Since 22 July 2019, the tighter restrictions under the new NI plant health legislation apply to imported oak for planting where the stem is 8cms or more at 1.2 metres above the
root collar.
'Picus Sonis Tomograph inspection is also recommended every two years on trees with a percentage of cavity or decay exceeding 15 per cent,' it said, adding that roots that showed signs of rotting should be made to undergo
root collar excavation to reduce the potential for failure and prevent trees from threatening the safety of people.
Data collection was carried out every six months, considering the following parameters: survival (%), total height (m),
root collar diameter (cm), crown length (m) and canopy projection area ([m.sup.2]).
Shoot height (SH) and
root collar diameter (RCD) of both plant species was measured fortnightly, starting 30 days after germination.
Tree height and
root collar diameter were measured and the prescncc of flower buds was identified.
At 60 after of experiment, the following biometric variables were determined: shoot height (H),
root collar diameter (D), number of leaves (NL) and number of leaflets (NLf).
At the end of experiment, seedlings from all types of containers were measured for height and
root collar diameter, whilst leachates were collected to determine nutrient concentrations of available phosphorus (P), potassium (K), ammonium and nitrate nitrogen (N) therein.
Analysis of Variance (ANOVA) was then performed on the transformed germination percentages, plant height, and
root collar diameter and survival percentage using GenStat for Windows version 13 [16].
Dig down into the planting medium to find the
root collar so you know how deep to plant the tree."
Two primary lateral roots were randomly selected and excavated to approximately 3 meters from the
root collar. Roots were removed from trees and carefully dissected.
At the conclusion of the experiment (three months after germination), we measured shoot length, leaf number, and diameter at the
root collar. We also calculated the area of the largest leaf on each plant based on the model obtained by Liv et al.
Pitch pine is a fire-adapted species with thick bark, epicormic branching, and the ability to resprout from the
root collar when the main stem is killed (Burns and Honkala, 1990).
