Why You Need a Tissue, a Leaf Tissue Analysis
By Erika DeBrouwer, Tree Fruit Specialist, OMAFRA
What is Leaf Tissue Analysis?
Leaf sampling is one of the most valuable and standardized analysis tools to monitor and diagnose nutrient status within the established orchard. Leaf tissue analysis tells us 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, 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).
Why Utilize Leaf Tissue Analysis?
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.
When to Conduct Tissue Analysis?
Most areas across the province 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.
Where to Leaf Sample?
Best practices for collecting leaf samples are listed below.
- Sample each cultivar, age, rootstock, and block of apple trees separately.
- Sample from the same trees year to year to better interpret leaf analysis reports over the years
Collect fully mature leaves from this season’s growth at shoulder height (Figure 1).
How to Leaf Sample?
- Collect at least 100 leaves for each sample.
- The best way to get a representative sample is to take 10 leaves each from 10 trees.
- Do not combine healthy and unhealthy leaves, avoiding damaged or abnormal leaves.
- Collect tissue samples into labelled paper bags as the leaves will rot in plastic bags and deliver right away.
- If they cannot be delivered immediately, they should be dried to prevent spoilage. Samples may be dried in the sun or in an oven at 65°C or less.
- Plant tissue should be sampled separately from variable areas large enough to sample soil and fertilize separately.
- Plants suspected of nutrient deficiency should be sampled as soon as a problem appears. Take tissue samples from a problem area and submit a separate sample from an adjacent, non-affected part of the orchard. Also collect and submit a soil sample from both affected and non-affected areas to aid diagnosis.
- Take precautions to prevent contamination with dust or soil. Avoid contact of samples with brass, copper or galvanized (zinc-coated) metal.
Remember, plant tissue sampling does not replace soil testing, the results are the most useful with a visual assessment of the crop and current soil conditions and a recent soil test.
For leaf nutrient sufficiency ranges for apples see Table 18 in the OMAFRA Soil Management, Fertilizer Use, Crop Nutrition, and Cover Crops for Fruit Production webpage.