Leaf sampling is one of the most valuable and standardized analysis tools to monitor and diagnose nutrient status within the established orchard says Erika DeBrouwer, OMAFRA tree fruit specialist. Leaf tissue analysis tells growers which elements are present, whether they are adequate, deficient, or excessive and what nutrients were taken up. A complete leaf analysis should be highly considered because this test includes total nitrogen (N), phosphorus (P), potassium (K), sulphur (S), boron (B), calcium (Ca), Magnesium (Mg), Zinc (Zn), Manganese (Mn), Copper (Cu) and Sodium (Na).

Leaf tissue analysis is the most validated form of assessment and is a cost-effective approach to identify tree fruit nutrient status. It should be analyzed annually to monitor trends of nutrient levels and used in unison with other nutrient sample results, such as soil analysis, fruitlet sap analysis and harvest nutrient analysis.

Utilizing leaf analysis with soil testing allows for adjustments to your fertilizer program. Fertilizer recommendations can be adjusted based on management practices, tree age, rootstock, soil type and previous fertilizer applications. Growth, fruit size, colour and storage quality must also be considered to determine the fertilizer required.

Most areas in Ontario are experiencing terminal bud set, meaning ideal timing for leaf tissue sampling. This is when nutrients are most stable as they are not being exported to shoots and other portions of the tree. Terminal bud set occurs when this season’s vegetative growth stops, and a bud is formed at the end of a branch.

Leaf tissue sampling is recommended to take place within the last two weeks of July and potentially into August in Ontario. Consistency is key and comparison from year to year should be done to give yourself a better idea as to tree health and nutrient flow.

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Source:  ONFruit July 11, 2022 e-newsletter