Mineral oil residues in soil and apple under temperate conditions of Kashmir, India.

The study was undertaken to ascertain the persistence of Orchol-13, a mineral oil used against insect pests of horticultural fruit crops in soil and apple following the dormant and summer applications of 2 and 0.75% respectively. Soil samples were collected during dormant, while as both soil and apple samples were collected during summer season. Samples were collected at 0, 1, 3, and 5 days post treatment in both the seasons. Average recoveries of paraffinic constituents (which constitute about 60% of mineral oils by composition) from soil and apple at 1 µg ml-1 spiking level were found to be 74.18 and 76.81% respectively. The final quantification of paraffinic constituents was performed on gas chromatograph equipped with flame ionization detector (GC-FID). No paraffinic constituents of mineral oil could be detected in soil and apple at 0 day post treatment in both the seasons.

Dissipation patterns of the fungicide difenoconazole (25% EC) in apples grown in Kashmir, India.

Dissipation patterns were studied following two applications of difenoconazole (score 25% EC) at 300 and 600 g ai ha(-1) as single and double dose respectively on Golden Delicious and Starkrimson cultivars of apple. Samples were collected at 0, 3, 6, 9, 12 and 30 days (harvest) post treatment. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.004 and 0.008 µg g(-1), respectively. Half-life periods for Golden Delicious were found to be 6.09 and 6.70 days, and for Starkrimson, these values were observed to be 5.34 and 5.80 days, at single and double doses, respectively. Difenoconazole residues dissipated below its LOQ of 0.008 µg g(-1) after 30 day post treatment at a single dose in both the cultivars. Waiting periods of 13.06 and 10.72 days are suggested for Golden Delicious and Starkrimson cultivars at a recommended dose of 300 g ai ha(-1), respectively.

Degradation of chlorpyrifos residues in apple under temperate conditions of Kashmir Valley.

The present studies were carried out to observe the dissipation pattern of chlorpyrifos on apple in Kashmir Valley. Persistence of chlorpyrifos in apple was studied following two applications rates of chlorpyrifos (Dursban 20 EC) at 200 g a.i. ha(-1) (single dose T 1) and 400 g a.i. ha(-1) (double dose T 2). The average initial deposit of chlorpyrifos was found to be 1.61 and 1.98 µg g(-1) for T 1 and T 2 application rates respectively on apple. The residues dissipated to 0.09 and 0.06 µg g(-1) after 15- and 30-day post treatment with half-life periods of 3.34 and 5.47 days in T 1 and T 2 application rates, respectively. The residues of chlorpyrifos dissipated to below limit of quantification (LOQ) of 0.04 µg g(-1) after 30 day at T 1 application rate. A waiting period of 6 days must be observed for chlorpyrifos on apple at recommended application rate for the safety of consumers. Theoretical maximum residue contribution (TMRC) values were found to be far less than maximum permissible intake (MPI) at 0 day in both the dosages suggesting chlorpyrifos on apple in Kashmir is unlikely to cause health risks.

Thyrostroma carpophilum insertional mutagenesis: A step towards understanding its pathogenicity mechanism.

Thyrostroma carpophilum, a causal agent of shot hole disease of stone fruits, cause severe loss in economically important fruit crops of Kashmir. Understanding its pathogenesis at molecular level will aid in devising a better management strategy. In this study, we optimized Agrobacterium tumefaciens mediated transformation (ATMT) conditions for T. carpophilum using PBIF2-EGFP construct. Using this protocol, we obtained 328 positive transformants per 104 spores and subsequent sub-culturing of transformants on selective and non-selective media resulted in stable T-DNA integration. Southern blot analysis revealed that most of the transformants embodied single T-DNA integration. Using this method, we obtained a small-scale transformant library (2050 transformants). Among this pool, we tested 1005 transformants for their pathogenicity; out of which 185 showed complete pathogenicity loss, 35 displayed reduced virulence and 785 were pathogenically similar to wild type. Out of this experimental stock, three transformants from each category were randomly selected to dissect the infection assay. The findings deciphered that transformants with complete pathogenicity loss failed to penetrate the host tissue and a few transformants failed to sporulate in laboratory. Transformants from reduced category could not form appressorium and occasionally sporulated. Transformants similar to wild type were morphologically and pathogenically similar to wild type because of un-alteration in their modus operandi. Our work provides a new platform to understand the pathogenicity mechanism of T. carpophilum. The optimized ATMT protocol will help in developing large transformant library that can help to identify the virulence arsenals necessary for the pathogen to cause disease.