2017 年7 月中旬於南投縣埔里鎮大坪頂地區之百香果果園中發現一種新病害，受害果實出現墨綠色至黑色塊斑而外圍有黃暈，病斑易擴大聯結成大範圍灰黑色並呈現凹陷的塊斑，又於塊斑上出現黑色小點 (為病原菌之柄子器)。剖開果實可見果皮內側黑化且易產生黑灰色菌絲，果肉失去原有的風味。本研究自罹病果實穩定分離得到一種真菌，培養於馬鈴薯葡萄糖培養基 (potato dextrose agar; PDA) 培養基上，該菌絲生長快速，於24℃下培養4 d 後，其菌落呈現灰黑色毛絨狀，具有濃密之氣生菌絲。本菌之分生孢子初期呈卵圓形、透明、單室且細胞壁厚，逐漸轉變成褐色，中間有一隔膜且具有明顯縱紋。依據本病害之病徵表現、病原菌形態特徵及分子序列鑑定結果，將此菌鑑定為Lasiodiplodia theobromae。經人工接種孢子懸浮液於「台農1 號」百香果果實後，發現L. theobromae 對百香果具有病原性，並能再分離得原接種的真菌，完成柯霍氏法測，證明此菌為引起百香果果腐病之病原菌。另外，無傷口者，則不易造成果實發生果腐病。本文由L. theobromae 引起百香果果腐病，為台灣百香果病害新紀錄。
A new disease caused by fruit rot of passion fruit (Passiflora edulis) was found in major passion fruit production areas at Puli Township, Nantou County of Taiwan in 2017. The infected fruits showed dark green to black patches with yellow halo. The lesions usually enlarged and joined into a large black and sunken patch with the appearance of black dots (the pycnidia of the pathogen). The flesh inside was blackened with soar flavor and easy to produce black gray hyphae. A kind of fungus was consistently isolated from the diseased tissue. The mycelium of the fungus grew rapidly on potato dextrose agar and formed a grayish-black fluffy colony with dense aerial hyphae at 24℃ after being cultured for 4 d. The conidia of the fungus were initially oval, hyaline, unicellular and had thick cell wall, but days later showed dark-brown color and developed one septum with longitudinal lines. The causative fungus was identified as Lasiodiplodia theobromae based on morphological characteristics and internal transcribed spacer (ITS) rDNA sequence blasting on National Center for Biotechnology Information (NCBI) GenBank database. The identified L. theobromae could cause similar symptoms on the fruits on trees and the detached fruits by inoculating the tested fruits with conidia suspension through wound treatment, and the same pathogen could be re-isolated from the diseased fruit tissue to fulfill the Koch’s rules. Immature and mature passion fruit could show disease symptoms when inoculated with L. theobromae through wound treatment but no symptom was found to those without wound treatment. This study is the first report about fruit rot of passion fruit caused by L. theobromae in Taiwan
