Studies on the microbial diseases of dendrobium hybrid (orchids)

There is no baseline data available at present on the nature of various diseases that occur in a orchid population, under cultivation, in any commercial orchid farm maintained by small scale entrepreneurs who invest considerable amount of money, effort and time. The available data on type of disease symptoms, causative agent, , nature of pathogens, as to bacteria or ftmgi or any other biological agents, and their source, appropriate and effective control measures could not be devised, for large scale implementation and effective management, although arbitrary methods are being practiced by very few farms. Further influence of seasonal variations and environmental factors on disease outbreak is also not scientifically documented and statistically verified as to their authenticity. In this context, the primary objective of the present study was to create a data bank on the following aspects 1. Occurrence of different disease symptoms in Dendrobium hybrid over a period of one year covering all seasons 2. Variations in the environmental parameters at the orchid farms 3. Variations in the characteristics of water used for irrigation in the selected orchid farm 4. Microbial population associated with the various disease symptoms 5. Isolation and identification of bacteria isolated from diseased plants 6. Statistical treatment of the quantitative data and evolving statistical model

Studies on seed pathology and seedling diseases of some important indigenous tree species of kerala

In forestry, availability of healthy seeds is an important factor in raising planting stock. Initial seed health and storage conditions are the major factors governing the germinability of seeds. Like seeds of agricultural and horticultural crops, forest tree seeds are also liable to be affected by micro-organisms during storage, which affects the germination, and reduces the viability. Further introduction of seed-borne diseases into newly sown crops/areas on account of using unhealthy seeds is also not ruled out. Availability of healthy stock of seedlings is intrinsic for raising plantations and to meet this requirement elimination of nursery diseases by appropriate chemicals is of prime imortance. As exotic tree species may become susceptible to various native pathogens, it is generally considered better to select indigenous tree species for large scale plantations as they are well adapted to local environment. However, before taking up large scale afforestation progranme involving any indigenous tree species, it is essential to have knowledge about seed disorders and seedling diseases and their management. with a View to select appropriate tree species with fewer seed disorders and seedling disease problems for use in further plantation programme, four indigenous tree species such as Albizia odoratissima (L.f) Benth., Lagerstroemia microcazpa Wt., Pterocazpus marsupiwn Roxb. and Xylia xylocarpa (Roxb.) Taub. were evaluated to meet the above parameters

Studies on diseases of bamboos and nursery management of rhizoctonia web bligi-it in kerala

Bamboos are vulnerable to various diseases which affect them in nurseries, plantations as well as in natural stands. In India, rot and blight of emerging culms have already been identified as the limiting factor of the bamboo production in many bamboo growing areas, especially in the coastal belts of Orissa (Jamaluddin et a1., 1992). Similarly, foliage blight and rust have been recorded to pose threat to nursery as well as outplanted seedlings which are in the early establishnent phase (Bakshi et a1., 1972; Harsh et a1., 1989). With the increased emphasis and priority on raising multipurpose tree species, large—scale planting of bamboos has been initiated recently in the State. Limited experience in raising the bamboo seedlings together with the lack of information on bamboo diseases and their control measures often resulted in partial to complete failure of many nurseries. Also, poor handling of bareroot seedlings for outplanting affected seriously the planting programme. This was clearly reflected by the large-scale nortality of outplanted young seedlings reported from many plantations. So far, no systanatic attempt has been made to study the diseases affecting bamboos in nurseries, plantations and natural stands in the country. Hence, the present investigation was taken up to conduct a systematic study of the diseases affecting bamboos in Kerala.