Crop Update: So grateful for rain and truly hope those who wanted and needed rain received it! An update to soil moisture profile as of 5/17/18 can be found at http://jenreesources.com.
A number of crop issues surfaced this week. One being root burn and wilted-looking corn seedlings from anhydrous ammonia applications with the dry winter/spring we’ve had thus far. Anhydrous ammonia can expand in soils 2.5-3” in all directions and potentially more in dry soils. Pivots were running to help with that and hopefully rain events will help non-irrigated fields that were suffering in this way. Another problem observed in some non-irrigated corn fields has been fomesafen carryover injury from products such as Flexstar, Reflex, Prefix, etc. These products have a 10 month planting window back to corn which is fine in most years, but dry conditions didn’t allow for the herbicide to break down in all situations from applications last June. This active ingredient is in Group 14 (PPO inhibitors) and the injury from this particular active ingredient is unique in that it causes yellow/brown striping of the veins themselves instead of interveinal chlorosis/necrosis. Seedlings most affected right now are found on field edges or wherever there was overlap of application. Hopefully corn should grow out of this injury in time. Herbicide carryover may be a something to watch for in soybean as well from other active ingredients. We also saw regrowth occurring on plants affected by wind/dust/debris damage but there are situations where replanting will be needed on endrows, etc. Roger Elmore has a photo gallery explaining regrowth in this week’s CropWatch at http://cropwatch.unl.edu.
Another situation that surprised me this year was finding seed corn maggot damage in
soybean. At first I was puzzled as the beans were clearly treated but then learned the beans didn’t have an insecticide added to the seed treatment. In scouting a number of fields, I’ve actually seen quite a bit of seed corn maggot damage, particularly in tilled fields and those with manure applied or those with cover crops that were green or where termination included tillage. I’ve also been surprised how many have told me they don’t use an insecticide seed treatment on early planted beans. We didn’t have any research in our early soybean planting studies without insecticide + fungicide seed treatment so we just automatically recommend both. Unfortunately this year we’re seeing what can happen without it with higher insect pressure in some fields. For seedlings with the insecticide seed treatment, I’m seeing light scarring on the cotyledons and hypocotyls but no maggot penetration. In fields without the seed treatment, I’m actually seeing penetration of the cotyledons and hypocotyls. The good news is that most of the maggots were also pupated, pupating or will be soon. But it is something to watch for, particularly in fields that have been tilled and especially if manure was applied or they were tilled and had a cover crop on them. They are not as attracted to no-till fields. Regarding stands, from my experience with soybean pops and stand loss due to crusting, hail, herbicide injury, etc., I keep stands of 60,000 plants/acre or more. It really stinks to talk about replanting anything right now with guys still trying to finish planting. If you choose to replant soybeans, consider proving it to yourself by planting strips and leaving strips. If you’re interested in that, I’d be happy to work with you. You can learn more about seed corn maggots here: https://crops.extension.iastate.edu/cropnews/2016/04/look-seedcorn-maggot-corn-and-soybean.
Wheat in the area ranges from boot to flowering. A couple of wheat fields I know of
were taken for hay. For those still considering silage, check out the CropWatch article this week where Todd Whitney shares data on wheatlage (wheat silage): https://go.unl.edu/qkbr. The rainfall will greatly help our wheat right now. And, rainfall at heading to flowering makes me think about the potential for Fusarium Head Blight (scab). The wheat scab prediction monitor http://www.wheatscab.psu.edu/ is predicting medium to high risk for scab in Nebraska for the next 48-72 hours. Some years I feel the model is delayed in prediction, but I still feel it’s a good tool and resource. Scab is caused by Fusarium graminearum and is favored by warm (70-80°F temps), humidity, and rain events before and during flowering. Once wheat begins flowering (Feekes 10.5.1), many foliar wheat fungicides are off-label. In fact, recent research presented at the 2017 Fusarium Head Blight meetings shows that in general, strobilurin products can actually increase the presence of deoxynivalenol (DON) in wheat if applied at full heading (Feekes 10 or 10.5). Thus, your better fungicide options for preventing scab are Caramba and Prosaro and these products can also kill any fungal diseases present on leaves (such as powdery mildew, tan spot, and rust). These products aren’t 100% for scab prevention due to the variation of heading and flowering that occurs in so many fields. Better efficacy is obtained with more uniform plants which begins at seeding time. So I would recommend watching the growth stage in your fields, the weather, and the prediction tool regarding if you feel you need to treat any fields this year to prevent scab. Research has shown best efficacy to be obtained when at least 50% of the plants are at 1/3 flowering. Flowering begins with yellow anther sacs in the middle of the head with flowering continuing throughout the head from there. Once the pollen is released, the anther sacs turn white.
LBNRD Open House Public Hearing: The Little Blue Natural Resources District (LBNRD) is hosting a public hearing on May 29th from 6:30-9:00 p.m. at the Davenport Community Center in Davenport, NE. The purpose of the hearing is to provide information and receive testimony on proposed amendments to Groundwater Management Rules and Regulations. The hearing will be an open house format allowing individuals to ask questions of the NRD staff, look at exhibits, and offer testimony. The proposed rule changes and additional information can be found on the LBNRD website at: http://www.littlebluenrd.org/. Please contact the NRD with any questions at (402) 364-2145.
Not part of my news column: on a more positive note after mentioning all the crop problems, the lilacs in general were beautiful and smelled amazing!!!
It was great to see so many fields of corn and even soybean emerging throughout the
area this past week! Also grateful for the rain we received in York and for those who received some in other areas. There are still areas who continue to miss rains and I remain concerned about the soil moisture situation. I have another soil moisture update this week at http://jenreesources.com if you’re interested in checking that out.
Thursday night/Friday morning’s high winds caused some damage with overturned pivots/corner systems and tree damage. We also saw newly emerged corn and even soybean cut off or
buried due to blowing debris/soil, particularly in soybean stubble. It will be important to watch the plants in these fields the next several days. By late Friday afternoon, I was already seeing new growth occur, which is good. Typically, that has been the response in the past-new regrowth in corn as the growing point is still below ground. However, it will be important to watch the corn plants for any bacterial issues that may kill seedlings. One can also split open a few plants and look for a healthy growing point. Regarding the soybean, I have seen soybean lose cotyledons due to hail, crusting, freeze, and wind damage, and still produce a plumule at the top of the soybean stem. It’s just hard to know for sure what will happen so it’s best to watch the plants in the fields.
Wheat in Nuckolls, Thayer, and Webster counties ranges from elongation to near boot and is turning blue-gray from moisture stress. Wheat is a crop that I’m always learning about-it can look really bad (or really good) and then end up surprising a person regarding yield either way. Lower leaves
in fields are turning yellow-brown. Some of this is due to moisture stress while there’s also powdery mildew pretty thick in lower canopies of wheat that had more tillers. A few have talked with me about using the wheat for hay or silage and then potentially going in with short season corn, sorghum, or a forage crop. Our forage specialists would recommend that if the wheat variety has awns, it’s best to either take for hay or silage at the boot stage so the awns don’t cause issues with livestock feeding. Todd Whitney, Extension Educator in Phelps/Gosper counties, had worked with a feedlot using an awnless wheat variety. Because of the additional growth that occurs in wheat (and other small grains) from boot to full head elongation, they found biomass production may be increased 25% if the forage was harvested during the later pollination period.
Evergreen Trees: There’s also been a lot of evergreen tree questions. For those noticing spruce trees looking kind of yellow with early morning sunlight, spruce spidermites have been working hard with the cooler, dry weather. They tend to build populations in spring and fall. You can check for spidermites by taking a white piece of paper and banging the needles on it. Then look for the presence of tiny dark green to nearly black spidermites crawling on it. Rainfall is a great way to wash them off of trees as are strong streams of water (easier done with smaller trees). There are also a number of miticides available that homeowners can purchase from lawn and garden stores (look for products that say they can be applied to trees for control of spidermites). A great brochure on insect pests of evergreen trees can be found at: https://nfs.unl.edu/documents/foresthealth/insectevergreen.pdf.
Many of us also noticed our spruce trees turning red/brown/purple/yellow in color last fall. This is most likely a disease called needle cast of spruce and can be prevented by spraying trees now (mid-May) with a product containing copper sulfate. Regarding Ponderosa or Austrian pines, if you look closely at the needles and observe dark bands or rings on them followed by death of the needle either direction from the band, the tree problem is most likely due to a fungal needle blight like dothistroma or brown spot in Scotch pines. They can all be prevented by spraying a fungicide containing copper sulfate now. The following brochure on diseases of evergreen trees is really helpful: https://nfs.unl.edu/documents/foresthealth/diseasesevergreen.pdf. Sometimes the problem is finding the products listed on these brochures in our smaller towns as these brochures were developed in Lincoln. If these specific products aren’t available from your local lawn/garden store, box store, or coop, I would recommend looking at the products available and look for a product that says it is effective against needle blights on trees. Not all the products I’m seeing have copper as an active ingredient, but other fungicides are listed and the key would be the fact that the site (trees) and even better, the site with problem (trees with needle blights), is listed on the label.
We also continue to see pine wilt affecting our Scotch (short needles in groups of 2) and Austrian pines (long needles in groups of 2). Pine wilt disease is caused by the pinewood nematode that is carried within the gut of a long-horned beetle. The beetle is what creates the ‘shotholes’ often seen in bark of infected trees. The nematode is native to Nebraska, as are Ponderosa pines (long needles in groups of 2 and 3). This is why we don’t see the problem in Ponderosa pines but do in Scotch and Austrian, which are non-native to Nebraska. A tip, if you’re trying to distinguish Ponderosa vs. Austrian pines, anytime you see needles with a group of 3 it’s a Ponderosa. Pine wilt is caused by beetles carrying pinewood nematodes vomiting them into the water-carrying vessels of the tree (xylem). The tree senses the nematodes and essentially blocks water to those branches. Often you will observe a branch then perhaps a side of the tree and eventually complete death of the tree within 6-9 months. While I have diagnosed many samples of pine wilt, more often when I visit homeowners the tree problems are due to fungal diseases which occur on the needles.
Lawns: Please remember the importance of sweeping or blowing fertilizer and pesticide products back into the lawn instead of leaving them on sidewalks. Leaving them on the sidewalks puts them in contact with people and pets walking on sidewalks and moves them into storm water systems via rain that can eventually end up in streams. I’m also seeing a number of 2,4-D/dicamba products being sprayed around tree bases to kill weeds which is affecting the new growth emerging on trees. Consider applying a wood mulch layer around the base of trees to help avoid this situation in the future and be sure to read and follow all pesticide labels.
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.”
Well, winter seems to be sticking around. My thoughts and prayers have been with those of you calving with the difficult conditions this year.
I provided an update regarding soil moisture status in non-irrigated fields both in this week’s UNL CropWatch at cropwatch.unl.edu and my blog at jenreesources.com. We’ll see what happens with moisture in the next few weeks and I’ll post updates to my blog.
Very few have tried planting in this part of the State that I know of. Grateful for all of you who keep me updated on what’s going on through your questions and comments! In this week’s UNL CropWatch, Dr. Roger Elmore took the lead on an article addressing corn planting. The message is to ideally wait till soil temperatures reach 50F with weather conditions allowing soil temperatures to remain at 50F or higher for the next 48 hours. We’ve observed when seed was planted and a cold snap with cold rains was received within 48 hours, some problems with seed germination and emergence. Hybrids vary in cold tolerance and seed companies are a great resource for that information as to which hybrids could be planted first in colder soils. Soil temperature information can be found at the UNL CropWatch site at: https://cropwatch.unl.edu/cropwatchsoiltemperature. We’d also recommend you take the soil temperature in the field before you plant and can do so by using a meat thermometer.
Last year I remember receiving questions from April 21-24 regarding planting corn and soybeans with an anticipated cold snap later that week. At that time, I was recommending growers switch to soybeans. The reason? Soybeans imbibe (uptake) water more quickly than corn seeds and while we hear 48 hours to be on the safe side, the critical period is more like 24 hours. Also, several years of both small plot and on-farm research in Nebraska has shown the primary way to increase soybean yields is to plant early. Dr. Jim Specht’s research showed soybeans produced a new node every 3.75 days once V1 occurs. The nodes are where pods and seed occur. Our on-farm research planting date studies also showed regardless if the spring was cold/wet or warm/dry, the early planted soybean always out-yielded the later planted with a total average across trials of 3 bu/ac. The data ranged from 1-10 bu/ac. We never planted early without using an insecticide/fungicide seed treatment to protect that seed, so we recommend you add that if you do plant early.
Our recommendation would be to plant the last week of April or as close to May 1 as conditions allow. We’ve also seen good results after April 20 in years if the soil temperatures were around 50F with good weather conditions at least 24-48 hours after planting to maintain that soil temp. It’s important to know your level of risk, though. Crop Insurance planting date for replant considerations is April 25 and there may also be replant options from your seed suppliers. We never replanted any of our studies and I have only observed frost on soybean cotyledons one year where growers planted early with soybeans coming out of it. We had the largest number of acres I’ve seen planted by April 24 last year with thankfully no issues and they were able to take advantage of a high-yielding bean year. Perhaps this is something you wish to try for yourself this year? Consider planting some passes of soybeans early and come back with some passes three weeks later. You can use this Soybean Planting Date Protocol if you’re interested in trying this for yourself. Please let me know if you’re interested in this!
Depending on the number of acres you have, some growers are now planting soybeans first. Others are planting corn and soybeans at the same time by either running two of their own planters/drills or custom hiring someone to plant soybeans for them. This also spreads risk and can help with harvest. Regarding maturities, a study conducted at UNL East Campus compared a 2.1 vs. 3.0 maturity group variety at 10 day intervals beginning April 23 through June 19. Yield was highest for early planted soybean and a yield penalty of 1/8 to 1/4 bu/ac per day of delay in planting for MG2.1 and MG3.0 varieties, respectively was found. The study also indicated that yield of the MG3.0 variety was higher relative to the MG2.1 variety in early plantings (late April and early-mid May), but the opposite (greater yield in MG2.1 versus MG3.0 variety) was found for late plantings (late-May and June). In our part of the State, we’ve observed really high yields from strong genetics in the MG2.4-2.5 varieties when planted early; so I have a hard time automatically recommending later MG varieties without more data. Thus, I would love to work with anyone interested in planting early comparing a high yielding MG2.4-2.5 vs. a high yielding MG3.0-3.5 to obtain more data. Here’s a Soybean Maturity Group Comparison with Early Planting protocol to consider and please let me know if you’re interested in this!
Wheat: My colleague, Dr. Nathan Mueller in Dodge County, has taken the lead on
sharing wheat information for Eastern Nebraska. He’s put together an excellent resource on his blog at http://croptechcafe.org/winterwheat/. Every Friday he’s sharing an update called “What’s up this Wheat“. He also started an Eastern NE wheat listserv and his website explains how to subscribe to it. Grateful for his effort in this as we both have goals of increasing crop diversity in the areas we serve and there are many benefits to wheat in rotation!
Crabgrass prevention in Lawns: Just a quick note that while our Extension lawn calendars promote applying crabgrass preventer in mid-April, our horticulture experts say to wait till soil temperatures are 55F on a seven day average and we are currently far from that! Check out https://cropwatch.unl.edu/cropwatchsoiltemperature for soil temp info.
On-Farm Research Protocols:
Hail and wind damage occurred throughout the area I serve last week. Overall, I’ve been encouraged by the regrowth observed on corn and soybean plants affected by the June 14th storm. We were blessed with warmer weather and sunshine that allowed for regrowth to occur in many situations other than some fields around the Deweese area.
You can look for regrowth on leaves within the whorl of corn plants and on the axillary buds of soybeans. Even what appeared to be soybean ‘sticks’ may show regrowth by now.
The concerns I have for plants affected by these storms is all the stem bruising on both corn and soybeans and the potential for bacterial diseases to affect corn.
For those of you affected by June 16th storms, we recommend to wait a week to assess damage and any decisions. I realize we’re also at a critical stage for replant decisions as we continue later in the season. Ultimately, decisions need to be made on a field by field basis.
- CropWatch Hail Damage Resources
- Resources from storm damage in 2014
- Fungicide Use After Hail or Wind
There’s no good research to Dr. Tamra Jackson-Ziems or my knowledge to support this. Fungicides only control fungal diseases. Bacterial diseases are favored after hail events and we have already seen bacterial leaf streak in the area prior to the storm. From past-years’ experience of prior wind/rain events, we can expect to see more of it in about a week. Fungicides won’t help that disease nor Goss’s wilt which is another we often see come in after hail events.
However, if you’re considering this, I’d like to have several farmers prove it to yourselves with on-farm research this year so we do have data for the future. It’s this simple. All you do is spray fungicide in enough width to complete 2 combine passes. Then skip an area for 2 combine passes. Then treat again and repeat across the field. Fungicide Protocol for Hailed Corn and Soybean. Please let me know if you’re interested in this!
Timing of fungicide app: ISU did a study to simulate hail damaged corn at tassel stage within an average of 3 or 8 days post-hail. They didn’t find the timing to provide any yield effects. They also didn’t find a statistical yield increase (90% confidence level) in fungicide application to hail damaged plants vs those which weren’t hailed although they also reported a numerical increase in 12 of the 20 fields.
Herbicide application: I spoke with Dr. Amit Jhala, Extension Weed Specialist for his thoughts regarding this. He said ultimately herbicides shouldn’t be applied to stressed weeds in order to achieve greatest efficacy. The concern for many including me right now is how well the weeds survived the hail and how quickly they are regrowing compared to the damaged corn and soybeans. This again is a field by field assessment regarding how well your corn and soybean regrowth is occurring and how rapidly your weeds are. I watched one palmer plant in one field after June 14 storm: 1 day post hail and 2 days post hail put on two sets of leaves in that time period. I also took pictures of soybeans reduced to sticks while waterhemp in that field was virtually untouched. I think many are trying to wait 5-7 days post-hail to apply herbicides but there were some fields I was suggesting to apply over the weekend with the recovery already occurring and less damage.
Corn replant: The biggest concerns with corn would be stands, eventual stalk rot/downed corn due to stalk bruising, and bacterial diseases. I’ve essentially watched stands reduced over the course of the growing season after early-season hail storms mostly due to bacterial diseases like Goss’ wilt. It will be important to have your crop insurance adjuster look at the field again prior to harvest. Splitting the stems of damaged plants across the field can help you assess any damage to growing points; they should be white/yellow and firm not brown and soft. Tattered leaves that are wrapped around the whorl should eventually turn brown and break off with the wind. They can sometimes impede new growth from the whorl as well though.
Soybean replant: Soybeans can compensate so greatly for reduced stands. From hail at this stage in the past, we’ve said to leave stands of non-irrigated at 60,000 plants per acre and irrigated at 75,000 plants per acre. Some soybeans reduced to sticks are shooting axillary buds. My biggest concern on soybeans is the stem bruising which isn’t accounted for in hail adjustments. If you want to prove replanting or not to yourself, consider slicing in soybeans next to the old row in strips across your field. Be sure to inoculate the soybeans and be sure to take prior stand counts. Soybean Replant Protocol.
There’s nothing like doing these studies and seeing the results on your own ground or from your peers’ farms. In 2006, I worked with a grower in the Lawrence, NE area on a non-irrigated soybean plant population study where he tested seeding rates of 100K, 130K, and 160K seeds/acre. He received hail at the cotyledon stage and because he was non-irrigated, chose to leave the stand. His actual stand counts were 74.4K, 89.4K, and 97.9K plants/acre respectively for the previous mentioned seeding rates which resulted in yields of 38.6, 40.6, 42.7 bu/ac respectively. Another soybean replant study occurred near Columbus, NE where the grower had an average plant stand of 75,000 plants per acre on June 11th. He chose to replant five strips across the field at a diagonal to the existing rows. The replanted soybeans ended up yielding 1 bu/ac less than the original plant stand. I realize it’s hard to want to do these extra steps for on-farm research, but this is why it’s important; it’s the way to answer these questions for yourself! Please contact one of our team members if you’re interested in on-farm research this year!
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 year I was counting my blessings as we made it through May with no tornadoes in Clay County and no Memorial Day storms! Yet history seems to repeat itself on days. Last year, hail went through the counties north of us on June 3. This year, hail hit us on June 3rd….an estimated 30% of Clay County. Please also see the resources listed at the end of this post for more specific information regarding decision-making.
For more information on hail and replant decisions, please see: