What are the days of Al-Husum and the days of Ath-Thurayya, and what happens during them?

The Pleiades is a star that rises in the morning at the beginning of summer, when the heat intensifies and fruits ripen. Its morning rising occurs in the middle ten days of May. Ibn Abd al-Barr mentioned that Umar asked al-Abbas about the rising of the Pleiades (nawʾ al-Thurayyā), considering it a time when rain is hoped for. Ibn Hajar stated that its rising coincides with the intensification of heat and the beginning of fruit ripening, citing a hadith from Ibn Umar regarding the prohibition of selling fruits until their blight is gone, and that this occurs until the Pleiades rises. Al-Munawi said that the dawn rising of the Pleiades protects crops from blight, and usually marks the beginning of fruit صلاح (soundness/ripening).