Pear Scab
A dynamic model for the infection biology of pear scab that calculates the infection risk from the number of spores produced by wood scab cankers and distributed by rain splash, and their opportunity to germinate and infect pear fruits.
Testing the model under field conditions has proved difficult because of the strong effect of disease pressure on the results, and the limited efficacy of the fungicides available for organic pear production. From the field results 2017-2020 obtained in organic pear orchards in The Netherlands and Belgium we can however conclude that:
1- In organic pear orchards where in previous year’s harvest, after storage, less than 5% of the fruits showed scab symptoms, a curative schedule based on the use of sulphur, bicarbonate and lime sulfur, aimed at infection moments as indicated by the model was effective.
2- In organic pear orchards with more than 5% fruit scab post-storage, the curative schedule needed support by preventive low-rate copper applications to be reasonable effective.
Pear Scab (Basic)
An addtional traditional static model, only showing the germination conditions for pear scab spores based on research data published by Spotts 1991, 2010, and Villalta 2000.
This is for who wants to play 100% save, and does not care to spray more often than necessary. The danger in this is, that with all these critical moments announced, you cannot see anymore which moments are really crucial. So even following this basic model, keep eye on the dynamic model to cover the key infection moments well.