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Aflatoxin Contamination: Occurrence and Management Thomas Isakeit Cooperative Extension, The Texas A&M University System

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AFLATOXINS: WHAT ARE THEY? - TOXIC CHEMICALS PRODUCED BY FUNGI (Aspergillus flavus and A. parasiticus) GROWING IN CROPS - CAUSE DISEASE IN ANIMALS AND HUMANS (MYCOTOXICOSIS) - MAY BE PRODUCED IN THE FIELD OR AFTER HARVEST - AFFECT MANY TYPES OF CROPS

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TYPES OF AFLATOXINS STRUCTURE OF B 1, THE MOST POTENT AFLATOXIN, SPECIFICALLY REGULATED IN SOME COUNTRIES ALSO: B 2, G 1 AND G 2 M 1 AND M 2 IN MILK: SPECIFICALLY REGULATED

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AFLATOXIN TOXICITY - HUMANS HEPATIC AND GASTROINTESTINAL INJURY IMMUNOSUPPRESSIVE TERATOGENIC ONCOGENIC SEVERE LIVER INJURY, SOMETIMES FATAL (2-6 MG/DAY FOR A MONTH)

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AFLATOXIN TOXICITY - ANIMALS LUNG LESIONS IN A PIG POISONED BY AFLATOXIN VARIOUS SYMPTOMS: FROM REDUCED GAIN TO DEATH VARYING SENSITIVITY AMONG SPECIES

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AFLATOXIN POISONING FROM CORN RECENT CASES TEXAS, 1998: 25 DOGS DIED 100-200 PPB, FULL DIET FOR 90 DAYS KENYA, 2004: 125 PEOPLE DIED, 192 POISONED DAMP STORAGE OF CORN, UP TO 8,000 PPB

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LOSS FROM AFLATOXIN IN TEXAS CORN IN 1998 YIELD LOSS FROM DROUGHT PRICE DROP ($2.20/BU vs. $2.80) $407 MILLION VALUE W/O TOXIN 18 31% CROP CONTAMINATION TOXIN VALUE: $1.30 - $1.40 / BU $17 - $40 MILLION LOSS

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HISTORY IN TEXAS AFLATOXIN? LOSING TURKEYS: I CUT THEM OPEN AFTER THEY DIE AND FIND A BIG LIGHT COLLORD LIVER; THE GIZZARD IS ENLARGED, ALSO THE GALL IS TWICE AS LARGE AS SHOULD BE. - LETTER TO FARM AND RANCH, MAY 19, 1917 FROM VAN ZANDT COUNTY, TX

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HISTORY IN TEXAS J.J. Taubenhaus documents A. flavus as a pathogen

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A. FLAVUS IS A WEAK PATHOGEN THAT DOES NOT ALWAYS PRODUCE SYMPTOMS ASPERGILLUS EAR ROT PHOTO: G. ODVODY

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CONSEQUENTLY, AFLATOXIN DETECTION REQUIRES A CHEMICAL ANALYSIS EXTRACTION PURIFICATIONANALYSIS DETECTION IS DIFFICULT!

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SAMPLING IS MORE DIFFICULT! CONTAMINATION IS NOT UNIFORM: - WITHIN A REGION - WITHIN A FIELD - ON A PLANT - WITHIN AN EAR - WITHIN A SEED

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AFLATOXIN DISTRIBUTION IN TEXAS 2002 CORN ACREAGE 2003 CONTAMINATION

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COMPILED BY: OFFICE OF THE TEXAS STATE CHEMIST

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AFLATOXIN IN AN EAR OF CORN PHOTO: G. SCHUSTER CONCENTRATIONS ARE DIFFERENT FOR EACH KERNEL

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WHERE AFLATOXIN OCCURS IN A CORN SEED (SHOWN IN RED) PHOTO: N. KELLER AS SHOWN BY THE RED COLOR MUTANT, AFLATOXIN IS FOUND IN THE ALEURONE

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A SMALL PROPORTION OF CORN IS HIGHLY CONTAMINATED: 1 KERNEL WITH 400,000 PPB WILL MAKE A 10-LB SAMPLE MEASURE 26 PPB

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WHERE DOES THE FUNGUS COME FROM? Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. airborne infective spores survival in soil MODIFIED FROM: WICKLOW, 1983, SO. COOP. SER. BUL. 279 BROWN & BROTZMAN, 1979, U. OF MO.

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SCLEROTIA OF A. FLAVUS DETAIL: RED BAR IS APPROX. 1 MM

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HOW THE FUNGUS ENTERS THE EAR Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. SPORES FALLING INTO WOUNDS CAUSED BY INSECTS (E.G. CORN EARWORM AND SOUTHWESTERN CORN BORER), OR CARRIED ON THEM CAN GROW DOWN SILKS (NO WOUNDING NECESSARY), SHORTLY AFTER POLLINATION

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HOW THE FUNGUS ENTERS THE SEED Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. A WOUND IS USUALLY NEEDED

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SILK CUT STRESS-RELATED LOSS OF KERNEL INTEGRITY PHOTO: G. ODVODY

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PREDISPOSING FACTORS FOR CONTAMINATION Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. Figure 3. Aflatoxin content of early, intemediate and full season hybrids Figure 4. Relationship between aflatoxin content and maturity. Figure 5. Husk cover of early, intemediate and full season hybrids Figure 6. Relationship between husk cover and aflatoxin content.. DROUGHT HIGH TEMPERATURES AT FLOWERING INSECT INJURY STRESS ON PLANT + INCREASE IN PATHOGEN REPRODUCTION

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FACTORS AFFECTING AFLATOXIN PRODUCTION ACTIVITY DOES NOT START UNTIL KERNEL MOISTURE