Papaya stem soft and rotting at the base, plant toppling over (papita)

A soft, water-soaked, rotting stem at the base with the plant wilting and finally toppling over usually means stem rot or collar and foot rot, caused most often by Phytophthora and related fungi that attack the base in wet, poorly drained soil. Waterlogging, planting in low spots, and water collecting around the stem are the main triggers. Confirm with your KVK, but the soft rotting collar after wet conditions is typical. The key is water management, since this disease lives on excess moisture. Plant papaya on raised beds or mounds so the base stays above standing water, keep irrigation away from the stem by watering away from the collar, and ensure the field drains quickly after rain. Do not overwater, and avoid injuring the base during weeding. Remove and destroy affected plants so they do not infect neighbours, and do not replant immediately in the same wet spot. Where pressure is high, your KVK may advise a soil drench or collar treatment with a recommended fungicide such as a copper or metalaxyl-based product and use of Trichoderma, but follow the label and local advice. Fix the drainage first, as no spray will save a waterlogged plot. Get it diagnosed before treating.