op mal method for detec ng latent infec ons. Fig. 1: Symptoms associated to. Anthracnose of olive. INTRODUCTION. Fig. 2: Effects of. Anthracnose of olive on oil.
A bioassay method for detec1on and quan1fica1on of latent infec1ons of Colletotrichum spp. in olive fruit Romero, J., Cherifi, F., Santa Bárbara, A., Moral, J., Roca, L.F., Trapero, A.
UNIVERSIDAD DE CÓRDOBA
Dpto. de Agronomía, Unidad de Patología Agroforestal, Universidad de Córdoba, Campus de Rabanales, Edif. C4, 14071 Córdoba.
INTRODUCTION Anthracnose of olive (Olea europaea), caused by Colletotrichum spp., is the most important disease adversely affecVng the olive oil quality. Early detecVon of latent infecVons on fruits could help to determine
Fig. 1: Symptoms associated to Anthracnose of olive
Infected fruit (Incidence=20%)
the control strategy in early autumn. However, there are no
Healthy fruits Acidity: 0,46% Stability: 11
Acidity: 2,68% Stability: 4,60
techniques for detect latent infecVons in olives that are easy to use,
Fig. 2: Effects of Anthracnose of olive on oil quality
fast and economical. The main objecVve of this work is develop an opVmal method for detecVng latent infecVons.
RESULTS
MATERIAL AND METHODS
The treatments were evaluated using naturally and arVficially inoculated olives. The evaluated treatments were paraquat (with and without wounding), etephon, freezing, ethanol and sodium hydroxide at different concentraVons (from 0.01 to 5%) and exposure Vmes (from 3 to 96 h). There were two control treatments which included washed and disinfested olives, or washed and no disinfested olives. Then, olives were incubated in humid chamber unVl symptoms develop. Incidence of symptomaVc olives (%) and T50 (days unVl the appearance of 50% symptomaVc
Control Control + washed + double disinfestaVon Paraquat Sodium hydroxide
Ethanol Freezing Ethylene Fig. 3:. Humid chamber used for the evaluaVon of treatments for detecVon of latent infecVons. SymptomaVc, asymptomaVc and contaminated olives are observed.
WOUND No No
CONCENTRACION EXPOSURE TIME (%) (hours) -‐ -‐ -‐ -‐
ABBREVIATION
more of diseased fruit in 8.9 days less than the Paraquat. T50 was useful to determine the most efficient treatments. TRIAL 2 2 Inoculación artificial
TRIAL 1 Inoculación artificial 1 40
80
a
A B
30
20
b A
a
A
Variety Variedad
AB
c
HOJIBLANCA ARBEQUINA
BC
C
0.29% 0.29% 5 1 0.5 0.1 0.05 0.05 0.05 0.05 0.05 0.05 0.01 70 -‐ 0.6*10-‐6 (m3/l)
0.02 0.02 48 48 48 48 96 72 48 24 12 3 48 48 48 Sprayed
PAR PAR+W NAOH 5% NAOH 1% NAOH 0.5% NAOH 0.1% NAOH 0.05% 96 NAOH 0.05% 72 NAOH 0.05% 48 NAOH 0.05% 24 NAOH 0.05% 12 NAOH 0.05% 3 NAOH 0.01% OH 70% FZ ETH
T
T+L+2D
C
PAR
PAR+HER
NAOH 0.05%
PAR+W NAOH 0.05% PAR Tratamientos 48
C+W+2D
0
ETILENO
PAR
ETI
PAR+HER
PAR
PAR+W
NAOH 0.1%
NAOH 0.05%
NAOH 0.1% NAOH 0.05% 48 Tratamientos
NAOH 0.01%
NAOH 0.01%
TRIAL 4 Infección natural
b bc
>91 días
60
HOJIBLANCA ARBEQUINA
CD
CDE
EF
Variety Var
DEF
d
Hojiblanca Arbequina
F
d
30
c
A
AB
c
C
PAR
BC
60
40
A
AB
abc
bc
c Variety Variedad
PAR
a
ab
PAR+HER
BC T+L+2D
PAR+W Tratamientos C+W+2D
NAOH 0.05%
0
NAOH 0.05% 48
NaOH 96
NaOH 72
NaOH 48
NaOH 24
NaOH 12
NaOH 3
NAOH NAOH NAOH NAOH NAOH NAOH Tratamientos 0.05% 96 0.05% 72 0.05% 48 0.05% 24 0.05% 12 0.05% 3
Paraquat
PAR
T+L+2D
C+W+2D
Fig. 4: Number of days required to detect 50% (T50) of infecVons caused by Colletotrichum acutatum in olives infected in which different detecVon treatments were applied. For each variety, means followed by the same lener are not significantly different according to Fisher's LSD test (P = 0.05)
CONCLUSIONS
Immersion of olive fruit in sodium hydroxide with the longer exposure Vme was the treatment more effecVve detecVng latent infecVon of Colletotrichum spp., being also more economical and safer than reference treatment Paraquat. Sodium hydroxide technique could be a great tool in making decisions about fungicide applicaVons on commercial farms.
ARBEQUINA
a
90
a
0
HOJIBLANCA
d
80
20
Variety Variedad
a
a
TRIAL 3 Infección natural
No Yes No No No No No No No No No No No No No No
B
20
d
0
B a
a
40
B
d
10
C C+W+2D
>84 días
60
T50 ((días) T50 days)
TREATMENT
reference treatment). Sodium hydroxide 0.05% for 96 hours detected 4.4 %
T50 ((días) T50 days)
olives) were assessed.
detect latent infecVon of Colletotrichum with results than Paraquat (the
T50 ((días) T50 days)
(moderately suscepVble) were subjected to six treatments to detect latent infecVon.
Sodium hydroxide at 0.05% for more than 1 day of exposure Vme allowed to
T50(days) (días) T50
Olive fruit of two olive cvs. Hojiblanca (highly suscepVble to disease) and Arbequina
ACKNOWLEDGEMENT This research was financed by the project of excellence AGR 08-‐3635 of Junta de A n d a l u c í a a n d B a y e r CropScience company.
