The biocontrol potentials of Candida tropicalis YZ1, C. tropicalis YZ27 and Saccharomyces cerevisiae YZ7 against the postharvest anthracnose pathogen Colletotrichum musae were investigated. Treatments with all the three biocontrol agents (1 9 10 8 CFU/ml) significantly reduced the natural anthracnose disease severity of harvested banana fruits stored at ambient condition. Germination and survival of C. musae spores were markedly inhibited by all the three yeast strains in in vitro tests. The niche overlap index (NOI) was used to determine the interaction between the antagonists and C. musae, and the results (high NOI values) suggest competitive exclusion of C. musae by the yeast strains. C. tropicalis YZ27 inoculated on banana wounds exhibited rapid colonization and maintenance of its population on the inoculated site. The biocontrol efficacy was also observed as a function of concentration of the antagonist applied. The fruits treated with C. tropicalis YZ27, 36 h before pathogen inoculation, showed the best results with 96.0% disease inhibition followed by those treated 24 h before with 84.0% inhibition. The above results point to competition for nutrients and space as the main mechanism of antagonistic action of C. tropicalis YZ27 against C. musae.

No abstract

Crop protection chemicals known as pesticides are playing a significant role to ensure food security. Besides controlling pests in agriculture, they are also used in human and animal health programmes. Development of resistant pests poses a real challenge towards the effectiveness of these toxic pesticides leading to their increased application associated with residual toxicity in food and environment. An estimated 954 pest species which include arthropods, weeds and plant pathogens have developed resistance against various types of pesticides, viz. insecticides, herbicides and fungicides. Resistance development in pest populations is influenced by biological, genetic and operational factors. Various mechanisms involved in resistance development in insects, microbes and weeds are discussed. The extent of insecticide, fungicide and herbicide resistance in various pest species is also highlighted. Effective pest and resistance management practices require understanding the factors influencing its development. The important role of Insecticide Resistance Action Committee (IRAC), Fungicide Resistance Action Committee (FRAC) and Herbicide Resistance Action Committee (HRAC) for resistance management is indicated. Strategies to mitigate the resistance development in conventional pesticides, use of Plant Incorporated Protectants (PIPs) and biopesticides as alternative to chemical pesticides along with some general recommendations are suggested for adoption.

No abstract

Collar rot disease caused by Sclerotium rolfsii attacks lentils at the seedling stage and reduces plant population considerably in the field. Although soil moisture and temperature influence disease development much, no concrete attempts to find the optimum level of moisture, temperature, and seedling age have been made in lentils. Here, we identified optimum soil moisture, temperature, and seedling age that allow successful infection by S. rolfsii and maximum seedling mortality in a controlled environment inside a plant growth chamber. Screening of one hundred and ninety genotypes for two consecutive years in the field identified some resistant genotypes. Ten genotypes were selected from earlier screening and further evaluated in sick plots at two different locations with different pH for three consecutive years. About 80% variation in disease resistance was due to genotypes, and minor infection of collar rot disease was observed in acidic lateritic soil than in neutral alluvial soil. Furthermore, low mycelial load in a selected resistant genotype was confirmed by quantitative real-time PCR using an S. rolfsii specific primer pair. The identified resistant genotypes will be helpful to breeding collar rot resistant cultivars and mapping disease resistance. In addition, the study improves the understanding of the development of collar rot disease, which is critical for expanding the area under cultivation in Asia, especially in rice fallows.