Tissue Testing in Fruits

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Early August is the time to collect leaf samples for nutrient analysis in tree fruits, grapes, and blueberries. As shoots grow and leaves age, nutrient concentrations change. Mid-summer is the standard time to sample because levels of most nutrients are relatively stable, so results can be best interpreted by comparing them to known values.

Leaf analyses is be used to diagnose nutritional problems and to identify developing problems before growth or yield is affected. Sample young plantings every one to two years and established plantings every two to three years. The whole farm can be sampled in the same years, or portions sampled on a rotating basis.

Collect a minimum of 50 leaves from different plants throughout the field block. Select healthy leaves from the middle of this year’s shoots. If the leaves are dusty, rinse briefly in tap water and lay leaves out on a tabletop until they are dry to the touch. For vineyards, only the petioles (leaf stems) are collected. Send to a respected agricultural testing laboratory for mineral nutrient analysis.