Treatment with insecticide and fungicide on the physiological quality of lentil seeds

The low Brazilian productive index and the high demand have aroused interest in the cultivation of lentils, however the legume is little known and needs further studies. The objective of this study was to analyze and identify the effects of treatments with insecticides and fungicides on the physiological quality of lentil seeds, CA-1512 strain. The experiments were conducted in the seed laboratory in a completely randomized design with seven treatments and four replicates. Seed treatment with Thiophanate-methyl; Fluazinam® (180 ml) + Pyraclostrobin; Thiophanate-methyl; Fipronil® (150 ml) promoted higher levels of germination under accelerated aging, lower number of abnormal seedlings and longer lengths of shoot and radicle for the emergence in paper. Treatment with Carboxin; Thiram® (250 ml) + Imidacloprid® (150 ml) allowed a higher value in the first count of germination in sand, lower number of dead seeds under accelerated aging and longer root length, in the emergence in sand. Shoot length in the emergence in sand increased after seed treatment with Metalaxyl-M; Fludioxonil® (75 ml) + Pyraclostrobin; Thiophanate-methyl; Fipronil® (150 ml). Treatments with fungicides and insecticides considerably improved the physiological properties of the seeds, thus being able to guarantee greater phytosanitary qualities in the field, generating healthier seedlings and with protection against possible pests and diseases, and consequently guaranteeing greater productivity.

Control of Microdochium albescens in pre-germinated and dryland rice seeds

ABSTRACT: The fungus Microdochium albescens can interfere in the germination of seeds and in the death of rice seedlings; however, there is not technical indication for its control by seed treatment. This research evaluated the efficiency of fungicides in the treatment of pre-germinated and dryland rice seeds in the control of M. albescens. Seeds of the cultivars, Epagri 109, SCS116 Satoru, SCS121 CL and SCS122 Miura were treated with the following fungicides (g a.i./100 kg of seeds): fluazinam + thiophanate methyl (9.45 + 63), pyraclostrobin + thiophanate methyl (5 + 45), carboxin + thiram (60 + 60), metalaxyl-M + thiabendazole + fludioxonil (3 + 22.5 + 3.75), carbendazim + thiram (45 + 105), carbendazim (45). Seeds without fungicide treatment constituted the control. The treated seeds were sown in potato-sucrose-agar (PSA) culture medium and incubated at 25 ± 2 °C and photoperiod of 12 hours for 14 days. Treated seeds were also submitted to the germination test. Fluazinam + thiophanate methyl and metalaxyl-M + thiabendazole + fludioxonil showed greater control of M. albescens, not differing statistically between them, in the five cultivars and in the two cultivation systems. The tested fungicides provided seed germination above 90% in the four cultivars.

Fungicides and Bacillus subtilis against fungi isolated from commercial seed of Side oats grama (Bouteloua curtipendula)

Banderita (<em>Bouteloua curtipendula</em>), produces abundant and appetizing forage for cattle under extreme arid conditions. The demand for its seed in Mexico is a direct function of the potential for the establishment of pastures and therefore, the sanitary quality of this is fundamental. Phytopathogenic fungi affect the seed and establishment of prairies. The objective was to evaluate<em> in vitro</em> the effect of six agrochemicals and one biological against fungi associated with Banderita seed, to reduce losses caused by these. Treatments were carried out in PDA culture medium combined with Captan, Thiophanate-methyl, Mancozeb, Benomil, Prochloraz, Thiabendazole and <em>Bacillus subtilis</em> at concentrations according to the case of 0 (control), 0.005, 0.001, 0.05, 0.01, 0.5, 0.1, 1.5, 10, 100, 150, 200, 250 and 300 mg L-1, against <em>Alternaria alternata</em>, <em>Bipolaris cynodontis</em> and <em>Fusarium incarnatum</em>. The bi-directional colony diameter was measured every 48 h. The effective concentration of 50% was estimated by a non-linear regression model; in relation to the percentage of inhibition of mycelial growth. <em>Bacillus subtilis</em> presented higher mycelial inhibition 97% (P &lt;0.05), followed by Thiophanate-methyl (96%), Prochloraz (94%), Captan (93%) and Mancozeb (92%). Benomyl and Thiabendazole showed low inhibition of fungi with 46 and 37%.<em> B. subtilis</em> and Thiophanate-methyl are the products with the greatest possibility of controlling pathogens associated with Banderita grass seeds.

A Selective Medium for the Recovery and Enumeration of Fomitopsis meliae, Causing Lemon Canker and Wood Rot

A selective medium (FMS medium) was developed for the isolation and quantification of Fomitopsis meliae, the causal agent of lemon canker and brown wood rot, from plants, soil, and air. The optimal concentration and combination of fungicides and antibiotics was evaluated to determine the most selective condition for growing F. meliae. The resultant composition of the medium (FMS) per litre (pH 3.5) was: 16 mg thiophanate-methyl, 8 mg dichloran, 5 mg 2-phenylphenol, 100 mg fluopyram, 0.5 mg fludioxonil, 100 mg chloramphenicol, 100 mg streptomycin, 15 g malt extract, 2.5 g mycological peptone, and 15 g agar. The fungus was successfully isolated and enumerated from air, soil and plant tissues using FMS medium. Furthermore, FMS medium almost completely inhibited the growth of other plant pathogenic fungi, soil and air saprophytes. This selectivity was high enough to estimate spore inoculum of F. meliae in an air sample or as a spore trapping device in commercial lemon orchards. FMS medium will be useful for studying epidemiology and management of F. meliae.

Comparing the Fungicide Sensitivity of Sclerotinia sclerotiorum Using Mycelial Growth and Ascospore Germination Assays

The infection of the floral tissues of snap bean and other crops by Sclerotinia sclerotiorum, the causative agent of white mold, is by ascospores. Irrespective of the fungicide mode of action being evaluated, in vitro fungicide sensitivity tests are conducted almost exclusively using mycelial growth assays. This is likely due to difficulties and time involved in sclerotial conditioning required to produce apothecia and ascospores. The objective of this research was to compare estimates of fungicide sensitivity between mycelial growth and ascospore germination assays for S. sclerotiorum. Sensitivity assays were conducted using serial doses of three fungicides commonly used to control white mold: boscalid, fluazinam, and thiophanate-methyl. A total of 27 isolates were evaluated in replicated trials conducted for each fungicide and assay type. The effective concentration to reduce mycelial growth or ascospore germination by 50% (EC50) was estimated for each isolate, fungicide, assay type, and trial. The median EC50 values obtained from ascospore germination assays were 52.7, 10.0, and 2.7 times higher than those estimated from the mycelial growth for boscalid, fluazinam, and thiophanate-methyl, respectively. No significant correlation was found between EC50 values estimated by the two methods. These findings highlight differences that may be important in evaluating the sensitivity of S. sclerotiorum given the fungicide mode of action and how they will be used in the field.

Molecular diagnosis of thiophanate-methyl resistant strains of Fusarium fujikuroi in Japan

Fusarium fujikuroi is the pathogen of rice bakanae disease, and is subclassified into gibberellin and fumonisin groups (G- and F-groups). Thiophanate-methyl, a benzimidazole fungicide, has been used extensively to control F. fujikuroi. Previous investigation showed that F-group strains are thiophanate-methyl sensitive (TMS), while most G-group strains are thiophanate-methyl resistant (TMR) in Japan. The minimum inhibitory concentration (MIC) in TMS strains was 1–10 μg mL-1, while that in TMR strains was higher than 100 μg mL-1. E198K and F200Y mutations in β2-tubulin were detected in TMR strains. A loop-mediated isothermal amplification-fluorescent loop primer (LAMP-FLP) method was developed for diagnosis of these mutations, and was applied to 37 TMR strains and 56 TMS strains. The result indicated that 100% of TMR strains were identified as having either the E198K mutation (41%) or the F200Y mutation (59%), while none of the TMS strains tested showed either mutation. We found one remarkable TMR strain in the F-group which had a F200Y mutation. These results suggest that E198K and F200Y mutations in β2-tubulin contribute to thiophanate-methyl resistance in F. fujikuroi.