Time for leaf and petiole sampling

Over the next several weeks and months leaves and petioles should be sampled in perennial crops. Leaf analysis can assist in evaluating this season's crop nutrition management and plan next season's program. The table below outlines sampling times, plant part to sample and number of leaves to submit for perennial fruit crops¹.

Calendar date Crop Plant part sampled Approximate number to collect
July, last 2 weeks

Apple

Cherry, Montmorency

Peach

Pear

Mature mid-shoot leaves of current year growth at shoulder height from all sides of tree 10 leaves from 10 representative trees
Late July Raspberry Fully expanded leaves from fruiting cane 100 leaves throughout sampling area
Late July-early August Blueberry, Highbush Mature mid-shoot leaves of current year growth 100 leaves throughout sampling area
Early August Strawberry non-fruiting Fully expanded, recently matured leaf blade - discard petiole immediately 50 blades throughout sampling area
Early September Grapes Petioles from mature leaves of fruiting canes. Remove from leaf immediately 75-200 depending on variety size

¹OMAFRA Fruit Production Recommendations, Publication 360 2010-2011

Before you start sampling:

  • The plant part sampled and stage of growth affects the interpretation of the results.
  • For example, the table below shows the differences in some referenced critical ranges for wine grapes, Vitis vinifera, sampled at different growth stages and for different plant parts being sampled. Keeping records of cultivars sampled, timing of sample collection, and plant part sampled will help in building a historical reference.
  Whole leaves, opposite bunch cluster, early summer¹ Petioles opposite basal flowers, full bloom¹ Petioles from mature leaves of fruiting canes²
Nitrogen, %
2.0-3.0
1.7-3.0
0.8-1.4
Phosphorus, %
0.3-0.4
0.15-0.5
0.15-0.4
Potassium, %
1.3-1.4
1.5-2.0
1.2-2.3

¹Mills & Jones. 1996. Handbook of Plant Analysis II.

²OMAFRA Fruit Production Recommendations, Publication 360 2010-2011

Sampling tips:

  • Sample varieties or blocks separately that require different management practices.
  • If variable areas are large enough to fertilize separately, sample them separately. Match your leaf sampling to your soil sampling program
  • Avoid collecting damaged leaves or leaves from plants that appear abnormal.
  • Collect tissue samples in clearly labelled paper bags. Plant tissues will rot if stored in plastic bags.
  • Avoid contamination of the sample with soil. Even a small amount will cause the results to be invalid, especially for micronutrients.
  • Plants suspected of a nutrient deficiency should be sampled as soon as a problem appears. Take tissue samples from problem areas and submit them separately. Also collect and submit a non-affected plant from adjacent areas. Collect and submit soils sample from both areas as well.
  • Fresh samples should be delivered to the laboratory directly. If they cannot be sent immediately, they should be dried to prevent spoilage. Samples may be air dried as long as they are not contaminated by and dust or debris while drying. They can also be dried in an oven at 65°C or less.
  • For perennial crops, leaf analysis is an important complement to soil testing. Over the long term, it can tell you whether your soil fertility program is supplying adequate nutrients for optimum growth. It is also a useful tool for trouble shooting problems. If your soil tests show adequate nutrient levels, deficiencies indicated by a leaf test may give clues to other problems restricting nutrient uptake.

Where to send samples:

Several Ontario commercial soil testing laboratories can provide you with leaf analysis. Their contact information can be found on the OMAFRA website.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca