The most importunate problem in using bermudagrasses (Cynodon sp.) for turf in the northern extremity, where semitropical grasses are adapted, is winter survival. This research was primarily conducted to investigate the effects of deacclimation of dormancy, duration of dormancy, and freezing temperatures on survival of bermudagrasses.

'Tifgreen' bermudagrass taken from the field in February, 1976, was deacclimated for 0, 2, 4, or 8 days at 27C/13C (day/night). Subsequently, rhizomes and stolons were subjected to +2, 0, -2, -4, or -6C for 24 hours. One third of the samples from each treatment were planted after 0, 45, and 90 days storage at 2.8C±1.6C.

Rhizomes and stolons subjected to -4 or -6C did not survive. Deacclimation of rhizomes up to 8 days augmented growth as compared to no deaccli~ation. Increased storage periods caused decreased rhizome growth. At +2 and 0C, the percent rhizome growth was similar but significantly higher than at -2C.

With 0 storage, stolon growth declined after 8 days deacclimation; however, after 45 or 90 days of storage, significant reductions occurred after only 4 days deacclimation.

Fully deacclimated as well as dormant field samples of 'Midiron', 'Tifdwarf', 'Tifgreen', 'Tifway' and 'Tufcote' taken in March and April, 1977, were subjected to -2, -4, and -6C.

All cultivars survived -4C whether dormant or actively growing. 'Tifgreen' bermudagrass frozen while dormant and 'Tifgreen' and 'Tifdwarf' frozen while actively growing had high recuperative potentials during regrowth.

Comparing these cultivars under field conditions showed best winter survival for 'Midiron', which was the only cultivar that survived with simulated traffic. Traffic imposed immediately prior to bermudagrass dormancy reduced spring recovery more than for traffic imposed during winter.