Crop Update: So grateful for this past week’s weather in aiding harvest progress! Also grateful to all the growers who worked with me in on-farm research this year and for all the studies harvested this past week!
One of the more frequent questions/comments I’ve received the past few weeks is regarding yields. It sounds like irrigated yields for corn and even soybean are around 5-15% lower than what farmers hoped for in this part of the State. Most aren’t necessarily ‘bad’ yields, just not what was desired. Irrigated corn is mostly going 225-245 bu/ac with high-yielding genetics and everything else aligned correctly going 250-265 bu/ac. And, as more fields are harvested, there may be some better yields due to the long grain fill period. There’s irrigated fields of soybeans that did 50-60 bu/ac. What is positive is non-irrigated yields for both corn and soybeans with non-irrigated beans sometimes out-yielding the irrigated ones.
The impacts of the difficult cold, wet planting season could be seen season-long in fields
with uneven plant emergence and eventually variable ear height and kernels/ear. That plant to plant variability can add up to yield impacts more than one realizes. There’s also field variability due to ponding/flooding in fields, hail/wind damage, and additional challenges during harvest with wind and moisture leading to lodging and/or ear loss and some soybean shatter.
The high humidity and leaf wetness along with cool, wet weather allowed for more disease in both corn and soybean. Perhaps one reason why non-irrigated corn and soybean are yielding well was due to reduced disease pressure from reduced plant population and increased air flow. I know of a handful of irrigated soybean fields in 2019 planted on seed corn acres where, to the line, the soybean on seed corn had more sudden death syndrome (SDS) pressure and less yield than the soybean on soybean corners of fields. I had never before seen this so striking.
My hypotheses: 1-Test for soybean cyst nematode in the seed corn acres vs. corners. Anything that will move soil will move SCN, including equipment. 2-Fusarium virguliforme (pathogen that causes SDS), reproduces best on corn kernels followed by corn residue, followed by soybean seeds and residue. Even if the seed corn acres had a cover crop and were grazed, cattle don’t easily pick up loose kernels lost to the 2018 hail storm or harvest loss. 3-SCN in the field + great conditions for SDS in 2019 allowed for synergistic effect of more SDS and yield loss.
Cloudy weather also played a role in photosynthesis and ultimately yield. Dr. Roger Elmore and colleagues shared the following research on shading and yield impacts. “Many researchers have investigated the effects of lower solar radiation on corn using shade cloth of different densities. These can effectively block solar radiation by 10% to 90% or more (e.g., Schmidt and Colville 1967, and Reed et al. 1988). Invariably they found that shading the crop two to three weeks after silking (R1) reduced yields more than shading before R1. Most also find that hybrids differ in their responses to shading.” (This can help explain the tip back due to kernel abortion some of you asked me about after pollination). “Very few researchers used shade cloth during the grain-fill period, which would be similar to the reduced solar radiation period central Nebraska experienced the third week of August.
Early et al., 1967, shaded plants around the “reproductive phase” for 21 days as well as during the “vegetative stage” for 54 days and the “maturation phases” for 63 days. Shading during reproductive stages reduced plant yields the most, but 30% shading during the maturation stages ― what we consider the seed set and grain-fill periods (R2-R6) ― not only reduced yield per plant 25% to 30% but also reduced kernels per plant and the amount of protein per plant. Researchers in a new study shaded plants from silking to maturity (R1-R6) (Yang et al., 2019). Shading reduced yields more with higher plant populations than with lower populations.” (This may also help explain why non-irrigated fields with lower plant populations may have good yields in spite of cloudy conditions in 2019).
Grateful for beautiful weather and harvest progressing again! We got the York County Corn Grower Plot out on Friday and special thank you to Ron and Brad Makovicka for their work and dedication to that effort! I will share the official plot results next week. The York County Corn Grower Banquet will be held on Thursday, November 15 at Chances ‘R in York with social time at 6:30 p.m. and meal at 7:00 p.m. Tickets are only $10 per person for a wonderful meal! Tickets can be obtained from any of the local directors or from the York County Extension Office at (402) 362-5508.Nate Blum from Nebraska LEAD Class 36 will give a presentation on his international tour and there will also be updates from Local, State, and National Corn Directors. For those who estimated yields during the plot tour, you need to be present in order to win the Yeti cooler.
Corn Yields: There’s an interesting article in this week’s CropWatch at http://cropwatch.unl.edu regarding final yield forecasts. Interesting to me are the box plots showing the range of ’30 year average’ vegetative and reproductive stages vs. 2018. The high heat in June shortened the vegetative time-frame. However, the silking through grain fill period was relatively typical for most locations and the long grain fill period with lower temperatures allowed for the better yields we’re experiencing (where drought and late-season hail wasn’t a factor).
Soybean Harvest Losses: Four soybeans in one square foot equals 1 bu/ac harvest loss. Various publications show how to determine harvest losses in areas of 10 to 25 sq. feet. For those with the SoyCorn Pocket Field Guide, page 78 shows estimating loss based on combine header width: http://nebraskasoybeans.org/wp-content/uploads/2017/02/SoyCorn-Field-Guide.pdf.
Evergreen Trees: Some evergreen needles are also changing color right now. It is good to look at your trees to determine the cause of the needle color changes. Evergreen trees actually go through a natural needle drop process with some years resulting in more thinning than others. I think this year may be one of those years as stress events can make needle drop heavier. Needle drop appears as needles turning yellow and falling from the tree. Pine trees may keep their needles for 2-3 or more years while spruce keep theirs for 5-7 years before needle drop occurs. Natural needle drop tends to appear along the main trunk and inside needles of the tree.
I also check for the presence of fungal disease. If the pine tree needles have dark spots/bands on them, it may be a fungal disease like dothistroma needle blight (on Ponderosa and Austrian pines) or brown spot (on scotch pines). The fungi actually kill the needles both directions from the location of the infection. With our heavy rains and high periods of humidity, I’m seeing increased fungal disease in evergreen trees this year. Fungicides applied in mid-May and again in mid to late June can help prevent this.
Pine wilt disease occurs in Scotch and Austrian pines. It’s caused by a bark beetle that has nematodes in its gut. The nematodes are native to Nebraska but Scotch and Austrian pines are not. Ponderosa pines aren’t affected because they’re native to Nebraska. The beetle ‘vomits’ the nematodes into the xylem (water-carrying vessels of the tree). The tree senses the presence of the nematodes and shuts down water to various branches as a way to prevent the nematodes from attacking. Thus why one sees a major branch then side of a tree turning gray-green then yellow-brown. Unfortunately, the entire tree will die typically within 3-9 months. Some farmers have tried trunk injections and drenches around their trees in hopes of saving them, to no avail.
On spruce trees, I’m seeing yellow/purple/browning of needles. This often is due to a fungal disease called rhizosphaera needle cast. One way to determine if this is the culprit is to look for tiny black dots on the gray twigs next to affected needles. The black dots are actually fungal structures that allow for infection to occur. Fungicide applied in May and after heavy rains can help. I always intend to spray my spruce tree each May but have failed to get it done the past several years. With recent rains, I’m trying it this fall to see if it can help; will let you know!
There have been several calls about arborvitae rapidly turning brown and I’m seeing evidence of heavy spidermite pressure at one time. Spruce spidermites affect spruce, juniper, arborvitae, etc. The rains and snow washed them off, which is one way to manage them. Evidence can be stippling (tiny yellow-green dots on needles) and also using a magnifying glass, one may see some webbing on undersides of needles. One can also just bang the needles on a white piece of paper to see if any mites are still active. Mites are most active in the cooler times of the season…so August through October in this case. Great resources for additional information include: Diseases of Evergreen Trees and Insect Pests of Evergreen Trees which can be obtained here: https://nfs.unl.edu/publications.