Aim
Powdery scab of potatoes is considered a major problem in the potato-growing industry in Australia. This disease is caused by a protozoan pathogen and results in lesions full of brown powder that cover the potato tuber (Lin et al. 2018). Not only does this powdery scab blemish the potato tuber, but it also negatively impacts the root system of the plant (O’Brien & Milroy 2017). That is because powdery scab is a root infection that disrupts root function, leading to reduced uptake of water and nutrients.
The causal agent of powdery scab can survive a range of environmental conditions. Once the pathogen has become established in the soil, it can remain a source of infection even for years following the absence of potatoes (Lin et al. 2018). Many sites of spore balls are generated inside the diseased roots and tubers and dispersed into the soil during the harvesting process. For the next season, these spore balls will act as the primary inoculum. Thus, the problem of powdery scabs is ongoing; it is also serious as it causes significant economic loss since infected potatoes suffer low acceptance at the market. In that light, the disease has always been of great concern among potato growers.
Control measures for the biotrophic protozoan pathogen that causes powdery scab are critical to preventing economic losses. Strategies that are currently being used include planting only healthy potato tubers, rotating crops, and chemical control (O’Brien & Milroy 2017). A vast number of fungicides are presently available for application to seed tubers to prevent powdery scabs. However, fungicide resistance in the pathogen population is growing stronger in response to fungicide application. This problem is compounded by the lack of efficacious agrochemicals and resistant potato cultivars against powdery scabs. In addition, the wide genetic diversity of the pathogen makes the development of management practices based solely on the use of chemicals a challenging task (Lin et al. 2018). Other problems that can arise due to the use of chemicals include the deregistration of fungicides and concerns associated with the use of chemical substances in potato growing and production (O’Brien & Milroy 2017). Apart from these problems, common strategies used for the prevention of the disease have the potential to cause harm to the environment.
Biological control is considered a promising and environmentally friendly measure for the prevention of powdery scabs of potatoes. The use of biological control agents in combination with fungicides can be equally effective as the use of synthetic fungicides (O’Brien & Milroy 2017). This study will examine the effect of a mixture of biocontrol agents and chemicals on the suppression of powdery scabs based on screening of endophytic or rhizosphere bacteria and fungi for the prevention of pathogen growth. The control of disease by biological control agents will be investigated to determine which agents yield the most consistent and controllable results. Different methods of application of biological control agents (tuber dressings, foliar spray, or soil drenches) will be compared, and the right time of application will be determined. In short, the project aims to create a management practice that makes use of biological control agents to provide reliable and full control of powdery scabs of potatoes. The results will be further evaluated and compared with those achieved from the use of fungicides. Finally, the right combination of biological control agents and fungicides will be determined.
Output
The output will be the determination of a mixture of biological control agents and chemicals that shows stable and controllable suppression against root and tuber infection. It is expected that a significant reduction in powdery scab levels after treatment of seed tubers with biocontrol agents will be observed. In combination with chemical control, this management practice will provide reliable protection throughout the growing season. In addition to discovering the best management practice, mechanisms for disease suppression by biological control agents alone and in combination with fungicides will be studied. Along with the determination of the most effective biological control agents, their suitability across production environments and effective methods of application will be investigated. Integration of the mode of use of biocontrol agents with other chemicals will enable obtaining a single management practice that works for diverse environments and climatic conditions. Data collected during the research will be further used in the elaboration of new approaches for the prevention of powdery scab as well as mechanisms through which biocontrol agents may control the disease.
Adoption
Although the given project is aimed at the expansion of effective and ecological techniques to control powdery scabs of potatoes, the results obtained may be important for many stakeholders. In particular, potato growers, researchers, producers of potato products, and consumers may benefit from this project. The investigation of biocontrol agents, their combinations, and the additive effect of fungicides are relevant for potato growers who experience powdery scabs as a serious challenge that diminishes the market value of their crop. The given project is aimed at a thorough investigation of biological agents and their further utilization to suppress the disease in a more ecologically friendly manner compared to the application of fungicides. The anticipated results will allow potato growers to suppress disease development, saving the market value of the harvest and avoiding economic losses. Also, potato growers will be able to prevent the deterioration of the quality of seed potatoes and increase crop productivity by reducing powdery scab incidence and the powdery scan index.
Moreover, using ecological components in combination with chemicals may contribute to an increase in the market value of the crop. Considering that the pathogen’s resistance to fungicides is developing dramatically, the combination of biological control agents and fungicides promises to be a more effective tool against powdery scabs of potatoes than that offered by fungicides alone. For example, potato growers will be enabled to abandon strategies that harm the soil (in particular, soil amendment by changing its pH using chemicals and soil treatment with chloropicrin).
Producers of potato products can also benefit from the results of the given project. Using a more ecological approach to growing potatoes for the further processing and production of potato products will not only increase their quality but also attract more consumers. In terms of economics, this will mean that customer benefit from purchasing such products will increase. As a result, it may be anticipated that the competitiveness of such potato producers will considerably increase. Consumers will also benefit from the proposed project since they will be allowed to choose potato products of higher quality made from potatoes subjected to lower concentrations of chemicals. It may be expected that the nutritional value of potatoes grown with a limited amount of applied fungicides will be higher than that of potatoes treated only with fungicides.
Findings obtained from this project will be of professional interest to researchers in the field of agriculture and biology. Currently, little research has been done regarding the use of biocontrol agents in agriculture. This project will thus contribute to the scientific field by discovering mechanisms of biological control, identifying biological antagonists, and evaluating the additive action of fungicides. Implementation of the suggested project will also promote a better understanding of the pathogen’s diversity as well as the genetic differences in potato cultivars.
Outcome
The ability to control the pathogen more effectively and in a more eco-friendly manner will lead to the prevention of poor potato yield and low market value linked to poor product quality. In practical terms, Australian horticulture will benefit from a reduction in potato yield losses associated with powdery scabs. Ecological disturbances due to the use of chemicals will also diminish along with the pollution of the land. All the benefits of the project will be delivered to the horticulture industries after one season of using the suggested management practice. Furthermore, providing consumers with food containing lower levels of synthetic chemical residues will lead to higher customer satisfaction. Since biological control agents can be applied before planting, farmers will find such an approach advantageous in light of the lower investment of time involved. Potato producers will be able to use a proven management practice that provides an effective and environmentally friendly alternative instead of reliance on chemical insecticides. Such enhancement of commercial aspects of potato production will create better economic opportunities for other sectors in the value chain.
References
Lin, C, Tsai, C, Chen, P, Wu, C, Chang, Y, Yang, Y & Chen, Y 2018, ‘Biological control of potato common scab by Bacillus amyloliquefaciens Ba01’, PLOS One, vol. 13, no. 4, p. e0196520.
O’Brien, P & Milroy, S 2017, ‘Towards biological control of Spongospora subterranea f. sp. subterranea, the causal agent of powdery scab in potato’, Australasian Plant Pathology, vol. 46, no. 1, pp. 1-10.