Leaf
analysis sampling now for future planning
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, potassium, 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.
| Stage of growth/timing | Crop | Plant
part sampled | Approximate number to collect |
| June | Strawberry, fruiting | Fully expanded, recently matured
leaf blade - discard petiole immediately | 50 blades throughout sampling
area |
| July, last 2 weeks | Apple, Peach, Pear, Montmorency
Cherry | 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 |
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 fertilizer 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 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 over 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 at:
www.omafra.gov.on.ca/english/crops/resource/leaf.htm
