Identifying issues in the field: diseases, nutrition or something else?

November 2023 | Presented by Garrett Bishop, G.S. Long Company, Washington USA | Future Orchards® Spring Series slides

Garrett Bishop presents a practical diagnostic workflow for orchard problems that may arise from disease, nutrition, irrigation or other stresses. The starting point is disciplined field observation: scout the entire block, identify visual symptoms and patterns, and record background information such as rootstock, irrigation use and block history before deciding what to sample.

The presentation recommends mapping affected trees and grading symptom severity so that high-, medium- and low-severity trees can be compared with apparently healthy trees. Bishop stresses careful sample selection, avoiding dead trees where secondary pathogens may dominate, collecting material across severity levels, understanding the biology of the suspected pathogen and getting samples to the laboratory quickly under cool conditions.

Laboratory tools are then used to support, rather than replace, field diagnosis. The slides explain how real-time qPCR results can indicate relative pathogen load and show examples involving Phytophthora and nematode testing in Washington apple blocks. The overall message is to combine field pattern recognition, representative sampling, laboratory testing and repeated observations over time before concluding whether a problem is pathological, nutritional or environmental.