Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Heat treatment of plant propagation material for the control of fire blight.

Abstract

The thermal sensitivity of Erwinia amylovora was determined at 45° and 50°C. In vitro assays with 8 different strains showed that thermal death times did not exceed 70 min at 45° and 50 min at 50° (95% confidence interval). Heat treatments of naturally infected apple and pear shoots were performed using a moist and a dry heat procedure. When shoots were wrapped in wet cotton cloths (wet heat) and maintained in an incubator, no bacterial growth could be detected after an incubation of 5 h at 45°. When shoots were sealed in polythene bags and immersed in water (dry heat), no E. amylovora could be isolated after an immersion of 3 h at 45°. Incubation at 50° for 1-2 h in either condition did not eradicate the pathogen entirely. The failure rate of grafts using budwoods treated at the effective time-temp. combinations did not exceed 25%. It is concluded that the use of thermotherapy techniques for controlling E. amylovora in propagation material of apple and pear might be possible.