Leaf tissue analysis is the best indicator of plants’ nutritional status as it directly measures the concentration of nutrients in the plant. A soil test can be a useful tool as well, however results of a soil test do not always correlate with the amount of nutrients that plants are actually up taking. A good recommendation for growers is to take foliar samples on an annual basis and a soil test every 3 years.

Foliar nutrient analysis is the best way to assess the effectiveness of your fertility program, as it allows growers to detect when nutrient levels in the plant are approaching deficiencies before visual symptoms are observed, allowing growers to take corrective action in advance.  The analysis provides information on N, P, K, Ca, Mg, Fe, B, Mn, and Zn levels in leaves sampled and a guideline with the concentration range for these nutrients expected in healthy plants.

When and how to collect a tissue sample

The standard recommendation for foliar sample collection is mid-summer because during this time of the year nutrient levels are most stable in the plants. A general recommendation is to collect the leaves across the planting /orchard in a zigzag pattern. Leaves should be sampled from plants that are representative of the entire field, and separate samples should be collected from areas where plants have poor growth or present visual symptoms of nutrient deficiencies.

Tree fruit should be sampled between 60-70 days after the average petal fall date (this is normally the end of July, early August). Select at least 60-100 leaves for each sample. Collect healthy leaves from the middle of this current season terminal shoots.  if you are collecting 60-70 days after petal fall.

For blueberries, 80 to 100 leaves should be collected from the middle section of shoots (not old leaves from the base, nor new leaves from the tip) selecting young newly matures leaves fully exposed to the sun, between July and August.

For raspberries, collect a minimum of 50 fully expanded leaves from primocanes (non-fruiting canes) during the month of August.

For strawberries a minimum of 50 leaves should be collected from first fully expanded leaves after renovation.

Sample preparation

In the case of fruit trees, you can place the samples in open paper lunch bags. Make sure you have separate labeled bags for each sample, and let them air dry.

For berry crops, once you have collected the leaves, gently wash them with distilled water to rinse off soil and spray residues and let them air dry. Place the leaves in a clearly labeled open paper lunch bag and let them air dry at room temperature. If you cannot wash the leaves after collecting them, place them in a cooler or refrigerator until you can process them (do not allow leaves to wilt before you wash them). Also, do not let leaves to stand in water – complete the washing and rinsing process in one minute or less.

This article was posted in Apples, Berries and tagged berry crops, Blueberries, fruit trees, Raspberries, Strawberries, tree fruit.