They can be blown further than a kilometre, but most land within a few hundred metres of the source. After the initial infection, the disease spreads within the crop. Some conidiospores may be blown several metres by the wind that accompanies rain fronts. After landing on a susceptible leaf, the spore will germinate and initiate a new infection if the leaf surface remains wet for 12 to 24 hours. The weather is, therefore, the principal factor in translating disease risk into disease severity.
Infection can occur at any stage of plant growth following either rain or heavy dew.
Ascochyta blight requires cool conditions for infections to grow, and frequent rain to move spores about and provide moist conditions for their germination. Control of ascochyta blight Rotation. Avoid paddocks in which faba bean has been grown in the past two years or which are within 500 m of stubble from the previous year's crop. North of the Great Eastern Highway and in areas remote from previous plantings, do not sow seed with any ascochyta infections. Elsewhere, do not sow seed that is more than 15 per cent infected with ascochyta.