1990 Volume 56 Issue 2 Pages 252-256
The causal bacteria of bacterial black node of barley and wheat, Pseudomonas syringae pv. japonica, invaded the leaf blade, leaf sheath, internode, node, awn, palea and lemma through the stomata, multiplied in the intercellular spaces of parenchyma, but never invaded the vascular bundles of infected plants. Brownish black lesions spread widely in spite of limited location of the bacterial multiplications in the parenchyma. In case of the palea, stomata existed on both sides of them, and they were connected with each others through the intercellular space of parenchyma. Thus, in the palea tissue, bacteria are able to move from one side to another side. This infection process is regarded as a main cause of the seed-borne mechanism of this disease. The causal bacteria infected the palea and lemma at first, then invaded the caryopsis through the funiculus, and multiplied in the intercellular spaces of parenchyma of caryopsis, but no bacteria were observed in the vascular bundles.
