Wiles Bros Fertilizer, Inc. Plattsmouth, NE (402) 298-8550

Corn planting in some parts of the state is has begun. The soil temperatures for April 6th through the 12th at Mead averaged 49.2 degrees—4.4 above normal for the week. It is much easier now to plant corn with confidence as most all of the reporting stations across the state have soil temperatures at or above 50 degrees. This is attributed to the soil temperature "evening out" with not as many wild temperature swings on a daily basis. Most all of Eastern Nebraska received "some rainfall" last week. Some rainfall can be categorized by a few drops to up to 1 inch in places last week. Subsoil moisture is still basically at field capacity to the 12" soil layer in most areas.
I have not noticed any emerged corn as of yesterday, which is expected given the soil and air temperature patterns of late. Germination, although slow, has begun however with corn that was planted on April 2^nd. This is attributed to corn hybrids having better germination and emergence in cold/wet environments. Under warm and moist conditions, corn emergence can occur in 4-5 days after planting, but under cool or dry conditions it may take up to 2 weeks to emerge dependent on the hybrids ability for germination under cold conditions—Hybrids do vary in this aspect!. Even though the soil temperature is warm enough for water absorption to begin into the kernel, active growth will be slow until we have some extended warm conditions to accumulate enough Growing Degree Day (GDD's) for the corn to emerge.

This spring is SHOULD produced insect pressures in fields being planted to corn at levels which, may potentially cause many producers to consider replanting the affected areas. Evenwith in-furrow or broadcast insecticide treatments, Eastern Nebraska will likely experience widespread amounts of black cutworm. There is also evidence of a large population of whitegrub, which may also impact the emerging stand. These insects and the amount of them should not be surprise given last years infestations as well as the winter conditions (lots of snow acts as an insulation blanket) which increased the amount of eggs that survived the winter. Cool wetter weather slows down corn germination and plant growth down just enough to cause significant feeding to occur. The bad news is that if an insecticide treatment is not made as an in-furrow application, feeding can occur and there is not much recourse from a insecticide application-The insecticide must get into the germination zone to have much of an affect. Many producers can manage this problem through waiting just a few more days to plant cornallowing the warmer weather to germinate and emerge the corn plant in a quick manner. This decreases the chances of seed feeding insects to have an opportunity to cause economic injury. The good news is that corn’s normal growth rate, once past the 3-leaf stage, is usually fast enough to withstand the feeding until the soil profile is warm enough (consistently in the 70s) to force the larvae of the worms deep into the soil out of rooting zones of the corn. Stand loss after this point of plant development is rare.

Fields treated with insecticides are not immune to these insects. There are many reasons, which can contribute to the insecticide failures, but the predominant cause is the cool, wet weather during this seedling establishment phase of the corn development, causing higher, viable populations of these insects. These conditions also slow down crop development. Given the right soil type and organic matter, ample soil moisture has the ability to also leach many treatments out of the their effective zones in the soil for insect and weed control. Insecticides create a “barrier zone” in the seedling rooting depth. That zone is vulnerable to leaching much like fertilizer solutions are during periods of abundant moisture and slow crop growth. Many of the soil insecticides being used have only a one to two week soil residual.

Winter annual weeds are emerging. Recent rainfall of various amounts have gone a long way to re-charge weed germination and development. Soon summer annuals such as foxtail and velvetleaf will emerge and actively grow in you fields. While your method of control has likely changed with the development of Roundup Ready Technology, crop and weed competition has not changed for some time. It brings up the question of "How long can I wait to make a post-emergence herbicide application?" Waiting longer to make applications to summer and winter annual weeds not only decreases the efficacy of any herbicide but also increases the chances of weed resistance. This year it is possible that you may be finishing planting activities while first planted fields need post-emergence applications for weed control. Potential for yield reduction involves many things such as weed height at application, crop height at application, weed type, weed density and weed distribution throughout the field. Planning when to make your applications can be determined mainly by the type of weeds you have present along with their density and in what crop they have occurred.

Crops compete with weeds for water, sunlight, and nutrients needed to sustain active growth. Corn competes differently than soybeans, sorghum or wheat can against different species of weeds. The following is some work done from 1996 to present through the University of Nebraska Weed Science Department that addresses just this issue. Note the number of broadleaves compared to the number of grasses it takes to cause the same percentage of potential yield reduction. Table A. represents the number of weeds per 100 ft² that will cause a given yield reduction in corn. This assumes that weeds emerged with corn and no herbicide has been applied. These numbers only consider the effect of the weed in the current year and do not take into account future weed problems due to weed seed production. This should be considered if these numbers are used to make long-term decisions.

A good rule of thumb regardless of what herbicide you are using in corn or soybean production is to make the application prior to broadleaves reaching 4" in height and grasses more than 2"in height. I realize that this is easy to say and based upon the number of acres you have to cover, may be difficult to achieve. Applications prior to this stage of weed development can minimize the competitive affects (yield injury, water, nutrient utilization) the weeds are having on the developing crop. It also improves your chances of a high percentage of weed control.

Soybean diseases such as damping off from Phythium and Phytophthora are and will likely be prevalent this spring as soybean planting begins. Low lying areas prone for ponding water or water-logging are most suspect for these disease issues. “Damping off” is a cover-all term used to describe symptomology of these diseases. The rule is if damping-off occurs in warm soil (70 to 80 degrees) it is more likely to be caused by Phytophthora Root Rot (PRR). There are upwards of 45 races of Phytophthora, which greatly complicates breeding for resistance and adds confusion to growers when selecting appropriate resistant varieties. The specific gene resistance, known as Rps1 genes that is bred into many soybean varieties provides protection against several known races of PRR. The gene Rps1a provides protection against 17 races of Phytophthora; Rps1c, against 23 races; Rps1k, against 24 races. However, none of these specific genes provides protection from race 25, which is becoming more common in many areas in Eastern Nebraska.

PRR may attack soybeans at any growth stage. Seed rot and preemergence damping-off can occur in flooded or ponded soils, while postemergence damping-off and seedling stem rot cause wilting and plant death. Symptoms of older seedlings on "low-tolerance" varieties include soft, water-soaked stems with leaves yellowing and wilting — often leading to plant death. Older plants of affected low-tolerance varieties may be killed gradually. The roots turn brown and the upper leaves become yellow between the veins and leaf margins, accompanied by complete wilting of the plant. Generally, symptoms occur on isolated plants scattered across areas of a field, rather than large patches of infected plants as seen with sudden death syndrome or soybean cyst nematode damage

Damping off occurring in cool soils (50-60 degrees which we have right now) it is more likely to be caused by Phythium. Both diseases cause the root and lower stem tissue to turn brown/purple with a slimy texture, which can lead to seedling death. The best line of defense is to purchase genetic packages with strong tolerances to these diseases. Seed Treatments over the past few years have also proven to add to emergence percentages as well as yield given these types of conditions. You may consider a seed treatment for these areas and conditions to improve your bottom line.