Spring planting conditions were good through early May after which conditions were cooler and wetter than average. The north and eastern areas of Wisconsin had record rainfall during May and early June often delaying planting. Many acres in eastern Wisconsin were not planted until July. Accumulation of growing degree units was below average. Insect and disease pressure was not significant. Plant emergence and stands were above average. Corn development was behind average due to cool growing conditions, but development caught up somewhat during September. A killing frost did not occur until early-October, but in some areas light frost occurred in late August. Both corn silage and grain harvest were delayed due to slow development caused by cool temperatures during the growing season.

Silage and grain yields were quite variable Tables 1 and 2). Yields were above average in southwestern Wisconsin. During the fall harvest season, hybrids generally had good standability and grain moisture was greater than normal. The plots at Fond du Lac were variable due to wet field conditions after planting and wildlife damage. Plots at Rhinelander were not harvested due to high grain moisture (>40%). Lancaster was the highest grain yielding site and was 31% above its 10-yr average (Table 1). Lancaster was the highest silage yielding site, but Valders was 28% above its 10-yr average.

Table 1. Summary of the 2004 UW corn hybrid performance trials for grain yield (bu/A) conducted at twelve locations in Wisconsin. N= number of hybrids tested.
	1994-2003		2004		Percent
Location	N	Yield	N	Yield	change
Arlington	1841	197	174	210	7
Janesville	1840	194	174	236	22
Lancaster	1840	184	174	241	31
Fond du Lac	1623	174	171	168	-3
Galesville	1620	175	171	208	19
Hancock	1619	194	171	215	11
Chippewa Falls	1523	149	145	174	17
Marshfield	1357	156	145	150	-4
Seymour	1199	162	145	154	-5
Valders	1525	151	145	183	21
Spooner	1697	141	123	137	-3
White Lake/Rhinelander	564	109	---	---	---

Table 2. Summary of the 2004 UW corn hybrid performance trials for silage yield (T/A) conducted at nine locations in Wisconsin. N = number of hybrids tested.
	1994-2003		2004		Percent
Location	N	Yield	N	Yield	change
Arlington	491	9.4	52	9.7	2
Lancaster	491	7.9	52	10.1	27
Fond du Lac	476	8.5	57	7.7	-10
Galesville	477	8.6	61	9.1	6
Chippewa Falls	104	7.5	51	8.1	8
Marshfield	486	6.8	52	7.1	5
Valders	491	6.6	52	8.5	28
Rhinelander	42	6.3	27	6.4	2
Spooner	84	6.6	54	7.9	19