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The earliest recorded observation of this behavior in plants dates back to 324 BC when Androsthenes of Thasos, a companion to Alexander the Great, noted the opening and closing of tamarind tree leaves from day to night. [15] Carl Linnaeus (1729) proposed that this was the plants sleeping, but this idea has been widely contested.
Sunflowers in full bloom are not heliotropic, so they do not follow the Sun. The flowerheads face east all day, so in the afternoon, they are backlit by the Sun. In the case of sunflowers , a common misconception is that sunflower heads track the Sun across the sky throughout the whole life cycle.
There are eight different species that cause yield loss of sunflowers; however, Alternaria helianthi is the primary causal agent and most widespread. [5] The main hosts are sunflowers (Helianthus annuus); however, it has been proven that safflower (Carthamus tinctorius), noogoora burr (Xanthium pungens), cocklebur (Xanthium strumarium), and Bathurst burr (Xanthium spinosum) can serve as ...
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A trip to see the field of sunflowers is worth adding to your summer bucket list.
Bacterial diseases; Apical chlorosis Pseudomonas syringae pv.tagetis: Bacterial leaf spot Pseudomonas syringae pv.aptata. P. cichorii Pseudomonas syringae pv.helianthi
Stem canker on sunflower is caused by the fungal pathogen Phomopsis helianthi (teleomorph = Diaporthe helianthi). [1] There are many "Phomopsis" species that have a broad host range, but "Phomopsis helianthi" is the primary pathogen that infects sunflower, although it has also been seen to infect other, secondary hosts.
Permanent wilting leads to the plant dying. Symptoms of wilting and blights resemble one another. The plants may recover during the night when evaporation is reduced as the stomata closes. [2] In woody plants, reduced water availability leads to cavitation of the xylem. Wilting occurs in plants such as balsam and holy basil，and other types of ...