HOST SUSCEPTIBILITY AND FIRE BLIGHT CONTROL ON APPLE AND PEAR

Changes in host susceptibility can be considered as an important part in the control strategy of the fire blight disease.
Interesting possibilities for fire blight control were recently mentioned for the new growth regulator prohexadione-Ca, that has been developed in different countries of the European Union for use on apple and pear (Rademacher and Kober, 2003) and for benzothiadiazole.
Prohexadione-Ca reduces the vegetative shoot growth on apple strongly while its effect on vegetative shoot control on pear is not so strong and the growth reduction response is strongly cultivar dependent.
The reduction in host susceptibility after prohexadione-Ca is based on changes in flavonoid metabolism of the fruit trees (Roemmelt et al., 1999). Experiments on pear with artificial infections of blossoms and young shoots under controlled conditions in climate rooms has shown that application of prohexadione-Ca can reduce fire blight infections on shoots and blossoms.
The treatments of prohexadione-Ca should be sprayed 2 weeks prior to a possible infection.
Treatments with prohexadione-Ca during bloom can interfere with the fruit set.
For the secondary blossom and shoot protection, prohexadione-Ca can be more interesting and can be considered to be a part of the whole fire blight control strategy.
Benzothiadiazole is a compound that acts a functional analogue of salicylic acid and can interfere with the defence mechanism of the plant.
In our experiments on pear, benzothiadiazole was applied 3 times at a dose of 100 g a.i./ha, and slowed down the progression of infection in young shoots.

X International Workshop on Fire Blight

H. Schoofs, T. Deckers

Erwinia amylovora, defence response, prohexadione-Ca, benzothiadiazole

https://doi.org/10.17660/ActaHortic.2006.704.30