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Leónides Castellanos González, María E. Lorenzo Nicao and Berta Lina Muiño

Effect of six fungicides on Lecanicillium (Verticillium) lecanii (Zimm.) Zare & Gams. Leónides Castellanos González, María E. Lorenzo Nicao and Berta Lina Muiño . (CETAS) Centre of Studies for the Sustainable Agrarian Transformation. University of Cienfuegos, Rodas road. Cienfuegos.

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Leónides Castellanos González, María E. Lorenzo Nicao and Berta Lina Muiño

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  1. Effect of six fungicides on Lecanicillium (Verticillium) lecanii (Zimm.) Zare & Gams. Leónides Castellanos González, María E. Lorenzo Nicao and Berta Lina Muiño (CETAS) Centre of Studies for the Sustainable Agrarian Transformation. University of Cienfuegos, Rodas road. Cienfuegos. Email: lcastellanos@ucf.edu.cu Presented at the 3rd e-Conference on Agricultural BioSciences (IeCAB 2010), held online from1st -15th June 2010 at http://www.m.elewa.org/econferenceIeCAB.php

  2. Objective and methodology The objective of the present work was to evaluate the effect of six fungicides on the entomopathogenic fungus Lecanicillium (Verticillium) lecanii (Zimm.) Zare & Gams), isolate Y–57. • The assays were carried out in Petri dishes using the entomopathogenic fungus L. lecanii,isolate Y- 57 • Fungicide concentrations tested 10, 100, 200, 500, 1000 and 2000 mg kg-1. • The experiment was a totally randomized design of seven treatments, replicated five times.

  3. In the culture medium containing fungicide, a mycelial disk of 0.5 cm in diameter of the fungus L. lecanii was placed. On the 10th day mycelial growth was evaluated by measuring the colony diameter in mm. With the obtained data the percentage of inhibition of the growth was calculated for each treatment Percentages were transformed in 2 arc sine √% for the analysis. variance analysis SPSS for Windows version 11.0. Duncan’s multiple range test, with 5% of probability of error

  4. The DL-50 and DL-95 values were determined for each fungicide according to the curve dose/ percentage of the fungus growth inhibition The toxicity of each fungicide was classified according to the values of percentage of inhibition (OILB) (Viñuela et al., 1993): Determine the effect of each fungicide on spore production capacity The effect of the fungicides on the germination of L. lecanii conidia; The percentage of germination was determined 24 hours later by means of an optic microscope.

  5. To define the compatibility of each fungicide with the entomopathogenic fungus, the T value, proposed by Alves et al. (1998) was calculated T = 20 [CV] + 80 [ESP] / 100 Where; T = corrected value for the classification of the product; CV = percentage of vegetative growth with relationship to the control. ESP = percentage of conidia production intensity with respect to the control According to the T value calculated and the established scale, the fungicides were classified as:

  6. RESULTS AND DISCUSSION Table 1: Percentage of growth inhibition of Lecanicillium lecanii by six fungicides. * Unequal letters differ according to the Duncan multiple ranges test for p≤0.05

  7. Table 2: LD-50 and LD-95 values of the entomopathogenic fungus according to inhibition of the mycelial growth at 10 days.

  8. Table 3: Toxicity classification of fungicides on Lecanicillium lecanii at field doses.

  9. Table 4: Spore production by L. lecanii at different concentrations of six studied fungicides after 10 days.

  10. Table 5: Classification of the compatibility of six fungicides with Lecanicillium lecanii at field doses.

  11. Table 6: Percentage of conidia germination of Lecanicillium lecanii at different fungicide concentrations after 24 hours.

  12. Conclusions • 1. Difenoconazol and tebuconazol of the triazol group were the fungicide that most affected Lecanicillium lecanii isolate Y – 57, with regard to mycelial growth, conidia production and their germination. These were classified as toxic by the OILB scale and very toxic according to the compatibility scale. • 2. The copper derived fungicide, cuprous oxide, was lightly toxic according to the OILB scale and toxic according to the compatibility scale. It affected the conidia germination from the very inferior concentrations to the field dose. • 3. Metalaxyl of the acylalanines group was lightly toxic according to the OILB scale and compatible with Lecanicillium lecanii isolate Y – 57, not affecting the conidia germination at any of the studied doses. • 4. The fungicides mancozeb and zineb were lightly toxic to Lecanicillium lecanii isolate Y – 57, according to the OILB scale and moderately toxic according to the compatibility scale. Nevertheless mancozeb affected conidia germination at all the studied concentrations, while the second only affected it at doses above 500 mg kg-1.

  13. THANKS

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