Goal

• To assess trees' nutritional requirements to maintain balanced nutrients for optimum tree growth

• To prevent any nutrient deficiency or toxicity that can compromise tree health and yield or reduce revenue

Timing

• Leaf nutrient concentrations continually change throughout the year; therefore, timing of the leaf sampling process is critical.

• The best time to collect is July and August, targeting 4-to-6-month-old spring flush.

Procedure

• Grove area should be 20 acres or less.

• Each sample set should be the same variety and rootstock that has received the same fertilization plan.

• Leaves should be a representation of the entire grove; gather 100 leaves from nonfruiting twigs from 15 to 20 uniform trees, selected randomly.

• Label a clean, new paper bag with information to reference when results are received.

• Wash leaves soon after collection. Do not let the leaves get dehydrated before washing.

• Wash and air-dry leaves the day of collection.

• If you are not able to wash on the day of leaf sample collection, store in the refrigerator overnight.

• Using thumb and forefinger, rub the leaves gently while soaking in mild detergent solution, and then thoroughly rinse with clean water.

Examples

Additional Suggestions for HLB-Affected Trees

Sampling from HLB-Affected Trees

Sampling from HLB-Affected Trees

• Because the majority of trees (if not all) have HLB, the leaf nutrient sampling should be done from trees that are representative of the grove.

• Severely declining trees should not be considered for nutrient analysis.

• Fully expanded, average-size leaves should be collected; don't collect small leaves or leaves with psyllid damage.

When to Sample

• HLB-affected trees perform better under a good fertilizer program. Sampling three to four times per year is suggested so that you have enough time to adjust the fertilizer program to address tree nutrient needs.

• The below guidelines for leaf nutrients are for 4-to-6-month-old spring flush leaves; therefore, the table cannot be used as the sole guide for leaf nutrient sampling conducted throughout the year.

• Sample after a month if a soil-applied program was applied, or two weeks after foliar fertilization.

• Take 1–2 sample sets per 10-acre block.