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Your Dianthus buds may be empty because of pests like budworms, aphids, and cutworms or fungal diseases like bud rot. You can get rid of most pests by using insecticidal products. To prevent the spread of fungal diseases, remove the infected buds.
Based on research, this article will explain in great detail why your Dianthus buds become empty and damaged.
What Causes Empty Dianthus Buds?
Those who are involved in the task of growing carnations should know that there is a plethora of disease problems that can affect the plant. You should take special attention to propagation by cuttings, as it is the usual culprit for disease spread (source).
A general advice for preventing the spread of fungi and pests is regularly disinfecting your gardening tools. That way, if you happen to make a cutting in an infected plant, you won’t spread the disease to the rest of your garden.
Below are the top reasons your dianthus buds are empty or damaged over time.
1. Cutworm Damage
Cutworms are the usual culprits for your Carnation’s empty bud. They are especially damaging when there is ineffective soil fumigation in young plants.
The larvae of the Peridroma saucia can gouge out the buds of the flower, especially of older plants. These pests can be identified by their mottle brown or ash-gray color, each with distinct yellow dots on their bodies (source).
Cutworm damage is so noticeable due to its ability to climb stems and eat holes into the plant’s buds.
2. Carnation Rust
Another threat to carnation health is the phenomenon of carnation rust. Caused by the fungus Uromyces caryophyllinus, this pathogen-induced disease is the most common cause of carnation foliar disease.
Symptoms begin with tiny, slightly raised blisters on flower buds. These form pustules and rupture after some time. Over time, buds become damaged, and the plant’s leaves become yellow and eventually die.
Fortunately, one can prevent carnation rust through a handful of ways:
- You need to water its bottom carefully, with a regular dusting of Ferbam, zinc, or a mixture of Ferbam and sulfur.
- You can also create a mixture of dry lime sulfur following the ratio of 4 pounds (1.8 kg) to 50 gallons (189 L) of water.
- You can also prevent the spread of rust from the spore inoculum to propagation cuttings if you douse the cuttings in Ferbam.
3. Boron Deficiency
The lack of boron is another factor that leads to carnations having empty buds or losing them altogether to damage.
This deficiency’s symptoms primarily manifest through the yellowing and twisting of leaves and dead terminal buds. Flower buds also become abnormal and die before they can open.
4. Carnation Bud Mites
Carnation bud mites are also notorious offenders against the Dianthus plant. The leading causes for the bud rot it creates are grass mite bacteria (from Pediculopsis graminum) and saprophytic fungi.
The buds already decay internally once the mite invades the damaged tissues. The infection manifests through the empty buds. Either they look crooked when opened or fail to open.
Bud mites or budworms also cause empty buds by laying eggs on an opened bud’s outer parts, eventually consuming all of its contents (source).
5. Cabbage Loopers
Cabbage loopers are pests that attack carnations, chrysanthemums, and geraniums. They are pale-green larvae with distinct white lines on their sides and backs.
They eat a flower’s buds and chew leaves. Fortunately, any insecticide containing permethrin can eradicate these pests (source).
6. Beet Armyworms
Another group of pests persistent in feeding on leaves and flowers is the beet armyworm. Adult beet armyworms are heavy-bodied moths that can chew off entire flowers and leaves, particularly on the insides of buds (source).
7. Carnation Bud Rot
This fungal disease is another possible suspect. Blame the fungus Fusarium poae. Buds won’t open entirely, and if they do, the petals have already emerged deformed.
What’s worse about the decay inside is that it causes brown, moldy, or pink decay. The fungus and mites live together and introduce spores directly on the buds.
You can handle this condition by removing infected buds. This helps the plants develop new, healthy flower buds (source).
You can also prevent carnation bud rot by not allowing extreme temperatures and avoiding high humidity, as these conditions favor the disease. Ensuring good air circulation also helps.
Regarding fumigants, you can control the mites through organic phosphate compounds. Steam sterilization is also a prudent step when re-soiling beds.
General soil steaming and reducing the use of new sod will also encourage better growing conditions for your Dianthus plants.
8. Gladiolus Thrips
This pest commonly damages gladioli but occasionally infects flowers like lilies, begonias, amaryllises, and carnations. They feed on the flower’s petals and leaves until they become withered.
The outcome is seriously damaged flower buds that fail to open. The overall growth of the plant also turns out stunted.
Moreover, the gladiolus thrip—its pupae and larvae—thrive on the buds directly or on leaf sheaths. Other than damaging buds, any plant that these thrips infect turns out to have spotted, bleached appearances (source).
9. Aphids Infestation
Aphids, specifically its leaf curl plum and green peach variants, infest the buds and young leaves of the pink Dianthus plant. They suck the sap, causing much trouble for the plant.
You may want to use specialized compounds to battle these insects. You can use malathion, insecticidal soaps, and ultra-fine horticultural oil.
Another option is applying Imidacloprid for soil drenching and long-term control against aphids (source).
10. Carnation Tortrix
The Carnation Tortrix is a leaf-rolling moth and a commonly encountered greenhouse pest of flowers. It damages buds and leaves by mining them or rolling terminals together.
The tortrix’s larvae damage the plant through their webbing and feeding. These document feedings have affected more than 160 plant species, including economically significant crops like apples, avocados, tomatoes, and strawberries (source).