According to Mr. Bonneau, C.N.R.F. Nancy

When to Sample: During the dormant period, from late October to late December. Sampling should be done before January in Mediterranean or Aquitaine climates and before February in oceanic or continental climates to avoid inaccurate foliar diagnostics due to element movement between needles and buds.

Where: From 10 healthy and homogeneous trees, representative of the plot.

How: Sample from the upper, well-lit part of the crown of current-year branches, excluding the terminal shoot of the main stem. Choose the terminal shoot or the annual bilateral shoots from the first or second whorl below the terminal bud. It is not necessary to detach the needles from the branch; they will separate easily after drying.

Quantity: Approximately 10 g of dry matter, equivalent to 30 to 50 g of needles in total for the 10 trees constituting each sample.

Conditioning: Place the batch of needles in a clean, sturdy plastic bag. Label each batch clearly with: Name, address, variety, rootstock, date of sampling, and plot reference.

Precautions: To avoid mold or contamination during drying, please send the sample immediately and by express to the laboratory.