Evaluating Two Fungicides, Prochloraz–Manganese Chloride Complex and Seboctylamine Acetate, to Control Cobweb Disease in White Button Mushroom Caused by Cladobotryum mycophilum

Cobweb disease in white button mushroom (<i>Agaricus bisporus</i>) is a newly identified disease caused by <i>Cladobotryum mycophilum</i> in China. Currently, there are few highly effective and safe fungicides for controlling this disease in the field. This study assessed the fungicidal effect of prochloraz-manganese chloride complex and seboctylamine acetate against <i>C. mycophilum</i>, as well as their ability to control cobweb disease. Additionally, the residues of these fungicides in the mycelium and the mushroom were evaluated. The extent of the fungicidal effect against the pathogen was determined based on the efficiency of crop production. The results revealed that, in addition to the potent inhibitory effect of prochloraz-manganese chloride complex on the hyphae of <i>C. mycophilum</i>, the domestically developed seboctylamine acetate exhibited high toxicity, inhibiting both mycelial growth and spore germination of <i>C. mycophilum</i>, with EC₅₀ values of 0.990 mg/L and 0.652 mg/L, respectively. Furthermore, the application of the two chemical agents had no adverse effects on the mycelial growth and fruiting body growth of <i>A. bisporus</i>, and the residual amount of chemical agent was lower than the maximum residue limit standard. The field application results showed that 400 mg/L of prochloraz-manganese chloride complex and 6 mg/L of seboctylamine acetate resulted in 61.38% and 81.17% disease control respectively. This study presents efficient and safe fungicides for controlling cobweb disease in white button mushroom. Additionally, a residue determination analysis of the fungicide seboctylamine acetate in mushroom crops is described.