<i>Fusarium solani</i> and <i>Lasiodiplodia pseudotheobromae</i> , fungal pathogens causing stem rot disease on durian trees ( <i>Durio zibethinus</i> ) in Eastern Thailand

Durian (Durio zibethinus) is known as the king of fruit in Southeast Asia (Bampenrat et al., 2020), and one most economically important export fruits Thailand (Charoensumran 2021). However, a major problem affecting durian plantations stem rot disease. Symptoms infected trees are bark trunk canker, twig blight, yellow leaves, wilting. Thirty symptomatic wood samples were collected November 2020 from different orchards Rayong Chanthaburi Provinces Eastern (Fig. 1). The cut into 1×1 cm fragments, surface sterilised with 0.5% sodium hypochlorite solution, washed three times water similar to method used by Chantarasiri al. (2021). plated on dichloran Rose Bengal chloramphenicol (DRBC) agar selective medium potato dextrose (PDA) relatively rich medium. plates incubated at 30°C for seven days under 12-hour light/dark photoperiod. isolated fungal colonies hyphal tips placed PDA culture purification. All isolates primarily categorised according their colony conidial morphology. first group had white cottony colony, producing slightly curved macroconidia two-four septa 2). second also woolly but these grew rapidly, turned dark grey after days, did not produce conidia 3). DNA representative was extracted using GF Fungus Extraction Kit (Vivantis, Malaysia) PCR amplified ITS1/ITS4 primers (White 1990). resulting products sequenced Macrogen Inc. (South Korea) deposited GenBank Accession Nos. MZ461923, MZ461933, MZ493230, MZ493231, respectively. Sequence alignment BLASTn showed that related Fusarium solani strain GP (MN658459.1) 100% coverage 95.81-98.99% identity. Lasiodiplodia pseudotheobromae isolate KEGA_11 (MK922068.1) 99–100% 96.64-98.94% Phylogenetic analysis SeaView version 5.0.2 software confirmed sequence results (Figure 4). One hundred milliliters each fungus cultured broth inoculated seedlings glasshouse ambient temperature days. same volume controls. experiment performed triplicate. White mycelia brown lesions visually observed seedlings, whereas controls remained healthy. fungi re-isolated identified F. L. pseudotheobromae, thus fulfilling Koch's postulates. This report provides evidenced pathogens causing disease trees. Previous reports described hackberry mango (Khanzada 2004; Liang 2020). To date, Phytophthora sp. has been attributed cause Thailand. Misidentification could result use inappropriate methods control authors would like thank orchardists kindly providing this study.