THIS part of downy mildew consists of sclerospora and perenosclerospora. Downy mildew fungi are plant pathogens that cause significant damage to a variety of crops, including grapes, cucumbers, lettuce, and onions. These fungi thrive in cool, moist environments and can spread rapidly through a field, causing devastating losses for farmers. This slide deck provides an overview of downy mildew fungi, including their life cycle, symptoms, and management strategies. The presentation begins with an introduction to the various types of downy mildew fungi, including the species that affect grapes, cucumbers, and other crops. Next, the slides detail the life cycle of downy mildew fungi, from spore germination to the development of lesions on plant leaves. The presentation also explains how these fungi spread from plant to plant and from field to field, and highlights the conditions that favor their growth and reproduction. The slide deck then goes on to describe the symptoms of downy mildew infection, including yellowing and wilting of leaves, stunted growth, and the development of characteristic downy white or gray spores on the undersides of leaves. Finally, the presentation offers practical tips and strategies for managing downy mildew fungi, including cultural control measures such as crop rotation and sanitation practices, as well as chemical control methods such as fungicides. Overall, this slide deck provides a comprehensive overview of downy mildew fungi and their impact on agricultural crops, as well as practical strategies for preventing and managing these devastating plant pathogens.

1. ANNAMALAI UNIVERSITY
FACULTY OF AGRICULTURE
DEPARTMENT OF PLANT PATHOLOGY
PAT-501 MYCOLOGY
GENERAL CHARACTERS AND LIFE CYCLE OF GENUS PERONOSPORA ,
PSEUDOPERONOSPORA, PLASMOPARA , BREMIA , SCLEROSPORA ,
PERONOSCLEROSPORA
BY
R.LOKESH
I -M.sc.,Agriculture
Plant pathology
Annamalai university
TOPIC:
Part-3

15. Peronosclerospora sorghi
Scientific classification
Kingdom: Chromista
Phylum: Oomycota
Order: Peronosporales
Family: Peronosporaceae
Genus: Peronosclerospora
Species: P. sorghi
Binomial name
Peronosclerospora sorghi
(W. Weston & Uppal) C.G. Shaw, (1978)

16. SYMPTOMS
• Infected plant chlorotic and sometime stunted, white-stripped leaves &
abnormal seed set.
•The chlorotic area of leaf always includes the base of the blade, and
transverse margins usually sharply defined between the diseased and
healthy tissues
•A white, downy growth may appear on both surface of infected leaves.
Sometimes tassels of diseased plant may exhibit phyllody.
•Tolerant plants may show symptoms of systemic infection but have normal
seed production.

17. HEALTHY LEAF INFECTED LEAF AND PLANTS

20. Disease Cycle
• The primary infection is by means of oospores present in the soil
which germinate and initiate the systemic infection.
• Oospores persist in the soil for several years. Secondary spread is by
air-borne sporangia.
• Presence of mycelium of the fungus in the seeds of systemically
infected plants is also a source of infection.
• The disease has been known to occur through
a collateral host, Heteropogen centortus on which the fungus
perpetuates of the host. The breakdown of tissue causes shredding.
• The oospores either fall to the soil or are wind blown, often within host
tissue. They can remain viable in the soil for 5-10 years.
• Conidia are formed at night in large numbers. The optimum
temperature for production is 20-230C.