Bacterial wilt disease caused by Trinickia (Burkholderia) caryophylli poses a significant threat to carnation cultivation in many regions around the world, often leading to severe damage once established. In this study, we developed a BIO-PCR method with high sensitivity and accuracy to detect and quantify T. caryophylli in soil, enabling precise evaluation of pathogen contamination levels. Single PCR (using a touchdown PCR program) was performed using the bacterial cells pre-incubated in a selective liquid medium as a template. The detection limit for this assay was 3 colony-forming-units (cfu) per g dry mass soil. By combining the most probable number (MPN) method and touchdown BIO-PCR, T. caryophylli can be quantified simultaneously. We validated this method in carnation cultivation fields and found a correlation between the degree of disease in each field and the measured density of the bacteria. This method will help develop and establish effective pest control techniques because it targets only live T. caryophylli in soil and can measure the density with high sensitivity and accuracy.

Soil-borne pathogens have economic significance regarding the damage they cause to crop production worldwide. Arid lands are even more susceptible to soil-borne pathogens damage due to climate extremes such as high temperature and evapotranspiration to precipitation ratio that limits the diversity of crops. More so, some soil-borne pathogens are highly adapted to arid lands' high soil temperature and water limitations. Chemical controls like fungicides and bactericides are widely used in managing soil-borne diseases, but they come at a significant environmental, health, and agricultural cost. On the other hand, biological control of soil-borne pathogens is relatively environment-friendly, safe, has no reported effect on human and animal health, and can improve soil health for optimum ecosystem functioning. Thus, this review presents an overview of soil-borne pathogens infestation in arid lands and the potential of using biological control agents (BCAs) in managing plant disease outbreaks. Some common pathogens in arid lands include Fusarium spp. (pathogenic), Pythium spp., Rhizoctonia solani, and Meloidogyne incognita. Investigations have, however, revealed effective BCAs against soil-borne pathogens, and some examples include Bacillus cereus, Streptomyces atrovirens, Phlebiopsis gigantea, Pseudomonas putida, Trichoderma harzianum, Pythium oligandrum, and Enterobacter amnigenus. The most common mechanisms used by BCAs for controlling soil-borne pathogens include antibiosis, induced systemic resistance, parasitism (mycoparasitism), antagonism, competition for nutrients and space, and indirect plant growth promotion. Recent advances in molecular biology, such as metabarcoding and biomarker transformation, offer promising ways to increase the success rates with the use of BCAs under field conditions. This study suggests that the effectiveness of BCAs can be further enhanced with the addition of soil organic amendments coupled with the cultivation of arid lands adapted crops such as agave and Opuntia spp.

Film mulching is one of the most important methods to control soil-borne diseases. However, the traditional mulch may cause microplastic pollution and soil ecological damage. Herein, a biodegradable film was developed using oxidized starch and carboxymethyl chitosan and incorporated ZIF-8 carrying fludioxonil to sustainably control soil-borne disease. The microstructure, mechanical properties, optical properties, and water barrier properties of the composite films (Flu@ZIF-8-OS/CMCS) were investigated. The results show that Flu@ZIF-8-OS/ CMCS had a smooth and uniform surface and excellent light transmittance. The excellent mechanical properties of the films were verified by tensile strength, elongation at break and Young's modulus. Higher contact angle and lower water vapor permeability indicate water retention capacity of the soil was improved through using Flu@ZIF-8-OS/CMCS. Furthermore, the release properties, biological activity, degradability and safety to soil organisms of Flu@ZIF-8-OS/CMCS was determined. The addition of ZIF-8 significantly improved the film's ability to retard the release of Flu, while the Flu@ZIF-8-OS/CMCS has good soil degradability. In vitro antifungal assays and pot experiments demonstrated excellent inhibitory activity against Rusarium oxysporum f. sp. Lycopersici. Flu@ZIF-8-OS/CMCS caused only 13.33 % mortality of earthworms within 7 d. This research provides a new approach to reducing microplastic pollution and effectively managing soil-borne diseases.