Valsa eugeniae . [Descriptions of Fungi and Bacteria

Abstract

Abstract A description is provided for Valsa eugeniae . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On clove ( Eugenia aromaticd ), rose apple ( E. jambos ), cashew ( Anacardium occidentale ) and pimento ( Pimenta dioica ). DISEASE: Sudden death of cloves in Zanzibar and Pemba (32: 278). Also reported causing the death of cashew (35: 496) but is not pathogenic to pimento in Jamaica, where dieback is attributed to Ceratocystis fimbriata (45, 2918, CMI Descript. 141). On clove the classical symptoms occur only in mature trees. A barely discernible yellowing of the foliage is followed by a heavy green-leaf fall and wilt of the remaining leaves which wither to a russet colour. A few days after death, a yellow stain in the wood is seen at the collar. This spreads up the trunk and is generally distributed 9 months later but occurs much earlier in the roots. The stain is often separated from healthy wood by a sharp black zone line and a narrow bluish-grey zone. Tyloses and gum occur in the vessels. Some 3-4 months after death of the tree the perithecia appear, through cracks in the bark, at ground level, and fructification moves upwards. Fruiting can continue for several years on trunk and branches. The pycnidia, which appear before the perithecia, are abundant on cut, split or broken woody surfaces in moist conditions. Where new plantings of clove are made in areas killed off by sudden death, young trees up to nearly 20 years old exhibit a slow decline and unthrifty appearance with yellowish and sparse foliage accompanied by a slow but progressive root rot. Seedlings are immune from infection by V. eugeniae and plants up to 4 years old are very resistant. GEOGRAPHICAL DISTRIBUTION: Jamaica, Malaysia (W.), Tanzania and Thailand. Its presence in the Malagasy Republic seems doubtful. TRANSMISSION: Not known. In mature trees natural infection probably begins in the absorbing roots spreading into larger roots and thence to the collar. Valsa eugeniae can also cause a stem dieback functioning as a wound parasite. Yellow stain is formed as in the root disease.