Phytoparasitica (2001) 29, 274-275

D. Shtienberg, Miriam Zilberstaine, Z. Herzog, D. Oppenheim, S. Levi, H. Shwartz and G. Kritzman (2001)
Factors affecting the progression of Erwinia amylovora in pear branches
Phytoparasitica 29 (3), 274-275
22nd Congress of the Israeli Phytopathological Society, February 12-13, 2001, Bet Dagan, Israel, lecture
Abstract: The most destructive symptom of fire blight (caused by Erwinia amylovora) is the progression of the bacteria from infected blossom-clusters to the branches of the trees. The disease progresses from branch to branch, inducing wilting and death; when it reaches the trunk, the entire plant may die. Observations made in pear orchards where blossom-clusters were naturally infected by E. amylovora, revealed that the rate of disease progression within the woody parts varies from tree to tree. Whereas in some trees the rate of disease progression reached 1-2 cm/day, in other trees the disease did not progress at all and the symptoms remained restricted to blossom-clusters. In the latter case the damage induced by the disease was limited. In a series of experiments and observations conducted in pear orchards, factors affecting the rate of disease progression within the woody parts of the plants were studied. One-year-old branches were artificially inoculated in spring (April) or autumn (October), and the rate of disease progression on the branches was recorded over time. The main results of the experiments are as follows. (i) The disease progresses much more rapidly on herbaceous than on woody branches. (ii) In the spring, the rate of disease progression in branches of trees with many sprouts is faster than in trees with few sprouts; in autumn the situation is the opposite. (iii) Progression of infections originating in the spring stops in June-July, but infections originating in autumn progress until the next spring. (iv) Pruning of infected branches may result, in some cases, in rapid progression of the disease on the branches and in much more severe damage to the trees than in non-pruned trees.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Dani Shtienberg

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Erwinia amylovora	Pear (Pyrus)	Israel