Cause Numerous species of fungi, including Alternaria alternata, Fusarium spp. including F. oxysporum, and Helminthosporium spp. Fusarium proliferatum is one species that has been reported to pathogenic to wheat if it occurs on seed. Preliminary investigations by OSU have shown that wheat seed can be infested with Fusarium species and levels of infested seed appears variable among varieties. The fungi listed above infect kernels during seed maturation, especially green kernels, and are favored by high relative humidity or rainfall. Limited studies have preliminary evidence showing that sometimes infection by F. proliferatum can result in a reduction in the number of kernels produced per spike. Some fungi can be pathogenic on seedlings that develop from infested seed. Seed infested with F. proliferatum showed reduced germination when planted under cool temperatures (50ºF) in laboratory studies conducted in Alberta, Canada.
Symptoms Affected areas are light brown to black in coloration and kernels may be shriveled.
Chemical control Seed treatments can improve germination and seedling health if more pathogenic species incite black point (See seed treatments listed under Wheat-Seed Decay and Damping-off).
Fungicide application to protect seed heads during maturation are usually not economical.
- Miravis Ace (Group 3 + 7) at 13.7 fl oz/A. Apply between Feekes 10.3 and 10.5.4. Harvest interval is 7 days for forage and hay. 12-hr reentry.
- Trivapro (Group 3 + 7 + 11) at 9.4 to 13.7 fl oz/A. Apply from Feekes 8 through Feekes 10. Do not make more than two (2) applications per season. Do not apply within 7 days of harvest for forage or hay. 12-hr reentry.
References Conner, R.L., Hwang, S.F., and Stevens, R.R. 1996. Fusarium proliferatum: a new causal agent of black point in wheat. Can. J. Plant Pathology 18:419-423.
Wiese, M.V. 1987. Compendium of Wheat Diseases, 2nd ed. St. Paul, MN: APS Press.