page_title: Phytophthora nicotianae
section_title: Environment
hierarchical_section_title: Phytophthora nicotianae / Environment
caption_attribution_description: English: This image was taken with permission from the APS website. The picture portrays the segmenting pith symptom of Black Shank on tobacco.
context_page_description: Phytophthora nicotianae or black shank is an oomycete belonging to the order Peronosprales and family Peronosporaceae.
context_section_description: This pathogen thrives in temperatures ranging from 84–90 °F (29–32 °C). Disease is prominent in many agricultural productive regions and therefore is a major host to many warm environment crops. Black Shank needs water for germination and movement. Saturated soil optimizes disease spread because water is used for dissemination of motile zoospores and sporangia. Low-lying areas of the soil that remain wet for prolonged periods of time will have more disease. Splashing water from rain or irrigation can infect healthy plant leaves leading to more repeating secondary cycles. Soils that are not saturated will lead to little to no disease development, so water management is important. Optimum soil pH for development is between 6 and 7. Levels of calcium and magnesium in the soils can affect disease progress.
caption: Discing of Tobacco Pith
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