Narrow Sense Pesticide Research
Narrow sense sustainability deals with the long-term productivity of planted stands of trees on specific sites over indefinite forest cycles. This is largely silvicultural and forest management related research that is focused on determining:
- The avenues for improving the current operating procedures; and
- The identification, mitigation and monitoring of key factors that could negatively impact productivity.
Completed narrow sense research projects TIPWG has been involved in.
Insecticides for control of eucalypt foliar insect pests
Person(s) responsible | Funding/Supporting bodies | Problem | Action/s | Outcomes (progress) | Written outputs |
Keith Little Lindokuhle Dlamini | Nelson Mandela University ICFR TIPWG Chemical Companies | Problem: The magnitude of tree growth impacts from foliar insect pests (Gonipterus and Thaumastocoris) were un-quantified, and with that the need for control. Objective/Need: Quantifying the impacts of foliar pests (Gonipterus and Thaumastocoris) on tree performance in Zululand | Two trials implemented in Zululand (GC and GU), with two treatments (insects excluded through the repeated application of an insecticide versus a no-treatment control). Insect occurrence and tree growth was monitored over successive rotations | Significant improvements in 5 year tree growth (25 %) were detected only in the GU trial, this despite the application of an insecticide over a 10-month period only. The abundance of G. scutellatus at Palm Ridge may also have been due to its preference for GU rather than GC. | Dlamini LS, Little KM, Sivparsad B, Nadel. R 2018. Quantifying the impact of foliar insects on two Eucalyptus hybrids in Zululand, South Africa. South African Journal of Plant and Soil. In press. |
Keith Little Lindokuhle Dlamini | Nelson Mandela University ICFR TIPWG Chemical Companies | Problem: The magnitude of tree growth impacts from Leptocybe invasa were poorly-quantified, together with a lack of understanding of appropriate control methods (cultural and/or insecticides) Objective/Need: Understanding the interactions between tree susceptibility (GU; GC + tolerant; susceptible) and insecticides (systemic; contact; natural) for the management of foliar insect pests | One trial was implemented in Zululand testing the interaction between GC and GU susceptible (_s) and tolerant (_t) clones, insecticides (systemic, contact, natural) and the timing of insecticide application. | L. invasa damage recorded over the trial period indicated that irrespective of treatment, damage was lower in the GU clones than the GC clones resulting in a 63.9 m3 ha-1 volume difference at 5.5 years. In addition, the difference between the GU_s and GU_t clones (3.2 m3 ha-1) was marginal when compared to the GC_s and GC_t clones (37.2 m3 ha-1). Although the three insecticides tested delayed the onset of L. invasa damage, they did not result in improved tree performance at 5.5 years. Results indicate that the planting of a tolerant species (hybrid in this trial) was the most viable option for the management of L. invasa. | To access the thesis in full, click here0801?conjunction1=AND&conjunction2=AND&f0=ss_state%3A%22A%22&source=Advanced&f1=sm_creator%3A%22Dlamini%2C+Lindokuhle+Sithembiso%22&site_name=GlobalView&field1=text&root=&from=&to=&field3=text&query1=Lindokuhle+Dlamini&field2=text&query2=&query3=">To access the full thesis, click here |
Keith Little Lindokuhle Dlamini | Nelson Mandela University ICFR TIPWG Chemical Companies | Problem: Limited FSC compliant insecticides registered for control of foliar insects in eucalypts Objective/Need: Testing of ecologically sound insecticides (synthetic and/or natural) for the management of foliar insect pests in eucalypts | Two trials were implemented in the KwaZulu-Natal Midlands in October 2016 (at Ingwe and Balgowan plantations), to test the efficacy of eight different insecticides (synthetic and organic) for the management of foliar insect pests | A higher population and damage of Gonipterus spp. was found in the E. dunnii (Ingwe trial) and very little to no damage was observed in the E. badjensis (Balgowan trial). All insecticides tested were not effective in managing Gonipterus spp. in these specific sites. A low population of insect pests could offer a plausible explanation of results |
Insecticides for control of soil borne insects
Person/s responsible | Funding/Supporting bodies | Problem | Action/s | Outcomes (progress) | Written outputs |
Evidence Siwela (MSc Forestry) Keith Little | Nelson Mandela University ICFR TIPWG Chemical Companies | Problem: The relationship between soil borne insects and seedling size and quality as a form of cultural control is poorly understood Objective/Need: Testing of ecologically sound insecticides (synthetic and/or natural) for the management of foliar insect pests in eucalypts | Two pine trials were implemented in KwaZulu-Natal (Sappi Demagtenberg plantation) and Mpumalanga (York Timbers Klipkraal plantation) to understand the impact of seedling quality and use of a soil-applied insecticide on tree performance | Complete | To access the thesis in full, click here |
Evidence Siwela (MSc Forestry) Keith Little | Nelson Mandela University ICFR TIPWG Chemical Companies | Problem: Limited FSC compliant insecticides registered for control of soil borne insects in eucalypts Objective/Need: Testing of ecologically sound insecticides (synthetic and/or natural) for the management of soil borne insect pests at planting | One trial implemented in the KwaZulu-Natal Midlands in February 2018 to test the efficacy of seven different insecticides (synthetic and organic) for the management of soil borne insect pests | Complete | |
Evidence Siwela (MSc Forestry) Keith Little | Nelson Mandela University ICFR TIPWG Chemical Companies | Problem: Little data exists as to the cost:benefits for using an insecticide for the control of soil pests Objective/Need: Link insecticide application costs to tree performance | Costs associated with soil-applied insecticides at planting from 8 trials will be linked to that of tree performance | Complete |
Optimising the use of herbicides for the management of Eucalyptus coppice in South Africa
Person/s responsible | Funding/Supporting bodies | Problem | Action/s | Outcomes (progress) | Written outputs |
Jonathan Roberts (MSc Forestry) Keith Little | Nelson Mandela University CSIR SETA TIPWG Chemical Companies | Problem: The cost-effectiveness of killing eucalypt stumps has never been determined in relation to the treatment coppice regrowth with glyphosate if the stumps are not killed. Objective/Need: Determine the most cost-effective method for stump management (cultural, killing of stumps at felling, or spraying regrowth) so as to reduce overall costs and herbicide-use. | One trial was implemented in Mpumalanga to determine the most cost-effective method of killing eucalypt stumps together with a reduced reliance on herbicides for control of resulting coppice regrowth. Selected cut-stump and basal-frill treatments with triclopyr were applied E. macarthurii, with the resulting coppice regrowth either manually removed, or glyphosate applied to foliage. These treatments were integrated with non-chemical control methods, where E. dunnii were planted either between each stump row or within the row, to determine whether such treatments could further reduce the level of coppicing through shading. | At rotation end, the different treatments tested had no significant influence on any of the E. dunnii growth variates. As there were no significant differences, the treatment with the lowest overall cost and herbicide used would be preferred. The application of triclopyr to the cut-surface following felling was the most cost-effective treatment. The differences in cost obtained is directly related to follow-up coppice regrowth control operations and quantity of total herbicide applied (both triclopyr and glyphosate). It was hoped that the non-chemical control method (planting position of seedlings) would reduce the level of coppicing, however, within this trial, this did not occur | Roberts JC, Little KM, Light ME. 2016. The use of glyphosate for the management of secondary coppice regrowth in a Eucalyptus grandis x E. urophylla coppice stand in Zululand, South Africa. Southern Forests 78(3): 217-223 |
Jonathan Roberts (MSc Forestry) Keith Little | Nelson Mandela University CSIR SETA TIPWG Chemical Companies | Problem: Current recommendations regarding the use of glyphosate for secondary coppice regrowth control are not based on trial data, with the possibility of incorrect and/or over-application of herbicides Objective/Need: To determine the optimum rate of glyphosate application and timing of control so as to avoid glyphosate from being over-applied when managing this regrowth | A trial was implemented in Zululand on Eucalyptus grandis x E. urophylla coppice to investigate different methods to control secondary coppice regrowth through either manual removal with a bush-knife, or the application of glyphosate (360 g L-1 a.i.) to the foliage. A range of herbicide rates (0.6%, 1.2%, 1.8%) was applied to the foliage of the secondary coppice regrowth when it reached a predetermined mean height (0.5 m, 1.0 m, 1.5 m). | The use of glyphosate, irrespective of rate and/or timing of application (as assessed by secondary coppice regrowth height) proved to be more cost-effective compared to manual removal of secondary coppice regrowth. Treatment efficacy in terms of treating secondary coppice regrowth increased with an increase in the rate of glyphosate applied (0% < 0.6% < 1.2% < 1 .8%), especially when treated at either 1.0 or 1.5 m in height. Although the volume of the glyphosate used increased with increasing secondary coppice regrowth height (0.5 m < 1.0 m < 1.5 m) due to the larger foliar spraying area, there was little difference in total glyphosate used when comparing the same herbicide rate across the three different heights. The most cost-effective treatment was that where glyphosate was applied at 1.2% when the secondary coppice regrowth was 1 to 1.5 m | Roberts JC, Little KM, Light ME. 2017. A comparison of the cost-effectiveness of different Eucalyptus macarthurii cut-stump control management options for the regeneration of a Eucalyptus dunnii stand in Mpumalanga, South Africa. Southern Forests Published online |
Jonathan Roberts (MSc Forestry) Keith Little | Nelson Mandela University CSIR SETA TIPWG Chemical Companies | Problem: Current coppice management recommendations are based on manual, rather than mechanical harvesting (as currently practiced). A need existed to determine coppice management regimes that would facilitate mechanised harvesting. Objective/Need: To determine the optimum coppice management regimes (including manual and chemical control of regrowth) that would facilitate mechanised harvesting | E. grandis x E. urophylla coppice shoots were reduced to one stem per stump in one thinning operation (3.5 m, 4.5 m and 6.5 m), with the impact of increased secondary coppice regrowth monitored together with the testing of different control methods. These regrowth control methods included the testing of adjuvants so as to potentially improve glyphosate efficacy. | At 23 months after felling, DBH was found to be significantly larger for the stems thinned to one stem per stump to those where stems were first thinned to two stems per stump. However, the Stocking of these treatments indicated that a reduction to one stem at 3.5 or 4.5 m resulted in lower stocking, likely due to windthrow. The addition of an adjuvant to glyphosate did not increase the efficacy of regrowth control. Within this trial, reducing coppice shoots at 6.5 m to one stem per stumps was the most effective treatment in terms of growth and survival. | Roberts JC, Little KM, Light ME. 2017. Interaction between Eucalyptus grandis x E. urophylla coppice reduction heights to single stems and secondary coppice regrowth in Zululand, South Africa. ICFR Technical Note 03/2017 |
Optimizing herbicide-use for the killing of eucalypt stumps
Person/s responsible | Funding/Supporting bodies | Problem | Action/s | Outcomes (progress) | Written outputs |
Tshilidzi Mavhungu (MSc Forestry) Keith Little | Nelson Mandela University SETA TIPWG Chemical Companies | Problem: Current eucalypt stump killing techniques that make use of herbicides have not been tested on E. cloeziana Objective/Need: Extend current stump control practices to include E. cloeziana | One trial implemented in Limpopo at felling of an E. cloeziana stand to test current herbicides (triclopyr and/or glyphosate) and application method (basal frill, cuts-surface, foliar) for the killing of stumps | Complete - Thesis submitted February 2021, results pending | |
Tshilidzi Mavhungu (MSc Forestry) Keith Little | Nelson Mandela University SETA TIPWG Chemical Companies | Problem: Herbicide rates of application for killing of eucalypt stumps need to be reduced in accordance with certification requirements Objective/Need: Currently available natural/synthetic surfactants need to be tested to determine if herbicide rates can be reduced without compromising efficacy | One trial implemented in Limpopo at felling of an E. cloeziana stand to test various natural/synthetic surfactants in combination, such that the rates of herbicide application can be reduced without compromising efficacy in terms of killing eucalypt stumps | Complete - Thesis submitted February 2021, results pending | |
Tshilidzi Mavhungu (MSc Forestry) Keith Little | Nelson Mandela University SETA TIPWG Chemical Companies | Problem: Current recommendations for killing eucalypt stumps require herbicide application within one-two hours, whereas labour safety means that herbicides can only be applied +12 hours following the felling and after the timber has been extracted Objective/Need: Extending the time after felling that herbicides can be applied, yet remain effective for the killing of eucalypts stumps | Based on the outcomes from the above two trials, one trial to be implemented whereby the most promising herbicide-adjuvant combinations will be tested so as to extend the time after felling that herbicides can be applied, yet remain effective for killing stumps | Complete - Thesis submitted February 2021, results pending |
Testing alternatives to paraquat dichloride for the preparation of fire-break tracer (desiccants for fire-break management)
Person/s responsible | Funding/Supporting bodies | Problem | Action/s | Outcomes (progress) | Written outputs |
Keith Little | Nelson Mandela University TIPWG Chemical Companies | Problem: 1. Up until 2012, paraquat dichloride was used for the preparation of tracer lines, but due to it being listed as a highly hazardous pesticide, it can no longer be considered. Objective/Need: Screening of potential alternatives to paraquat for fire-break management | As a first screening trial, pyraflufen-ethyl + glyphosate and pelargonic acid were tested in April 2012 at various rates for the preparation of tracer lines together with a control, paraquat (current herbicide of choice) and glyphosate | Of all the alternative products/rates tested, pyraflufen-ethyl at 0.5 l ha?1 was the only treatment that gave reasonable initial control (59.8% relative to the control), together with excellent recovery (81.3% relative to the control). If pyraflufen-ethyl were to be considered, further testing in terms of rates and timing of application is needed to confirm these findings and to refine its potential for use. Pelargonic acid at the rates tested was not effective. | Little KM, Nadel R. 2014. Testing pelargonic acid and pyraflufen-ethyl with glyphosate as alternatives to paraquat dichloride for the preparation of fire-break tracer lines at Underberg, South Africa Southern Forests, 6(2): 6773 |
Keith Little | Nelson Mandela University TIPWG Chemical Companies | 2.Problem: Pyraflufen-ethyl placed on FSC list of HH chemicals so can no longer be considered as an alternative to paraquat for the preparation of tracer lines Objective/Need: Re-test pelargonic acid at higher rates and with adjuvants to improve efficiency | One trial implemented in 2016 to retest pelargonic acid (at higher application rates, with and without adjuvants), and two additional desiccants (pyraflufen-ethyl: Ecopart 2S; carfentrazone-ethyl: Aurora), together with a Control and paraquat | Of the products tested, pelargonic acid applied at 7%, 10% and 13% produced results most similar to that of paraquat (82% desiccation at 16 d; 95% vegetation recovery at 83 d). Further testing is required on different sites, and with different vegetation, to improve the timing, rates and methods of application | Little KM, Roberts J. 2017. Desiccant herbicides tested for the preparation of fire-break tracer lines, South Africa. South African Journal of Plant and Soil - Published online |
Keith Little | Nelson Mandela University TIPWG Chemical Companies | 3. Problem: Pelargonic acid at the rates tested resulted in only 80% desiccation. Objective/Need: Test pelargonic acid on contrasting sites whilst focusing on improved desiccation through application methods and/or rates | Two trials implemented in KwaZulu-Natal in April 2017 2016, with pelargonic acid applied at 2 rates (7 and 10%) using various nozzles (air induction, twin fan, droplet sizes, volume of delivery) to improve canopy penetration and cover. | Regrowth was due to be monitored in October 2017, but plot markers removed, so vegetation recovery could not be determined. Report pending | Trials and report completed for AVIMA, but due to change in formulation the product was not registered. Currently testing Belchim product, with report due April. |
Keith Little | Nelson Mandela University TIPWG Chemical Companies | 4. Problem: Pelargonic acid only ever tested in controlled trials and not under commercial conditions Objective/Need: Based on the initial outcomes from the two KZN trials (3 above), pelargonic acid was tested on a commercial basis in comparison to paraquat | Four commercial spray blocks implemented in April 2017, burnt and with regrowth monitored in October 2017 | Assessments completed. Report pending | Trials and report completed for AVIMA, but due to change in formulation the product was not registered. Currently testing Belchim product, with report due April. |
Keith Little | Nelson Mandela University TIPWG Chemical Companies | 5. Problem: Nozzles tested in 4 above trials not appropriate for commercial application of pelargonic acid Objective/Need: Source and test different formulations of paraquat and pelargonic acid to improve efficacy and to reduce applicator risk. Also test more appropriate nozzles for commercial spraying based on outcomes from commercial spraying trials | One trial implemented to test the different formulation pelargonic acid (and paraquat as a gel) in combination with organic adjuvants. Nozzles appropriate for commercial application tested. | One trial implemented in January 2018, but inadvertently mowed. Trial re-implemented in April 2018, with results and report pending | Trials and report completed for AVIMA, but due to change in formulation the product was not registered. Currently testing Belchim product, with report due April. |
Keith Little | Nelson Mandela University TIPWG Chemical Companies | 6. Problem: The use of systemic herbicides and mechanical methods of fire-break preparation results in erosion, but with limited supporting data available. Objective/Need: Obtain soil runoff data to understand the impacts of various forms of tracer line management (desiccant/mowing/hoeing) on site and soil. | One trial implemented using a rainfall simulator whereby water and soil runoff was monitored for 4 management methods (control, mowing, hoeing, desiccant herbicide) | Trial completed, with results and report pending | Trials and report completed for AVIMA, but due to change in formulation the product was not registered. Currently testing Belchim product, with report due April. |
The use of natural synthetic adjuvants to reduce herbicide use and or improve efficacy for the control of difficult to kill forest weed species
Person/s responsible | Funding/Supporting bodies | Problem | Action/s | Outcomes (progress) | Written outputs |
Josias Letoana (MSc Forestry) Keith Little | Nelson Mandela University NCT TIPWG Chemical Companies | Problem: Current herbicides and application methods are only c. 75% for the killing of mature woody plants (for example Solanum mauritianum) Objective/Need: Can we reduce the quantity/volume of herbicides applied to the cut-surface/basal stem of mature bug-weed by adding adjuvants, while maintaining and/or improving herbicides efficacy? | One trial implemented in the KwaZulu-Natal Midlands on mature bugweed in a pine stand where triclopyr was tested in combination with five natural/synthetic adjuvants, either as a basal stem, or cut-surface application. | Completed | To access the thesis in full, click here |
Josias Letoana (MSc Forestry) Keith Little | Nelson Mandela University NCT TIPWG Chemical Companies | Problem: Current herbicides and application methods are only c. 75% for the killing of some perennial grasses (for example Setaria megaphylla) Objective/Need: Can we reduce the quantity/volume of herbicides applied in either spring or autumn to the foliage of setaria adding adjuvants, while maintaining and/or improving herbicides efficacy? | Two trials implemented in the KwaZulu-Natal Midlands (one in spring and one in autumn) on mature setaria where clethodim and glyphosate was tested in combination with five natural/synthetic adjuvants as a foliar spray | Completed | |
Josias Letoana (MSc Forestry) Keith Little | Nelson Mandela University NCT TIPWG Chemical Companies | Problem: Wild ginger, a perennial herbaceous plant, is becoming an increasing problem within plantations, with no known herbicides registered for control Objective/Need: To test various herbicides + adjuvant combinations together with various methods of application for the control of wild ginger | One trial implemented in the KwaZulu-Natal Midlands on wild ginger in a pine stand where metsulfuron-methyl and glyphosate was tested in combination with five natural/synthetic adjuvants, either as foliar or cut-surface application. | Completed |
Wattle rust research
Person/s responsible | Funding/Supporting bodies | Problem | Action/s | Outcomes (progress) | Written outputs |
Keith Little Richard Payn (MSc Forestry) | Nelson Mandela University SAWGU NCT Chemical Companies | Problem: No fungicides registered for control of wattle rust Objective/Need: Registration of FSC-compliant fungicides | Three trials implemented in 2014 for the Initial screening of FSC-compliant fungicides for the management of wattle rust | Based on results of trials, 3 x FSC-compliant fungicides registered for the control of Wattle Rust | Little KM, Payn RG. 2016. Screening of fungicides for the management of wattle rust (Uromycladium acaciae) in Acacia mearnsii plantations, South Africa Southern Forests 78(2): 151-158 |
Richard Payn (MSc Forestry) Keith Little | Nelson Mandela University SAWGU NCT SETA Chemical Companies | Problem: Repeated spraying of fungicides at 28 day intervals impractical and costly Objective/Need: i. Will adjuvants prolong fungicide efficacy ii. Can once reduce the number of application required for wattle rust control | Two trials implemented using various adjuvants and/or altering the timing of fungicide application so as to reduce the number of applications (and costs) over a season | The outcomes confirmed previous results in that the application of fungicides do reduce the incidence of wattle rust. i. The use of adjuvants were equally effective as applying fungicides alone, and as such provide no additional benefits in terms of wattle growth ii. Drought over the trial period meant that the development of wattle rust was not severe and/or variable over the season. This meant that the optimization of the timing of fungicide application could not be determined. | Payn RG, Little KM. 2017. Use of adjuvants for the control of in Uromycladium acaciae in Acacia mearnsii plantations, South Africa. South African Journal of Plant and Soil 34(5): 333-338 |
Richard Payn (MSc Forestry) Keith Little | Nelson Mandela University SAWGU NCT SETA Chemical Companies | Problem: Wattle rust symptoms are expressed in many forms, not all of which occur simultaneously. Objective/Need: Linking the expression of symptom to tree performance would assist with the timing of fungicide application | Various disease symptoms (individually and in combination) from 3 trials were linked to that of tree performance using linear and multiple regression | No individual symptom emerged as a significant predictor of tree growth, indicating that fungicide application should take place with the onset of any of the wattle rust symptoms tested | To access the thesis in full, click here |
Richard Payn (MSc Forestry) Keith Little | Nelson Mandela University SAWGU NCT SETA ICFR Chemical Companies | Problem: Due to the recent expression of wattle rust, little data existed as to the cost:benefits for using fungicides for control Objective/Need: Link fungicide application costs to tree performance | Costs associated with fungicide application (rates and timing) from 6 trials were linked to that of tree performance | The largest portion of treatment costs was attributed to the cost of fungicide. No single treatment was found to be optimal for the recommended rate of application. The use of adjuvants increased the cost of treatment, without additional benefit in growth. Control of wattle rust is beneficial, although costly if over-applied. Rotation-end data is required to determine whether fungicide use is economical for managing wattle rust over an extended period of time | |
Keith Little | Nelson Mandela University NCT Chemical Companies | Problem: Fungicides with limited modes of action currently registered for the control of wattle rust, which may result in the development of resistance Objective/Need: Source systemic/contact fungicides with different modes of action (curative and preventative) to prevent the development of resistance | One trial implemented to screen 6 synthetic and/or natural fungicides from different chemical groups and/or modes of action | Completed - Testing natural/biologically derived products (NCT report) | |
Keith Little | Nelson Mandela University NCT Chemical Companies | Problem: Limited range of fungicides registered, together with need to test combined application with a registered insecticide so as to reduce need for repeat applications Objective/Need: i. Screen additional synthetic formulation to complement existing fungicides ii. Determine if the delayed application of a fungicide may assist in reduced use and associated costs iii. Combine an insecticide and fungicide for control wattle myrid and wattle rust | Four trials implemented on contrasting sites to test efficacy of new fungicides for control of wattle rust, if a fungicide x insecticide tank mix would be feasible for the control of wattle myrid, and if fungicide costs could be reduced through delayed application | Completed - Fungicides and an Insecticide tested in combination for control of rust and mirid (ADAMA report) |
For more narrow sense pesticide research projects being conducted in South Africa visit www.icfr.ukzn.ac.za