladiolus thrips are a major pest, causing irreparable damage to both the plant's tubers and flowers. These tiny, sucking insects are almost invisible to the naked eye. They reproduce extremely quickly, producing several generations in a single summer. In addition to damaging the bulbs, thrips also damage gladiolus flowers. Whitish spots appear on the petals, the flower loses its decorative appearance, turns yellow, and dries up. Severely damaged buds die on the stems without opening.

The cutworm

This caterpillar has yellow, green, or brown stripes on its body. It extensively eats leaves and buds, leading to the death of the plant. Like all parasites, it "works" at night, primarily in May and June.

Root mite

It attacks the tubers of both in-ground and stored plants. The main conditions for their growth are high humidity and air temperatures above 10 degrees Celsius. It's easy to recognize. The mite settles in the flower bulb and can completely eat it from the inside. If the root becomes dark and rotten, this indicates the mite's presence.

It resembles a small white spider and has highly developed jaws. It burrows into the skin of the bulb and burrows inside. It reproduces very quickly. Under favorable conditions, it can even settle on the soil surface and feed on the above-ground parts of the plant.

Mole cricket

Prefers organically rich soils. Therefore, adding fresh mullein when fertilizing is not recommended. It lives primarily underground, creating tunnels and burrows. It damages roots, bulbs, and flower stems.

Slugs

They thrive only in very damp areas and can burrow into the soil to a depth of up to 1 meter. They feed in the evening or at night, but in damp weather they can emerge during the day. They cause severe damage to gladioli bulbs and leaves. By feeding on especially young shoots, they can completely destroy the plant.

Wireworm

It causes irreparable damage to bulbs, gnawing at them, chewing holes and passages, not only killing them but also introducing infections. In addition to pests, gladioli are susceptible to various diseases. There are about 15 species. Fusarium wilt can lead to widespread plant mortality. Scientists have not yet developed immune varieties.

The causative agent is the soil-borne fungus Fusarium. Infection occurs through the roots. Fusarium is an incurable disease of gladioli. Infected plants develop stem bending, and flowering is delayed. In severe cases, the bulb dries up, and the flower dies. The disease is triggered by excess nitrogen fertilizer, high humidity, and warm weather.

Sclerotinia leaf spot is an equally dangerous disease. In humus-rich soils, it forms foci of infection and can persist for about 20 years. During heavy fog and dew, or when grown in heavy soils, it can infect plants en masse. With dry black rot, gladiolus leaf tips begin to yellow, stems begin to rot and break, tissues split, and the root dies. Infection occurs in the soil.

Botrytis

It is transmitted by airborne transmission, most often in damp, cool weather. Fungal spores, along with droplets of moisture, settle on the plant and penetrate its tissue. Reddish-brown, round spots begin to appear on the leaves. Water-soaked spots appear on the petals. The plant begins to rot. Botrytis can be controlled by spraying with a solution of copper sulfate and green soap during the growing season.

Scab

The disease thrives in clay and peat soils. Infection occurs in the soil. Signs become noticeable when the corms are harvested. Ulcers about 5 mm in size appear on the corms. Gray, black, and sometimes red spots are visible on the scales. Scab causes the leaf tips to turn yellow and wilt. Rotting begins at the base of the plant. There are no treatments for this disease. Therefore, only healthy planting material should be used.

Cancer

The disease is caused by a soil-borne bacterium transmitted by nematodes. Instead of bulblets, malformed growths appear on the bulb. Infected bulbs should be discarded and burned. They are not suitable for planting. Viral diseases of gladioli include bean yellow mosaic, cucumber mosaic, aster yellows, tobacco ringspot, and tomato ringspot.

When gladioli are infected with bean mosaic virus, light or dark green spots appear on the leaves. Affected flowers begin to turn pale or dark. The virus does not affect the bulb.

Cucumber mosaic is a very dangerous disease. It can be confused with thrips damage. Whitish stripes appear on the leaves, and spots also appear on the flowers. It causes the plant to become stunted, and the flowers become small.

Cicadas are the primary vectors of the aster yellows virus. They are especially active during droughts. Leaf tips gradually turn yellow and die. Later, the inflorescences curl.
Ringspot viruses are transmitted by nematodes. Leaves become distorted, fringed, and develop brown spots or stripes. The tubers are very small and unsuitable for planting.

Prevention of diseases and viruses in gladioli

Currently, plant breeders have not yet developed disease- and virus-resistant gladioli. Therefore, the only way to save the plant is to prevent the disease. The most effective preventative measures are:

Crop rotation

Gladioli don't tolerate being planted in a permanent location. After a couple of years, they start to get sick. It's very helpful to plant calendula or marigolds after the flowers. They will disinfect the soil. They can also be planted around flower beds.

The diseased plant must be removed immediately to avoid infecting other plantings. It must be removed along with the root ball.

Flowers should be planted in a well-ventilated area to prevent fungal infections.
Spray with preventative solutions. It should be noted that sprays do not cure the disease, but only protect plants located near the affected one.

Mulching with pine needles or sphagnum moss also provides effective prevention. Avoid planting infected or diseased bulbs. Not only will they prevent good flowering, but they will also infect other plants.

Before planting the corms, it is necessary to dig up the soil in the flowerbed and treat it with a solution of manganese and fungicides.