# Natural Salicylaldehyde for Fungal and Pre- and Post-Emergent Weed Control
## 2 Materials and Methods  
### Testing the Level of Fungal Contamination on the Surfaces of Weed Seeds or Nutshell Particles  
A representative bioassay to determine the level of fungal contamination on the surfaces of weed seeds was performed by placing _Schrizachrytium scoparium_ (Little Bluestem) or _Lagurus ovatus_ (Bunny Tails Grass) seeds (Table 1) on potato dextrose agar plate (PDA; 100 mm \(\times\) 15 mm) (Corning Inc.-Life Sciences, Tewksbury, MA, USA). A total of 10 seeds per species were placed on each PDA (in duplicate). Petri plates were sealed with Parafilm (Bemis Associates Inc., Shirley, MA, USA), covered with aluminum foil to maintain a dark condition, and kept at room temperature (22 \({}^{\circ}\)C) for 3 to 5 days. The level of fungal contamination was monitored during seed germination.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Fungi** & **Characteristics** & **References/Source** \\ \hline _Aspergillus fumigatus_ & Human pathogen (aspergillus), & The University of Texas, MD Andersen Cancer Center, \\  & Reference clinical strain & Houston, TX, USA [19] \\ \hline _A. fumigatus_ & Human pathogen (aspergillus), MAPK mutant & The University of Texas, MD Andersen Cancer Center, \\  & derived from AF293 & Houston, TX, USA [19] \\ \hline _A. fumigatus_ & Human pathogen (aspergillus), MAPK mutant & The University of Texas, MD Andersen Cancer Center, \\  & derived from AF293 & Houston, TX, USA [20] \\ \hline \multirow{4}{*}{_Aspergillus flavus_ 3357} & Plant pathogen (aflatoxigenic), & \\  & Human pathogen (aspergillus), & National Center for Agricultural Utilization and \\  & Reference aflatoxin used for & Research, USDA-ARS, Peoria, IL, USA \\  & genome sequencing & \\ \hline _Penicillium expansum_ W1 & Plant pathogen & Washington State University, Wenatchee, WA, USA [21] \\  & (Patulin-producing, Parental strain) & Washington State University, Wenatchee, WA, USA [21] \\ \hline _P. expansum_ FR2 & Plant pathogen & Washington State University, Wenatchee, WA, USA [21] \\  & derived from _P. expansum_ W1 & \\ \hline _Penicillium expansum_ W2 & Plant pathogen & Washington State University, Wenatchee, WA, USA [21] \\  & (Patulin-producing, Parental strain) & Washington State University, Wenatchee, WA, USA [21] \\ \hline \multirow{2}{*}{_P. expansum_ FR3} & Plant pathogen, Fludioxosil resistant mutant & \\  & derived from _P. expansum_ W2 & Washington State University, Wenatchee, WA, USA [21] \\ \hline \multicolumn{2}{c}{**Plant Seeds**} & **Characteristics** & **References/Source** \\ \hline _Brassica napus_ var. _pcknensis_ (dicot) & Chinese cabbage; field weed & Plant nursery, Oakland, CA, USA \\ \hline _Centaureux solisttilis_ (dicot) & California invasive weed & USDA-ARS, Albany, CA, USA \\ (Yellow starthistle) & & USDA-ARS, Albany, CA, USA \\ \hline _Salsolai traps_ (dicot) & California invasive weed & USDA-ARS, Albany, CA, USA \\ (Russian thistle) & & USDA-ARS, Albany, CA, USA \\ \hline _Genista mongsellanna_ (dicot) & California invasive weed & USDA-ARS, Albany, CA, USA \\  & (French broom) & \\ \hline _Lagurus oatus_ (monocot) & & \\ (Bunny Tails Grass) & & Plant nursery, Berkeley, CA, USA \\ \hline _Schizachryium scoparium_ (monocot) & USA native grass & Plant nursery, Berkeley, CA, USA \\ (Little Bluestem) & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: List of fungi and weed seeds used in this study.  
To test the level of fungal contamination on the surface of walnut shell particles (6/10 mesh) (Kramer Industries, Inc., Piscataway, NJ, USA), a total of 0.3 g of walnut shell particles were placed at the center of the PDA plate (100 mm \(\times\) 15 mm), sealed with Parafilm, and the level of fungal contamination in duplicate plates was monitored at 22, 28, and 35 \({}^{\circ}\)C, respectively, for 3 to 5 days.