June 3, 2013

                Wet, that seems to be the theme to this spring season. After coming off a record amount of moisture in May one can only hope June will bring warmer, dryer weather. With most planting conditions not being ideal due to the great amount of moisture we have accumulated this past May, soils are left saturated. Saturated soils will pose a challenge not only at planting time but, for the rest of the growing season.

                Fungicide at V5-V7 is going to be more important this year because of the wet soils. The more moisture in the soils, the more prone the early stage corn is to disease. The main disease this fungicide application would be targeting is anthracnose stalk rot. Anthracnose survives in the residue and turns the bottom half of the corn plant a black color. Although the plant is infected in June one will not see the rot show up until August. Fungicides are a great tool to help prevent the start of anthracnose.

Anthracnose Stalk Rot

                The spring rains have also delayed planting of corn and soybeans. Since the calendar reads June 3, most everyone has had to make the decision to switch corn or bean maturities. When it comes to switching corn we are at the point of the year where one must take a good look at the GDU’s (Growing Degree Units) till physical maturity, or black layer. The less GDU’s till black layer the sooner it will be ready in the fall. Our main concern is if we were to get an early frost.

When looking at soybean maturities we believe one should wait till at least June 15 before looking at switching to earlier maturities. In a later planting scenario, like this year, a soybean variety of 0.5 to 1.0 shorter maturity group is recommended after June 15. Also since soybeans are photoperiod sensitive, they will flower at the same time despite planting date and relative maturity. Earlier planted soybeans simply have more nodes and greater yield potential. There has been some research done at Iowa State's research farm located in Nashua. The graph below shows you that with the research gathered the late maturity varieties had greater yield potential across all the planting dates.  A few other tips when planting beans after June 1^st would be to increase populations by 10%. The increase in population will help get more nodes in the field and the increased plant density will hasten canopy closure, make the beans taller and increase the number of pods per acre. The use of narrower rows has also been proven to be better with the later planting date.

 



Influence of planting date on soybean yield of early (1.7) and late (3.0) maturity varieties (2004-2008).