• Journal of Korean Society of Forest Science
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• v.81 no.2
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• pp.191-199
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• 1992

This study was conducted to identify fungi causing canker dieback and melanconis disease of walnut trees (Juglans sinensis Dode) in Korea and clarify the pathogenicity and factors affecting the growth of these fungi. The causal fungi isolated from infected walnut stems and branches obtained from the commercial walnut orchards in Cheonwon, Goesan, Youngdong were identified as Botryosphaeria dothidea (Moug, ex Fries) Casati et de Notaris, Phoniopsis albobestita Fairman, Melanconis juglandis (Ellis et Everhart) Graves and their pathogenicity was confirmed by inoculation test. Temperature range for minimum growth of three fungi was 8 to $35^{\circ}C$ and the optimum temperature for mycelial growth of B. dothidea and P. albobestita ranged from 25 to $30^{\circ}C$, while the optimum temperature for M. juglandis ranged from 20 to $25^{\circ}C$. The optimum pH range for mycelial growth of P. albobestita was 4.0~5.0 and that for B. dothidea and P. juglandis 4.0~8.0. Glucose, sucrose, starch or maltose, as a carbon source, and histidine or potassium nitrate as a nitrogen source were more suitable compounds for growth. of B, dothidea, P. albobestita grew very well on the medium containing alanine and potassium nitrate as a nitrogen source, and utilized well glucose and sucrose as a carbon source. M. juglandis grew well on the medium containing glucose, and sucrose as a carbon source and utilized well potassium nitrate as a nitrogen source. The dieback and twig blight caused by P. albobestita were more severe than those by B. dothidea and M. juglandis at three locations investigated. Incidences of canker and dieback were more frequently observed in aged walnut trees than in young ones.

• Research in Plant Disease
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• v.19 no.1
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• pp.55-59
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• 2013

The purpose of this experiment was to investigate the development of new spot disease on the leaf and stem of rosemary (Rosmarinus officinalis) in commercial greenhouses at Jeonju and Namwon in Korea. Incidence of target spot on rosemary was higher at the end of the rainy season with high humidity. Those symptoms were black ring spots (3-5 mm in diameter) and withering on green leaves and stems. Conidiophores and conidia were formed on the infected tissue in moist chamber and conidia were shown as the cylindrical and oval types in chain, ranged from 55 to $275{\mu}m$ in length, and 7 to $14{\mu}m$ in width. Conidia with eight to ten pseudosepta were formed on the conidiapore. The optimum growth temperature of isolates was $30^{\circ}C$ on the PDA medium under the dark condition. In the pathogenesis test, the target spot and withering symptoms were appeared on the leaves and stems 3 days after inoculation showing similar symptoms compared to those of in nature. The same fungus was re-isolated from infected lesion, indicating that Corynespora cassiicola caused leaf target spot and twig blight on rosemary. The rDNA ITS nucleotide sequences of the pure cultured isolate from the diseased area on rosemary showed 100% similarity to the sequences of C. cassiicola available in the GenBank database (JQ595296, JQ595297, FJ852715 and AY238606). Therefore, we report that the target spot of leaves and stems in rosemary was caused by C. cassiicola.