Nicotianae Var Research Articles

Assessing the Susceptibility of Local Citrus Species to Phytophthora Root Rot in Malaya

SummaryLarge scale destruction of mature mandarin orange groves due to root rot has occurred in Central Malaya. During the course of an investigation on the aetiology of this malady, Phytophthora nicotianae var. parasitica (Dast.) Waterhouse was isolated, and a test on the susceptibility of nine common citrus species to Phytophthora root rot was carried out by a modified water-culture inoculation technique. This appears to be an efficient and rapid screening method suitable for tropical conditions. The results showed that none of the species tested was resistant, although the degree of susceptibility varied significantly among species and between groups of species.

Phytophthora nicotianae var. parasitica . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Phytophthora nicotianae var. parasitica . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On a very wide range of host plants comprising 58 families including: avocado, castor, Cinchona spp., citrus, cotton, eggplant, guava, lucerne, papaw, parsley, pineapple, Piper betle , rhubarb, sesame, strawberry, tomato. DISEASES: Damping-off of seedlings (tomato, castor, citrus, cotton); root rot (citrus, avocado, strawberry, lucerne); crown rot (parsley, rhubarb, strawberry, lucerne); brown stem rot of tobacco; stem canker and tip blight of Cinchona spp. ; leaf blight (castor, sesame, pineapple, Piper betle ) and fruit rot (citrus, tomato, guava, papaw, eggplant). GEOGRAPHICAL DISTRIBUTION: Africa (Ethiopia, Mali, Madagascar, Mauritius, Morocco, Nigeria, Sierra Leone, Southern Rhodesia, Tanganyika); Asia (Burma, Ceylon, China, Formosa, India, Israel, Japan, Java, Malaya, Philippines); Australia & Oceania (Australia, Hawaii, Tasmania); Europe (Cyprus, France, Germany, Great Britain, Holland, Ireland, Italy, Poland, Portugal, U.S.S.R.); North America (Bermuda, Canada, Mexico, U.S.A.); Central America & West Indies (Costa Rica, Cuba, El Salvador, Guatemala, Jamaica, Montserrat, Puerto Rico, Trinidad);. South America (Argentina, Brazil, British Guiana, Colombia, Paraguay, Peru, Venezuela). TRANSMISSION: Soil-borne, spreading rapidly after heavy rain or where soil remains moist or water-logged (40: 470). Also recorded in drainage water in India and in reservoirs and canals supplying citrus groves in U.S.A. (23: 45; 39: 24). A method for determining a disease potential index in soil using lemon fruit has been described (38: 4). Also present in testas of seeds from diseased citrus fruit which may infect nursery seedbeds (37: 165).

Phytophthora nicotianae var. nicotianae . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Phytophthora nicotianae var. nicotianae . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Nicotiana plumbaginifolia, N. tabaci, N . spp., and on Amaranthus sp., Commelina benghalensis, C. nudiflora, Lycopersicon esculentum, Ricinus communis, Solanum melongena ; also on wound inoculated Buxus sp., Daucus carota, Hedera helix, Ipomoea batatas and Trema amboensis . DISEASE: Black shank of tobacco. GEOGRAPHICAL DISTRIBUTION: Africa (Malawi, Mauritius, Uganda); Asia (Ceylon, China, Formosa, India, Indonesia, Japan, Java, Malaya, Philippines, Sumatra); Central America & West Indies (Cuba, Jamaica, Puerto Rico, Santo Domingo, Trinidad); Europe (Bulgaria, Germany, Greece, Italy, Poland, Romania, U.S.S.R.); North America (U.S.A.); South America (Brazil, Colombia, Venezuela). TRANSMISSION: Soil-borne, persisting in soil for at least 4 years between tobacco crops, and not eliminated by a 3 year rotation or a 4 year fallow (41: 409; 39: 126). Tobacco leaves have been used to indicate disease potential in infested soil after serial dilution with sterile soil (42: 408). Spread in contaminated pond water used in overhead irrigation also suspected (43, 1413). Wind-borne spread up to 800 ft. has been recorded (39: 500).