Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Show Questions - April 19, 2012
1. We have a question from a viewer that has a bigger older linden tree. The leaves are smaller. In the past they have been curled in the summer. They are wondering if what they are seeing is Japanese beetle issues or not?
a. This time of year we will not be seeing Japanese beetles. We would be seeing those in June/July. It could be an environmental issue.
2. A viewer wonders if they have nimblewill in the fall, should they control it in the spring?
a. Yes, they can control it now with Roundup or have it professionally treated with a product called Tenacity which is selective and will leave desired turf behind, unlike Roundup which is not selctive and will kill everything it touches. It is important to always read the label on whatever product you are applying and follow the directions carefully. The packaging may have look the same but the product may have new or different active ingredients than in past years. (For example, be aware that if you use Roundup Extended Control, you will not be able to plant anything in that area for months.)
3. A viewer has a boston ivy which is located in full sun. It has leaf spots with curling edges.
a. With any plant in mid to late summer when it has been hot, leaf spots are a sign of environmental stress. The plant is scorched. Boston ivy does not like full sun. The plant should be relocated. The best time to do this would be fall, the second best time would be early spring
4. We have a viewer from Seward that has algae in their fountain and bird bath. Is there a product to put in the water without harming any wildlife?
a. In an acreage situation they should use a copper-type product. It might be difficult to find a product that would not be sold in large quantities for such limited use. The best suggestion is old-fashioned elbow grease. This will need to be done throughout the summer.
5. The first picture of the day is one from a viewer with a group of worms eating the needles of a pine tree.
a. This is pine saw fly. They can come and go rather quickly and just because you have them one year, does not mean they will return. You can use the hose to wash them off or tap the tree and they will fall off. They are unable to crawl back up the tree.
6. A viewer wants to know how to remove fescue from a bluegrass lawn?
a. The best way is to dig it out in patches. If large parts of the lawn are involved it might require using Roundup and removing the entire area and starting over.
7. A branch on an unidentified shrub has curling leaves but the rest of the plant looks healthy.
a. Knowing what the plant is would be very helpful. A dark spot on a branch could be a canker that has formed. That could inhibit water movement. Other possibilites are insects, spider mites, or aphids. It's not really possible to say without a photograph or at least knowing what the shrub is.
8. We have a viewer from Norfolk who had a bad hail storm and had serviceberries damaged. The bark was slashed and stripped. Will they be ok? They also had peonies damaged.
a. The peonies might send up some shoots. They will probably not do much this year. The serviceberries likelihood of survival is poor if much damage was done to the bark. But if less than half the circumference of the branch is damaged, it may be able to seal up the wounds in time. Good basic care is important; mulch but don’t fertilize.
9. Our next question is from a viewer in Lincoln. They have a large population of moths on the door in the morning and garage. What would this be?
a. They are collectively referred to as miller moths. They could be a range of species. The main one is army cutworm moths. They are active at night but cause no damage at this time of year. They feed on the nector from the trees and shrubs. They will move west to the Rocky Mountains and return in the fall when they can cause major damage.
10. The next question concerns a photograph from a viewer who wants to know if it is a weed or a plant?
a. This would be in the eyes of the beholder. It is wild violet and grows in poor conditions in grass, usually in shade. It survives where turf grass can’t. If you choose to get rid of it, use a broadleaf herbicide. Two applications in the fall. Creeping Charlie is definitely a weed. It needs two applications in the fall.
11. A Bellevue viewer has several concolor fir trees. They are seeing browning on the branches on one side of the trees. The exposure is south and east, in a windy area. Please address disease and environmental possibilities.
a. Concolor fir is affected by very few diseases. When you see needles browning, it is probably an environmental issue. Too much wind will make the needles turn brown. They do not like wet feet. So another cause could be overwatering with a sprinkler system. If the water is directly hitting the needles it could be that a fungus is occurring. Adjust the height/reach of the sprinklers.
12. Another Bellevue has 45 different roses in full sun. Is it too late to trim them back? Should they fertilize them?
a. No, it is not too late to prune them. You should prune them back for the best growth this year. Prune them to the outward facing buds, to about pencil sized stems, or to the first five-leaflet leaves. Shrub roses don’t need additional fertilizer but a slow release fertilizer would be ok.
13. This question is from a viewer who asks if mosquito dunks are safe around tadpoles?
a. The dunks are safe for tadpoles; they are specifically targeting flies, black flies and mosquitoes.
14. What is the best way to control speedwell in the lawn?
a. Speedwell, since it is a winter annual, is nearing the end of its lifecycle. It is large and setting seed. It is not really worth trying to control it at this time. If you want to treat it, any one of the three-way herbicides should be fine. The best time to treat it is in the fall.
15. A viewer in Ogallala has a brown area in the lawn about 6 feet in diameter. What is the difference between winter kill fungus and grub damage?
a. A brown patch affecting the lawn at this time of year would be necrotic ring spot. If you look at the roots, they will be dark brown or black and short. The patch affected will be uniform. If the roots are long and white it will not be necrotic ring spot, possible drought. An area affected by drought will not be as uniform but will follow a wind pattern or relief pattern. It could possibly be an insect problem. Cut the turf and pull it back to expose grubs. Skunks, raccoons, and grackles are very attracted to grubs. The other insect could be billbugs. You can find these by pulling up the turf up and they will pop out of the stems.
16. This question is from an Omaha viewer who wants to know whether Knockout roses will thrive in the root zone of a Black Walnut tree.
a. No, unfortunately not. They’re one of those plants that are sensitive to the juglone that walnut trees put out through its leaves, roots, and all of its parts. Plant them outside of the drip line of the walnut tree. That’s the best location for it. There's a good publication online from Ohio State about black walnut toxicity. It has a list of plants that are sensitive to the chemical and plants that are not. It will give you an idea of what to plant.
17. This is a viewer in central Nebraska. They have mounds that look like ant hills. They’re about five inches high, the opening is one inch around, and the mound is 12 inches across. And, they are located in the crawl space under the house.
a. Well, after some conference here, these are likely crayfish. Crayfish do burrow through the soil. There are a lot of prairie crayfish not associated with permanent bodies of waters, such as streams and lakes. Probably the real issue in this crawl space is it’s too wet. There’s another issue here. Like carpenter ants, they're a sign of another problem.
18. This is an Onawa, Iowa viewer. Most of the turf in the area is bluegrass and many yards are dead. They didn’t have a lot of snow cover. They had a dry winter. It is winter desiccation, most likely, or what is it?
a. That's a pretty good chance its winter desiccation. It got too try. The best way to fix that is to overseed it. If it is Kentucky bluegrass, they do have rhizomes so with moderate fertilization it will come back. To speed the process, overseed with more bluegrass.
19. This is a viewer who has a Silver Maple tree. It has a hole in its trunk and flowing from the hole we have some interesting something creeping down. Pathology? Insects? Combination?
a. This is most likely a combination. It may have started as a little hole. It could have been a fungal or bacterial canker that began there. Those move into any wound we have present and continue to grow. The tree will try to protect itself and grow around it. That tissue ends up dieing. The stuff coming out would not be due to the fungus or bacteria. Most likely, there is an insect that has colonized there and is feasting on the tree. We have a lot of beetles that will get into wood that is rotting. Those clumps in that picture are not rotting wood. It's insect frass. That rot is going to continue to move in the tree. You will see decline, the structural integrity of the tree will be compromised. It’s going to become a hazard in the landscape. Sooner or later there's going to be a high wind that will take it out.
20. Is it too late to plant potatoes? This is from Western, Nebraska.
a. No, it it’s not too late to plant potatoes. There’s plenty of time.
21. This is an Omaha viewer. Is it too early to plant dalias and cannas?
a. It’s too early to plant cannas. The potential for cold nights is still there. I would wait until after the last frost date before you put those out.
22. This viewer has shiny black wasps, one and one-half to two inches long in the basement. This occurred both last spring, late April and early May, and again this year.
a. Those are probably one of the hunting wasps. They could either be the cricket hunter especially if you have cricket problems. And there are other hunting ones that are black and that size range. Likely the cricket hunter. Get rid of the crickets.
23. This viewer has clover in the lawn and wants to know what to do.
a. Again many parts of the clover are edible. Best time to treat clover is in the fall. Right now it’s going strong. It will flower it in the next three, four or five weeks. Again, it’s a perennial. We would like to control it in the fall.
24. We have a Papillion viewer who has peach trees. They are in the process of using a preventive fruit tree spray program. It's the generic spray. What are they controlling?
a. With peaches we’re usually trying to control shot holes, one of which is caused by a fungus (which is what you're controling) and one that's bacterial. If you have a copper product, they do have a little control on bacterial diseases. The shot hole will effect the leaveyou'll get holes in the leaves. And, it can affect the fruit which will get spots and a gummy appearance. That's what you're trying to avoid. If you don't have a lot of infection, start with the fruit spray in the spring and continue throughout the summer months.
25. A viewer from Wausau sent in this picture. The viewer wants to know what it is growing in with the lilacs. And should they control it?
a. This is vine called Woodbine. It’s spread by little berries that birds like to eat and then sprout all over the place. It will climb up your bush and cover it. If you don't like it you can dig it out. You can treat it like any woody plant weed: cut it down and paint the stump with Roundup to get rid of it.
26. This viewer has a question about cucumbers. Are there insects, things that go bump in the night and kill the cucumber vine? Because they get big and then the cucumbers croak.
a. Cucumber beetles. There is bacterial wilt which is transmitted by cucumber beetles. Controlling the beetle is the key. Or there is a resistant variety. 'County Fair' cucumber is a resistant variety. If you have cucumber beetles and the wilt, remove the plant; don't throw it in the compost pile, because the beetles will find it in your compost pile. You have to throw it away.
1. Suckers on ornamental crabapples are really causing problems, what's the control for those?
a. Unfortunately there isn't a great control; you just have to keep trimming it down.
2. We have viewer who cut down a chokecherry and it has suckered all over the lawn. What do you do about that?
a. If there are small suckers in the lawn you will need to do a topical spray, with something like Tricolpyr. You will need to keep after it. If there are bigger stems you could them down again and paint them with concentrated Roundup as a stump treatment. And that might help kill the root system too.
3. When should a 50-year old yew and hemlock hedge be fertilized? They usually do it in late May or June.
a. Again, that wouldn't need fertilization. Certainly not every year.
4. Are there residual pesticides to worry about in Oma-Gro or LinGro?
a. No, that’s monitored very closely.
5. A viewer’s rhubarb froze and now the new plants are really small, and don't have good stems anymore. Start over?
a. Yes. There may be some crown damage.
1. When should viewers expect to see Black Knot in plums and what do they do about it?
a. You will see it now. There will be big galls. You need to prune it out.
2. A viewer has bark blasting off their ornamental pear trees. Is that pathologic or abiotic?
a. It is abiotic. Water freezing or lightening strikes can make it look like the bark is blowing off.
3. There are rusty looking spots on the buckeye and horsechestnut leaves. What can they do now?
a. Typically we don’t recommend anything. I’ve been working on that for the past 2 – 3 years and I don't have it identified. It's some type of fungus.
4. A viewer has dark masses back in a ways on their spruce tree twigs. The mass is tough on the twigs. Is that a fungus?
a. It depends on how big they are. If they are large I would be wondering what it is. Pictures there would be very helpful.
5. A viewer has leaf spot on hydrangeas. What is it?
a. We have some bacterial diseases which are common on hydrangeas. The amount of rain we had last week and this week favor these. Typically they will go away when we get warmer and the rain settles down a little bit.
1. A viewer wants to know about nutsedge control now. Should they treat it now and with what?
a. Yes, I would. Because Nutsedge is coming early. I would spray it now with sulfentrazone or halosulfuron (Sedgehammer) and make sure you make multiple applications.
2. Is there a preemergent which controls both grassy and broadleaf weeds?
a. Generally, no. The crabgrass preemergence will do a little control on broadleaf weeds, but not effective.
3. Is there a low-water, low-mow turf for clay soil in part shade?
4. How do you do crabgrass control if you want to also re-seed?
a. Get the seed in the ground first. Let the seed grow up. Then apply a post-emergent. Depending on the time of the year, you can come in with the post and pre-emergent.
5. Is there preemergent for sandburs south of Norfolk that should be put on now?
a. Yes, but it should have been put on a while ago. They germinate so early. Pendimethalin is a good preemergent. It's a tough weed.
1. A viewer wants to know about grub control timing this year. Should treatment be in June as always or earlier?
a. Probably earlier as soil temperatures are up.
2. We have an issue with biting insects that are like the itch mites from the oaks here in Lincoln.
a. It could be the pine woody itch mite off of oaks. I've seen mosquitoes.
3. One of your lightning round questions was about the mosquitoes. What about those?
a. Yes, they are out.
4. What do you do?
a. Standard mosquito control. Control your standing water in the yard. No standing water. If you have bird baths, empty those every other day. Change the water every 24 – 48 hours.
5. Are mosquito dunks effective in ponds?
a. Yes, especially in slow moving water.
6. This is a Kirwin, Kansas viewer. Is there a way to stop the spread of borers from felled ash trees?
a. When you are talking about borers, you’ve got to burn or chip that wood right away. Those borers continue to develop and grow even in firewood if it’s stored.
7. This is a follow-up to the mosquito dunk question. Are they safe for tadpoles?
a. Yes. The mosquito dunks utilize Bacillus thuringiensis that is a particular variant of that bacterium that is specific to flies and mosquitoes. They do work on some black flies as well.