Fusarium graminearum

Abstract

DISTRIBUTION: Grows on different grains, e.g. maize and sorghum. Maize is produced mainly in the North-West, north-western, northern and eastern Free State, the Mpumalanga Highveld and the Kwazulu-Natal Midlands.

BOTANICAL DESCRIPTION: General: • A phytopathogen of especially maize which infests the cobs during the silking stage. • If the weather is rainy and the ears of corn are maturing in late summer and early autumn, F. graminearum may infect only a few to a third of the kernels. • Whatever amount of the ear is infected, all the kernels in that portion becomes heavily infected and decayed by the fungus. It manifests as a pink cob rot progressing from the tip to the base of the cob. • Alternating moderate to low temperatures favour growth and toxin production. • There are many types of cob rot and identification is not straightforward.

TOXIC PRINCIPLE: Zearalenone metabolised to zearalenol. Relatively heat stable.

MECHANISM OF ACTION: Binds to intracellular oestrogen receptor.

SYNDROMES: Hyperoestrogenism.

SYSTEMS AFFECTED: Urogenital system.

CLINICAL SIGNS: • Latent period 5 - 8 days. • Recovery about 7 days after withdrawal of contaminated food. • Frank oestrogenism. • Only pigs affected in S.A.

Female: • Seen especially in prepubertal gilts • Swollen vulva, slight turbid discharge • Development of mammary glands • Prolapse of vagina and rectum • Sterility of sows, smaller litter size, agalactia.

Male: • Development of mammary glands • Swollen prepuce • Atrophy of testicles • Decreased libido.

NECROPSY: Usually not fatal.

DIAGNOSIS: Characeristic syndrome in large number of pigs. Send feed specimen to laboratory for chemical determination of zearalenone content.

TREATMENT: Withdraw contaminated feed. Avoid storage of high moisture grain on cob in open cribs.