Major Beetroot diseases are:-
1.Beetroot Leaf Spot: Cercospora beticola
- This is a commonly occurring disease on the foliage of beet roots. High humidity usually favours the spread of this disease.
- Numerous small circular spots appear on the leaf surface. The spots increase in size, becoming brownish or purplish in colour.
- Individual spots are usually circular but several may coalesce into larger areas of dead tissue.
- The spots dry up giving a shot-hole appearance to the leaves. In the case of severe infection, spots cover the entire leaf surface resulting in premature death and dropping of the leaves.
- As leaves die, the crown becomes cone-shaped with a rosette of dead leaves at the base.
- Defoliation occurs throughout the growing season resulting in a reduction in root size and yield. Older leaves are mostly affected.
- Removal and destruction of affected plants and practicing crop rotation are beneficial in controlling the disease.
- Spraying with Copper oxychloride (0.3 %) thrice at an interval of 15 days controls the disease effectively.
2.Beetroot Downy Mildew: Perenospora schachtti
- The disease is most prevalent during the cooler months.
- Symptoms appear as irregular greasy greyish areas on the leaves. Under moist conditions, these areas expand rapidly and a white powdery growth appears on the lower surface of the affected leaves.
- Affected leaf dries and shrivels quickly. Flower shoots on infected plants become stunted and distorted.
- The entire inflorescence has a compact appearance and excessive leaf development may give an appearance witches broom.
- The fungus survives on the crop residues in the soil and is also carried by the seed.
- Preventive measures such as good field sanitation, crop rotation and use of resistant cultivars is recommended.
- Seed treatment with Thiram (2.5-3 g/kg of seed) protects the emerging seedlings from the disease attack.
- Spraying with Dithane Z-78 (0.3 %) thrice at an interval of 15 days is also recommended as an effective control measure.
3.Curly- top virus of Beetroot
- This disease is transmitted by beet leaf hoppers. External symptoms of curly top virus infection may appear in leaves, stems, flowers, fruits, or roots of infected plants.
- Generally, mottling is absent, but infected plant parts may become distorted through curling, twisting, rolling, stunting, etc.
- Leaves become thickened and leathery. The Curly top virus may impair both yield and quality of the root of an infected plant.
- Some of the most pronounced symptoms resulting from curly top virus attacks are internal and non-observable with the unaided eye.
- Such internal symptoms consist of death of the food conducting vessels, as well as of extreme variations from the normal in numbers and sizes of cells composing the plant tissues
- Losses can be reduced by the use of resistant varieties;
- Adopting sanitary measures including the eradication of susceptible weeds and susceptible volunteer crop plants from a previous planting;
- Regulating the time of planting in order to avoid the main flights of the beet leafhopper;
- Use of barriers of trap crops and early removal and destruction of infected plants.
- Spraying malathion (2ml/litre of water) controls the population of beet leaf hoppers.
4.Beet Yellows: Virus
- This disease is transmitted mainly through aphids.
- The important symptoms of the disease include yellow spots on the young leaves in the initial stages of infection.
- As the disease progresses, the leaves exhibit irregular yellow patches alternating with the normal green colour of the leaves.
- The older leaves of infected plants become chlorotic, noticeably thickened, leathery and brittle. The foliage becomes abnormally red or yellow and often dies.
- Control measures include removal of infected plants and weeds from the field.
- The disease incidence can be minimized by controlling the population of aphids by spraying oxydemeton Methyl 25 EC (2ml/litre of water)
- TamilNadu Agritech Portal