CLASSIFICATION OF SPHAEROTHECA
Kingdom :- Mycota
Division :- Eumycota
Sub-division :- Ascomycotina
Class :- Plectomycetes
Order :- Erysiphales
Family :- Erysiphaceae
Genus :- Sphaerotheca
The fungus is an ectoparasite on cucurbits like Lagenaria, Luffa and Cucurbita. These plants are seasonal and are grown for their edible parts. The fungus can be easily collected from them during their growth season
STUDY OF HOSTS, DISEASES AND SYMPTOMS OF SPHAEROTHECA
- Sphaerotheca fuliginea causes powdery mildew of cucurbits like Lagenaria, Luffa and Cucurbita. Tiny white superficial spots appear on leaves and stem. The spots become powdery on enlarging. Ultimately, there is premature defoliation.
- Sphaerotheca pannosa is parasitic on roses.
STUDY OF VEGETATIVE STRUCTURE OF SPHAEROTHECA
- The thallus is mycelial and consists of richly branched and septate hyphae. The cells are uninucleate.
- The mycelium is superficial but develop simple, globose and lobed haustoria inside the host cells.
- The superficial mycelium bears erect conidiophores
- Conidia, the bodies of asexual reproduction, are present in chains in basipetal succession at the tip of conidiophore.
- The conidia are barrel-shaped, hyaline and uninucleate. It germinates to produce a forked germ tube.
ASCOCARP, ASCI AND ASCOSPORES OF SPHAEROTHECA
- Ascocarps are closed ball-like structures called cleistothecia. These are the products of sexual reproduction.
- Cleistothecium is globose and dark brown in colour. It bears simple myceloid appendages all over the surface.
- The wall of the cleistothecium is thick and two layered. Each layer is several cells thick. The outer cells are darker.
- Each cleistothecium has only one obovoid to elliptic ascus. Inside the ascus are present eight haploid ascospores.
IDENTIFICATION OF SPHAEROTHECA
- Kingdom – Mycota
- Chlorophyll absent
- Reserve food glycogen
- Cell wall of fungal cellulose.
- Division – Eumycota
- A definite cell wall present.
- Sub-division:- Ascomycotina
- Mycelium septate.
- Spores borne endogenously in the ascus.
- Spores in definite numbers, in multiples of two, usually eight.
- Class:- Plectomycetes
- Ascocarp, a cleistothecium.
- Order– Erysiphales
- Family – Erysiphaceae
- Aerial mycelium hyaline
- Enormous production of conidia on host surface gives it a white powdery appearance.
- Genus – Erysiphe
- Ascocarp with a single ascus.