Phyllosphere epiphytic microorganisms of 15 Sri Lankan rice varieties were determined and 81 different recognizable taxonomic units of microbes were isolated. Three bacterial and 18 fungal isolates inhibited the growth of Magnaporthe grisea and Rizoctonia solani in vitro. Copyright © 2006 John Wiley & Sons, Ltd

A novel antimicrobial formulation based on carboxymethylcellulose (CMC) spray-coated Cu2+ intercalated montmorillonite (MMT) nanocomposite material was prepared and its morphology, internal structure, and bonding interactions were studied. Meanwhile, the antibacterial efficacy and release behavior of Cu2+ was also determined. PXRD patterns indicated the intercalation of Cu2+, while FTIR spectra and TGA traces confirmed the association of Cu−MMT with CMC. SEM study revealed the improvement of nanocomposites by CMC, without disturbing the clay structure. TEM and EDAX studies indicated the distribution of Cu (copper) throughout the composite. In vitro antibacterial assays performed with Erwinia carotovora revealed effective bacterial growth suppression, indicating the potential of this material in controlling soft rot of potatoes (Solanum tuberosum); also observed was a connection between growth inhibition and concentration of CMC spray coats indicating a positive relationship between Cu2+ release and concentration of the CMC coatings. The activity pattern of the nanocomposite displayed a significant degree of sustained-release behavior.

In the present study, the relationship between the in banana by Colletotrichum musae and fruit peel pH was investigated. The results of a survey showed that anthracnose In contrast, the highest susceptibility to anthracnose was Variations of the pH of fruit peel exudates (FPE) of different banana cultivars were monitored during the ripening stages. The effects of FPE, collected from different banana cultivars at two maturity stages, on germ tube formation and elongation and appressoria development of C. musae were also determined. Furthermore, the effects of culture medium pH on the growth of C. musae, anthracnose development and the expression of a pelB were determined. With ripening the pH of FPE and fruit pulp decreased. The highest pH of FPE stage, pulp of all cultivars had pH values less than 4.5 with the lowest being 3.9 in Embul. When grown in culture media C. musae was observed at 4.5, indicating that an exogenous pH of 4.5 can favour colonization by C. musae. The expression of pel C. musae grown in a culture medium having a pH of 4.5. In addition, soluble factor responsible for the variation in anthracnose development among different banana cultivars, and its effects on germ tube formation, elongation and appressoria formation are discussed. fruit peel exudates, germ tube, pelB

Bean (Phaseolus vulgaris L.) is one of the major vegetable crops cultivated in tropical, sub-tropical and temperate regions in the world. Bean yellowing disease still a serious viral threat to bean cultivation causing severe yield reduction. In this study, polymerase chain reaction (PCR) assays using degenerate (universal) primers were conducted with the aim of developing molecular techniques to detect the virus. Two degenerate primer pairs, namely, Deng 540/541 association of a begomovirus with the BYD by giving the desired core coat protein amplicons of 520 bp and 550 bp, respectively. The resulting amplicons were subjected to DNA sequencing and the sequence data were analysed to determine the phylogenetic and molecular evolutionary relationships with other related begomovirus sequences obtained from the GenBank. The analysis revealed that the virus associated with BYD (BYVD-GN-SL-Partial) is closely related to Horsegram [ isolate (HgYMV-LK: 09-Bean) reported in Sri Lanka. Further, the DNA sequence of BYVD-GN-SL-Partial was distinctively clustered with the Indian HgYMV sequences and positioned in between the Mungbean yellow mosaic virus (MYMV) sequences.

The common bean (Phaseolus vulgaris L.) yellowing disease (BYD) is caused by the Horsegram yellow mosaic virus (HgYMV), which is a begomovirus transmitted Bemisia tabaci Genn.). It is a serious threat to the common bean cultivation in Sri Lanka. Despite the long time, its etiology and virus vector relationships are not understood well. Therefore, the present work was carried out to identify major aspects of the etiology of the virus. Initially a survey was conducted to determine the prevalence of the virus in representative bean growing locations in Sri Lanka, followed by a host range study using 54 plant species. Characteristics of virus-vector relationships were determined by conducting a series of virus transmission tests under glasshouse conditions. The survey results revealed the incidence of BYD at some time or the other in most of the sampled localities, which are scattered around all four major districts where the common bean is grown. Through the host range study, it was demonstrated that Ageratum sp., Glycine max Merrill., (Lam.) Verdc., and Phaseolus lunatus L. are susceptible to HgYMV, indicating a narrow host range. In addition to the symptomatology, the successful entry of the virus following 96.7 %, which corresponds to 0.24 of the estimated probability could be transmitted through probing by a single viruliferous acquisition access period and inoculation access period were 20 min in each case and the respective disease incidence values could retain the virus in an active state for up to 9 days. : Begomovirus, Bemisia tabaci Genn., common bean yellowing disease, Horsegram yellow mosaic virus (HgYMV), host range, virus transmission.