Friedel Eggers of UCL urges foresters to plant the best black wattle clones on the right sites to reap the benefits of good bark and timber yields
NCT Forestry organised an informative field day in October for its members and farmers in South Africa’s KwaZulu-Natal (KZN) Midlands region. Terry Wolhuter of Elands Spruit Farm in New Hanover hosted the event.
Roger Poole, from NCT, explained that the wattle farming area in KZN has been decreasing over the past decade due to various factors such as land returned to new owners who are not interested in tree farming, wattle being vulnerable to pests and diseases, and damage caused by wild and domesticated animals.
The theme for the day was 'Back to Basics', meaning it is crucial to focus on getting the basic principles of tree farming right to ensure the health of your trees and to get a return on your investment.
Open for business. Rob Thompson delivered the good news that NCT’s Richards Bay mill is open
NCT’s Greytown District Manager Cliff Walton provided info on the log specs required by the mills
The day was divided into two parts. Indoors, attendees heard presentations on pests and diseases by Brett Hurley from the Forestry & Agriculture Biotechnology Institute (FABI) and the demand for pulpwood during the 2024-2025 financial season by Rob Thompson of NCT.
The outdoor session included presentations from NCT's tree farming manager, Craig Norris, on wattle clones, planting, pruning, thinning, and maintenance by Friedel Eggers of UCL, as well as the timber specs required by the NCT mills for harvested timber by NCT's Greytown area manager Cliff Walton.
INDOOR SESSION
Wattle pathogens
Brett Hurley of FABI and the Tree Protection Cooperative Programme (TPCP) started the day's programme with information on the latest pest and pest-related diseases affecting wattle trees.
These include the wattle rust fungus, which infects the foliage of trees and stems of saplings, flowers, and seed pods. Telia, resembling brown powdery masses, develop dry on young host tissue but become slimy under wet conditions. In severe cases, wattle rust can reduce the growth of young black wattle trees by up to 40%. A lot of work is being done through the Institute for Commercial Forestry Research (ICFR) to breed rust-tolerant trees.
NCT’s Craig Norris provided info on the growth performance of the latest black wattle clones and the benefits of planting green wattle
Seedlings or clones are planted in a rip-line created by this customised ripper at Eland Spruit Farm
Other noteworthy pathogens in the KZN region are Ceratocystis wilt and Phytophthora species. The Ceratocystis wilt is a relatively new disease that affects wounds on black wattle. Hence, it is crucial when pruning to make clean cuts and avoid unnecessary stem damage, as these can become entry points of this pathogen.
Phytophthora spp is present in the midlands area, causing leaf and root rot. The Tree Protection Cooperative Programme (TPCP) is doing research to gain a better understanding of this pathogen.
Wattle pests
Brett said tree pests affecting wattle includethe Melanterius seed weevil, Aqrilus grandis, a wood-boring jewel beetle, and white grubs.
The Melanterius weevils are seed feeders that lay eggs and feed on wattle seed. Lately, it has been noted that there has been a shift in its feeding pattern, and it is now infesting and feeding on young shoots and twigs of the black wattle. The weevils typically have one generation per year, coinciding with seed maturity. The Melanterius weevil is present in the Howick region.
The Agrilus grandis jewel beetle is a wood borer in the Melmoth region. It is native to the South and East African areas. It bores underneath the bark and leaves a network of tunnels. Researchers are trying to find out why it is now attacking wattle.
Ongoing work is being done on white grubs to learn more about the different species and what drives them. Brett requested growers to alert the FABI team if they detect heavy white grub infestations on their farms and plantations.
Brett said FABI’s Diagnostic Clinic is open to NCT and TWK members and partners free of charge. Individuals and organisations that are not members are charged a fee for the service. The clinic identifies plant pests and diseases so that appropriate management strategies can be adopted.
Pulpwood demand 2024-2025
NCT's Rob Thompson began his presentation with a reality check: "If you thought we were the only ones with problems, please think again".
He said 46,000 American workers in all 36 ports went on strike for about four days recently, demanding a wage increase of up to 50%. The strike cost America over $5 billion per day and caused shortages of items ranging from bananas to essential goods.
Shifting the focus closer to home, Rob announced that NCT Richards Bay Mill's two chipping lines are operating well. Durban Wood Chips has recently reopened after a successful mill service shutdown in September, with the damaged vessel loader now back in operation.
Rob noted that NCT's current challenges included the strong Rand-Dollar exchange rate (R17,44 on 8 October 2024) and the hard and dry wattle being received by the mill, which negatively affected chipping blades. This old stock has been significantly drawn down at the mills and NCT farm depots.
Pulpwood demand for the 2024 – 2025 financial period indicates that Durban Wood Chips will require an estimated 500,000 tons of wattle and 120,000 tons of Eucalyptus smithii. Richards Bay Wood Chip would need about 1,3 million tons of wattle. Thompson hoped 2025 would be prosperous for NCT, its members, and partners.
IN THE FIELD
A customised planter applies water and fertiliser when sowing seeds on the Wolhuter farm
Terry Wolhuter, owner of Eland Spruit farm near New Hanover in the KZN midlands, hosted the NCT wattle field day
Wattle clones
NCT's Craig Norris explained why planting clones in modern forestry is preferable. Wattle clones are genetically identical which means they grow better, there is more uniformity and need less thinning. For example, rust-tolerant clones have a higher MAI (mean annual increment) than commercial seedlings.
He advised farmers to plant the frost-tolerant clones at the exposed valley bottoms where frost occurs. “Frost tolerant does not mean frost-resistant”, he warned, “they are more likely to survive severe frost events”.
SP644 was the first commercial rust-tolerant clone released in SA and was fast-tracked to combat the impact of wattle rust. It shows increased growth and better uniformity than commercial black wattle seedlings.
Craig said AF01 is currently the best-performing rust-tolerant wattle clone. Corrective pruning may be necessary due to heavier branching.
JC108 is the latest rust-tolerant clone to be released. It is similar to AF01 but with a better stem form. FW54 is currently the only frost-tolerant wattle clone on the market. It is explicitly bred for rust tolerance but shows no growth advantage over commercial seedlings.
Craig urged growers to remember:
- Plant rust tolerant clones (SPs, AFs or JCs) on good wattle sites or sites prone to rust infection and NOT in frost areas.
- Avoid sites exposed to windthrow and don’t plant root-bound seedlings.
- Planting espacement of 1.8m x 3m is critical especially for the SP644 clone susceptible to windthrow.
Silviculture
Friedel Eggers of UCL stressed the importance of good site preparation before planting, including the correct pit depth and width (25cm x 25cm) and pre-plant weeding (weed-free pits). Planting espacement of 3m x 1.8m is recommended for clones, and you need to maintain the compartment weed-free for the first year.
Callum MacKenzie of Midlands Spraychem demos the Faka-Plenty planting tube
Two two-person teams equipped with Stihl earth augurs can make as many pits in a day as a manual planting team of 12 people using picks
Pruning should be done in winter before the trees are two metres tall. Prune only the double leaders and branches competing with the prominent stem leader. Do not over-prune, as it can inhibit tree growth. Make clean cuts, not too close to the main stem, to avoid infection.
Friedel said that if the above is observed and the site is ideal for wattle, it is easy to get yields of up to 120 tonnes per hectare from wattle clones. This produces a nett standing value (after harvesting and transport costs are deducted) of roughly R90,000/hectare.
Specifications
NCT’s Greytown District Manager Cliff Walton provided info on the log specs required by the mills
NCT's Cliff Walton outlined the timber specifications for harvesting wattle. Logs must not be fire-damaged as it is difficult for the mills to bleach burnt timber. The correct length for logs is 2.4m, with diameters between 5cm and 40cm. There must be no knots, bark, and mud. The logs must be delivered 4 to 10 weeks after felling.
Ensure that the logs are free of contamination like nails, steel, plastic, fungal growth, oil or anything else that may negatively influence pulp quality. Other factors to watch out for include drought-stressed timber, which is identified by low moisture and the presence of wood borers.
Thanks to the sponsors
The field day ended with a braai and drinks courtesy of NCT and other event sponsors, including Stihl, Midlands Spray Chem, Sunshine Seedlings, TWK, Rhino Charcoal, Rolfes Agri, and Eland Earth Moving.
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