Early in my Extension career, I inherited the job of injecting trees with a solution of iron sulfate. There would often be a waiting list of people to help, particularly in Sutton, when they’d see the jugs hanging from trees. As a plant pathologist, I was concerned about how much damage we were doing to the trees with repeated injections every five years or so…if secondary pathogens would affect these areas we were drilling in the trees. I was also concerned about providing a free service that took a great deal of time and if we were competing with industry by doing so. Eventually we stopped providing the service but we do rent out the equipment and can provide the recommendations on how much iron sulfate to add based on tree diameter if you are interested. But you may be interested in another less invasive method instead.
You most likely will not see any changes the first year, although the grass under the tree may appear greener. The goal is to change the soil pH to make the iron more available to the tree in the future. This may be a process that needs repeated for several years in a row and while it doesn’t show instantaneous results, it will most likely aid in the longevity of your trees by reducing the symptoms without additional harm to the tree through injections.
Special thanks to Dr. Scott Dewald for the wonderful evening of information he provided at our tree care workshop last week!
This was a fun workshop for me with the right size of group and great hands-on demonstration where we also learned from pruning mistakes and how best to correct them. Thanks again Scott!
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.
Somehow April flew by without me reminding you to apply fungicide sprays to Austrian and Ponderosa pines that have had problems with Sphaeropsis tip blight in the past. I’ve also received several scotch pine samples in the office to diagnose for pine wilt nematode. While there is no cure for pine wilt, I recommend to take a 6” long, 1-2” diameter sample of a dead branch to your local Extension office for diagnosis before cutting down the tree. Pine wilt affects Austrian (long needles groups of 2) and Scotch pines (short needles in groups of 2) as they are non-native trees while the nematode is native. Since ponderosa pines (long needles in groups of 2 and 3) are native to Nebraska, they don’t seem to be affected by pine wilt nematode.
Pine wilt is caused by beetles carrying pine wood 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. If you look closely at your 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 in Austrian and Ponderosa pines or brown spot in Scotch pines. They can all be prevented by spraying a fungicide containing copper sulfate in the spring.
With everything about 3 weeks early this year, now is the time to spray Ponderosa and Austrian pines for needle blight and spruce trees that have had problems with needle cast or shoot blight where the new growth has died in the past. In early June spray for needle blight problems in Scotch pine and cercospora blight on cedars. If you have a windbreak of combinations of these trees and don’t want to spray twice, I recommend at least spraying in early June to catch all of them. Increasing air flow by cutting out some trees is another way to reduce fungal diseases on your trees.
Also watch trees for bagworms as you may be able to tank mix a fungicide/insecticide application in early June if needed. We would recommend picking the bags off trees and burning them, but that’s just not feasible in windbreak situations. To know when to spray, take a few of the bags off the tree, place them into a plastic ziplock bag, and place outside on the south side of your house. When the larvae emerge from the bags, check your trees to see if larvae can also be observed on them. Pyrethroid insecticides are recommended for managing bagworms because they cause an irritation that makes the larvae leave the bags and allow them to be exposed to the pesticide.
Great brochure! Evergreen Diseases
April 1st, while typically a day of pranks and jokes, has one obvious truth. Spring has arrived in full force with flowering plants at least 2-3 weeks earlier than normal. I couldn’t believe that my lilacs, which typically bloom around mid-May were blooming for the first time today! I planted many of the bulbs and shrubs last fall and have been rewarded with beauty, color, and lovely smells via God’s creation this spring; enjoy the pics!
Well, this weekend I mowed my yard for the first time this spring-hard to believe for March! For two weeks I’ve been advising people to wait on fertilizing or applying crabgrass preventer on their lawns. It’s hard for me not to stop my vehicle everytime I see someone using a lawn spreader right now and ask them to wait! It’s too early to apply pre-emergent herbicides and fertilizer. Wait another month (till at least April 20) before the first fertilizer of 1 lb/1000 sq. ft is applied. At that same time, pre-emergence herbicides can also be applied. Wait to overseed Kentucky bluegrass lawns till April 1 and Fescue lawns till April 15. You can check out a calendar of recommendations for all things concerning your lawn at the following site: http://turf.unl.edu/lawncalendars.cfm. When overseeding winter-killed areas, core aerate or power rake the lawn prior to overseeding to encourage seed to soil contact for better germination. Also, don’t apply herbicides to areas where you have overseeded as this will affect the germination of new seedlings.
A timely meeting for lawn care has been scheduled and you can learn more by attending a Lawn Care for Home-Owners meeting Thursday, April 12 from 5:30-7:00 p.m. There is no charge and light refreshments will be provided. Learn about fertilizer labels and timing, calibrating your lawn spreader; irrigation timing for lawns; and calendars for lawn care maintenance. Please RSVP to the Clay County Extension Office at (402) 762-3644 or email@example.com.
Garden: It’s been hard for me to resist the temptation to remove the winter mulch I had on my perennials and flower beds but in the event of frost which still is a good possibility, it may be good to leave it on awhile longer if new growth has not occurred. Kelly Feehan, UNL Extension Educator from Platte County advises if new growth is beginning to occur on your herbaceous perennials, to rake the leaves/mulch into a nearby pile. This allows the new growth to get acclimated to sunlight but allows the mulch to be raked back onto the growth in the event we end up with a cold snap.
I know some people have planted peas and potatoes. Check out the Vegetable Planting Guide that Gary Zoubek, UNL Extension Educator in York developed for suggested vegetable planting dates for our area: http://york.unl.edu/water-environment. Thursday, April 5th, Backyard Farmer returns for its 60th season on NET1 at 7:00 p.m.! Also, on Thursday, April 19th, we will have a workshop on Container Gardening Fun at the Clay County Fairgrounds from 5:30-7:00 p.m. More information to come! Please RSVP to firstname.lastname@example.org or (402) 762-3644.
The warm weather is creating the temptation to get outside and garden! But patience is a virtue and it’s only March! Here are some great tips from Elizabeth Killinger, UNL Extension Educator in Hall County about waiting on spring tasks.
The warm weather these past few days has gotten everyone ready to head outside and get their hands dirty. Just because it feels like spring, doesn’t mean we have to finish all of our spring to-dos now.
It may be tempting to completely remove all of the leaves and mulch from around tender perennials, but don’t give in. Strawberries, roses, chrysanthemums, and other tender plants can be protected from the fluctuating winter temperatures with winter mulch. If the mulch is removed too soon, new growth can form on the plant too early. This new growth is susceptible to damage caused by cold temperatures. Try and delay the removal of winter mulches as long as possible, but be sure it is removed before new growth begins. If the warm temperatures have caused new plant growth, rake the mulch to the side, but don’t remove it completely. If freezing temperatures are forecasted…
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Happy Belated Spring! I meant to get this posted earlier this week but just didn’t get it done. I love living in Nebraska and being able to observe God’s creation via the changes in seasons! Spring and Fall are probably my favorite, but there’s beauty in all of them. Everything is 2-3 weeks early this year so will be interesting to see if we end up with March going out like a lion or if we end up with an Easter freeze like we did a few years ago. While it wasn’t a bad winter, I always enjoy seeing new life and green in the springtime!
Grass greening up in front lawn. Sending this pic out to my husband who has seen grass very little in 9.5 months in Afghanistan! Will look forward to you helping me mow when you return! : )
My favorite tree is the magnolia and someday I hope to have one! I always enjoy going to UNL East Campus in the spring and seeing the magnolias in bloom. However, I was surprised how quickly they bloomed this year and that they were already loosing their blossoms!
Through the leaf mulch even my iris and daylillies are emerging. I haven’t removed mulch yet in the event we end up with a cold snap. It’s still early, though tempting!