Leaf rust (Cerotelium fici)
Introduction
Leaf rust, caused by Cerotolium fici also called as black rust is a very important foliar disease of mulberry in India. The disease generally appears during late winter and prolong up to early summer (September to February). Black rust generally appears on mature leaves and cause 5-10 % loss in leaf yield (Siddaramaiah et al., 1978). Besides, the disease significantly reduces moisture, crude protein, sugars and total sugars in infected leaves (Sundeswaran et al., 1988).
Symptoms
The infected leaves shows pin head like eruptive brown pustule on the lower side of the leaves and dark tiny angular spots on the concomitant upper surface of the leaves. As the disease become severe, leaves become yellow, wither off and fall prematurely.
Causal organism
Cerotelium fici
Systematic position
Kingdom: Fungi
Division: Basidiomycota
Class: Teliomycetes
Order: Uredinales
Family: Phakopsoraceae
Genus: Cerotelium
Species : fici
Description of the pathogen
Hemi-form. Pycnia and aecia unknown. Uredia hypophyllous, scattered ± irregularly or in groups, sometimes on conspicuous angular spots between the veins, often dense and often profuse over part or all of the leaf, pale to ferrugineous, circular, 0,15-0,4 mm diam., like minute blisters open in the centre, often with inconspicuous cylindric-clavate, thin-walled, hyaline paraphyses. Urediospores globose, ellipsoid or obovoid, sometimes rather irregular and angular, 19-30 x 15-23 µm; wall hyaline to cinnamon, occasionally even darker, 1-1,5 (-2) µm thick, finely to strongly echinulate with spines 1-3 µm apart and 0,5-1 µm high; pores usually very obscure, but definitely 3 (-4?) and equatorial in some of the deeper coloured spores .
Predisposing factors
The disease is highly influenced by environmental factors, host age and genotype. The low atmospheric temperature (22-24°C) following monsoon (September-February) is highly favourable for the disease development. The leaves on the branches more than 45 days older are more prone to the disease and the younger leaves are generally free from the disease. The pathogen perennates through the dried leaves and plant parts found in the mulberry gardens.
The pathogen Cerotelium fici is an obligate microcyclic rust fungus. It exists primarily as mycelium, uredium and uredinospores. The uredinospores are oval to round produced singly on uredophores in uredia. In favourable conditions for the growth of pathogen is 22-24°C temperature and high humidity favour the disease. Uredospores germinate and produce hyphae which enter the leaf through stomata. The hypha grow inter cellular in the host tissues sending haustoria in to the host cells to draw nutrients. Uredospores disperse through water droplets and wind currents and spread the disease.
Disease cycle
Resistant varieties
|
Resistance reaction |
Name of the variety |
|
Immune |
- |
|
Resistant |
C1726, S700, China Peking, Cattaneo |
|
Moderately resistant |
AB x Phill,K2 x Kosen, ACC115, Almora local, MS7, S13, MS2, MS6, ACC217, S34, ACC201, S25 |
Control
Cultural control
Adopt wider spacing, do not allow the plants to over mature and prune off the whole plant immediately after rearing. Keep the mulberry garden clean and remove the dried leaves from the garden and burn.
Chemical control
Spray Kavach (Chlorothalonil 75 WP) 0.2% i.e. dissolve 3 gram Kavach in 1 lit. water and thoroughly drench the leaves while spraying the fungicide.
Safe period: The leaves can be used for silkworm rearing 14 days after the fungicide spray.
Related literature
Biswas S, Sengupta K, (1994) Genetic control of disease resistance in mulberry. Sericologia, 34(1): 33-42
Dutta, Ghosh MK, Borah A, Bindroo BB, (2012) Development of Disease Forecasting Model for Leaf rust of Mulberry (Morus alba L.) of Dimapur of North East India. Nature and Science 2012; 10(8) 66-69.
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.
Gunasekhar V, Govindaiah, Himantharaj MT, (1995) Efficacy of fungicides in controlling mulberry leaf rust caused by Cerotelium fici. Indian J. Seric., 34 (1): 60-62.
Nishitha Naik V, Sharma DD, Ma!a VR, Rekha M, Govindaiah, Gupta VP, (2008) Prediction of leaf rust disease in mulberry for timely management. Sericologia, 48(2): 195-202.
Philip T, Gupta VP, Govindaiah, Bajpai AK, Datta RK, (1994) Diseases of mulberry in India- Research priorities and management strategies. Int. J. Tropical Plant Diseases 12:1-21
Philip T, Mala VR, Kamble CK, (2009) Role of botanicals in the management of mulberry pests and diseases- a review. Sericologia, 49(2): 151-160
Philip T, Sarkar A, Govindaiah, (1996) Screening of some promising genotypes of mulberry for leaf spot and rust resistance. Indian J. Seric. 35(2): 158-159.
Philip T, Mala VR, Kamble CK, (2009) Role of botanicals in the management of mulberry pests and diseases- a review. Sericologia, 49(2): 151-160
Philip T, Sarkar A, Govindaiah, (1996) Screening of some promising genotypes of mulberry for leaf spot and rust resistance. Indian J. Seric. 35(2): 158-159
Pratheesh Kumar PM, Maji MD, Gangwar SK, Das NK, Saratchandra B, (2000) Development of leaf rust (Peridiopsora mori) and dispersal of urediospores in mulberry (Morus spp.). International J. Pest Management. 46(3): 195-200.
Pratheesh Kumar PM, Qadri SMH, Gangwar SK, Saratchandra B, (1999) Enhanced efficacy of fungicides using sticker in foliar mulberry disease control. Sericologia, 263-266.
Sundareswaran P, Govindaiah, Srinivasan EB, Jolly MS, (1988) Effect of leaf rust disease on the nutritive composition of mulberry (Morus alba L.). Indian J. Seric. 27(2): 159-160.
Teotia RS, Rao KM, Mandal SK, (1994) Influence of growth regulators on the development of leaf rust and powdery mildew disease of mulberry. Sericologia, 33(4): 669- 673.
Teotia RS, Sen SK, (1994) Mulberry diseases in India and their control. Sericologia, 34(1)1-18.
Teotia RS, Sen SK, Mandal SK. Sinha SS, (1994) Varietal resistance in mulberry to leaf rust (Aecidium mori Berclay). Sericologia, 34(4): 759-763.
Teotia RS, Sen SK, Mandal SK. Sinha SS, (1994) Varietal resistance in mulberry to leaf rust (Aecidium mori Berclay). Sericologia, 34(4): 759-763.
Teotia RS, Mandal SK, (1991) controlling the leaf rust disease of mulberry, Indian Silk, April 1991, pp12-14