Sunday 28 May 2006

Basket Case

When you’re thinking of planting large trees you will be making a choice between two popular types of nursery stock. Traditionally trees between two inches in trunk diameter and four inches in diameter have been available with their roots wrapped in a burlap ball. The trees were excavated by hand in the growing field. Once the sides of the tree were excavated burlap was wrapped around the root ball to help maintain the soil around the roots. Then, carefully the wrapping material was worked under the roots. The burlap was all eventually stitched together into a ball. This type of stock is called balled and burlapped. This was the industry strand for many years. The problems with this labor intensive system are two fold. The first problem is the loss of roots. A typical ball and burlap tree has had over eighty percent of the roots removed. Many times the ball will fall apart when planting, resulting in more root damage. The second problem is the incomplete removal of the balling twine and burlap. The twine may be wrapped around the top of the roots, the root collar. This will result in the tree being girdled as it grows and the trees dying as a result. Synthetic burlaps and treated natural burlaps decompose slowly in certain soil environments.

Many times you will find burlap intact on trees that have been wind thrown years after they were planted? Roots can have a tough time penetrating these materials. Natural burlap also acts as a wick and will draw water away from roots resulting in moisture stress in newly planted trees. It is important to remove all twine and burlap from the top of the root ball once trees are in the planting hole. It is recommended to remove the burlap from the sides to a height 4 inches below the final soil grade. This will allow roots to establish quickly in the top 4 inches of the soil and prevent the burlap from wicking. It is also a good idea to cut several slits to aid root penetration in the lower portion of the root ball burlap. It is best to do this once the tree is in the hole. In recent years a new format of tree planting container has emerged.

Planting baskets are galvanized wire baskets lined with burlap that allow trees to be dug moved and planted with much less labor. Trees are typically dug with a tree spade on the front of a small front end loader. They are then placed into a wire basket lined with burlap. The burlap is then folded over the top and the handles of the basket are folded over the top and bound with twine to complete the root ball. The same cautions apply when planting wire baskets. Remove all burlap and twine from the top of the ball. Remove all wire that may girdle the roots or stick above the soil level. Remove all burlap from the top 4 inches of the basket to allow for root growth one planted. Failure to allow the roots to establish will result in increased chance of wind throws and tree mortality. I have seen trees that were planted fourteen years previously still have intact burlap when they blow over and the roots popped out of the ground. Large trees give instant results, small trees establish quicker and will eventually over take their larger counterparts in the landscape.