Control of bacterial black spot of walnut

Walnut bacterial black spot mainly harms walnut fruit, the diseased fruit rate is 10% Mur40%, resulting in fruit blackening, decay, early fall, walnut kernel dryness. In addition, it also harms leaves, tender shoots, and the damage rate of some plots is up to 20%, 40%. [symptoms] the damaged young green fruit produces brown oil-soaked spots on the pericarp at the initial stage, then expands into a round or irregular shape, with no obvious edge, surrounded by a water-immersed halo, and in severe cases, the lesion is sunken, which goes deep into the endocarp (core and shell). And make the whole pericarp black and rotten, and the kernels dry and early fall. The disease spot on the leaf is less, dark brown, nearly round or polygonal, the outer edge shows semi-bright oil-immersed halo, severe disease spot union, leaf shrinkage, scorch, petiole blackening, micro-depression. [control methods] (1) remove diseased and residual fruits, fallen leaves, disease and insect branches, etc., in order to reduce the source of disease; (2) spray 0.5-200-fold Bordeaux solution during the growing period, or 500-800-fold solution of 50% methyl thiophanate wettable powder for 3 times (1 time before flowering, 1 time after flowering and 1 time in young fruit stage).