the Symposium on Wheats for More Tropical Environments - cimmyt

150InoculationInoculation is done at <strong>the</strong> two-leafgrowth stage (about eight to ten daysafter germination). using a handsprayer. Each tray receivesapproximately 100 ml of inoculum.Inoculated plants are <strong>the</strong>n kept in amist chamber. with two hours ofcontinuous misting. and <strong>the</strong>n 15minutes of misting every two hours<strong>the</strong>reafter for 24 hours. Later. <strong>the</strong>seedlings are transferred into achamber and kept at 22° to 24°C and75 to 80% relative humidity for fivedays.Evaluation and selection of materialInoculated materials are evaluated afterfive to seven days. according to <strong>the</strong>follOWing I-to-5 scale:1 = a few small black lesions onleaves2 = more black lesions. some withsmall chlorotic halos3 = lesions surrounded by chlorotichalos. many of which startconverging; some drying effectsat leaf tips4 = broad lesions with amplenecrotic zones; drying over alarge part of <strong>the</strong> leaf5 = large lesions; drying of <strong>the</strong>whole leaf25 1 5 10 15 20 25 1 5 10Figure 1. Disease development on four late-maturing wheat varieties. fromfiowering to milk stage, January 25 to March 10, Poza Rica. Mexico,1983-848--"-.­..,.'.....•............":;;"'''.............. ,-'........