The defecation reflex involves two postive feedback loops. these loops are the stretch receptors in the rectal walls and the sacral parasympathetic system. Defecation reflex empties the rectum by peristaltic movements push fecal matter from the sigmoid colon into the rectum. Then this distension of the rectal walls stimulates stretch receptors which results in defecation.
Polycyclic disease cycle produce secondary inoculum which results in the infection on same crop or other crops during vegetation seasons. See attachment to observe the cycle how it happens.
