Finally a few days with average temperatures at Arlington, WI! On June 18, the first five planting dates, from April 15 to June 5, were 130 to 40 GDUs behind average accumulation. Since 1963, an April 15 and May 3 planting date would accumulate by June 18, an average of 704 and 591 GDUs with a standard deviation of + 99 and 80 GDUs. The GDU accumulation to June 18 for the April 15 and May 3 planting dates during 2003 is 578 and 473 GDUs, significantly less than an average year. Since 1963, only three years have been cooler: 1997 (501), 1983 (508), and 1966 (561) for the period April 15 to June 18. For the period between May 3 and June 18, the coolest years were 1997 (431), 1974 (456), and 1983 (470). The most GDUs accumulated between April 15 and June 18 occurred in 1977 (955), and for May 3 to June 18 occurred in 1991 (772).

In this experiment, plants continue to achieve growth stages at appropriate model GDU benchmarks. The VE stage tends to be achieved in later planting dates with slightly fewer GDUs accumulated. The morning of June 18 had about 10% of the spikes emerged for the June 13 planting date. The V6 stage was achieved by the April 15 planting date on June 13 taking slightly more GDUs than the model benchmark. The earliest planting dates are rapidly growing taller now and management options becoming fewer as fields near lay-by.