The bacterium Erwinia amylovora causes a severe disease called fire blight in pear trees. In pear trees that were artificially inoculated with E. amylovora cells the bacteria were found neither in the conducting elements of the xylem nor in the phloem (vessels and sieve tubes). They were found only in the intercellular spaces of the parenchyma cells of the bark. Therefore, the bacteria were not migrating through the conducting systems. Exopolysaccharides secreted by the bacteria in the intercellular spaces of the parenchyma cells decreased the water potential in the spaces, resulting in water and solute leakage from the living cells into the spaces. This led to cell plasmolysis and disintegration. We suggest that when ooze (the bacteria, materials secreted by the bacteria, water, and solutes leaked from the host cells) is accumulated in the intercellular spaces, it drives the air outside, blocks the oxygen supply, and inflicts additional stress on the dying cells. The outcome of the accumulated ooze in th...

Pre-plant application of nematicides is strongly recommended for effective control of nematodes. In certain situations, mainly in perennial crops, or in long season vegetables, nematodes emerge from deep soil layers and thus diminish the effect of the pre-plant treatment. The use of pesticides for post-planting control is limited due to their toxicity to plants and humans. BioNem WP is a biological nematicide, based on a unique strain of Bacillus firmus, It is conveniently applied in commercial fields through irrigation systems. BioNem WP is effective against phytopathogenic nematodes, and is registered in Israel for the control of root knot nematodes in vegetable crops (cucumber, tomatoes, pepper, eggplant and herbs) and in perennial crops (peaches, olives, ornamentals). Long term suppression of nematode population was observed following single application of BioNem WP, either pre or post-planting. This feature may be attributed to activity in deep soil layers and to persistent nematicidal activity in the treated soil, which was observed even under water recirculation. The long term activity of BioNem WP combined with its safety makes it a unique tool for nematode control in perennials, during harvest of edible crops, and under chronic infestation with nematodes.