Thirty seven isolates of Erysiphe necator were collected from different vineyards from three regions and nine cities of Khorasan Razavi province within two time periods i.e. May to June and August to September 2009.Their RESISTANCE to AZOXYSTROBIN+difenconazole (OrtivaÒ) fungicide as well as cross RESISTANCE to penconazole and hexaconazole fungicides registered in Iran for the control of powdery mildew was investigated. A leaf disk bioassay was carried out to determine the RESISTANCE of powdery mildew isolates on the basis of EC50 values derived from log-logistic dose-response curves. These subcultures were analyzed for RESISTANCE to AZOXYSTROBIN+ difenconazole. The mean EC50 values of AZOXYSTROBIN+difenconazole on E. necator subcultures from vineyards was 0.279 mg L-1. The highest and the lowest EC50 values were found in Mashhad (0.622 mg L-1) and Khalilabad (0.143 mg L-1), respectively. Frequency distributions were skewed most toward higher RESISTANCE to AZOXYSTROBIN +difenconazole. The present study demonstrated a steady and significant increase in EC50 values for AZOXYSTROBIN+difenconazole during the growing season after multiple applications. Also, there was no cross RESISTANCE (P>0.05) among fungicides.

The compatibility studies of Pseudomonas fluorescens (Pf1) with AZOXYSTROBIN at different concentrations viz., 100, 150, 200, 250 and 300 ppm revealed that it was compatible with all the concentrations of AZOXYSTROBIN tested and the growth of the bacterium was unaffected even at the maximum concentration of 300 ppm. The field experiment revealed a foliar application of Pf1 (2.5 kg ha-1) and AZOXYSTROBIN (250 ml ha-1) combined, reduced downy mildew as well as powdery mildew disease severities more than AZOXYSTROBIN (250 and 500 ml ha-1) alone. An application of Pf1+AZOXYSTROBIN treatment recorded only 2.22 and 1.00 Percent Disease Index (PDI) of downy mildew and 1.85 and 0.50 PDI of powdery mildew during the first and second seasons, respectively. The treatment also recorded a maximum fruit yield of 14.30 and 15.65 tonnes ha-1 for the first and second seasons, respectively. Application of Pf1 along with AZOXYSTROBIN significantly increased the survival of Pf1 in the phylloplane of cucumber crop. In addition, there was multifold increase in peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, b-1, 3 glucanase, chitinase and phenolics in plants treated with Pf1+AZOXYSTROBIN.

AZOXYSTROBIN is a broad-spectrum, systemic and soil-applied fungicide used for crop protection on more than 80 different crops. AZOXYSTROBIN use has induced water pollution and ecotoxicological effects upon aquatic organisms, as well as heath issues. Such issues may be solved by phytoremediation. Here, we tested Plantago major L., Helianthus annus L. and Glycine max L. to clean soils under laboratory conditions. Results show that the accumulation efficiency of AZOXYSTROBIN and AZOXYSTROBIN acid in roots was higher than those of leaves. G. max roots were an efficient accumulator of AZOXYSTROBIN (25.32 mg/kg), followed by P. major roots (20.62 mg/kg) and H. annus roots (18.29 mg/kg), within 10 days, respectively. In the leaves, AZOXYSTROBIN significantly translocated into the P. major leaves and reached the maximum after 10 days of exposure (15.03 mg/kg), followed by H. annus leaves (9.8 mg/kg), while it reached the maximum after 3 days of exposure (3.12 mg/kg) in G. max leaves. AZOXYSTROBIN acid significantly accumulated in P. majorroots more than the G. max and H. annus roots. In the leaves, AZOXYSTROBIN acid significantly accumulated in G. max more than P. major and H. annus. The presence of P. major with Tween 80 had effects on AZOXYSTROBIN desorption from soil, plant uptake metabolism and translocation more than P. major alone.

Chemical control using fungicides is considered as the most important method to control Botrytis cinerea in different crops. However, effective management of this pathogen requires information on presence and frequency of fungicide-resistant strains and levels of RESISTANCE as well as mutations associated with the RESISTANCE. In this research, sensitivity of 103 B. cinerea isolates collected from vineyards in different regions of West Azarbaijan province was assessed to carbendazim (60 WP) and AZOXYSTROBIN (25 SC). Among the studied isolates, 39 (38%) and 35 (34%) isolates were highly resistant to carbendazim and AZOXYSTROBIN, respectively. Partial sequencing of the beta tubulin gene indicated that in carbendazim-resistant strains GAG had changed to GCG which led to the substitution of glutamic acid by alanine at the codon position 198 and subsequently appearance of Ben R1 phenotype. Analysis of the partial cyt b gene sequence revealed that in AZOXYSTROBIN-resistant strains GGT had changed to GCT (point mutation) leading to substitution of glycine by alanine at the codon position 143. Further, one of the AZOXYSTROBIN-sensitive isolates had Bcbi-143/144 intron immediately after codon 143 in cyt b. The results indicated that application of benzimidazole and strobilurin fungicides groups are not recommended for B. cinerea management in the vineyards of the region. However, given that benzimidazole-resistant strains had Ben R1 phenotype, benzimidazole fungicides can be used with diethofencarb or zoxamide as a mixture partner to effectively control both sensitive and resistant strains.

Quinol oxidation inhibitors (QoIs) are one of the most important classes of fungicides used in agriculture. They block electron transfer between cytochromeb and cytochrome c1, thereby impeding the production of ATP via oxidative phosphorylation. QoI fungicides are generally at high risk of provoking RESISTANCE in fungal phytopathogens. RESISTANCE has been reported in more than thirty species, amongst others, in Botrytis cinerea. In various QoI-resistant monosporic B. cinerea isolates from Hungary, a G-to-C point mutation was identified in the mitochondrial gene that encodes the QoI target, cytochromeb, resulting in a glycine to alanine substitution at position 143 (G143A). Analysis of Hungarian group I and group II strains further indicated the frequent occurrence of an additional group I-type intron in the cytb gene directly downstream of the glycine-143 codon. Mutual presence of distinct mitochondrial DNAs specifying different cytb alleles (heteroplasmy) has also been detected in monosporic strains. Remarkably, a number of group II field isolates were found to be highly resistant to AZOXYSTROBIN although they did not appear to carry the G-to-C mutation (G143A) generally associated with fungal QoI-RESISTANCE.