What a beautiful weekend! It was a welcome change from the winds we received last weekend and early week. The high winds early in the week created difficult situations from many perspectives-soil loss, visibility, accidents, and drying out the seed bed.
Great to see several on-farm research plots going in and to have some new cooperators this year! I also started a very small soybean planting date demo at the York County Fairgrounds on April 24. A farmer on Twitter was encouraging other farmers to try planting a few seeds every week for yourselves in a garden plot and count the nodes and pods. Thought it was a great idea and will have it signed at County Fair regarding soil temps for first 48 hours and nodes. Thanks to Jed Erickson from Pioneer for the seed!
Rain events on May 1-2 allowed for some soil moisture recharge in the first and second feet in some locations. Unfortunately, the rainfall was still fairly spotty. We could really use rain overall for getting moisture back into drying seedbeds, activating herbicides, and settling dust. Pivots are running in some fields because of these factors. I provided an update on the locations I’m monitoring regarding soil moisture as of 5/3/18 on my blog at http://jenreesources.com. The farmers were interested in continuing this monitoring throughout the growing season this year, so will continue sharing as often as I can.
Wheat: Wheat’s joined in the area and ranges in height depending on soil moisture. For the past few weeks we’ve been noticing yellowing leaves. Some of that may have been due to cold temperatures. I was also seeing powdery mildew within the canopy of several fields I looked at. No rust has been observed yet in Nebraska fields. I also noticed tan spot in wheat on wheat fields. One concern was the cool weather has allowed for bird cherry oat aphids in area wheat. My concern is that they can vector barley yellow dwarf virus which is one we see when the flag leaf emerges. According to K-State, there’s not strong developed thresholds. They’re recommending if 20 or more aphids are observed per tiller with lady beetles observed on fewer than 10% of tillers, spraying may be justified.
Lawn and Garden Information: With this year’s cool spring, crabgrass preventers can still be applied the first few weeks of May. Germination begins with soil temperatures around 55F but prefers warmer soil temps. UNL Lawn calendars for Kentucky Bluegrass, Tall Fescue, and Buffalograss and all UNL lawn resources can be found at https://turf.unl.edu/turf-fact-sheets-nebguides. Mowing heights should be maintained at 3-3.5″ for the entire year. We also recommend just mulching clippings back into the lawn to allow for nutrient recycling. If you like to use mulch for your gardens, it’s important to read pesticide labels on products applied to your lawn. Some labels say it is not safe to use the clippings as mulch. Others say to wait at least three mowings before using the clippings as mulch.
Garden centers have been busy with the warmer weather and some have asked about temperatures for hardening off transplants. Kelly Feehan, Extension Educator in Platte County shares, “May is planting time for most annual flower and vegetable transplants. To avoid transplant shock and stressing young plants, wait for soils to warm up and take time to harden off transplants. Soils are colder than average this year so waiting to plant will be beneficial. And then, plants moved directly from a warm, moist greenhouse to windy and cooler outdoor conditions will be stressed by transplant shock. This can negatively affect plant growth, flowering, and vegetable production. Harden off transplants by placing them outdoors, in a protected location, for at least a few days before transplanting outdoors. Another way to harden transplants is to plant them in the garden, then place a cardboard tent or wooden shingle around them for a few days to protect them from full exposure to wind and sun. Planting young transplants on an overcast, calm day or during the evening also reduces transplant shock.” Specifically when it comes to tomatoes, it’s best to wait till mid-May otherwise “gardeners who plant earlier need to be prepared to protect tomato plants with a floating row cover or light sheet if cold threatens. To help tomato transplants establish quickly, begin with small, stocky, dark green plants rather than tall, spindly ones. Smaller plants form new roots quickly and establish faster than overgrown transplants. Do not plant too deep or lay tomato stems sideways. Although roots will form on stems below ground, this uses energy better used for establishment. Use a transplant starter solution after transplanting tomatoes to be sure roots are moist and nutrients are readily available in cool soils. Wait until plants are growing well before mulching or mulch will keep soils from warming and may slow tomato growth.”
Damage to heads from frost/freeze is beginning to appear as white awns/florets in wheat heads. Thankfully this damage is very minor in area wheat fields right now.
Barley yellow dwarf is also appearing in fields and is noticeable by flag leaves with a yellow/purple color. This is a disease vectored by various aphid species. The aphid in this photo is a corn leaf aphid and I’m seeing these in wheat as well right now in addition to lady beetles which are feeding on them. We also observed aphids last fall and were concerned about them potentially vectoring this disease. I would say this is my least favorite wheat disease because you can do many things correct with wheat just to have this one show up and affect yield.
Also seeing some loose smut in fields which again is fairly minor. Both loose smut and stinking smut (common bunt) can be prevented by using a seed treatment fungicide at planting. Often these diseases occur in fields where wheat has been planted and smut has occurred before and when using bin-run wheat that has not been treated with a seed treatment fungicide. Also notice all the yellow ‘flecks’ on these leaves which are indicative of fungal infection (most likely rust) on these leaves.
According to research, wheat is susceptible from flowering through soft dough development stage. “Typical” fungicides used for control of fungal leaf diseases are off-label thus illegal to apply once the wheat has flowered and they do not have activity on the Fusarium fungus causing scab of wheat. Management for scab includes the use of the preventive fungicides Caramba or Prosaro. Both are labeled for headed and flowering wheat. There’s a 30 day pre-harvest restriction for both. Rainfast varies from ¼ hour to 2 hours or when dry depending on environmental conditions. Both fungicides can help prevent scab and control rust on the plant.
Research from the US Wheat and Barley Scab Initiative (which is a combined effort of several Universities in the U.S. and Canada) has found that the best prevention using these products occurs when wheat is headed and 30% of the plants are in the beginning flower stage. Application within five days of these criteria still showed positive results. This research also showed that application before or after this time period greatly reduced effectiveness of preventing scab. Understandably, the economics of fungicide application are difficult in wheat, yet, if you are aiming to make one application, this could be your best option for both scab prevention and controlling rust in your plants. The risk map for scab can be found at: http://www.wheatscab.psu.edu/. With wheat at heading to beginning flower and rain/humidity this risk in reality could be higher for us.
This past week was a blur of calls, questions, and visits to homes and fields but it was a great week and flew by staying very busy! I’ll touch on a few of the common questions I’ve received this week.
Trees: Some trees such as willows, hackberries, tops of maple trees, ash, and black walnut are just taking time leafing out. Some trees leafed out once already and dropped leaves. Things that may have caused this were the sudden flux of temperatures from very warm to cool and the strong winds we received. Some trees have also unfortunately had herbicide drift damage that caused leaves to drop. On those trees, watch for new buds as nearly every situation I’ve looked at thus far have new buds forming after about a week-10 days. With all these situations, give the trees a few weeks to leaf out again and if they’re still not doing it, feel free to give me a call. Trees are interesting plants as sometimes environmental impacts that happened 3-5 years ago will show up that much later-and sometimes environmental impacts show up right away!
Disease/Insect issues: This year has been a strange year all around but with our warm winter, I was concerned about an increase in diseases and insects. Thus far, we’re experiencing increases in both-so hang on-it may be a long growing season! Our high humidity, warm temps, and heavy dews have created perfect conditions for fungal diseases on our trees, ornamental plants, lawns (I’m currently fighting a bad case of powdery mildew-as a plant pathologist it is kind of pretty but I don’t like what it’s doing to my lawn!), and in our wheat and alfalfa crops and some pasture grasses. Fungicides may help in some of these situations, increasing airflow can also help as can more resistant varieties or hoping the weather will change. In the case of most ornamentals, we don’t usually recommend doing anything. The same goes for insects as insecticides can help in some situations. I’ve received several calls this past week of people afraid they had herbicide drift damage. While there were a few cases of that, many of the cases were actually fungal leaf spots on leaves. There are various fungicides and insecticide products available from home/garden centers, etc. Be sure to read and follow all label directions and only apply the product on places the label specifies it can be applied.
Crops Update: Later this week we may have a better idea on the extent of storm damage and if some fields will need to be replanted after the storms from last week. Dr. Bob Nielsen from Purdue University reported that most agronomists believe young corn can survive up to about four days of ponding if temperatures are relatively cool (mid-60’s F or cooler); fewer days if temperatures are warm (mid-70’s F or warmer). Soil oxygen is depleted within about 48 hours of saturation and we know soil oxygen is important for the root system and all the plant’s life functions. So we’ll have to wait and see what happens.
Have also had a few calls regarding rye cover crops. When rye is killed out and decomposing, it releases toxins that can affect the germination of other cereal crops such as corn if it’s going to be planted into that rye cover crop. Thus we recommend at UNL that the producer kill the rye and then wait at least two weeks to prevent any major damage to the crop. I realize at this point with the rains to get in and kill that crop on top of waiting an additional two weeks, we’re getting close to the end of the month and will most likely be looking at reduced yields…and depending on maturity, you may need to consider different seed if you end up having to plant in June. If you have specific questions about this, please let me know and we can talk through some situations.
Stripe rust and powdery mildew have been obliterating mid-lower canopies of many wheat fields. I’ve received several calls on why wheat canopies are yellow-that’s the main reason but other factors such as the dry spell prior to these rains and/or deficiencies in nitrogen/sulfur or some viruses may also have been factors. Wheat in Nuckolls County last week was beginning to flower. Fungicides such as Prosaro, Folicur, or Proline are labeled for up to 50% flowering and cannot be applied after that. Remember the wheat head begins pollination in the middle-so if you’re seeing little yellow anthers at the top or bottom of that head, you’re towards the end of flowering. All those products have a 30 day pre-harvest interval-which has been the other main question-are we going to be harvesting in a month? I do believe we’ll be harvesting a month earlier than normal just because pretty much everything in wheat development is about a month ahead of schedule. I still feel the 30 day window for the fungicide application is worth it with the large amount of disease pressure we’ve seen. Wheat in Clay Co. and north still may have time for a fungicide application; those products mentioned above will help prevent Fusarium Head Blight (scab) as well as kill the fungi causing disease already present on your leaves. A list of all fungicide products, pre-harvest restrictions, and rates can be found here. Also check out my previous blog post with video on scouting for wheat diseases.
The other major disease appearing in wheat is barley yellow dwarf virus. This is a virus vectored by bird cherry oat aphids which we were seeing earlier this year. Unfortunately, this disease causes the flag leaves to turn bright yellow-purple causing yield loss (at least 80% of the yield comes from the flag leaf) as there’s nothing you can do once the virus manifests itself in those leaves. If you have a large incidence of barley yellow dwarf in your fields, you may wish to reconsider spraying a fungicide as the fungicide won’t kill the virus; however, it will help kill the fungi on the remainder of your leaves and potentially help protect some yield from the two leaves below the flag leaf.
Questions have been rolling in regarding dead leaves in the mid to lower wheat canopy. Wheat is heading in much of South Central Nebraska and in some cases has begun to flower. When considering a fungicide application, once your wheat has begun to flower, there are only certain products that are labeled for use. These include but are not limited to fungicides such as Proline, Folicur, and Prosaro. All of these have a 30 day pre-harvest restriction and can only be applied up to 50% flowering. For more information on all fungicides, rates, and pre-harvest restrictions for wheat, please check out this resource from Dr. Stephen Wegulo, UNL Extension Wheat Pathologist. Below is a short video of me scouting a wheat field so you know what to look for in your fields. Fungicides will not help leaves affected with barley yellow dwarf as that’s caused by a virus; however, with the amount of stripe rust in our canopies and seeing it on the flag leaves already in addition to the rain and humidity allowing for increased risk of Fusarium Head Blight (scab), I still feel a fungicide is a good option.