September 2012 Archives

By John Lamb
Extension Soil Scientist

This year the crops have matured early and harvest is moving ahead of normal.  With a large amount of the soybeans and corn coming out, thoughts are turning to getting fertilizer applied for next year's crop.  For phosphorus and potassium, there are very few problems with an early fall application.  These nutrients are not mobile in most soils.  The only big concern with a broadcast application of P and K is getting the fertilizer incorporated into the soil so it is in a place for the plant roots to utilize them next spring.  Incorporation also reduces the chances of P and K being lost through erosion.

By Dean Malvick

Development of corn ear and kernel rots and associated mycotoxins in grain may have been favored by the dry and hot weather in some areas of Minnesota this summer. Although few problems with ear rots or mycotoxins seem to have been reported so far, only about 12% of corn was harvested in Minnesota as of September 16 and there is much grain to be harvested where potential problems may have occurred. Several different types of ear rots occur in Minnesota, but Aspergillus ear rot and Fusarium ear rot are of greatest concern because they produce mycotoxins and are favored by hot and dry conditions.

The unusually warm summer this year now means that there are many acres that have been harvested that potentially could be planted to winter wheat. It appears that the lack of rainfall could be a deterrent to winter wheat planting, at least to getting it planted during an optimum period. Our current recommendations are to plant winter wheat in the northern half of Minnesota by the middle of September and the rest of the state by October 1st. Unfortunately, there does not appear to be any rain in the immediate forecast. Planting into dry soil and waiting for rain is a viable option. In this scenario, put the seed about an inch deep so that it will be able to emerge quickly once rainfall is received. Though seeds that just begin the germination process will vernalize (meet the necessary cold requirement to produce a spike in the summer), a much larger seedling typically has a better chance of overwintering and being more productive. In the last three years of our research, the early planted treatments have always been more productive than those planted later than optimal, though the difference was not always large, depending on the year and the variety grown. If the warm weather we are currently experiencing spills over into the October, however, there should be ample time to produce a productive seedling, even if rains delay a week or two more.

The following are some guidelines to consider when planting winter wheat late or in conditions where it may germinate and emerge late:

• Increase your seeding rate by about 150,000 to 200,000 seeds per acre. There is no advantage to seeding more than 1.8 million seeds per acre, however.
• Select more winter hardy varieties. Late planted seedlings will be small as winter approaches and will be more prone to winter injury, particularly if there is little snow cover this winter. A winter hardy variety will help reduce the risk of winter injury and be more productive when conditions are conducive to winter injury. Check the most recent University of Minnesota Variety Trials Bulletin for information about the winter hardiness of varieties currently available for planting.
• Plant into standing stubble if you have a choice. Standing stubble will catch snow, if there is any, and help insulate the crop during the winter. Since late plantings are more prone to winter injury, management practices that increase the likelihood of warmer soil temperatures will improve the chance of winter survival.
• Add some phosphorous with the seed. This is especially true if your soil test for P is low. P helps to develop strong roots and crown tissue which will aid in the overwintering processes. The rate of P applied, should be limited by the amount of N that is applied with the P. With narrow rows, nitrogen should not exceed about 15 lbs/acre with the seed, particularly in these dry conditions. With wider rows, be more conservative with the rate.
• Consider treating your seed with fungicides and possibly an insecticide. Since the seed may lay in the soil for an extended period before germination, a fungicide applied to the seed will help protect it from diseases and an insecticide will be beneficial especially if wireworms are likely to be present.