ABSTRACT
Rapeseed and mustard crops are grown in tropical as well as in temperate zones. They are best adopted to areas having a relatively cool moist climate during the growing season and dry harvest periods. This chapter describes different diseases affecting the rapeseed and mustard crops. All the three species of Alternaria survive in soil on the affected debris of rapeseed, mustard or on weed host plants or on cultivated cabbage or cauliflower. Some of the weeds, such as flaxweed, hedge mustard, tumbling weed and stinkweed, are commonly affected due to the Alternaria species in Canada. Breeding for resistance to blackleg has been a major objective of rapeseed improvement programs in Australia and France. Several methods for screening for resistance have been used. The screening can be done by planting seed in soil in which diseased rape has been grown or by scattering plant debris contaning perithecia and pycnidia over young plants.
