June 27, 2013

                This past week we have once again been sidelined with some heavy rains. The southern locations have been a bit on the dryer side and able to work through some of the rain fall. The northern locations have been saturated with rain and in some cases flash flooding. These wet soils have led to many questions about the survival of crop and nitrogen loss.

                First let’s talk about the survival of corn and beans in the flooded or saturated areas. There are several factors that corn survival depends on: length of time flooded, partially submerged or completely submerged, temperature, and stage of development. Basically, corn in flooded soils depletes its available oxygen in 24 to 48 hours. Continued survival is better with cool temperatures, cloudy days and clear nights. Also, partially submerged crops can withstand flooding considerably longer than completely submerged crops. The crops which do survive may have disease problems later in their lifecycle. Soybeans follow almost all the same guidelines. They will only be able to survive for 24 hours without oxygen, and completely submerged fields will suffer a greater loss than partially saturated fields.

                The next big question is; “What is happening to my nitrogen?” There are a few different considerations one must look at. First, some areas where apparent nitrogen loss appears to be showing up may be a lack of oxygen to the corn roots. Oxygen is needed for normal root development and for efficient uptake of nutrients by the roots. Oxygen levels will be depleted in flooded soils and foliar symptoms can be exhibited that may look similar to nutrient deficiencies.  Second, we need to look back to when the nitrogen was applied. Early fall applications will obviously have the greatest risk of leaching, whereas late spring or side dress nitrogen will be the most likely to still be available. When the decision comes to rescue apply nitrogen we will have to take into consideration, timing, cost, current crop condition, yield potential and application method.

                Just last night we observed some of the first lighting bugs in the area. As most know when the lighting bugs show up we should start to be concerned with the root worm and corn borer hatch. According to Iowa State University the corn rootworm egg hatch typically occurs from late May to the middle of June, with the average hatching date around June 6^th. Egg development is driven by soil temperature, which is measured by degree days. Iowa State research suggest about 50% of egg hatch occurs between 684-767 accumulated degree days based on a soil temperature of 52 degrees. The map below shows the heat unit accumulation at Iowa State rootworm stations on 6-14-13. On an average summer day in northeast Iowa we accumulate approximately 18 heat units. This leaves us roughly 13 days from 6-14-13 until the hatch will begin.

Thanks for reading and if there are any questions about the topics discussed above please stop and ask one of the agronomists at a location near you.

June 13, 2013

                With the talk of preventive planting sweeping the country side there are several questions being asked about what to do with the preventive plant acre. Many of the questions will have to be answered by either your insurance man/women or county FSA office but there are plenty of cover crop questions the agronomy team at FFC would be happy to discuss. The three crops we are recommending as a fallow ground cover crop would be oats, rye and tillage radish. These three crops all are going to keep the soil working and nutrients available for next year’s growing season. The supply on these crops is all over the board with oats being very hard to get, rye being available but in a tight supply and tillage radish having a good supply. Feel free to stop by any location and talk to an agronomist about what cover crop would best fit your acre.

                The few days it hasn’t been raining we have been busy spraying post emerge corn, pre emerge corn, and pre emerge beans. A few things we have been noticing are that although the weather hasn’t been very favorable for vegetative corn or bean growth it seems that weeds in some fields have not slowed down. As difficult as it’s going to be to get in the fields this year to spray we are going to have to make sure we are using extra precautions for the best kill possible. This may mean slowing down, increasing gallons per acre and spiking in some extra chemical to make sure it kills the larger weeds.

                The scouts at FFC have been busy these past weeks covering many acres. They have been seeing a little bit of everything in the fields. In some areas the weed pressure is starting to develop and in other fields weed pressure is minimal. There hasn’t been much bug pressure yet but we expect that to be coming. The number one issue out there now is flooded out fields. In these flooded out or extremely wet fields we have discovered some rhizoctonia in beans and pythium in corn. Both diseases strive in the cool wet soils we have been experiencing. The only way to help combat these problems is selecting a good seed treatment. Although it is late in the season and some are leery about spending the money on a seed treatment, we are still recommending it on all bean acres. Below is an interesting picture of a farmer who was using treated beans and finished up the last of the field with some untreated beans. The beans on the left were treated and the beans on the right were untreated.

 

       Thanks for taking the time to read the blog and let’s keep our fingers crossed for some dry weather!

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).