Leaf analysis (also called tissue analysis or foliar anaylsis) is an
excellent means of monitoring plant nutrient levels. With perennial fruit
crops, leaf analysis is even better than soil tests for determining an
optimal fertilization program. While soil tests reveal the quantity of
certain nutrients in the soil, leaf analysis shows exactly what the plant
has succeeded in taking up. However, soil tests are necessary for determining
soil pH and thus lime (or sulfur) recommendations. If nutritional problems
are suspected in a given planting, it's a good idea to take both leaf and
analysis is helpful for detecting nutrient deficiencies in perennial
fruits before they affect plant health or yield. It is important to
sample fully mature leaves before they begin to senesce late in the
season. Follow specific instructions for ideal sampling dates each
crop. Do not submit plant tissue that has disease, spray residue or
oter potential contaminants.
Strawberry samples should be taken from the first fully-expanded
leaves after renovation, about July 15 to August 15. Raspberry samples
should be leaves from non-fruiting canes taken between August 1 and 20.
Blueberry samples should be leaves taken during the first week of harvest,
from July 15 to August 15. Collect a minimum of 50 leaves from raspberries or strawberries,
and 80 to 100 leaves from blueberries for each analysis. Do not mix
leaves from fields with different soil types or management histories.
Do not combine leaves from healthy plants with plants that are not
growing well. Note that grapes tissue analysis uses ~2 oz of leaf
petioles, not whole leaves, collected August 15 to September 10. Tissue
testing is alse very useful for tree fruits.
Place samples in sealed paper bags, clearly labeled with field or
block names, ad mail promptly. Options for tissue analysis include Dairy One (which provides Cornell fruit recommendations), University of Maine testing Lab. Current cost is $28 per sample. University of Connecticut testing lab cost is $30.
Here are the tables from the New England Small Fruit Management Guide
showing desired ranges of nutrient concentrations in small fruits. Vermont
growers can ask the lab to send me a copy of their test results, and then
contact me for specific fertilizer recommendations: email@example.com.