# Natural Salicylaldehyde for Fungal and Pre- and Post-Emergent Weed Control
## 3 Results and Discussion
### SA Herbicidal Efficacy during Soil Pasteurization
Nonetheless, compared to prior research, the SA fumigation developed in our investigation provides several advantages over the state-of-the-art, which include: (i) SA is a safe, natural constituent identified in many plant species, thus maintaining an intact structure (non-synthetic); (ii) compared to the derivatives of SA developed in prior research, SA lacks functional groups that hydrolyze under environmental conditions; hence, SA hydrolysis is not supposed to occur in the environment, warranting environmental safety (FDA-proven safety); (iii) binary functions (herbicidal and antifungal activity) of SA as a fumigant, the unique characteristics of SA, greatly lowers the pesticide burden in orchards, which also enables the sanitation of crop byproducts (SA delivery vehicles); and (iv) the adjuvant capacity of SA towards commercial fungicide fluidoxonil overcomes the fluidoxonil tolerance of fungi. Notably, in a preliminary bioassay, the fungicidal activity of SA was also greatly enhanced at an elevated temperature (42 \({}^{\circ}\)C) (Figure S3), indicating that the antifungal efficacy of SA would be heightened in the solarized soil surface, which can reach to 60 \({}^{\circ}\)C or higher with sunlight. Overall, once adopted, the SA fumigant system as a natural herbicide/fungicide will promote the stakeholders' sustainable agriculture. In the United States, California leads the nation in the production of agricultural commodities. Tree nuts (almonds, walnuts, and pistachios) are the largest commodity produced in California, representing over USD 9 billion in sales in 2018 [16]. However, there are serious food safety challenges that must be addressed; the tree nuts are commonly contaminated by aflatoxin-producing fungi (_A. flavus, A. parasiticus_) and are subsequently susceptible to aflatoxin contamination. Aflatoxins are hepato-/nephrotoxic carcinogens/mutagens deleterious to human and poultry health. Since aflatoxin is a serious threat to food safety and food/crop marketability, with many importing countries, including the EU, imposing limits as low as 4 ppb [49], new intervention strategies to reduce the incidence of this food safety challenge should be developed. As mentioned above, weeds are the field reservoir of important pests, including mycotoxic fungi [1]. In California, the eradication of weeds, such as the widespread alkaliieved (_Cressa truxiliensis_), along with other invasive weeds, is one of the prominent tasks for the tree nut industry [50]; around 9% of tree nut culture costs are currently spent on weed control. Hence, the SA herbicidal system can contribute to the cost-effective weed management endeavor in the orchards. In conclusion, the SA anti-pest system developed in this study could serve as a sustainable, complementary/alternative way to conventional weed and fungal control measures that is applicable to the agricultural industry, including the tree nut industry. The developed method will reduce costs, abate resistance, and alleviate the negative side effects associated with current anti-pest practices. The identification of more practical or improved usage of SA, such as the controlled release of SA to the target sites, as well as translation of the information presented in this study into agricultural practices, warrants future in-depth investigation. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app12083749/s1](https://www.mdpi.com/article/10.3390/app12083749/s1)]([https://www.mdpi.com/article/10.3390/app12083749/s1](https://www.mdpi.com/article/10.3390/app12083749/s1)), Figure S1: (a) Weed seed contamination with environmental fungi tested on potato dextrose agar (PDA) plates (28 \({}^{\circ}\)C). Fungal growth was observed during germination of tested seeds (_Lagurus owatus_ (Bunny tail grass), _Schizachrium scoparium_ (Little Bluesetem)) (10 seeds/plate).