This month’s Know Your Land looks at THE CASUARINA and how our perception of it has changed from ideal tree for re-forestation in the 1950s to problem invasive in the 21st century.When 95 percent of Bermuda’s cedar forest succumbed to the great scale epidemic in the 1950s, the introduced casuarina was perceived to be the ideal quick fix for re-foresting Bermuda because of its rapid growth, salt spray resistance and evergreen foliage. Moreover, it does not readily self-seed in Bermuda soil so nobody expected it to become invasive.The first sign that it might become a problem was when we discovered just how incredibly tall they grow in comparison with our native trees. This, combined with their relatively sparse and open foliage, not only diminished their value as a windbreak but actually aggravated the problem by causing wind turbulence and mini twisters in their lee during storms.These tall trees were tested by their first real hurricane event Emily in 1987 and we discovered that they uproot in droves, destroying everything in their path as they fall. Topping off the trees at intervals as they grow can prevent this problem, but it is dangerous work or hugely expensive if professional arborists are hired to do so.Another problem revealed itself in the 1990s. Soon after hurricane Dean in 1989 we began to notice that casuarinas were beginning to self-seed aggressively in the rocky coastline.It seems that hurricane waves washing high up the cliffs actually help to trigger self-seeding. This was subsequently confirmed by more self-seeding after hurricanes Felix in 1995 and Gert in 1999. By 2000 it had become apparent that casuarinas were becoming invasive all along the coastline, but unlike our native coastal flora, which grows prostrate and doesn’t obscure vistas of the sea, casuarinas grow just as tall in that environment as they do inland.Where rooted on cliff faces the levering effect of strong winds causes massive cliff falls, thus hastening erosion. This new treescape is not only shading out our native coastal flora but it is beginning to hide some of our finest coastal vistas as well.Short of eliminating the casuarinas completely from our landscape and thereby eliminating the source of windblown and wave washed seed a highly unlikely, if not unfeasible prospect the only solution for casuarina’s control on the coastline in future will be to cull them at intervals, a time consuming, and in certain situations, extremely dangerous task.Obviously, the younger the growth stage the easier this is to do. Recently germinated seedlings look just like a single ‘needle’ of the mature foliage and can be pulled out easily by hand.At two to four feet height saplings can sometimes be pulled out by hand or more easily using a weed wrench, but if too firmly rooted in a rock crevice they can be cut off at the base and painted with a drop of Tordon a systemic herbicide available in squeeze bottles.Young to mature trees are best cut off at the stump with a chainsaw and stump-painted with Tordon, but be extremely careful not to let the Tordon run off into the soil as adjacent native coastal plants can be poisoned as well.In rural situations where a dead tree poses no aesthetic or actual hazard in case of blow down it can save a lot of effort simply to girdle the tree in situ. Girdling is the procedure of cutting through the outer layer of bark all around the stem at the base. This starves the tree of nutrients and it will die within approximately one year. The dead wood will turn really hard at first and resist blow down or breakage for about five years but eventually rot sets in and the branches break off or the entire tree topples in a windstorm.