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Grey leaf spot (Pseudocercospora mori)
Introduction
Pseudocercospora mori (Hara) Deighton, the grey leaf spot pathogen of mulberry, has been reported from Japan, Congo, Taiwan, China, the USA and India. The fungus can cause significant damage to leaves of Morus spp. This is one of the major diseases during post monsoon season in the Gangetic plains of West Bengal and North-Eastern region.  The disease appears during September and continues up to November.  
Symptoms
The disease is characterized by small to medium size velvety gray to black spots appearing on the lower surface of the older leaves.. The spots are indistinct on upper surface, more conspicuous on the lower surface where they are brown, angular or spreading (particularly along leaf margins) and restricted by the larger veins, up to 7mm wide. Later, the spots cover whole lower surface.  Severely infected leaves turn yellowish and defoliate prematurely.
Causal organism
Pseudocercospora mori  (Hara) Deighton
Systematic position                                                                                                      
         Kin g Fungi  
         Phylum: Ascomycota  
         Class: Dothideomycetes  
         Order:  Mycosphaerellales  
         Family: Mycosphaerellaceae
         Genus: Pseudocercospora  
 
         Species: mori
Description of the pathogen

 Sporulationishypogenous, ranging from olivaceous and velutinous to darker brown and punctate. Immersed hyphaepale olivaceous, smooth, septate, branching, 1–3 μm diam. Superficial hyphaesparse, emerging from stomata, pale olivaceous, smooth, septate, 1–2 μm diam., bearing lateral conidiophores similar to those associated with stomatal egress. Stromata lacking, reduced to a few light brown cells in the substomatal cavity, or compact and light brown, filling the sub-stomatal cavity, 18–25µm diam. Conidiophoresare solitary or 2–22 in a divergent fascicle, olivaceous brown throughout or slightly paler at the apex, irregular in width, branched, straight, curved or sinuous, markedly geniculate towards a conic apex, conspicuously 1–4(–7) septate, 30–67 µm long×3–4.5 µm wide. Conidiogenous lociare not darkened, not thickened, non-refractive, 0.5–1 µm diam. Conidiaarepale olivaceous, straight or curved, smooth, narrowly obclavate, straight to mildly curved, occasionally constricted, usually narrowing gradually to a sub-obtuse or obtuse apex, and a little more abruptly to an obconic, truncate base, 1–5(–7) septate, 18–61×3–4 µm. Hilaare not darkened, not thickened, non-refractive, 1–2 µm diam . The pathogen grows in host extract agar medium.
 
Predsposing factors
 Temperature 25-30 and humidity 85-90 favoure the disease development.  The disease infection was found higher during the growth period 48-55 days of the shoot. 
Disease cycle
Since the low temperature favours the disease, the disease starts generally during the month of June with the onset of monsoon. The disease gradually develop with the lowering the temperature. The conidia disperse through the rain and during the month of September- October the disease will be very high and thereafter the severity will be low. The disease is generally not seen after the month of February due to the high temperature. 
 
 
Resistant varieties
 

Resistant reaction

Varieties

Highly resistant

Thailand lobed,M. multicaulis, Italian, M. australis,

Resistant

MS-8, Fernodias, MS-7, Thailand (lobed), PGDTR-9, Tomeiso, KNG, CSRS-II, Morus cathyana, Berhampore-B, Roznitul, Kurimoto, Kanmasari, Calabresa, Jodhpur, Morus australis, Thailand (unlobed), Berhampore-6, Assambola

 
Control
The disease is effectively controlled by foliar spray of 0.1% Carbendazim (Bavistin) - a broad spectrum systemic fungicide.
Related literature
Abbas SQ, Ali I, Niaz M, Ayesha R, Iftikhar T, (2010) new fungal records on Morus alba from Faisalabad, Pakistan  Pak. J.Bot., 42(1): 583-592.
Babu AM, Vineet Kumar, Govindaiah, (2002) Surface ultrastructural studies on the infection process of Pseudocercospora mori causing grey leaf spot disease in mulberry. Mycol. Res., 106(8) 938-945.
Biswas S, Pavan Kumar T, (1995) Pseudocercospora mori:  mulberry leaf spot fungus. Indian Silk,  December 1995.
Grice KRE, Beilharz DV, Shivas RG, (2006) First record of Pseudocercospora mori causing grey leaf spot on mulberry in Australia.  Australasian Plant Disease Notes, 1, 9–10.
Pratheesh Kumar PM,  Qadri  SMH, Pal SC, Saratchandra B, (1999) Evaluation of few fungicides against two leaf spot diseases of mulberry (Morus spp.). Bull. Sericult. Res., 10: 9-15.
Pratheesh Kumar PM, Chattopadhyay S, Maji MD, Raje Urs S, (2005) Severity of foliar diseases of mulberry in West Bengal during commercial crop seasons. Bull. Ind. Acad.  Seric. 9(1):1-6.
Pratheesh Kumar PM, Qadri SMH, Pal SC, (2011) Factors influencing development and severity of grey leaf spot disease of mulberry (Morus spp.). International Journal of Industrial Entomology, 22(1): 11-15.
Pratheesh Kumar PM, Qadri SMH, Pal SC, Misra AK, (2011)Quantification of relation between disease intensities and physiological and biochemical changes in mulberry due to grey leaf spot. Indian J. Sericulture. 50(1): 28-33.
Teotia RS, Kant AK, Mandal SK, (1992) Bavistin-an effective fungicide for sericulture. Indian Silk, May 1992, pp 25-26.
Teotia RS, Sen SK, (1994) Mulberry diseases in India and their control. Sericologia, 34(1)1-18.
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