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- 1. Siddu Lakshmi Prasanna CourseNo.: PATH 2.7.1. Course Title: Diseases of Fruit, Plantation, Medicinal and Aromatic crops By Dr. Siddu Lakshmi Prasanna Ph. D (Agri.) Dept. of Plant Pathology
- 2. Mint Sr. No. DiseaseCausal organism 1. Stolon rot Rhizoctonia bataticola Macrophomona phaseolina Theilaviopsis basicola 2. Rust Puccinia menthae 3. Alternaria leaf blight Alternaria alternata 4. Verticillium wilt Verticillium albo-atrum 5. Powdery mildew Erysiphe cichoracearum Important diseases list:
- 3. Aerial symptoms: • Initiallyyellowing of leaves & stunted growth. Advance stages the plants wilts followed by death of above ground parts. Below ground symtoms: • Stolons exhibit pinkish brown lesions initially which gradually turns into dark brown lesions. • Later turns to dark brown to black patches that increase in size resulting in soft decay. STOLON ROT: Causal organism: Rhizoctonia bataticola, Macrophomona phaseolina, Theilaviopsis basicola
- 6. ETIOLOGY: • Septate mycelia,sub epidermal haustoria • Asexual spores: Mycelial strands • Sexual spores: Basidium (Basidiospores) • Vegetative structure: Sclerotial bodies • Primary Sources of Inoculum : Sclerotial bodies present in the debris • Secondary Sources of Inoculum : Soil borne mycelial strands EPIDEMIOLOGY : • Warm weather, soil temp 28-32°C. Optimum moisture, neutral pH
- 7. MANAGEMENT: • Discard allthe diseased stolons while planting • Treat the stolons with 0.25% Captan or 0.1% Benomyl or zineb or mancozeb . • Follow 3-year-crop rotation with rice, wheat and mint. • Deep summer ploughing • Avoid excess irrigation. • Uproot and burn the affected plants. • Soil application of Trichoderma sp. • Drench soil with chlorothalonil 0.2%
- 8. Symptoms: • Brown, circularpustules appear on the undersides (Aceiospores) of leaves followed by leaf yellowing. • A yellow spore stage (uredospores) is in reddish blisters on young shoots in spring, and a black spore stage (teliospores) is on stems and re-growth in fall. • Telial stage is characterized by swelling on the upper portion of the stem. • Swollen shoots with elongated, chlorotic internodes are associated with systemic infection. RUST: Causal organism: Puccinia menthae
- 10. Etiology • Puccinia menthaeover winters on mint stubble and on wild and escaped mint. • P. menthae is macrocyclic, autoecious, produces uredosori on leaves, stems, and runners. • Teliospores are brown, 2 celled, pedicillate, obtuse to slightly pointed. Epidemiology: • Temperature 17-27°C • RH:90-92% • Long day hours 1-2 hours dew period in morning
- 11. Management: • Rabbing inApril 1 to May 15 is absolutely necessary for rust control. • Early harvest (before leaves drop due to rust). • Spray chlorothalonil or propiconazole or tebuconazole or mancozeb or plantovax or diclobutazole • Begin applications when plants are 5 to 10 cm high or when conditions become favourable for disease. • Make second application 10 to 14 days after the first application. • Crop rotation. • Removal and destruction of disease affected plants. • Use disease free planting material. Treat planting material with hot water
- 12. SYMPTOMS: • The mainsymptoms of the disease are appearance of the round to oval or slightly irregular dark brown spots on the upper surface of the leaves with concentric zones surrounding the pale yellow margin. • Later, these spots coalesce, enlarge and occupy the entire leaf or a portion of the leaf which leads to the dropping of leaves. LEAF BLIGHT: Causal organism: Alternaria alternata
- 13. ETIOLOGY: • Septate mycelia,coloured muricate conidia • Primary Sources of Inoculum : Dormant mycelia in infected plant debris • Secondary Sources of Inoculum : Air borne conidia Epidemiology: Nutritionally poor soil, temp 28-32oC, RH 85-90 per cent, susceptible host. MANAGEMENT: ➢ Use disease free planting material. ➢ Treat planting material with hot water. • Spray Mancozeb or Zineb 0.2% or Copper oxy chloride 0.3% at the initial stage.
- 14. • Symptoms firstappear in the foliage at the top of the plant. • The main symptoms of the disease are dwarfing, unilateral development of branches, etiolation and wilting. • Upper leaves are sickle-shaped and initially chlorotic or red, soon becoming necrotic. • Vascular discoloration in stems and roots observed and diseased plants are often stunted. • Premature defoliation and death of the plant. WILT: Causal organism: Verticilium albo-atrum
- 17. ETIOLOGY: • The pathogenis soil-borne and spread through soil. • Roots and stolons used as seed material. • The vegetative mycelium is hyaline, septate, and multinucleate. • Verticillium is named for this "verticillate" (=whorled) arrangement of the phialides on the conidiophore. • Conidia are borne on phialides and each phialide carries a mass of conidia. • Conidia are ovoid or ellipsoid and usually single- celled.
- 18. Primary Sources ofInoculum : Dormant mycelia Secondary Sources of Inoculum : Soil and air borne micro and macro- conidia EPIDEMIOLOGY: • Temp. 30-32 c, • RH-90-92%, • alkaline pH, • Black Clay soil, • low moisture, • susceptible host
- 19. MANAGEMENT: • Applying optimalrates of nitrogen and enhanced dose of potash. • Use of diseases free stolons • Follow crop rotation, five years of planting to maize. • Use bioagents like Trichoderma sp • Cross protection - V. nigrescens. • Deep summer ploughing. • Well drained field conditions.
- 20. Symptoms: • Small chloroticspots appear on the upper surface of leaves. The corresponding lower surface showing brownish discoloration prior to the appearance of powdery patches. • Later, circular white powdery patches appear mostly on the upper portions. • Later, these white patches turn to purplish black and produce large number of clestothecia. • Heavy defoliation occurs in severe cases having a banded appearance on stem and branches. POWDERY MILDEW: Causal organism: Erysiphe cichoracearum
- 23. Etiology: • External septatemycelia, Haustoria sub epidermal. Septate mycelia produces conidiophore on which barrel shaped conidia are borne in chains Asexual spores : Barrel shaped conidia borne on Oidium. Sexual spores : Ascospores borne in Ascus. Asci are situated in Cleistothecium Primary Sources of Inoculum: Dormant mycelia and Short period cleistothecium. Secondary Sources of Inoculum: Air borne barrel shaped conidia.
- 24. Epidemiology: • Warm weather,Temp: 28-32°C. • R.H: 85-86%. • Cloudy weather, Susceptible host Management: • Crop rotation with non host crops, Altering the date of sowing • Proper nutrient management, Avoid dense planting • Maintain proper row spacing, use of resistant or tolerant varieties • Prophylactic aerial spray- Wettable Sulphur 0.3% or Carbendazim 0.1% or Calixin 0.15% at 10-15 days interval