THE RESPONSE OF SWEET CORN CULTIVARS TO COMBINATIONS OF THIOCARBAMATE HERBICIDES AND THE INSECTICIDE FONOFOS

The response of 18 cultivars of sweet corn (Zea mays L.) to preseeding, soil incorporated applications of Eradicane [combination of EPTC (S-ethyl dipropylthiocarbamate) and R-25788 (N,N-dially1-2, 2-dichloroacetamide) as antidote] 4.5 and 6.7 kg/ha, Surpass [a combination of vernolate (S-propyl dipropylthiocarbamate) and R-25788] 6.7 kg/ha alone and in combination with the insecticide fonofos [Dyfonate (O-ethyl S-phenyl ethylphosphoro-dithioate)] 4.5 and 5.6 kg/ha was investigated over a 3-year period (1978–1980). Although results varied from year to year 10 cultivars proved moderately to extremely sensitive to the Eradicane-fonofos combination with Seneca Star having up to 65% deformed husks and ears, Golden Sweet EH 54%, Jubilee 41%, Golden Beauty 35%, Seneca Chief 23%, Silver Queen 17%, Sugar King 16%, Illinichief 14%, Stylepak 10%, and Tri-Gold 9%. The remaining cultivars could be considered tolerant to the combination with Morning Sun and Earlivee having up to only 4% malformation, Earliking 3%, Seneca 60 1%, Improved Carmelcross <1%, and Beacon, Spancross and Polar Vee 0%. These studies suggest that the response to Eradicane-fonofos combinations tend to be related to maturity, i.e., early maturing cultivars escaped injury while later maturing did not.
Eradicane alone generally did not affect ear quality but in 1979 Eradicane 4.5 kg/ha caused 3% ear malformation in Seneca Star and 2% in Golden Beauty; while the 6.7 kg rate caused 5% injury in Seneca Star, 4% in Golden Beauty and 2% in Jubilee.
Generally, when deformed ears exceeded 10% marketable yield was reduced.
None of the other treatments appeared to affect ear quality.
No treatment affected seedling emergence or mature height of the corn.
The data show that economic losses may occur in sweet corn when the herbicide Eradicane is applied simultaneously with the insecticide fonofos.

Weeds and Herbicides, XXI IHC

Jack A. Freeman

https://doi.org/10.17660/ActaHortic.1983.136.3