Field experiments were conducted in 1986 through 1988 to evaluate the effects of rates and timing of ethephon application on growth, yield, and lodging of `Jubilee' sweet corn (Zea mays L.). As a comparison, hand-topping was performed 10 days after early silking to simulate the commercial practice of mechanical topping to reduce lodging. Ethephon reduced plant height by 12% to 26%, with timing of application determining location of internode length reductions. There was greater reduction of ear height by ethephon applied at tassel elongation (TE) than at 1 and 2 weeks later. Effects of ethephon on husked yield varied from an 8% increase in yield to an 18% decrease, depending on rate, timing, and season. Topping reduced yield in one of the four experiments. Ear length was reduced by ethephon at 0.28 kg·ha-1 in two of the four experiments. A helicopter fly-over resulted in 66% of topped plants lodging, compared to 87% of untreated plants. Lodging of plants that received an ethephon application of 0.28 kg·ha-1 at TE averaged 51% for Expts. 2, 3, and 4. The amount of lodging tended to be least in those ethephon treatments with the largest reduction `in plant or ear height. Chemical names used: 2-chloroethyl phosphonic acid (ethephon).
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