Jim Deacon from Institute of Cell and Molecular Biology, University of Edinburgh, found that at temperatures of 12☌ and lower the majority of sporangia releases zoospores whereas at temperatures higher than 20☌ the majority of the sporangia germinates like conidia with germ tubes. The zoospores are swimming to stoma trough which its infects its host. Sporanigia in oomycetes usally germinating with zoospores which are mobile in free water. In literature we can find informations about sporandia germinating and infecting like conidia. Sporangia can be distributed by rain or wind. infestans sporangia formation will take place in nights with relative humidity higher than 90% and temperatures warmer than 10☌. Sporangia in oomycetes are formed in the absence of light if relative humidity and temperature are high enough. In the morning during and after such periods you will find potato sprouts covered by white sporangia. Plants formed by latent or symptomous infected tubers show extended systemic growth in periods with water logging. Systemic growth is enforced by high relative humidity and by high soil water content or low soil oxygen content. infestans growth like other oomycetes in the intercellular area of its hosts. The quantities with which we have to expect latent infected seeds is depending on the blight epidemics of the last season in the seed producing area. This showed that we have to expect this in the potato seed. Newer laboratory methods enabled us to check for latent infected tubers in the potato seed. Still of greater importance is the hibernation in infected tubers left as volunteers on the field because of undersize or other reasons or damped on the field as waste form potato storage. This is reported for Europe since the last 25 years. Oospores will only be formed in places where two different mating types of P. In the cool climate during winter the pathogen will find no green tissue and it has to hibernate in infected tubers or in its fruiting bodies the oospores. The economic important plants under its hosts are potato, tomato and egg plant. It can only live in the green tissue of its hosts. It is one of the most important diseases and therefore numerous models are available for it. It has led to starvings and emigration when it came to Europe. Tomato Late Blight caused by Phytophthora infestans is one of the most devastating plant diseases.
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