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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_at_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/econfere
nceIeCAB.php
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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 Y57.
Fungicide Chemical group Field dose
Difenoconazol Triazol 100 mg kg-1
Tebuconazol Triazol 200 mg kg-1..
Cuprous oxide Inorganic compound (cupric) 2000 mg kg-1
Mancozeb Ditiocarbamato 2000 mg kg-1.
Metalaxyl Acilalanina 200 mg kg-1.
Zineb Ditiocarbamato 2000 mg kg-1

• 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.

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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 v for
the analysis.
variance analysis
SPSS for Windows version 11.0.
Duncans multiple range test, with 5 of
probability of error
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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)
Inhibition of growth () Classification
lt 30 Inoffensive
3075 Lightly toxic
7590 Moderately toxic
gt 90 Toxic
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.
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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
0 to 30 Very toxic
31 to 45 Toxic
46 to 60 Moderately toxic
gt 60 Compatible
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RESULTS AND DISCUSSION
Table 1 Percentage of growth inhibition of
Lecanicillium lecanii by six fungicides.
Concentrations Concentrations Concentrations Concentrations Concentrations Concentrations
Fungicides 10 mg kg-1 100 mg kg-1 200 mg kg-1 500 mg kg-1 1000 mg kg-1 2000 mg kg-1
Difenoconazol 100 a 100 a 100 a 100 a 100 a 100 a
Tebuconazol 100 a 100 a 100 a 100 a 100 a 100 a
Cuprous oxide 27.7 b 33.3 c 41.6 b 47.2 b 66.6 b 69.4 b
Metalaxyl 25.0 c 30.6 d 42.2 b 41.6 c 41.6 d 52.7 c
Zineb 6.4 d 35.8 b 42.3 b 37.0 d 46.7 c 49.8 d
Mancozeb 6.2 d 18.7 e 12.5 c 25.0 e 31.2 e 34.3 e
E. Típico 0.02 0.005 0.05 0.08 0.07 0.06
C.V. () 2.8 0.6 5.9 9.2 7.6 6.3
Unequal letters differ according to the
Duncan multiple ranges test for p0.05
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Table 2 LD-50 and LD-95 values of the
entomopathogenic fungus according to inhibition
of the mycelial growth at 10 days.
Fungicides Equation of regression Coefficient of determination DL-50 (mg kg-1) DL95 (mg kg-1)
Difenoconazol _ _ ltlt 10 mg kg-1 lt 10 mg kg-1
Tebuconazol _ _ ltlt 10 mg kg-1 lt 10 mg kg-1
Cuprous oxide Y0.50723.7256 0.8260 325.47 mg kg-1 gt2000 mg kg-1
Mancozeb Y0.49512.9623 0.8992 gt 2000 mg kg-1 gtgt2000 mg kg-1
Metalaxyl Y0.25744.1395 0.9292 2202.72 mg kg-1 gtgt2000 mg kg-1
Zineb Y0.61983.1060 0.8336 1136.68 mg kg-1 gtgt2000 mg kg-1
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Table 3 Toxicity classification of fungicides on
Lecanicillium lecanii at field doses.
Toxicity (OILB) Toxicity (OILB)
Fungicide Growth inhibition Classification
Difenoconazol 100 Toxic
Tebuconazol 100 Toxic
Cuprous oxide 69.4 Lightly Toxic
Mancozeb 34.3 Lightly Toxic
Metalaxyl 42.2 Lightly Toxic
Zineb 49.8 Lightly Toxic

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Table 4 Spore production by L. lecanii at
different concentrations of six studied
fungicides after 10 days.
Concentrations Concentrations Concentrations Concentrations Concentrations Concentrations
Fungicides Control 10 mg kg-1 100 mg kg-1 200 mg kg-1 500 mg kg-1 1000 mg kg-1 2000 mg kg-1
Difenoconazol 7.2 x 107 0 0 0 0 0 0
Tebuconazol 7.2 x 107 0 0 0 0 0 0
C. oxide 7.3 x 107 2.7 x 107 1.7 x 107 1.9 x 107 2.3 x 107 2.2 x 107 0
Metalaxyl 7.2 x 107 5.3 x 107 4.0 x 107 3.8 x 107 2.6 x 107 2.9 x 107 2.7 x 107
Mancozeb 7.5x107 5.5x107 2.9x107 3.5x107 3.0x107 2.5x107 2.3x107
Zineb 7.5x107 3.9x107 3.5x107 3.5x107 3.4x107 3.3x107 3.3x107
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Table 5 Classification of the compatibility of
six fungicides with Lecanicillium lecanii at
field doses.
Fungicide Compatibility (Alves et al.,1998) Compatibility (Alves et al.,1998)
T Value Classification
Difenoconazol 0 Very toxic
Tebuconazol 0 Very toxic
Oxido cuproso 6.12 Very toxic
Mancozeb 45.44 Moderately toxic
Metalaxyl 53.16 Moderately toxic
Zineb 46.24 Moderately toxic
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Table 6 Percentage of conidia germination of
Lecanicillium lecanii at different fungicide
concentrations after 24 hours.
Concentrations Concentrations Concentrations Concentrations Concentrations Concentrations
Fungicides Control 10 mg kg-1 100 mg kg-1 200 mg kg-1 500 mg kg-1 1000 mg kg-1 2000 mg kg-1
Difenoconazol 100 0 0 0 0 0 0
Tebuconazol 100 0 0 0 0 0 0
Cuprous oxide 100 100 0 0 0 0 0
Metalaxyl 100 100 100 100 100 100 100
Mancozeb 100 0 0 0 0 0 0
Zineb 100 25 27 26.9 0 0 0
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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.

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THANKS