In the literature, recovery periods vary considerably, and include 7 days for Lolium tenulentum (Bettany 1995 b), 10 days for pear (Wu and Wallner 1983, 1984), 14 days for tobacco (Harrington and Alm 1988), and 15 and 30 days for sugar cane (Moisyadi and Harrington 1989) cells.