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.
I’ve received several questions on trees. If you have silver maples or pin oaks that are looking a little yellow, most likely the yellowing
is due to iron chlorosis. Symptoms of iron chlorosis include leaves with green leaf veins while the leaf tissue is yellow-green. Iron chlorosis is common in several of the towns in Clay County due to higher pH soils (more basic soils) which makes the iron unavailable to the plants. Trees can be injected with iron sulfate in the base of the trunk with the amount injected dependent on the diameter of the tree. There’s also another method of soil injection with micronutrients that can also be used. I also have a list of tree care providers for the area for trunk injections; please contact the Extension Office if you’re interested in obtaining this list.
On evergreen trees, spruces losing their new growth or inside needles may be doing so due to two different fungal diseases or spidermites. If you are noticing this problem on your spruces, the time to prevent fungal diseases will be May next year with products such as Bravo, Daconil, or copper-sulfate based products. Spidermites can be managed with insecticidal soap. Ponderosa, Austrian, and Scotch pine trees with brown fungal bands on needles causing the needles to turn brown can be sprayed with a copper-sulfate based product now to help prevent further browning. If large branches of your trees have needles dying, the culprit may actually be the pine wood nematode which causes pine wilt disease in Scotch pines. There is no cure for that disease. To determine if pine wilt is the problem, cut a piece of dead/dying branch that is at least 1 inch in diameter and 4 inches long and send it to the UNL Plant and Pest Diagnostic Lab for diagnosis. Cedar trees are also showing Cercospora blight right now with needles turning brown. We used to think nothing would kill a cedar tree, yet many cedar windbreaks have needles turning brown and this fungal disease is killing needles due to restricted air flow and high humidity within our windbreaks. Restricted air flow is something you’d like with windbreaks but many of the trees in windbreaks were planted too close together many years ago and we’re starting to see more of a problem with various fungal diseases. Another option to spraying fungicides is to consider removing every other tree from the windbreaks to allow for more air circulation to cut back on fungal diseases.
If you’re unsure how to tell what kind of evergreen tree you have, cedar trees have needles like ropes. Spruce needles are single and when you roll them in your fingers, they have edges to them. Fir needles are also single and when you roll them in your fingers, they don’t roll easily like spruce needles because they are flat (flat fir). Pine needles are always in groups-of 2, 3, or 5. Austrian and Ponderosa pines have the very long needles; Austrians will always have long needles in groups of 2 but Ponderosa’s will have long needles in groups of 2 or 3 (If you ever see 3 needles, it’s a Ponderosa pine!). Scotch pines always have short needles in groups of 2. White pines have needles in groups of 5.