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Leaf spot (Cercospora moricola Cooke)

Introduction
        The leaf spot caused by Cercopsora to mulberry was first reported by Patel et al. (1949) from Kamataka. The disease is reported to cause 10-12 % leaf yield loss even up to 20 % -35 % in severe conditions (Sikdar and Krishnaswamy, 1980; Sikdar, 1987). Maximum severity was found during July to October in Kamataka (Siddaramaiah et aI., 1978). The disease causes reduction in moisture, proteins and sugars in infected leaves (Madhava Rao et al.. 1981). Rearing with infected leaves affects health of silkworms and in turn quality and quantity of cocoons produced (Sikdar et al., 1979).
Symptoms
         The causal fungus produces minor circular light brown spots on the leaves which gradually increase in size and turn darkbrown. The tiny spots coalesce to form bigger ones. The dead tissues fall off resulting shot holes lining yellow circle around the shot hole. The highly affected leaves fall off prematurely 
 
 Causal organism
 Cercospora moricola
Systematic position

Fig1leafspot

 Kingdom -Fungi
 Division-Ascomycota
 Class-Dothideomycetes
 Order- Capnodiales
 Family-Mycosphaerellaceae
 Genus-Cercospora
 Species-moricola
 Description of the pathogen:
          The conidia are born on conidiophores. Conidiophores 2-15 in a fascicle, pale olivaceous brown, straight, rarely septate and geniculate, unbranched, scars conspicuously thickened,10-50 x 4-5.5 µm. Conidia are hyaline, solitary, acicular, multi-septate base-truncate, tip-acute hilum thickened and darkened, 40-150 x 2-3.5µm.
 
Pre disposing factor
             The disease is generally found during rainy season followed by winter. High disease development was recorded in the month of August and September when outdoor temperature and relative humidity are 25-30 ºC and above 80%.The disease starts progressing 35-40 days after pruning (DAP)/ leaf harvesting and becomes severe 70th day after pruning.
 
Disease cycle
         The disease is very common during June –December, conidia germinate on both surfaces of the leaves. However, germ tubes (single or branched) enter through stomata only whether open or closed, indicating the absence of direct penetration (Sukumar and Ramalingam, 1983). In mulberry, the stomata are distributed only on the lower surface of the leaves (hypostomatous). Therefore, successful infection of C. moricola is possible only when the conidia are deposited on the lower surfaces. Interestingly, conidia are carried to the undersurface by rain splashes ensuring natural portal for entry and assured moisture for germination and penetration (Sukumar and Ramalingam, 1981). The conidia are capable of producing new hyphae from any cell. It takes about 10-12 days after inoculation of conidia to produce a spot and another 3-4 days for the production of conidia 
 
Resistant varieties

Resistance reaction

Name of the variety

Completely resistant

Kalliakutahi, Bilidevalaya (Govindaiah et al., 1989)

Resistant

Goshoerami, Ichinose,Kanva-2, S54, C799, Shrim-2, Shrim-8,MR-2, Assambola, AB x Phill, mouli, Mizusowa, English black, K2xKosen, China peking, Cattaneo, Sujapur x Kukuso-13, China white, Jodhpur, AB x Kokuso-13, Calabresa, Miuraso, Acc-153, Acc-152,Acc-151, Acc-150, Acc-128, Acc-135, Acc-106, Acc-109, Acc-112, Acc-114, Acc-115, Acc-116, Acc-117, Acc-119, Acc-121, Acc-123, Acc-124,OPH-1,OPH-3, MS-2, MS-5, Acc210, Paraguay, RFS-135. RFS-175, S-146, S-523, MS-7, MS-8, Acc125, Acc-128, K2 x Kokuso, S1531, LF-1, Almora local, S31, S1096.

 
Control measures
Cultural control:
Follow wider spacing of plantation (90 cm x 90 cm) or paired row planting system [(90 +150) × 60 cm]. Avoid sprinkler irrigation.
Chemical control:
Various fungicides are identified for control of the disease.
  1. Spraying 0.2 % Bavistin (Carbendazim 50% WP) solution on the leaves. This can be made by dissolving 800g Bavistin in 200 liter water for spraying in 1 acre mulberry garden. The leaves can be used for silkworm rearing 7 days after the spray.
  2. Spray 0.2% Karathane. About 400-500 ml Karathane is to be mixed with 200-250 liters of water. A second spray can be made if the disease is more severe. The leaves can be used for silkworm rearing 10 days after final spray.
Related literature
Biswas S, (1992) Fungicides for mulberry disease control - an appraisal. Indian Silk, August 1992, pp 26-28.
Biswas S, Das NK, Qadri SMH, Saratchandra B, (1995) Evaluating different plant extracts against three major diseases of mulberry. Indian Phytopath., 48(3): 342-346.
Biswas S, Sengupta K, (1994) Genetic control of disease resistance in mulberry. Sericologia, 34(1): 33-42.
Gangwar SK, Pratheesh Kumar PM, Elangovan C, Qadri SMH, (1998) Response of mulberry varieties to leaf rust (Cerotelium fici) as influenced by fungicides. Sericologia, 38(4): 661-666.
Ghosh L, Alam MS, Ali MR, Shohael AM, Alam F, Islam R, (2003) Changes in some biochemical parameters of mulberry (Morus sp.) leaves after infected with leaf spot disease. Online Journal of Biological Sciences 3(5): 508-514.
Ghosh L, Neela FA, Mahal MF, Khatun MJ, Ali MR, (2012) Effect of various factors on the development of leaf spot disease in mulberry J. Environ. Sci. & Natural Resources,   5(1): 205 - 209, 2012
Govindaiah, Sharma DD, Sengupta K, Gunasekher V, Suryanarayana N, Madhava Rao, YR, (1989) Screening of mulberry varieties against major fungal diseases. Ind. J. Seric., 28(2): 207-213.
GovindaiahPhilip T, Sengupta K, Giridhar K, Suryanarayana N,  (1990) Incidence of leaf spot disease in relation to epidermal and cuticle thickness in some indigenous varieties of mulberry.  Sericologia, 30(2): 257-260
Gupta VP, Tewari SK, GovindaiahBajpai AKDatta RK, (1995) Observations on the surface ultra structure of conidal stage of Cercospora moricola and its infection process in mulberry. Sericologia, 35(1): 123-128.
Irfan I, Mittal V, Ramegowda GK, Dhar A, Khan MA, (2011) Occurrence of major foliar diseases of mulberry under temperate climatic conditions of Kashmir, India. International Journal of Science and Nature, 2(1): 51-54.
Raja Gopal Reddy C, Nirmala RS, Ramanamma CH, (2009)Efficacy of phytoextracts and oils of certain medicinal plantsagainst Cercospora moricola Cooke., inciting mulberry (Morusalba L.) leaf spot. Journal of Biopesticides, 2(1): 77-83.
Siddaramaiah AL, Govindan R, Desai SA, Bhat RP, Devaiah MC, (1980) In vitro efficacy of certain systemic and non systemic fungicides against Cercospora leaf spot of mulberry Ind. J. Seric. 19: 34-35.
Siddaramaiah AL, Krishna Prasad KS, (1978) Laboratory evaluation of fungicides against Cercospora moricola Cooke. Ind. J. Seric., 17: 33-36.
Siddaramaiah AL, Lingaraju S, Hegde RK, (1978) Toxic effect of the culture filtrate of Cercospora moricola Cooke the causal organism of leaf spot of mulberry. Ind. J. Seric.,  19: 32-33.
Siddaramaiah, AL, Srikanth Kulkarni, Krishna Prasad KS, (1978) Antagonistic action of Streptomyces sp. on Cercospora moricola Cooke. Ind. J. Seric., 17 (1): 64.
Sikdar AK, Krishnaswami S, (1980) Assessment of leaf yield loss of the two mulberry varieties due to leaf spot disease. Ind. J. Seric. 19: 9-12.
Sikdar AK, Shenoi MM, (1980) Control of leaf spot disease of mulberry by systemic fungicides. Indian Phytopath., 33(1): 38-41.
Sukumar J, (1988) Inhibition of conidial germination of Cercospora moricola by mulberry leaf leachates. Sericologia, 28(2): 249-252.
Sukumar J, Ramalingam A, (1986)   Epidemiology of Cercospora leaf spot disease of mulberry stages of infection spots and conidial production.  Sericologia   27(4):  685-688.
Tang AK, Salam KA, Samad MA, Absar N, (2005) Nutritional changes of four varieties of mulberry leaves infected with fungus (Cercospora moricola). Pakistan J. Biological Sciences. 8(1): 127-131.
Teotia RS, Sen SK, (1994) Mulberry diseases in India and their control. Sericologia, 34(1)1-18.
Teotia RSMandal SK, (1992). Integrated control of leaf spot disease of mulberry. Indian silk, January 1992 pp 45-47
Teotia RS, Kant AK, Mandal SK, (1992) Bavistin-an effective fungicide for sericulture. Indian Silk, May 1992, pp 25-26.
Umesh. Kumar NN, Shree MP, (1990) Some physiological changes in leaves of Morus alba L. under pathogenesis. Geobios, 17: 140-141.
Vijaya Kumar GC, (1994) Incidence of Cercospora moricola Cooke in mulberry leaves (Morus Indica L.): Histopathological and histochemical changes. Sericologia, 34(2) 363-366.

 

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