Selecting and Measuring Random Sample Trees for Benchmarking

To select random trees:

• Use a dice to select a row number

• Use a dice to select a tree number in the row

• Do not use any tree that is clearly not representative (not thriving or significantly larger)

• Do not include any tree on the edge of the block, as these may be affected by other influences.

• Keep a record of the random trees selected so that you can use the same sample each season.

To measure trunk diameter (mid May to mid June:

• For average trunk diameter select 25 trees by this method, note these trees as your permanent sample trees

• Diameter is measured at 600 mm above ground level

• Specialist tape measures can give diameter reading by measuring circumference; otherwise measure circumference in milimeters, multiply by 7 and divide by 22

To measure blight percentage (January):

• Select 10 random trees as above

• Stand on north of tree; inspect the five nearest nuts along the bearing line for signs of blight.

• Any black spots from blight mean that the nut is counted as blighted.

• Move to east side and repeat, then south, then west - this means you have inspected 20 nuts and have a count of how many of them were blighted.

• Repeat for all ten trees.

• Add up the number of blighted nuts out of the 200 inspected, then divide by 2 to find the percentage.