POTATO LEAFHOPPERS, FIRE BLIGHT AND PROHEXADIONE-CA: A LOOK AT THEIR INTERACTION UNDER FIELD CONDITIONS

Work done in Virginia in the 1990’s suggested that potato leafhoppers were able to facilitate the bacterial disease fire blight on potted Gala/M.9 trees in growth room conditions.
An abundance of research shows that the plant growth regulator Apogee® (prohexadione-Ca, a gibberellin biosynthesis inhibitor) has a significant effect in suppressing diseases, including fire blight, and some insects, on apple.
This study was initiated to see whether potato leafhopper feeding on apple was affected by prohexadione-Ca, and whether potato leafhopper feeding and fire blight incidence would correlate under field conditions.
A 2 x 2 x 2 field factorial trial was conducted using +/- prohexadione-Ca, +/- potato leafhoppers (using imidacloprid insecticide as an exclusion technique), and +/- Erwinia amylovora mist inoculation.
Mature Gala apple trees on M.26 rootstock were used for the trial.
Significant suppression of fire blight incidence was seen where potato leafhopper feeding was reduced using insecticide, as well as significant suppression of both potato leafhopper feeding and fire blight incidence where prohexadione-Ca was used.
Leafhopper injury on one sample date, July 20, was highly significantly correlated with all subsequent samples of fire blight incidence.

X International Workshop on Fire Blight

K. Leahy, D.W. Greene, W.R. Autio, J.L. Norelli

https://doi.org/10.17660/ActaHortic.2006.704.34