Fruit tree canker in apple is a serious problem in the Netherlands. Of course, there is a clear difference in susceptibility per variety. We know that Nicoter Kanzi® and Gala mutants are more susceptible than, for example, Elstar, Jonagold mutants and pear plantings. But we are also seeing an increase in “flying” fruit tree canker in pear orchards.
Besides the Netherlands, fruit tree canker as a fungal disease is a problem in more countries in northwestern Europe. These include countries with temperate climates such as Ireland, United Kingdom, Germany, Belgium, Germany, France, Denmark and Scandinavia. However, the problem of fruit tree canker in apple orchards is also growing in countries such as Brazil, Chile and New Zealand.
The fungus (neonectria) produces conidia and ascospores from cankers. What we already knew and is confirmed by research conducted by Wageningen University as part of the project “Integral chain approach to fruit tree canker control,” is that the spores spread and infections occur during rainy weather. Leaf scars and leaf wounds are important spots of infection. But frost cracks, bud scales, wounds from fruit picking and pruning wounds are also major risks for infection.
Very few infections and infestations were found in the chain stages before the orchard stage during the study conducted. These results are consistent with those of studies in New Zealand. There, less than 2% of canker infections were found to originate from maternal infections. Infections in the orchard were found to be the largest source in New Zealand.
cTo reduce cancer pressure in the orchard, a number of recommendations are made from the study. Among other things, it is important to remove cankers. In addition, it is better not to prune during rain. Important: Do not leave fruit tree canker-infected wood on the plot! Infected wood left within the orchard boundaries, remain a source of infection.
Be consistent with crop spraying. Especially during and after the period of leaf fall. Since picking tends to continue during rainy weather, resulting in many picking wounds, proper post-picking sprayings are also very important. In addition, a fruit tree canker warning model, from RIMpro or BODATA, for example, can help with better timing and more effective use of resources.
An interesting aspect within the project is the study of 24 potential host plants in the Netherlands. This shows that a number of tree species, such as alder, hornbeam, hazel, beech, ratchet poplar, pedunculate oak and rowan, are susceptible to fruit tree canker. The advice from this to fruit growers is therefore: monitor windbreak hedges and remove cankers from the hedge (and from the plot!).
The project ‘Integral chain approach for the control of fruit tree canker’, was carried out by Wageningen University Research and supported by various parties from the sector including the NFO (Dutch Fruit Growers Organization), Naktuinbouw and Stichtig Projectbureau Boomkwekerij on behalf of the Naktuinbouw Elite certified tree nurseries (Fruit tree nursery Morren is also Naktuinbouw Elite certified member). A complete overview of the funders of this project can be found on page 3 of the final report.
Source: final report “Integrale ketenaanpak voor de beheersing van vruchtboomkanker (Integral chain approach to fruit tree canker control),” Wageningen University Research (WUR). Download report >.
Authors final report WUR: M. Wenneker, P-F de Jong D.O.C. Hartveld
