Authors: Prativa Anand and Babita Singh
Division of Floriculture and Landscaping
ICAR- Indian Agricultural Research Institute, New Delhi-110012
- Root Rot (Pythium sp. and Phythophthora sp.)
- Rotting of stem cuttings in rooting beds in warm, moist conditions, is most common. The fungus may also enter the established plants through the wounds caused by pinching, etc.
- The infected parts like roots, stem and leaves wilt suddenly.
- Stem Rot and Wilt (Fusarium oxysporum)
- Disease develops only after the appearance of flower buds or when they show colour, although infection might have occurred even in rooting beds.
- Stem near soil becomes dark brown and dries.
- Lower leaves turn yellow and plants wilt permanently afterwards.
- Septoria Leaf Spot (Septoria obesa and Septoria chrysanthemella)
- This is the most common and serious disease of chrysanthemum.
- Brown spots appear on leaves that grow in size and number in humid conditions.
- Leaves turn yellow and die afterwards.
- Grey Mold (Botrytis cinerea)
- First girdling of stem takes place, which results in death of upper part.
- Leaf infection starts from margin and proceeds towards centre and base, showing semi-circular bands.
- Flower infection starts with brown water soaked spots on lower petals.
- Ray Blight (Didymella ligulicola)
- It affects all above ground parts but is most severe on the shoots and on the flowers which develop reddish petal spots on light coloured cultivars and brownish spots on darker coloured types.
- The lesions spread rapidly and the flowers collapse with the ensuing decay.
- On shoots, the disease often begins with the rotting of terminal buds while the leaves are affected by patches of brown black decay.
- Powdery Mildew (Oidium chrysanthemi)
- White powdery patches appear on the upper surface and on the tender shoots.
- In severe cases, leaves fall off and flower production is reduced.
- Rust (Puccinia chrysanthemi)
- Yellowish green spots on the upper surface and chest nut browny pustules on the lower surface of leaves.
- Severely infected plants are stunted and do not bloom properly.
- Verticillium Wilt (Verticillium albo-atrum and Verticillium dahliae)
- Symptoms appear at the flower bud initiation and plants wilt suddenly.
- Bacterial Leaf Spot ( Pseudomonas cichorii)
- Circular elliptical leaf spots appear, increase and coalesce to form large necrotic areas.
- The disease appears first on basal leaves and progresses upwards to flower buds which turn dark and die later.
- Viral Diseases
- Mosaic caused by Chrysanthemum mosaic virus, Chrysanthemum virus-B, Tomato aspermy virus shows yellow mottling of leaves and breaking and distortion of flowers.
- Tomato spotted wilt virus appears as pale mottling and necrotic spots on the leaves.
- Chrysanthemum stunt virus shows overall reduction in plant size, pale foliage with margins failing to enlarge giving stiff appearance, flowers may open prematurely, red and bronze flowers are often bleached.
About Author / Additional Info:
Working as Scientist, Division of Floriculture and Landscaping, ICAR-Indian Agricultural Research Institute, New Delhi-110012