Print

Phloeospora leaf spot (Phloeospora maculans Fuckel)

Introduction

          This disease also known as brown leaf spot occurs in almost all sericulture areas of the world. In India, the disease was first reported by Munshi et at. (1986) from the Kashmir valley. The disease occurs during rainy to autumn season (June – October).  The fungus causes heavy damage to the leaves, rendering them unsuitable for silkworm rearing. None of the mulberry cultivars grown in the valley was reported free from the disease.

Symptoms

           Infection starts with presence of small dark brown, then light brown later on yellowish or whitish; circular spots on both surface of the leaves. The spots turn grey in the centre surrounded by a broad yellow diffusion zone. The necrotic portion of the spots decay in the wet season and fall off and hence leaves will become perforated.  During the dry season the necrotic portion split open. The spots at maturity become yellowish grey.

Causal organism  

Phloeospora maculans  

Systematic position  

Division: Ascomycota 
Order: Dothideomycetes 
Class: Pleosporales 
Family: Pleosporaceae 
Genus: Phloeospora 
Species: maculans 

Predisposing factors 

The disease is air borne and spreads through conidia. High temperature and humidity especially high humidity is the key factor for severity of the disease. Therefore the wet condition in the mulberry field results in high incidence and severity. 

Disease cycle 

The pathogen overwinters in the form of pseudothecia or conidia on the leaves the plant remaining attached to mulberry trees or on decomposed organic matters. In the soil. The conidia disseminate in the wind and rain. The new infection will happen within 10 days and hence the re-infection occurs many times in a season. 

Control  

Spray Bavistin (0.05 and 0.1 %) or Captan (0.4 %) for effective control of the fungus. A safe period of 7 days in case of Bavistin and 14 days in case of Captan is required before using the fungicide sprayed leaves for silkworm rearing. 

Related literature 

Kim KH, Inoue S, Kawanami M, Furuya N,  Matsuyama N, (l999) Antagonistic action of Bacillus sp. AB89 to Phloeospora maculans, causal agent of mulberry leaf spot,  J. Fae. Agr. , Kyus hulJniv.,43 (3·4):337- 342

Munshi NA, Zargar MA., Tanki TN, Lone AH, (1991) Screening of some mulberry varieties against Phleospora leaf spot disease of mulberry under Kashmir condition. Sericologia, 31(4): 719-723.

Teotia RS, Sen SK, (1994) Mulberry diseases in India and their control. Sericologia, 34(1):1-8.

 

Friday the 29th. This is the official Website of CSRTI, Mysore - The R & D Organisation of Central Silk Board