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Virulence of Colletotrichum spp. from Different Isolating Source in Grape Orchards was Compared on Grape
Symptoms of grape fruits (cultivar: ‘Kyoho’) inoculated by <i>Colletotrichum</i> fructicola</i> isolate (A) F215147,(B) F215089 and (C–E) F216037 and (F) water <i>in</i> <i>planta</i>. The 1-month-old grape berries in the orchard were inoculated <i>in</i> <i>planta</i> with the conidia spore suspension (1 × 10 <sub>6</sub> conidia mL<sub>-1</sub>) of the isolates. After veraison, typical symptoms of grape ripe rot appeared on the berries inoculated with these <i>C</i>. <i>fructicola</i> isolates but not with <i>Colletotrichum</i> <i>tropicale</i> isolates F216025 and F212018.
Symptoms of grape fruits (cultivar: ‘Kyoho’) inoculated by Colletotrichum fructicola isolate (A) F215147,(B) F215089 and (C–E) F216037 and (F) water in planta. The 1-month-old grape berries in the orchard were inoculated in planta with the conidia spore suspension (1 × 10 6 conidia mL-1) of the isolates. After veraison, typical symptoms of grape ripe rot appeared on the berries inoculated with these C. fructicola isolates but not with Colletotrichum tropicale isolates F216025 and F212018.

Author:Chu-Ping Lin*, Jyh-Nong Tsai , Pao-Jan Ann , and Ming-Te Lu

Abstract:

Virulence of Colletotrichum viniferum, Colletotrichum fructicola, and Colletotrichum tropicale from different isolation sources were compared on grapes (Vitis vinifera). In vivo pathogenicity test on the detached grape berries showed that C. viniferum was the strongest virulent species, which could cause significant and larger spots of ripe rot on grape berries with or without wounds. Moreover, the virulence of fruit isolates seems to be stronger than that of the leaf isolates; C. fructicola was ranked second in virulence. Interestingly, the virulence of the C. fructicola isolate from goose weed (Eleusine indica) was stronger than other isolates from grape fruits and leaves; C. tropicale was the lowest virulent species, and all the isolates in this study required wounds to infect berries. In addition, in planta pathogenicity tests of C. fructicola and C. tropicale were performed. In young grapes inoculation test, only berries inoculated with isolates of C. fructicola could develop the typical ripe rot disease symptoms after veraison. The disease rate and symptoms were higher and severer with C. fructicola isolated from goose weed than those from grape isolates, while no obvious symptoms with C. tropicale isolates. As for whole potted plants inoculation test, no obvious disease symptoms appeared on leaves or other parts of plants inoculated with any of the selected isolates of C. fructicola and C. tropicale. To our knowledge, this study is also the first report of goose weed leaf anthracnose caused by C. fructicola, which showed water-soaked and browning symptoms on leaf. These data suggest that, in the field, goose weeds could be an alternative host of C. fructicola. C. fructicola might live in a saprophytic life on grape leaves, waiting for chances to infect grape berries.

Key words:Grape ripe rot, Colletotrichum viniferum, Colletotrichum fructicola, Colletotrichum tropicale, Virulence test.

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Journal of
Taiwan Agricultural Research
Vol. 72, No.3 (2023) ISSN: 2790-086X Vol. 72, No.3 (2023)
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