Back to basics focus for KZN wattle growers

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 — Open for business. Rob Thompson delivered the good news that NCT’s Richards Bay mill is open

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 — NCT’s Craig Norris provided info on the growth performance of the latest black wattle clones and the benefits of planting green wattle

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 — A customised planter applies water and fertiliser when sowing seeds on the Wolhuter farm

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 — Callum MacKenzie of Midlands Spraychem demos the Faka-Plenty planting tube

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 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.

FSA secures R18 m funding for forest protection

The arrival of the Sirex wood wasp in South Africa a few years ago was the cause of considerable damage to pine plantations across the country. Here a pine tree is inoculated with the nematodes of a parasitic wasp that was introduced to curb the spread of Sirex, which stunts tree growth and eventually kills infested trees.

A Memorandum of Agreement (MoA) concluded between Forestry South Africa and the Department of Forestry, Fisheries and the Environment (DFFE) is set to boost industry’s efforts to counter the impact of pests and diseases on the country’s timber resources with the injection of R18 million funding over two years.

“While long overdue, this partnership with DFFE will add greatly to our efforts to protect our timber resources against pests and diseases, conduct desperately needed research and development, build our human capacity in this crucial area and encourage ongoing investment by our sector,” commented FSA’s Research and Forest Protection Director, Ronald Heath.

The MoA focuses on five main outcomes:-

• Monitoring activities
• Awareness programmes
• Provision of diagnostic services to the forestry industry
• Conducting research on aspects of pests and diseases.

Wattle rust is a growing problem that causes severe damage to young wattle trees in KZN and Mpumalanga. Spores are spread by wind, rain splash and insects. Disease management strategies include chemical treatments and breeding of rust tolerant trees.

The MoA will be managed on behalf of the Industry by Ronald Heath with oversight provided by the National Pests and Diseases Steering Committee which includes representatives from DFFE, FSA, the National Forest Research Forum and the Tree Protection Cooperative.

After five years of continuous and active engagement with the DFFE, the process was concluded in the short space of one month thanks to the efforts of Mohammed Bhabha of the PPGI, Sabelo Malaza from the Masterplan Programme Management Office in DFFE and Director-General Tshabala, said Ronald.

The importance of securing this funding support from DFFE is underlined by the increasing impacts of pests and diseases on forestry in South Africa and around the world.

It is estimated that over the past 30 years the forestry industry has been losing the equivalent of 11.5% of its harvest to pests and diseases every year. When using current value estimates of 50% of the average value of the timber, the losses amount to R392 million of roundwood annually. This translates into an opportunity cost of R2,05 billion in additional downstream processing that is lost.

The losses outlined above - which exclude losses due to fire - have arisen from just a handful of pests and diseases. Now, with the rate of new pests and diseases landing on our shores increasing rapidly on the back of expanding global trade, the losses incurred from pest and disease damage are expected to increase dramatically in future.

The gall wasp Leptocybe invasa has caused extensive damage to eucalypts, especially in the Zululand area. The wasp causes galls on the mid-ribs of leaves and on the petioles and stems resulting in curling of leaves and malformation of stems. Management strategies include the release of a biological control in the form of a tiny wasp and the selection and breeding of more Leptocybe tolerant planting material.

New wattle rust disease spreading rapidly

New pests and diseases in the spotlight at NCT Midlands field day

Izette Greyling of the TPCP inspecting the rust damaged wattle compartment at Baynesfield.

The latest destructive disease to hit South African forestry is a ‘rust’ that attacks black wattle, Acacia mearnsii. Tree farmers first detected it last year in the KwaZulu-Natal midlands. Since then, the TPCP team has been working around the clock to find out what it is, where it comes from, and how to stop it.

Izette Greyling of the TPCP was in KwaZulu-Natal recently to do some field work and gave a presentation to tree farmers who attended the NCT field day at Baynesfield, where the rust is already causing damage to young wattle compartments.

Izette says that the speed with which the rust is spreading is cause for concern. This last summer, it spread from Harding in KwaZulu-Natal to Mpumalanga. It is a rust fungus and causes defoliation in mild cases, and stem deformation in more severe cases.

The only good news around this disease, according to Izette, is that it has now been positively identified as belonging to the Uromycladium genus, and is thought to be of the fusisporum species, although this has still to be confirmed.

The TPCP is currently working with NCT and the ICFR to come up with management options, including selecting tolerant trees and doing chemical sprays on affected trees. The only short-term option at this stage is chemical control, and NCT is planning a series of trials in conjunction with the ICFR and TPCP.

“The rust is causing stress on the affected trees and there will be follow-up insect and pathogen attacks,” said Izette.

Some of the local farmers at the field day said they had noticed intensified mired infestations in compartments where the rust was present.

Another cause for concern for tree farmers, said Izette, is that the introduction of new pests and diseases attacking Eucalyptus species has accelerated in the past few years. This is consistent with the increasing volumes of cross border trade taking place around the world, allowing pests and pathogens to move around far from their host ranges.

She said that the three major pests in the KwaZulu-Natal midlands were Leptocybe, Thaumastocoris and Gonipterus.

New eucalyptus pests that have arrived in South Africa in the past two years include the red gum lerp psyllid (Glycaspis brimblecombeii) detected in 2012, and the shell lerp psyllid, in the genus Spondyliaspis, detected in 2013.

Both are sap-sucking insects that can cause a lot of damage. The search is on for potential biocontrol agents for these insects.

The biocontrol for Leptocybe (S. neseri) has been released in all major eucalyptus growing areas, and it is spreading on its own, which is good news as this pest has caused extensive damage to susceptible eucalyptus species, especially in Zululand.

“Leptocybe is getting worse – but that’s to be expected as it has had three years in which to reproduce. It will be another two years before the biocontrol can catch up,” said Yzette.

Meanwhile, there have been limited releases of the biocontrol agent for Thaumastocoris. According to Izette, the so-called ‘fairy fly’ is very small and difficult to rear in the lab, but evidence suggests it has survived in the field following its release.

Izette also said that there had been more severe outbreaks of old foes like Gonipterus, and the Cossid Moth, which is spreading, and has been reported in the Mooi River area recently.

After the indoor presentations, participants visited various sites on Baynesfield Estate. The 3 000ha Baynesfield estate is planted to wattle (just under 50%) and eucalyptus, mainly Smithii, a little macarthurii and now G x U since the Leptocybe infestations which ruled out the planting of G x C.

At one stop, we saw a young wattle compartment badly affected by the new rust disease. It causes loss of growth and forking and branching, with mortality of over 30% reported in some areas. The younger the trees affected, the higher the mortality rate. Some farmers are using general agricultural sprays to treat the rust, with good results.

Farmers could try and collect seed from resistant trees. Given the accelerating introduction of pests and diseases affecting forestry, it is becoming increasingly important for farmers to spread their risk by planting several different species on their farms.

This Stihl earth augur, equipped with a long lasting, tungsten blade, produces uniform, high quality pits for planting. According to the operator, a pitting/planting team of five people can pit, water and plant 900 to 1 000 trees a day (six-hour shift) using the earth augur. The team needs to be multi-skilled with two or three team members taking turns operating the augur.

Craig Norris of NCT discussing the merits of planting G x U during the field day. Behind him is a compartment of 3.5 year-old G x U clones showing excellent growth at 1 100 metres altitude.

*The TPCP has made a special request to tree farmers to report occurrences of the wattle rust to Jolanda Roux (jolanda.roux@fabi.up.ac.za; 082 909 3202) or the diagnostic clinic (darryl.herron@fabi.up.ac.za). Early detection of the disease in new areas will greatly assist in assessing its status and informing management strategies.

*Published in June 2014