Sesamum diseases and management

Important diseses of sesamum,etiology,epidemeology and management practices.

1. WELCOME

2. DISEASES OF SESAMUM AND THEIR MANAGEMENT PAT 507: Diseases of field crops (2+1) Submitted by:- Jayant J P Dept. of agricultural Entomology . Submitted to:-Dr. Savita A S Dept. of Plant pathology.

3. One of the oldest oil seed crop and is under cultivation from ancient times. India contributes the highest sesame acreage of above 17.73 lakh hectare[1 st ] and production 8 lakh tones[1 st ] and productivity of 445kg/hectare[3 rd ]. It is also known as generally, till, popularly as “Queen of Oilseeds” due to its high degree of resistance to oxidation and rancidity. SESAMUM Sesamum indicum L. FAMILY:- Pedaliaceae

4. India is a major exporters to number of countries and has earned the foreign exchange of Rs 2800 crore . Sesame has one of the highest oil content (50-60%)of any oil seed crop and contains high amount of PUFA, mainly linoleic acid(37-47%). Sesame seeds are used in hindu culture as a “symbol of immortality” and known as “butler of middle east”.

5. MAJOR DISEASES OF SESAMUM Phyllody Stem and Root rot /Charcoal rot Cercospora leaf spot Powdery mildew Alternaria leaf spot Phytophthora blight Bacterial Blight Bacterial leaf spot

6. PHYLLODY C.O :- Phytoplasma It is a serious and wide spread disease of sesame and caused by a pleomorphic mycoplasma–like organism (MLOs) which is now called as Phytoplasma. The phyllody is transmitted by the insect vector Orosius albicinctus [Leaf hopper] . The disease has been recorded in India, Iran, Israel, Burma, Sudan, Nigeria, Tanzania, Pakistan, Ethopia , Thailand, Turkey, Uganda, and Mexico.

7. SYMPTOMS The infected plant is characterized by transformation of all floral parts into green leafy structures followed by abundant vein clearing in different flower parts. In severe infection, the entire inflorescence is replaced by short twisted leaves closely arranged on a stem with short internodes and abundant abnormal branches bend down. Finally, plants look like witches broom.

8. DISEASE CYCLE The pathogen has a wide host range and survives on alternate hosts like  Brassica campestris  var.  toria,B. rapa,   Cicer arietinum,Crotalaria  sp .,   Trifolium  sp.,  Arachis hypogaea which serve as source of inoculum. The disease is transmitted by Leaf hopper,  Orosius albicinctus .   Optimum acquisition period of vector is 3-4 days and inoculation feeding period is 30 minutes. The incubation period of the pathogen in leaf hoppers may be 15-63 days in sesame. Nymphs are incapable of transmitting the phytoplasma. Vector population is more during summer and less during winter months.

9. Orosius albicinctus

10. MANAGEMENT Remove and destroy infected plants. Intercropping of Sesame+Pigeonpea (6:1) is helpful for the management of phyllody. Use of tolerant varieties :-TKG 21, RT-125 and RT-103. To control vector…… Spraying of neem oil @10ml/l for vector (leaf hopper) control is helpful in managing the phyllody. Seed treatment with imidacloprid or carbosulfan protects the crop from all sucking pests including leaf hoppers for about a month. Soil treatment with Phorate 10 G @ 11 kg/ha at the time of sowing. Spray Dimethoate 30 EC 1ml/liter or Spinosad 0.5ml/lit.

11. Stem and Root rot/Charcoal rot C.O- Macrophomina phaseolina . Taxonomic classification: Kingdom: Fungi Phylum : Deuteromycotina Class: Coelomycetes Order: Sphaeropsidales Family: Sphaeropsidaceae Genus: Macrophomina Species: phaseolina Sclerotial stage - Rhizoctonia bataticola

12. SYMPTOMS The disease symptom starts as yellowing of lower leaves, followed by drooping and defoliation. The symptoms were produced at ground level, stem becomes black, which extends upward rupturing the stem and black dots appear on the infected stem. The roots will become brittle. In disease infected plants, black capsules are seen which open prematurely exposing shriveled seed.

13. Black coloured sclerotial bodies on pod (left) and on stem portion of the diseased plants.

14. ETIOLOGY The pathogen produces dark brown, septate mycelium showing constrictions at the hyphal junctions. The sclerotia are minute, dark black and 110-130µm in diameter. The  conidia  are hyaline, elliptical and single celled. Epidemiology Day temperature of 30˚C and above Prolonged drought followed by copious irrigation.

15. DISEASE CYCLE The fungus remains dormant as sclerotia in soil as well as in infected plant debris in soil . The fungus primarily spreads through infected seeds which carry sclerotia and pycnidia. The fungus also spreads through soil-borne sclerotia. The secondary spread is through the conidia transmitted by wind and rain water.

16. MANAGEMENT Field sanitation and Soil solarisation. Use of tolerant varieties - RT-46, RT0125, MT-75, TKG-22 and Nirmala. Treat the seeds with Trichoderma viridae at 5g/kg. Seed treatment with carbendazim + thiram (1:1) at 2g/kg seed. Spot drench with Carbendazim at 1.0 g/ litre .

17. Cercospora leaf spot C.O:- Cercospora sesami Taxonomic classification: Kingdom: Fungi Phyllum : Deuteromycotina Class: Deuteromycetes Order: Moniliales Family: Dematiaceae Genus: Cercospora Species: sesami

18. SYMPTOMS It appears as small, angular brown leaf spot 5-15 mm in diameter on both leaf surfaces. Under favorable conditions, the disease spreads to leaf petiole, stem and capsules producing linear dark coloured lesions. Extensive infection of foliage and capsule leads to defoliation and damage of sesame capsule and yield losses may range from 22 to 53% .

19. ETIOLOGY:- Conidia are elongated, 7-10 septate, hyaline to light yellow, broad at the base and tapering towards the apex. EPIDEMEOLOGY:- Humid conditions usually late spring and summer and dampness favours the disease. DISEASE CYCLE :- The fungus is externally and internally seed-borne. The fungus also survives in plant debris. Primary sources of infection are seeds and infected debris. The secondary spread is through wind-borne conidia .

20. MANAGEMENT Field sanitation. Early planting (immediately after onset of monsoon) . Intercropping of Sesame+Pearl millet (3:1) is helpful for controlling Cercospora disease. Treat the seeds with Carbendazin or Thiram at 2g/kg. Spray with Topsin -M (0.1%), Mancozeb (0.25%), Difenoconazole (0.1%) , Carbindazim 50wp+Mancozeb

21. POWDERY MILDEW C.O:- Erysiphae cichoracearum . Taxonomic classification : Kingdom: Fungi Division: Ascomycota Class: Filamentous ascomycetes Order: Erysiphales Family: Erysiphae Genus: Erysiphae Species: cichoracearum

22. SYMPTOMS It appears at vegetative stage to capsule formation stage as small patches of white powdery mass on upper side and occasionally on lower surface of leaves. Defoliation of severely infected plant occurs before maturity. The infection may be seen on the flowers and young capsules, leading to premature shedding.

23. ETIOLOGY:- Fruiting body is cleistothesia with many number of asci . Asexual spores are oidia which are ectophytic in nature. EPIDEMEOLOGY:- • Dry humid weather and Low relative humidity. Disease Cycle:- The Pathogen is an obligate parasite and disease spreads through conidia in the infected plant debris in soil. The secondary spread is through wind-borne conidia.

24. MANAGEMENT Remove the infected plant debris and destroy. Spray Carbendazim 0.1% , Wettable sulphur 0.3%, Hexaconazole 0.2%.

25. Alternaria leaf spot C.O :- Alternaria sesami Taxonomic classification: Kingdom: Fungi Phyllum : Deuteromycotina Class: Deuteromycetes Order: Moniliales Family: Dematiaceae Genus: Alternaria Species: sesami

26. SYMPTOMS It affects the plants at all stages and symptoms produce are small dark brown water soaked, round to irregular lesions with concentric rings varying from 1-8 mm in diameter. In severe infections several spots involving major portions of leaf blade and later leaf drop off from the plants. Dark brown lesions can also be seen on petioles, stem and capsules. Infection of capsules results in premature splitting with shriveled seeds.

27. ETIOLOGY :- The conidia are light olive coloured with transverse and longitudinal septa. These are around 3-5 septate and conidia are borne in chain over short conidiophore . EPIDEMEOLOGY :- Low temperature (20-25°C), High relative humidity Cloudy weather. Disease Cycle The fungus is seed-borne and also soil-borne as it remains dormant in the infected plant debris.

28. MANAGEMENT Field sanitation. Treat the seeds with thiram or Carbendazim at 2g/kg. Spray Mancozeb at 2gm/lit[2kg/ha] or Iprodion 1L/ha.

29. Bacterial Blight C.O:- Xanthomonas Compestris pv . sesami SYMPTOMS Initially water-soaked spots appear on the undersurface of the leaf and then on the upper surface. They increase in size, become angular and restricted by veins and dark brown in color. Several spots coalesce together forming irregular brown patches and cause drying of leaves. The lesions may also occur on petioles and stem.

30. ETIOLOGY :-The bacterium is a Gram negative, rod shaped with a monotrichous flagellum. Disease cycle The bacterium survives in the infected plant debris and in seeds. The secondary spread is by rain water.

31. MANAGEMENT Crop rotation. Use resistant variety like T-58 Early planting i.e. immediately after onset of monsoon. Destruction of crop residues. Steep the seed in Agrimycin-100 (250 ppm ) or Streptocycline suspension (0.05%) for 30 minutes. Foliar spray of Streptocycline (500 ppm ) as soon as symptoms are noticed. Continue two more sprays at 15 days interval if necessary.

32. Bacterial leaf spot C.O :-Pseudomonas syringe pv sesame SYMPTOMS The disease appears as water-soaked yellow specks on the upper surface of the leaves. They enlarge and become angular as resticted by veins and veinlets . The colour of spot may be dark brown with shiny oozes of bacterial masses.

33. ETIOLOGY The bacterium is gram negative aerobic rod with one or more polar flagella. Disease cycle The bacterium remains viable in the infected plant tissues. It is internally seedborne and secondary spread through rain splash and storms.

34. MANAGEMENT Keep the field free of infected plant debris. Spray with Streptomycin sulphate or oxytetracycline hydrochloride or streptocyclin at 100g/ha.

35. Results

36. References:- Status of sesame diseases and their integrated management using indigenous practices : KN Gupta, KR Naik and Rajni Bisen {International Journal of Chemical Studies 2018; 6(2): 1945-1952} Diseases of field crops and their management -Dr. p Kishore varma . Wikipedia http://ecoursesonline.iasri.res.in/Courses/Diseases%20of%20Field%20Crops%20and%20Their%20Management/PATH%20272/Start%20to%20read%20the%20Course.html