preventing mycotoxins in the field peter j. cotty
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Preventing Mycotoxins in the Field Peter J. Cotty Agricultural Research Service, United States Department of Agriculture School of Plant Sciences, University of Arizona, Tucson. Mycotoxins: Triple Threat to African Development Woodrow Wilson International Center for Scholars - PowerPoint PPT PresentationTRANSCRIPT
Preventing Mycotoxins in the Field
Peter J. CottyAgricultural Research Service, United States Department of Agriculture
School of Plant Sciences, University of Arizona, Tucson
Mycotoxins: Triple Threat to African DevelopmentWoodrow Wilson International Center for Scholars
Washington, DC, 14 February, 2012
During Crop DevelopmentIrrigation, Weed Control, Fertilize
Best cultivars, Insect Control
During transportRapid, Dry, No Damage
During ProcessingSort, Cull, Discard, Add binders.
During StorageDry, prevent moisture, cool
Prevent damage: insects, rodents
Prevent Formation of Dangerous Aflatoxin Levels Protect Crops Until Use
A Single application at 10 kg/hectare is enough to consistently reduce aflatoxins in maize, groundnut, and other crops.
Nigeria
Atoxigenic Isolates Occur Naturally on Crops
Isolates useful for biocontrol are endemic in and adapted to target agroecosystems.
Per
cent
of
A. f
lavu
s
0
10
20
30
40
50
60
1 2 3 4 5 6
Field 1 Field 2
Aflatoxin Produced in Culture (log ppb)
Aflatoxin-ProducingPotential
Field 1 = Low,3,400 ppb
Field 2 = High,54,000 ppb
Aflatoxin Production by A. flavus from Two Fields
Fungi Vary Across Areas in Aflatoxin-Producing Ability Farmers apply atoxigenic strains to reduce the average aflatoxin-producing potential of
fungi on farms & thus the vulnerability of crops to aflatoxin contamination
As Applied
AfterFungal Growth
Either Sorghum, Wheat, or Barley are used.
The grain is killed by cooking before use.
Sorghum is used in Africa.
Afla
toxi
n B
1 (ng
/g X
10,
000)
Isolates (%) in Applied Atoxigenic Strain
0123456789
0 20 40 60 80 100
r = 0.71, P = 0.0001
Dots Represent Values for Replicate Plots
Aflatoxin in Crop versus Atoxigenic Incidence
Cotty, 1994. Phytopathology:1270-1277.
Aflatoxin (ppb)Area Samples (#) AF36 (%) Mean Range
GraysonNorth 17 96 a 12 a 0 to 48
GraysonSouth 16 98 a 15 a 0 to 38
GraysonControl 8 24 b 230 b 5 to 530
Commercial Maize: North Central Texas 2008
Means in the same column with different letters are significantly different by Tukey’s HSD test, P < 0.001.
0%
20%
40%
60%
80%
100%
Bark
ley
Shar
p
Stuh
r
Bark
ley-
N
Shar
p-20
4W
Stuh
r-3W
Bark
ley-
29
Bark
ley-
95N
Bark
ley-
95S
Shar
p-20
5W
Shar
p-20
1
MV:
0.3
mi-S
E
YV: 0
.6 m
i-NE
MV:
0.7
mi-E
MV:
1.2
mi-W
Treated
Diagonal
Adjacent
Other
Incidence of AF36 within Aspergillus flavus Communities Prior to and One Year After Application
Inci
denc
e of
AF3
6= 1997 = 1996 =1997 & 1996 differ
Fungi Resident in the Soil
82%
53%
96%100%
0% 0% 0% 1% 17% 11%
77%74%
0%
20%
40%
60%
80%
100%
Par
ham
Soi
l
Rut
herfo
rdS
oil
Par
ham
Cor
n
Rut
herfo
rdC
orn
Par
ham
Cor
n
Rut
herfo
rdC
orn
2008 2008 2008 2008 2009 2009
Perc
ent o
f Asp
ergi
llus
flavu
s Grayson County, Texas: Carry Over to the Second Year Crop
= Atoxigenic isolate AF36
= S Strain, produces very high aflatoxins
Crop Treatment Year
Crop Year After Treatment
Soil Before Treatment