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seeded chickpea lines, lesions were light dark brown (Halfon-Meiri 1970; Maden<br />
et al. 1975) and ranged in size from 1-4 mm in diameter (Halfon-Meiri 1970;<br />
Sattar 1933). Black pycnidia containing mature spores of the fungus were observed<br />
in many lesions, some of which formed concentric zones (Hialfon-Meiri<br />
1970; Luthra and Bedi 1932; Maden et al. 1975; Sattar 1933). In seeds with<br />
lesions, the fungus frequently penetrated the seed coat and could be isolated<br />
from cotyledoihary tissues (Halfon-Meiri 1970; Luthra and Bedi 1932; Maden et<br />
al. 1975). The pathogen was detected also in embryos (Maden et al. 1975).<br />
Controfling Ascochyta Blight Tiwough Clean Seed<br />
The production and use of Ascoch ta-free seed is essental to prevent introduction<br />
of the pathogen into disease-free areas where environmental conditions may<br />
favor spread and development of blight. It may be necessary to use a combination<br />
of' pro 'tices, like crop rotation, field sanitation and chemical seed treatments to<br />
prodt,:e blight-free seed. These measures should also be effective in controlling<br />
other pathogens that are seed-borne in chickpea (Cother 1977a; Cother 1977b;<br />
Kaiser 1972; Singh and Chohan 1976; Suhag 1973).<br />
The following five factors are critical to the production of chickpea seed free<br />
from A. rabiei:<br />
Arid Environment<br />
Ascochyta blight of chickpea is dependent on cool, wet weather for its greatest<br />
spread and development (Kaiser 1973a; Luthra et al. 1935; Sattar 1933; Zachos<br />
et al. 1963). Surface-contaminated or internally infected seed is the most important<br />
metthod of spreading and perpetuating the disease (Kaiser 1973a; Luthra et<br />
a!. 1935; Maden et al. 1975; Sattar 1933). Dry, warm weather impedes disease<br />
development and spread. It is preferable to locate seed production fields in arid<br />
areas where little or no rainfall occurs during the flowering and fruiting periods,<br />
or at harvest. If plants are watered during the growing season, this should be done<br />
by furrow irrigation, rather than overhead sprinkling.<br />
Several seed-borne diseases of different food crops in the United States are<br />
controlled by producing seed in arid western areas (Snyder et al. 1965). For<br />
example, most of the bush sna p bean (Phaseolusvulgaris)seed used for planting<br />
in the United States is produced in an arid region of southern Idaho (Zaumeyer<br />
and Meiners !975).<br />
Crop Rotaion<br />
It is highly desirable to grow chickpeas in rotation with other crops such as<br />
cereals, to prevent the buildup of A. rabieion any infested trash that may be left<br />
in the field after harvest. Only chickpeas are susceptible to ascochyta blight in<br />
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