Main content area

Fire blight control strategy in Belgium

Schoofs, H., Deckers, T., Verjans, W., Bylemans, D.
Acta horticulturae 2014 no.1056 pp. 57-64
Aureobasidium pullulans, Erwinia amylovora, abiotic stress, antagonists, bacteria, copper, defense mechanisms, disease course, epidemiology, fruit growing, fruit quality, fruit trees, fruits, growing season, heavy metals, host plants, inoculum, manganese, orchards, phytotoxicity, risk, shoots, streptomycin, Belgium
Fire blight, caused by the bacteria Erwinia amylovora (Burill, Winslow et al.), is already more than 30 years present in Belgian fruit growing areas and still remains an important threat leading each year to economic losses in orchards as well as in fruit tree nurseries. Since 2005, the use of the antibiotic streptomycin is forbidden in Belgium and new strategies to control fire blight have been developed. Early season copper applications are considered to be important as they can drive bacteria in the Viable But Non Culturable (VBNC) state and contribute to reduce the inoculum in the orchards in the beginning of the season. During bloom, when the infection risk is high, it is possible to apply BlossomProtect, a compound based on the antagonist Aureobasidium pullulans. In the postfloral period, decreasing the susceptibility of the host plants towards fire blight infections using PDE molecules (Plant Defense Enhancing molecules) becomes the predominant strategy. Two PDE molecules Vacciplant (laminarin) and Aliette (fosetyl-Al) have been registered against fire blight. PDE molecules should be applied preventively, prior to the infection, so that the defense mechanisms of the plants can be switched on in time. Vacciplant (laminarin) is more considered for the protection of the blossoms while fosetyl-Al shows an effect against different types of infections on blossoms, shoots and fruits. A reduction in the disease progression and a clear reduction in the ooze formation on the infected shoots and fruits were observed on plants treated three times with fosetyl-Al and this is considered to be a very interesting factor in the fire blight epidemiology. An abiotic stress effect was observed with repeated heavy metal application like copper (Cu) and manganese (Mn) reducing fire blight susceptibility. Therefore, Mn applications during the growing season can be helpful for fire blight control and for fruit quality improvement. In contrast, during the same period, application of Cu is not recommended due to the cumulative phytotoxic effect.