Ecological Features of Spore Formation in the Fungus Peronospora Tabacina Adam
Abstract
Oospore formation of P. tabacina is affected by a number of factors: meteorological, biological and agronomic. Decisive among them are weather conditions; biological and agronomic factors may favor or hinder oospore formation. The oospore formation process starts with the green tissue in the affected tobacco leaf, i.e. from the very start of the disease. In the green tissue one may also find oogonia as well as the later stages of oospore development, including oospore formation. Oospore formation requires high atmospheric humidity (prolonged rain and fog), starting from the appearance of chlorotic spots on the leaves and lasting until they die. With favorable conditions in the field oospores develop largely in closely spaced tobacco plantings on lower leaves of normally developed plants. In plants which have been set out late, lagging in growth and development, oospores form quite often and in large numbers on leaves of any level on the plant. Oospore formation depends on immunological properties of plants. They are formed frequently and earlier on plants which are more susceptible to infection. A high level of fertilization (40 tons/hectare) is favorable to oospore formation. Oospores also develop in hot beds where plants are close together and overwatered and in greenhouses where there is high humidity (90%). Oospores are found in leaves with diffuse type of infection.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 12, 1968
- Accession Number
- AD0845739
Entities
People
- V. A. Markhasova
- V. F. Peresypkin
Organizations
- United States Army Biological Warfare Laboratories