Reading
the leaves
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.
Your leaf analysis is particularly useful to evaluate phosphorus, potassiu,
m magnesium and manganese. Soil tests for boron, copper, iron, and molybdenum
have limited usefulness, so leaf analysis is an important tool to assess
these micronutrients.
Your leaf analysis results are compared to established
normal ranges for the crop. This indicates whether a specific nutrient is deficient
or sufficient. Sample collection timing and the crop's growth stage have a major
impact on the reported results. Some nutrient levels can vary considerably with
the age and date of the sampled tissue. Results can be difficult to interpret
if sampled at other times than those suggested. The reported results may also
be affected by weather and crop management practices.
Sampling times and
tips for sample collection for perennial fruit crops are outlined in the table
below.
| Crop | Sampling
time | Sample collection |
| Apple | Last
2 weeks of July | - Mature mid-shoot leaves of current season's
growth at shoulder height from all sides of tree
- 10 leaves from 10 representative trees
|
| Blueberry, high bush | Late
July-early August |
- 100 leaves through out sampling area
|
| Cherry, Montmorency | Last 2 weeks of
July | - Mature mid-shoot leaves of current season's
growth at shoulder height
- 10 leaves from 10 representative trees
|
| Grape | Early September | - Petioles from mature
leaves of fruiting canes
- Remove leaf blade immediately
- 75-200 leaves depending on variety size
|
| Peach | Last
2 weeks July | - Mature mid-shoot leaves of current season's growth
at shoulder height
- 10 leaves from 10 representative trees
|
| Pear | Last 2 weeks July | - Mature mid-shoot leaves
of current season's growth at shoulder height
- 10 leaves from 10 representative trees
|
| Raspberry | Late July | - Fully
expanded mature leaves from fruiting canes
- 100 leaves through out sampling area
|
| Strawberry | Fruiting:
June
Non-fruiting: Early August
| - fully expanded, recently
matured leaves
- remove petioles immediately
- sample different varieties and plantings separately Collect
at least 50
|
Before
you start sampling, here are a few points to review:
- Sample varieties
or blocks separately that require different management practices
- If variable areas are large enough to fertilize separately, they should
be sampled 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 soil samples 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.
Where to send your samples:
Several Ontario commercial
soil testing laboratories can provide you with leaf analysis. Their contact information
can be found on the OMAFRA website under the Leaf
and Petiole Tissue Analysis Program.
