The guys need to potential sawlog trees in one cut
How many trees to form prune:
The aim is to ensure that there will be enough well-formed trees to grow an optimal final crop of sawlogs, without wasting time pruning every tree. Plantations are often established at about 1000 trees/ha, noncommercially thinned to about 500 trees/ha when 6-8 m tall and thinned again to a final stocking of 150-350 well spaced trees/ha, once the target pruned height has been achieved.
Assuming an initial planting density of 1000 trees/ha, a minimum of about one third of trees planted need to be of good form to achieve a final stocking of 300 sawlogproducing trees/ha. Given the risk of broken tops, windthrow etc., it is wise to initially manage (including form pruning as necessary) up to 500 well-formed, well-spaced trees/ha (i.e. up to 50% of trees planted) as crop trees. Over time that number can be reduced to 300 f nal crop trees/ha.
On lower rainfall sites, where the f nal crop will be only around 200 trees/ha, a grower may initially manage 400 wellformed, well-spaced trees/ha as crop trees. In areas where over 50% of the trees are well-formed and wellspaced throughout the plantation, little if any form pruning will be needed; only prune where necessary. Every branch removed slows down the growth of the tree so don’t prune unless it’s needed. Trees with clearly poor form in comparison to the majority can simply be left for culling.
Form pruning to correct fault
Remove double leaders that occur anywhere below 6.5 metres
Check the trees frequently but form prune only when necessary. Check their form every 6 months until the trees have grown beyond the target clearwood height, (often 6.5 m). This may be necessary for 2-3 years in fast growing trees such as blue gum and shining gum or 4-5 years in slower growing trees. Start form pruning when the trees are about two metres tall. By this stage they will be starting to show their potential and will be safe from wallaby damage. Later form pruning can be done at the same time as clearwood pruning. Pruning is best down in late winter when bark is less likely to tear and rapid occlusion of the wound is likely with the spring “flush” of growth.
Walk through the plantation with secateurs, loppers and pruning saw and scan the trees from top to bottom from at least two directions. Look at adjacent trees and so decide which, if any, need to be form pruned. Remember, only 40- 50 % need to be of good form initially. Select the appropriate proportion of crop trees, form prune those that need it, and leave the culls to be thinned later. If a crop tree has a single leader and no heavy branching, leave it alone.Try to have enough good-formed trees spaced evenly through the plantation.
Remember faults high on the potential log are just as bad as those near the ground – sometimes worse because they are harder to remove.
Double or multiple leaders should be corrected as soon as practicable after they reach 1 cm diameter. The longer they are left, the more form is compromised, and it’s too late once double leaders reach about 5 cm diameter. Retain the best leader and carefully cut off poorer ones.
If multiple leaders are of equal vigour and straightness, retain the one on the prevailing windward side as it may better withstand wind. Small double leaders (less than 6 mm diameter) are best left alone because one will usually become dominant and the tree will correct itself. Check them again within 6 months and consider form pruning if there is still a problem.
Early form pruning of this red ironbark would have resulted in growth being directed into a single, straight stem
