Tree Planting and Animals

by Nick Ledgard
Canterbury Branch Member
NZTCA archives

All planters of shelterbelts and woodlots are fully aware of the need to protect trees from stock. Most, like me, have learnt the hard way that there is no place for sub-standard fencing. Even just one breakthrough within the first 3-4 years can spell doom for most trees.

But few of us succeed in isolating young plants from smaller animals such as hares, rabbits and opossums.

Therefore, farmers will be interested to hear of a ‘vermin repellent’ which seems to be working for the Forest Research Institute at Ilam.

This repellent has yet to be thoroughly tested in a trial directly comparing treated and untreated trees but over the past two years damage to treated trees has been almost non-existent in areas where before it was very evident. I repeat that it is too early to offer this formula as the answer to all problems but if its use now saves a few more trees, then this pre-release will have been worthwhile.

The recipe is 10 parts mutton fat melted down and mixed with 1 part kerosene. Allow to set and then apply to the trees by means of a single rub up the stem with a greasy hand. Under no circumstances must it be put on lavishly. A wipe with a well greased hand which leaves no fat visible to the naked eye is sufficient. One taste will confirm that.

FRI’s procedure is to mould a cricket-ball sized lump between the hands. Then, holding this in one hand walk down the row of trees applying the ‘rub’ with the other. Between trees re-grease the applying hand from the grease ball in the other.
If using bare hands cancel all social engagements for that evening.

To date, the repellent has been used almost solely on conifers. Other than some browning of the more greasy needles it has had little ill effect on the plants themselves – some of the few eucalypts treated have shed their lower leaves but this could have been due to moisture stress rather than the repellent. On broadleaves just greasing the lower stem and small twigs should prove effective, as hares, in particular, are only interested in the woody parts, and the smell must be as big as a deterrent as the taste to other animals.

A very worthwhile spin-off of the above method of application is that the upward rub of each tree is an excellent test as to whether the trees have been well planted. If the slight upward pull lifts the tree clear of the ground then the tree has not been firmly enough planted.

This spring I greased all my shelterbelt plantings at home. I haven’t lost one to animals even though I have shot one rabbit (missed the other) and removed lambs from within the belt. Not 200m from my trees the neighbour has lost 50% of his Pinus radiata to hares and rabbits.

In the near future FRI plans to run some proper trials within their opossum pens at Rangiora. The animals to be used have been caught from all over New Zealand so the trial should be a fair test of the national population’s response to P. radiata à la mutton fat and kero – locally known as SFA or special fouling agent.

Addendum – in snowy areas, run the SFA just that little bit further above ground level where drifts of snow might provide a convenient step-stool for hungry animals.