Green Cape Timber at Lourensford supplies CCA treated poles and untreated eucalyptus poles.
Green Cape Timbers’ news that it manufactures and supplies untreated eucalyptus poles for vineyards adds fuel to ongoing discussions timber pole suppliers and users.
Vergelegen wine estate is presently trialling three different pole materials in five blocks of vineyards. Steel poles are used in one block and the remaining four are divided equally between commercially available treated pine poles and untreated eucalyptus poles.
An objective of the study is to determine the long-term durability and suitability of different support materials for organic product labelling.
Historically, preservative-treated wooden poles are the preferred material choice in agricultural support structures used on wine and table grape-producing farms. More recently, treated poles are also used in shade net structures to cover and protect fruit trees and various other crops against damage caused by natural factors such as wind, hail, excessive sunlight, frost, insects, and birds.
Regional statistics on the type and number of agricultural and vineyard poles procured each year, replaced before end-of-life, or discarded at end-of-life are difficult to find. It is estimated that 100,000m3 of poles are treated annually in the Western Cape, with agriculture absorbing about 60%.
Strong interest
Sean McGaffin and his company Green Cape Timbers supplied the untreated poles. The pole producer is certified by African Certification and Testing (ACT) to produce CCA (chromated copper arsenate) treated poles and operates from Lourensford, a wine estate abutting Vergelegen.
The news about the untreated eucalyptus poles spread rapidly, setting McGaffin’s phone and emails abuzz with questions and comments.
“The strong interest confirms that we are on the right track,” McGaffin states.
“Consumers are becoming environmentally aware and putting pressure on food suppliers to demonstrate the sustainability of the supply chain. Wine producers, particularly those seeking organic accreditation, need environmentally-friendly materials.”
Natural durability
Green Cape Timbers supplied Vergelegen with untreated Eucalyptus cladocalyx (sugar gum or clado) and E. gomphocephala (tuart) poles. McGaffin chose the species because of their natural durability
He explains that the natural durability of eucalypts varies between species. “I consulted widely before selecting clado and tuart. The natural durability of their heartwood makes them resistant to attack by insects and other pests and last longer without chemical protection.
“Research by Stellenbosch University confirms that the natural durability of the two species in South Africa places them in class 1, the highest level in the international natural durability classification system.
“It means that depending on their application, they have a life expectancy of more than 25 years without treatment.”
Sean McGaffin of Green Cape Timbers and Hugo Slabber of Tree and Fruit Solutions with untreated eucalypt poles.
Stellenbosch University research
Prof Brand Wessels, a leading wood scientist at Stellenbosch University, shared the results of a study into the viability of fast-growing eucalyptus in the dry West Coast region of the Cape with McGaffin.
Researchers evaluated trees from a 20-year-old field trial from two arid sites. They identified three genotypes among 46 pure and hybrid species for the study. The three most promising genotypes by volume growth were:
- E. grandis x E. camaldulensis hybrid
- E. gomphocephala
- E. cladocalyx.
The investigation compared physical and processing properties to determine their commercial suitability for lumber and pole production. The best performing species were tuart and clado. Both have high levels of twist in boards; however, “twist in clado was much better than tuart, giving the species a big advantage in product yield potential”.
Clado sawn timber
McGaffin’s interest in clado pointed him to Marc du Plessis of Universal Timber and Machine Company. Du Plessis says they discovered the physical and aesthetic properties of clado sawn timber by chance some years ago.
Universal Timber is a sawmill and value-adding plant located at Transnet Rail Engineering’s yard in Salt River, Cape Town. Universal’s vast product portfolio includes boat cradles, decking, cants, planed boards, architectural mouldings, post and beam construction, exposed roof structures and outdoor furniture.
“For years, we supplied the port with highly engineered keel blocks, docking blocks, wedges and shoring for the dry docks. We imported balau for the dry docking even though we receive truckloads of large diameter logs, including tuart and clado, from all over the country.
“One day, we ran short of balau and decided to try E. cladocalyx. We were surprised and delighted to find that its physical properties and machineability were the same as balau. Clado is now our timber of choice.”
Vergelegen is testing untreated eucalyptus poles in its vineyards.
Clado the catalyst
Du Plessis introduced Hugo Slabber of Tree & Fruit Solutions to McGaffin. Slabber, a qualified and highly experienced forester, is currently contracted by Lourensford to oversee clear-felling the remaining eucalyptus and pine plantations in the Helderberg catchment area on the estate.
The three companies are pooling their resources to establish Green Cape Forestry Consortium and are finalising the business model.
Sean McGaffin with E.cladocalyx poles.
Resource constraints
McGaffin and Slabber concede that Green Cape’s production of environmentally friendly poles is constrained because E. cladocalyx is not commercially available.
They say the consortium is investigating innovative ways of partnering with landowners to manage the eucalypts on their land sustainably. They are also working with Stellenbosch University to examine the possibility of tree breeding and growth trials of the species.
“We are not trying to compete with treated pole suppliers. We are establishing a niche market value chain for organic eucalyptus poles and sawn timber that meet the appropriate industry standards,” explains Slabber.
Research ref: CB Wessels, PL Crafford, B du Toit, T Grahn, M Johansson, SO Lundqvist, H Sall, R Seifert (2016): Variation in physical and mechanical properties from three drought-tolerant Eucalyptus species grown on the dry west coast of Southern Africa. https://link.springer.com/article/10.1007/s00107-016-1016-3