Diseases Of Sugarcane

By TamilNadu Agricultural University on 09 Nov 2016 | read
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1. Red rot

Causal organism : Colletotrichum falcatum

Symptoms: Symptoms are observed on the leaves and canes. On themidrib, circular to oval spots with red margin and straw colored center are observed. In the central region, acervuli could be seen black dots.The infected leaves break at the lesions. In the affected canes, the internal tissues become red with cross white patches. The stalks become hollow.

Favourable Conditions: Mono culturing of sugarcane;Successive ratoon cropping; Water logged conditions and injuries caused by insects;Mono culturing of sugarcane; Successive ratoon cropping.; Water logged conditions and injuries caused by insects.

2. Sett rot or Pineapple disease

Causal organism : - Ceratocystis paradoxa

Symptoms: The disease is observed as soon as the setts are planted. The central core of affected tissue turns black. Cavities are formed in the etts and the rotting tissues emit pineapple odor.

Favorable Conditions : Poorly drained fields; Heavy claysoils ;Temperature of 25-30o C ; Prolonged rainfall after planting.

3. Whip smut

Causal organism : Ustilago scitaminea

Symptoms: The affected plants are stunted and the central shoot is converted into a long curved whip like sorus. The sours is covered by asilvery, membrane which soon ruptures exposing a dark massofteliospores.

4.Favourable Conditions : Monoculturing of sugarcane; Continuous ratooning and dry weather during tillering stage.

5. Disease : Mosaic

Causal organism : Sugarcane mosaic potyvirus

Symptoms: The disease appears prominently on young leaves. Linearchlorotic stripes alternating with dark green areas are seen on the leaves.

At \ later stages yellow stripes appear on leaf sheath and stalk. Thevirus is a rod. The virus gets transmitted by setts and the aphid,Raphalosiphum maidis.

6. Disease : Grassy shoot Disease(GSD)

Causal organism : Candidatus phytoplasma

Symptoms: Large number of lanky tillers are produced from theAffected sett. Leaves become narrow, pale green to white in color. The internodes get shortened and plants appear bushy due to excessivetillering. The pathogen in transmitted by Aphids-Melanaphis sacchari and Rhaphalosiphum maidis

8. Disease : Phanerogamic parasite

Causal organism : Striga spp.

Symptoms: It is partial root parasite with chlorophyll bearing leaves.The parasite attaches to the host root by haustoria and suck the mineral nutrients and water. As a result the parasitised cane becomes stunted.

Management:

Red rot:

Selection of setts from healthy nursery program  growing of Recommended resistant and moderately resistant varieties viz., Co86249,CoSi95071, CoG 93076, CoC 22, CoSi 6 and CoG 5 Adopt sett treatment With Carbendazim before planting (Carbendazim 50 WP, @ 0.05% or Carbendazim 25 DS @ 0.1% along with 1.0% Urea for 5 minutes) theIrrigation interval in a red rot affected field must be lengthened. Once in 15 days during tillering, growth phases and once in 25 days during Maturity phase which restricts the spread. Removal of the affected Clumps at an early stage and soil drenching with 0.1 % Carbandazim 50WP or 0.25 % lime. The trash of red rot affected field after harvest maybe uniformly spread And Burnt The red rot affected field must be rotated with rice for one season and Other crops for two seasons.

Smut:

Growing of resistant and moderately resistant varieties viz., Co 86249,CoG93076, CoC 22, CoSi6 and CoG 5Sett treatment with fungicides viz., Triadimefon @ 0.1% orCarbendazim @ 0.1% for 10 minutes.Treating the seed setts with Aerated Steam Therapy (AST) at 50 ºC for1 hour or in hot water at 50 ºC for 30 minutes or at 52 ºC for 18 minutes Removal of smut whips with gunny bags/polythene bag and burnt Discourage ratooning of the diseased crops having more than 10per cent infection

Phanerogamic parasite

Regular weeding and intercultural operation during early stages of parasite growth. Spray Fernoxone (sodium salt of 2, 4-D) at 450g /500 litre of water.

General management

Select healthy setts for planting. In the seed crop, select plants which donot show symptoms of red rot, smut, grassy shoot and ratoon stunting.Setts showing red color at the cut end and hollows should be rejected and burnt.Set fire to residues of previous crop to eliminate debris of fungal pathogens. 

In fields which had shown high level of red rot disease, follow croprotation with rice. The setts should be soaked in 0.1% Carbendazim or0.05% Triademefon for 15 minutes. Treat setts with aerated steam at 50°C for one hour to control primary infection of grassy shoot disease.Clumps infected by grassy shoot, smut and ratoon stunting diseases should be immediately uprooted and destroyed.Use resistant varieties for the following diseases: Red rot CO 62198, CO 7704 (Resistant),

 

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