The response to anthracnose and walnut blight in 3 local and 5 recently introduced walnut varieties was studied in a field monitoring. A high level of leaf anthracnose incidence (100%) was reported for the Turkish varieties, in the Bulgarian varieties it was lower (60-80%), in Chandler (30%) and in Fernor – symptoms were completely absent.
Regarding the same feature in relation to walnut blight, the American varieties were the most strongly affected – almost 100% of the leaves. As to the fruit – the disease incidence of anthracnose was almost 100% in all varieties with the exception of cv. Perustinski (55%). The affected fruit surface in the American varieties was, however, only 1%. The spread of walnut blight in the fruit was about 70% in the American varieties and it was not registered in the Bulgarian varieties. Recommendations for organic walnut production have been made.