Effect of Pesticides and Surfactants On “Arrested Ear Syndrome” On Different Inbred Lines of Corn at Puerto Rico.

A strange biological phenomenon characterized by severely reduced growth of developing ears was observed in several inbred lines of corn at Santa Isabel, PR. While the growth of husks continued, the elongation of tip of ears completely stopped and eventually produced hollow ears without grains. This biological phenomenon was observed in few Mid-West states of US during 2006-07, and was designated as ‘Arrested Ears’. A study was conducted to find out whether spraying effects of pesticides and surfactants on inbred lines of corn cause ‘Arrested Ears’. The study was conducted in a split plot design, where 10 combinations of pesticides and surfactants were sprayed as a main plot, and five inbred lines of corn were randomly planted as a sub plot in each main plot. The study was conducted at two different locations with two replications within each location. All 10 combinations of pesticides and surfactants were repeated as five sprays at V4, V6, V7, V8 and V10 growth stages of corn inbred lines.  Percent ‘Arrested Ears’, and plant height at V6 and V10 growth stages were recorded and the data was analyzed by Proc Mixed procedure of SAS 9.2. The combination of multiple pesticides with R-11 (produced by Wilbur-Ellis), a non-ionic surfactant, was found to produce highest amount of ‘Arrested Ears’, followed with sprays of R-11 surfactant alone. Another non-ionic surfactant Cohere (produced by Helena), either alone or in combination with other pesticides also demonstrated symptoms of ‘Arrested Ears’, but in reduced numbers. The plant height also decreased when sprayed by R-11 alone or in combination with other pesticides at V6 and V10 growth stages. These results indicate that it may be necessary to exclude non-ionic surfactants from sprays during ear development to avoid the phenomenon of ‘Arrested Ears’ at Santa Isabel, PR.