WIRE BASKETS-CURRENT PRODUCTS AND THEIR HANDLING AT PLANTING

Journal of Arboriculture, Jul 2004 by Appleton, Bonnie, Floyd, Scharlene A

Abstract. When field-dug, balled-and-burlapped trees are planted to the landscape, several options exist relative to wire basket modification or alteration. New wire basket alteration research has been initiated due to considerable controversy that surrounds some of the alteration options, and to limited prior research specifically addressing this issue. To guide this research, and to determine what currently occurs in the tree care industry, surveys of manufacturers of wire baskets, and of landscape contractors and arborists who plant trees, were conducted. Summaries of those surveys are presented.

Key Words. Balled-and-burlapped; galvanized; hydraulic diggers; machine-dug; mechanical harvest; nongalvanized; nursery production; root protection; transplanting.

In a chronology of the U.S. nursery industry, 1956 is listed as the year hydraulic tree diggers were introduced (Davidson et al. 1988). The authors stated that mechanical harvesting "revolutionized digging plants in nurseries." Prior to mechanical harvest, field-grown trees were dug by hand and generally handled either bare root or with their root balls wrapped in burlap and drum laced with string or rope.

Mechanical harvesting creates considerable savings in time and labor over hand digging. It allows for the harvest of trees grown in sandier soils, where hand digging is generally impossible because root balls break apart. In addition, larger-caliper trees, which generally are not practical to dig by hand, can be harvested. Nurserymen believe that wire baskets, compared to rope-laced balls, drastically reduce the number of damage claims, increase tree survival chances in the landscape, and create an overall more appealing and marketable product (Desmarteau 2002).

WIRE BASKET EVOLUTION

To accommodate mechanical harvesting, an appropriate receptacle had to be developed to hold root balls extracted with hydraulic diggers. The question of the origin of wire baskets was posed to representatives of two major wire basket manufacturing companies-Peter Braun, president o (Braun Horticulture, Inc., Ontario, Canada, and Mark Frost, sales representative for Cherokee Manufacturing, South St. Paul, Minnesota (personal communications). Frost stated that, initially, crude versions of currently manufactured wire baskets were made by local "job shops" to fit hydraulic diggers as the machines were developed. Braun stated that the first real introduction of wire baskets was approximately 25 years ago by Remke Industries, Inc., Wheeling, Illinois. Baskets were designed around both the hydraulic digger blade configurations and the configurations of roots of different species of trees.

Several configurations of wire baskets are currently manufactured. Cone-shaped (pointed) root balls and baskets with a 30 degree angle are recommended for rocky or lighter (sandier) soils to help maintain root ball integrity. Root balls and baskets with lesser angles (truncated), which produce rounded and flat-bottomed balls, work well for heavier or tighter (more clayey) soils. Frost stated that "Neither one is better than the other. Soil type should dictate the shape or angle of the mechanical harvester and basket that is used."

THE WIRE BASKET CONTROVERSY

Most people in nursery production, landscape contracting, and urban tree care do not dispute that wire baskets are invaluable for protecting tree root balls during harvest, shipping, and storage, and during transport to and movement around landscape sites (positioning, lowering into the hole, etc.). What is disputed, however, is whether wire baskets pose any significant danger if left unaltered or modified at planting. The question of alteration applies not only to conventionally balled-and burlapped-trees in wire baskets, but also to trees whose wire basket-encased root balls have been containerized, with additional substrate often obscuring the wire baskets.

Many nurseries say removal or alteration is unnecessary. They fear that removal or alteration will result in root ball damage or tree stability problems and consequently often won't guarantee tree survival if basket removal or alteration occurs. However, many planting specifications mandate either partial or total basket removal, or some other form of basket alteration. This required removal or alteration places landscape contractors in a no-win situation between nursery nonremoval policies and specification removal/alteration requirements.

At the "other end" of a tree's life, many arborists who remove trees frequently point to unaltered baskets as "tree killers." They do not understand why removal or alteration is not required of landscape contractors; therefore, a very negative view of nursery production and landscape installation practices exists within much of the arboricultural community.

POTENTIAL WIRE BASKET DAMAGE TO TREE ROOTS

Many anecdotal reports exist that attribute tree stress, decline, or death to wire baskets left intact when balled-and-burlapped trees are planted. Requiring alteration or removal supposedly prevents detrimental cutting or girdling of tree roots or stems by the basket wire. This implied damage is never immediate but is said to generally occur years after installation, when burlap may have deteriorated but wire baskets are still intact. Those reporting implied damage say they generally see the damage when root collar excavations are performed or when tree removal becomes necessary.