Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Show Questions - April 12, 2012
1. This is a viewer who wants to get rid of carpenter ants in a weeping willow
a. When a willow (or any tree) has carpenter ants, rot is normally found in the tree. The ants are not the cause of the damage to the tree. Look for ant baits at your local store --check the the label for carpenter ants -- they are finicky eaters. You can also nsert boric acid powder into the affected area.
2. A viewer has a RTF fescue lawn and would like to know which is best way to irrigate: watering twice a week for an hour, each time or three time a week for forty minutes?
a. Neither. Fescues tend to need less water. Irrigation on a regular schedule can be okay when the weather is dry. If the soil moisture is adequate, irrigation may not be needed.
3. A viewer has bluegrass with patches of gray in it.
a. It is most likely powdery mildew; it will look like baby powder sprinkled in the turf. Try to increase air circulation, open up canopies of trees if possible. If management is required, look for a foliar fungicide application, read the label and make sure powdery mildew is listed.
4. Would the new sempervirens type boxwood 'Highlander' be a good privacy screen that will stand up to wind and snow?
a. Boxwood is not a good choice for a screen. 'Highlander' is very short, only two feet tall. As a broadleaf evergreen, the plant is prone to winter burn especially in windy areas.
5. Where do you find Boric acid?
a. Ask for Boric Acid or roach powder in most stores.
6. A viewer has plants that have a picture of plant with possible herbicide damage.
a. No, the leaves are rolling on the edges. If there was herbicide damage (2,4-D or a phenoxy type) you would see the leaves cup and be more misshapen. Leading us to an environmental cause -- most likely water stress.
7. This viewer has 'blight' in a garden plot.
a. In a home garden with tomatoes, peppers, and such, the plants can get a foliar blight. Practice good sanitation and make sure you clean the garden. If you have a large garden, rotation of crops is a good idea. Many times the fungi that cause these blights over winter in the soil. After the plants are established in the ground, use of mulches is a good idea. They keep the soil from splashing up on the leaves when you water. Finally, avoid overhead irrigation even if you have mulched.
8. A Bloomfield viewer has a lilac hedge that is suckering. How do they remove the lilac suckers?
a. This will be an ongoing problem. Pulling them out by hand is one solution. Hand digging them out with the roots intact will also work, and then you can share them with friends. There are some chemicals you can purchase from your local nursery, look for Sucker Stop or Finale. Read the label directions carefully.
9. Here's a picture of an insect in an asparagus bed. What is it?
a. This is an asparagus beetle. It occurs first thing in the spring. It over winters in the bed. Make sure you clean up the bed in the fall to help remove the insects' winter homes. They also deposit their grayish-colored eggs on the spears; they are very hard to remove. Clear off all beetles and cover the asparagus with a mesh cloth to keep the insects out. The chemical treatment is carbonyl or Sevin or permethrin, which will have a wait time to harvest.
10. How do you remove henbit in lawns?
a. Henbit is a winter annual weed. It is recommended that control of this weed takes place in fall. Keep mowing it and in the summer it should disappear for this season.
11. A viburnum has yellowing of the leaves.
a. It can be difficult to tell now with so many cultivars whose foliage that is a different color than what you are used to. This sample is supposed to be like this. Keep an eye on your plants and observe them. Sometimes when it is cooler the virus will show up and you will see the blotchy colors on the plant. Nothing you can do for it but rogue it out.
12. A lilac on the south side of the house has been in the ground for four years and has not bloomed
a. Many things could contribute to this: it could be the variety, and it could be age; give it a few years. You must prune the plant right after the bloom time. Lilacs set their flower buds for the next year right after the previous year’s flowering
13. A dwarf Alberta spruce lost many needles. They view thought it was deer but now think it was spider mites. How do they treat for spider mites? And will the tree fill back in?
a. It will not fill in but over several seasons the growth to the side should grow to help cover the bare spots . Look to see if there is webbing - the webbing will also catch dirt debris. To check for the mites, hold a white piece of paper below a branch and tap the branch over the paper. The mites should then fall onto the paper (little green bodies). If you see them, you can treat with Bifenthrin or horticultural soap on a cool day.
14. How do you control weeds in asparagus and blackberry beds?
a. At this time, it is late to control the weeds in the asparagus. The option for control is a Preen application but that has to be down before the weeds emerge. Hand pulling is your only option at this point. And for the raspberries, hand pulling is also your only option at this point.
15. This is a photo of a 2 ½ year old North Star cherry tree. It has a wound on the bottom and when it rains, it gets this growth coming out of the wound. When it dries up, it is sticky. They have been told it is a fungus and to use a 10 percent bleach solution on it?
a. The wound on the tree is at the bottom and is most likely from mower or animal damage, and is a canker. With damage of this size, you will have to remove the tree; the tree will be very weak and hard to keep alive.
16. The tomatoes crops from last year were damaged by little black slug like things, how do they control them?
a. If you had wounding from something else, you could have had slugs. Things often do not repeat themselves. Try to keep plant clean and upright.
17. How do you get rid of night crawlers
a. There is nothing to control night crawlers. Mow low and take a power rake to try to knock down those casting hills. They will go deep when the weather dries up.
18. How do you kill the plant Star of David
a. That plant is a perennial and applications of 2,4-D are effective. Multiple applications will be needed. Make sure you get good coverage on the plant.
19. Rhubarb plants are showing rust. They were planted by seed, not the transplanted rhubarb.
a. Rust does not show up on rhubarb very often. There is an environmental factor that happens that looks like rust.
20. In this photo an evergreen sustained damage from the heavy snow last year - will it recover?
a. At this point, if it has been a year, most likely it will not. They are very hard to prune back to green growth; it will not regenerate. You can prune it and some of the growth on the side will fill in but it will take many seasons.
1) Thorny vine in stand of timber
2) How to control it?
a) Spot treat carefully
3) Can you cut back Knock Out roses still?
a) If you need to control the size, yes
4) Is arborvitae a good windbreak in Nebraska?
a) No, it tends to winter burn
5) Is lavender a good cash crop for Nebraska?
a) It’s slow growing, maybe
6) A tree has become a scratch post for the cat. How do they protect it?
a) Put a ring of hardware cloth around the base
7) What does Limelight hydrangea require for growing conditions?
a) Part shade, moisture
1) How do you tell the difference between real morels and fake ones?
a) The real one have hollow stems
2) Is it wet or dry conditions that favor the powdery mildew now?
a) The dryer with the dew - overcast conditions favor powdery mildew, a lot of rain does not
3) Too late to spray for rust on fruit trees?
a) It is too late for the rust, but other diseases you can spray for with a good fruit tree spray
4) Do we have anthracnose in oaks in Nebraska?
a) It can occur but we do not see a lot if it
5) Beside sanitation, how do you control black spot in roses?
a) Avoid overhead irrigation, and look for a good quality foliar fungicide
1) What will get rid of cattails now so they are not a problem later?
a) Best time to treat is in June. If they treat now they may get regrowth.
2) What will be the date for the second pre-emergent application
a) Wait three to four weeks between applications - if it stays cool you may be able to extend that by a week
3) What is the new chemical for pre and post treatment of yellow nutsedge?
a) Look for chemical name sulfentrazone
4) Can you use that around ornamental sedges?
a) No, it will not discriminate
1) What is good soil treatment for borers in carrots and parsnips?
a) Soil treatment is not recommended - rotation of crops is better
2) Viewer has clover mites on the side of the house, how do they get rid of them?
a) Wait for them to move into the landscape.
3) How do you get rid of them?
a) Apply Bifenthrin on the perimeter of the house
4) A viewer thinks they have EAB, is it here?
a) It is not, it has not crossed the Mississippi - except for the northeast tip of Iowa. If you think you have it, contact your local extension office.
5) Is it time to treat for the other borers?
a) Yes, it is.