Extension Update from Jenny Rees

UPCOMING EVENTS:  

Apr. 22: Household Hazardous Waste Collection, 8-11 a.m., Parking Lot of City of Seward Wastewater plant
Apr. 22: Household Hazardous Waste Collection, 1-4 p.m., York County Landfill, York
May 30-21: Youth Tractor Safety Class, 8am, Kearney Fairgrounds (308) 236-1235
June 28: South Central Ag Lab Weed Science Field Day, SCAL near Clay Center (morning)
June 28: South Central Ag Lab Cover Crop Field Day, SCAL near Clay Center (afternoon)
July 10-11: Youth Tractor Safety Class, 8am, Grand Island College Park (308) 385-5088.

Farm Finance Clinic Sites and Dates To sign up for a clinic or to get more information, call Michelle at the Nebraska Farm Hotline at 1-800-464-0258.

Household Hazardous Waste Collection:  Reminder of Household Hazardous Waste Collection April 22 from 8-11 a.m. at the City of Seward Wastewater Plant Parking Lot and from 1-4 p.m. at the York County Landfill in York.  You can view the flyers at:  http://jenreesources.com.

Crop Update:  We’ve had several interesting articles in UNL’s CropWatch at http://cropwatch.unl.edu the past few weeks.  This week, we have an article looking at considerations and economics for those still considering putting soybean on soybean ground instead of corn ground.  Considerations for terminating a rye cover crop and when starter fertilizer is needed for corn are also discussed.  Soil temperatures at 4” depth have fluxed with the freeze last week following by warmer weather.  We were also blessed with warm rains that didn’t greatly drop the soil temperatures over the weekend.  The soil temperatures found on our CropWatch site are at a 4” depth and are the average for a 24 hour period.  The high, low, and midnight temperatures are also listed at: http://cropwatch.unl.edu/cropwatchsoiltemperature.    

Lawn Care:  With it now being mid-April, the first application of fertilizer (0.75 to 1 pound per 1000 sq. feet) can be applied if your lawn needs it until May 1.  Lawn calendars here: http://turf.unl.edu/turf-fact-sheets-nebguides.  Application of crabgrass preventer is recommended when soil temperatures at the 1” depth are sustained at 55F or greater for five days.  You can check this with a meat thermometer in the ground at the 1” depth or checking the website above (even though it shows 4” depth).  Some have asked me at what temperatures crabgrass actually germinate.  Research has shown daily average soil temperatures can range from 57-64F at the 1” depth but a greater amount of crabgrass germinates when soil temperatures reach 73F or above at the 1” depth.  This is the reason why applying crabgrass preventer too early can also be costly with a second flush of crabgrass germinating later.

If you’re finding white grubs in your yard or garden now, there’s no need for control as these full-grown larvae are difficult to kill.  They will soon pupate and emerge as beetles in late May through June to lay eggs which hatch in August.  It is this new generation that can damage lawns if populations are high enough. Finding grubs now does not mean there will be damage this summer. Since white grubs can be a serious lawn pest, base control decisions on past history and monitoring this year. If a lawn had grub damage last year, an application of a preventive insecticide, like imidacloprid, could be applied to lawns by mid-July. If a lawn had no damage last year, no insecticide is needed. Monitor the lawn in August. If five to eight grubs can be found per square foot at that time, an insecticide application may be needed.

Emerald Ash Borer:  I continue to receive calls about ash trees.  First, Emerald Ash Borer (EAB) has not been confirmed in our area of the State.  You can view a map of where it’s been found at:  http://nfs.unl.edu/nebraska-eab.  It’s recommended to wait to treat until EAB is confirmed within 15 miles of your location (I explain more below).  If you are told you need to treat your trees now, that is incorrect information.  Key points and recommendations can be found at:  http://nfs.unl.edu/documents/EAB/EABKeyPointsandRecommendations.pdf.

Second, other borers such as the ash/lilac borer commonly affect ash and lilac trees in Nebraska each year.  Carpenterworms also cause shade tree damage which may be the sawdust you’re seeing in trees right now.  Nebraska Forest Service materials share that the trunk of ash and lilac trees in addition to large branches can be sprayed with permethrin in mid-May to kill emerging beetles (http://nfs.unl.edu/documents/foresthealth/insectbroadleaf.pdf).  Look at the holes in your trees.  All the above-mentioned borers create exit holes that are round.  EAB creates an exit hole in the shape of a “D”. More Info:  http://nfs.unl.edu/ash%20decline%20borers%20with%20EAB%20full%20sheet.pdf.

Again, it’s recommended to not treat until EAB has been confirmed within 15 miles of your location.  The reason for this is two-fold:  it’s a slow moving disease and because of the amount of tree damage from trunk injections.  Our mindset is one of quick death as we’ve witnessed with pine wilt of Scotch and Austrian pines within a year, but this is not the case with EAB.  Emerald Ash Borer may be in trees for three to four years before symptoms of top-die back appear in the tree.  It then takes an additional several years, depending on condition of the tree, age, etc. before death does occur.  Treatments are still affective in trees infested with EAB with no more than 1/3 of the tree in decline. 

Regarding treatments, I’ve been receiving calls from people wanting to put on a soil drench.  We still would recommend this is not necessary until EAB is within 15 miles of here.  The soil drench is an option at that time, but the diameter of the tree needs to be less than 15” (47” circumference max) according to research for this method to be effective.  When considering a soil drench treatment, the active ingredient in that product is taken up by the roots and translocated throughout the tree.  The same will happen for landscape plants at the base of the ash tree.  Thus, it’s recommended to remove any landscape plants from below the base of ash trees and move them to other areas of the landscape to reduce the effects on pollinators. 

So if you own an ash tree, what should you do right now?  We would recommend being patient and reading for yourself about it.  Go to nfs.unl.edu/nebraska-eab for information.  A good publication is “How to Select Trees for Treatment” to help tree owners decide if their tree is a good candidate to treat. Even if a homeowner wishes to save an ash tree, not every tree should be saved.  Ash trees younger than 10 years are best replaced. Trees must be treated for their entire life span and healthy trees can typically withstand about 10 injection treatments (thus the reason to not begin trunk injections too early).