Dense colonies usually develop fewer stem turions. Tubers typically develop mid-summer through winter, but monoecious plants may also form them in spring. Under field conditions monoecious tubers survive for up to 5 years. Dioecious tubers may survive for up to 10 years. Dioecious tubers can survive up to 2-3 days under dry conditions.
Tubers can survive ingestion and regurgitation by waterfowl and are resistant to many herbicides.
Turions typically develop in fall and appear to lack a true dormancy period. Removing and destroying stem fragments from recreational equipment, such as boat propellers, docking lines, and fishing gear can help prevent the spread of hydrilla and Brazilian elodea . Suddenly removing dense canopies of hydrilla by mechanical harvesting or herbicide treatment may stimulate turion germination. Sterile triploid grass carp consume hydrilla and are useful in aquatic systems where total removal of all submerged vegetation is acceptable.