Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Show Questions - June 7, 2012
1. An Omaha viewer has Knock Out roses. They have lots of silvery-colored spots and holes in the leaves. They wonder what’s going on and what should they do about it?
a. That sounds like rose slug. These little slimy slug-like things that feed on the surface of the leaves. That's exactly what they do. They sort of strip away the upper surface, leaving the silvery window affect. That eventually blows out and you end up with holes. What the viewer needs to do is go out and see if there’s any still there, because the damage stays behind. If you don't see any of these green slimy looking things that look like a green slug, there's no point in treating-- because you can’t kill what’s not there. If there is, they are very easy to control. An insecticidal soap would work, a Neem oil treatment would work. Or, of course, something like Sevin or Permethrin, or any of the synthetic insecticides will just hammer them. Make sure they are there before you treat.
2. We always have questions about controlling nightcrawlers in the lawn. Fred says don’t do it and Roch asks what do we do about a lawn that’s really been lumped up by nightcrawlers.
a. Let’s start out by showing the benefits: Nightcrawlers aerate from the bottom up. You pay to have somebody to come in and plug your lawn. The nightcrawlers do a great job on their own. If you’re willing to take the time to rake that material up, it’s a great top dressing. Actually, we call it bottom dressing when a nightcrawler does it. It's only for a short time of the year. It’s not season-long. It’s kind of a problem for a while. It gets caught on your mower wheels and whatever. But you can rake it out. If you can get it spread out you are actually going to get some benefits from it. It’s very nutritional. It helps with thatch management if you’ve got a thatchy lawn, especially in bluegrass. So it’s really all benefit and minimal kind of other problems. Sometimes they do mound up. If that's the case, then you probably want to get a water ballast roller at a rental place. Put some water in it and roll it over the probelm areas. I know it’s going to compact the soil somewhat. But if you watch how much you put in, you will smooth that area out and then you won’t have that Mr. Toad's wild ride with your mower when you take it across your lawn. Leave them be because they are truly one of nature's wonderous pageantry. They are also a good source of food for wildlife.
3. Speaking of food: rhubarb patch, not producing well. It’s 15 years old. They do wonder if it needs to be relocated. They’re watering every three days or so, which doesn’t seem to have any affect at all other than they still don’t have very good rhubarb.
a. Unfortunately, watering every three days, depending on what the weather is doing, might actually not be helping at all. It might be hurting. It sounds like some kind of a crown or root rot. You can try dividing the plant and moving it to a different area. Unfortunately, whatever is killing the plant lives inside the plant. So you might cut it in half and you still have it in this half. These bacteria or fungi, it could be caused by either, live in the plant material in the soil. You can till the soil and try to get all that plant material in the soil to introduce the organisms into the other organisms in the soil. That will help kill the bad ones. But I would try to replant into a different area. And if you have an area that is infested, try to till it up.
4. We have two blueberry questions, not really related. One question is from an Omaha viewer who bought one called Blue Jay. Wonders if they need a second cultivar to be able to get the fruit. The second question is from Ralston. They have applied Miracle Grow. They’re wondering what kind of growth they can expect on those shrubs in the first year and is that the right product.
a. I'm not familiar with Blue Jay. I’m kind of familiar with the names we see in the catalogs. One of the places I look for cultivars is out of the University of Minnesota. They do a great job. There's North Country and a couple of others that come out of there that are pretty reliable in this area. I think I would be looking at those sorts of cultivars to bring into your garden. As far as using the Miracle Grow, there's Miracid that will help you with the blueberries. The biggest thing is that we need to amend the soils. If you have just planted the blueberries, you can lift them easily enough. Be careful. Add some peat, some organic matter, some compost and bring those soils up. We’re trying to change the pH of a giant ocean with a little eye dropper. So, it’s something that isn’t a one and done sort of thing.
5. We’re going to go to Tyndall, South Dakota, which is in southeast South Dakota. This viewer has an earwig question. Earwigs are eating the cucumbers, tomatoes and other vegetables. What can they use to treat them?
a. That's interesting. Earwigs are not that common in Nebraska. Sometimes we see them in the southeastern part of the state. Earwigs like moist conditions. One of the things you can do is put some mulch—some straw, or perhaps newspaper (I prefer straw), underneath the fruit and lift them up a little bit. It would make them less susceptible to that earwig feeding. It’s the interface between the moist soil and the fruit where you are probably getting most of the damage. And then they’ll tunnel in. The other thing, you can actually go ahead and use something like a Sevin dust or a Permethrin dust and lift them up and dust that before you put down the straw and lift up those individual fruits. That’s my best suggestion. It is a rather unusual pest. But treat the soil where they are living--no need the treat the plant. They won’t be up on the plant, just in the soil.
6. This is a viewer from Hastings who wonders how available Tenacity is. They’re thinking of it as a selective grass killer. Didn’t kill the bluegrass, does kill other types of grasses. Doesn’t seem to be able to find it at garden centers.
a. You would not find Tenacity at garden centers. It is primarily targeted to professional lawn care applicators, professional turf grass managers, and landscape people. That doesn't say you cannot get it. Some of the bigger distributor type people—there's a company in Omaha called Zimco, there’s a company called Lesco. You probably have to go to a bigger metropolitan area than Hastings. There might be an ag supplier that can get you Tenacity. When it first came out it was only sold in gallon sizes. It was like $780 a gallon which makes gas seem pretty reasonable. They’re making it in an 8 oz. container now. It still seems pricy but you put it on in such low doses. It does a really good job on crabgrass. It also controls a fair amount of broad leaf weeds and it’s safe at seeding. It has a lot of really positive traits. It controls nimblewill and tumble windmill grass so there’s a lot of reasons why you want to use it. Follow the directions. It’s going to take multiple applications. And understand that if you don't follow the directions you’re going to be unhappy and out a few dollars that you could have spent on something else. It's not as easy to use as some of these weed and feed products. Keep that in mind when you pick it up. You’re well within your rights, it’s not a restricted use pesticide, but it's going to take a bigger turf-type distributor to get it to you.
7. This is a coneflower question. We have had several questions about aster yellows. This is a viewer that says that half the flowers are green instead of the colors they should be. It’s the red, orange, and pink ones are all affected. They don’t think they’re deformed like the asters yellow picture, but is this asters yellow?
a. Absolutely. The fact that one half is green and not its normal color, that's just a dead giveaway. So what we need to do is rogue it out. Off with its head. That's the whole plant? Yes, the whole thing needs to be removed.
8. This is a Tekamah viewer. They have a question about a one inch caliper flowering crabapple. It was a container plant. They think they did it right--wide hole, good depth, mulched, watered. Came through the winter, bloomed, and then heavy rain and wind made that tree rock back and forth in the hole. They wonder what they can do. They can now actually see the original root ball between the interface with the surrounding soil.
a. All may not be lost. A couple of things, although they may continue to have problems with it. A couple suggestions would be-- if the plant is still doing pretty well, still in full leaf, I would get some nice sized, 6-foot tall T-posts, put them in, maybe in three locations. We want to secure this plant pretty well. We don’t want it to move too much. Give it several months secured so it’s not going to have a lot of action. And then go in with soil, top soil, work that around the plant with a shovel and a hose and really want to saturate that. Probably what has happened is that the containerized root ball is still just a big mass. It will be hard to break it up. We want to interject some stuff. Keep it tied up for a while. We've had good luck with that. Give it about a year.
9. This is also a Hastings viewer. They have cucumbers. The stem is yellowish-white. Sort of looks sheared off. They had flowered, they had one-inch cukes. Then they looked sick and the vine was sheared off at the soil level. Is this an insect or is this a bird?
a. No, that sounds like cutworms. That’s sort of classic. And we’ve certainly had a huge flight of cutworm moths across the state. Of course, those cutworm moths are going to be laying eggs and now there's going to be little cutworms. And that sounds fairly classic. There's a couple things one can do. If these are very small plants, you can put a collar around. Some sort of a cut-off like a plastic cup, just to keep them from getting to that stem. But if they’re larger that’s not particularly practical anymore. You might want to go in with your cultivator, a little hoe, and cultivate all around them and try to uncover those cut worms. And if you find them, destroy them. Dump in some soapy water or cut their heads off, or whatever. So that would be one approach. And then, of course, you could use something like Permethrin or one of the other dust products and put that all around the base of the plants to try to control the cutworms. I know it's so frustrating. It just about gets to a point where they are of real value and then the plant gets cut off. Cutworms are a very frustrating insect.
10. We have a lot of weed questions this year. Very large weed with white flowers right now, kind of all over Nebraska. People are wondering what it is. It’s in the ditches, ferny foliage.
a. It’s probably wild hemlock. There’s some other species that might look like that. This is an annual which is amazing when you think about it, because it gets huge. They’ll get seven to eight feet tall. They are relatively easy to rogue out with a hoe. They don't have a real strong root system on them. That’s one way to eradicate them. As a hemlock, they do have poisonous parts. You know, that's what killed Socrates, right? You don’t want kids chewing on it. It has a showy flower. It's attractive. People like to keep it around. It spreads by seed--it is an amazing plant because it grows very robustly from a single seed that’s fairly kind of small. But mostly you want to eradicate it.
11. We have a viewer that has an ornamental pear. They’re saying what happens, and this has been going on for a couple of seasons now, its leaves get sort of a yellowish color and spots to them and they begin to drop. They’re wondering what that might be and is there anything we would recommend for treatment on that?
a. It sounds, especially since they are getting chlorotic and they’re dropping right after fruit set, that they are unhappy. And they’re probably unhappy because of a nutrient issue. There are some foliar fungi that can cause trees to defoliate completely. But, usually it is in spots around the tree. When you see it on the whole tree--the whole tree drops its leaves, and it drops them at the same time-- it's usually some kind of an environmental trigger or they are not getting the right kind of nutrient. I guess I wouldn't know exactly what that nutrient would be that would cause them to drop. Is it usually this time of year, once it starts to warm up? I would say it’s probably a stem girdling root. Again, it’s probably a containerized tree. Pears and crabs typically are. We probably have a root issue. And as the tree matures, and we get into the heat of the summer, it can't keep up. Not a lot you can do unless you can see it. Then we all know we’re setting that tree back, perhaps, if we can find that root and pull it out. I would guess we have a root issue. So you are right, it's a nutrition thing that’s being cut off.
12. This is a white flowering plant question. Also in the ditches right now we are seeing elderberry with a flower. Are they good plants, bad plants? And we actually had a viewer ask us about Black Lace which is a different species. It actually died to the ground. We have the species that actually grows in the ditches and then this cultivar. Any thoughts on the pros and cons of those plants?
a. Elderberry is a fun plant. It’s native to this area. Anything that produces a fruit, I'll eat. I'm all for it. That's the up side. The down side is that they can be aggressive when in an inviting location. They can spread over time and it’s sneaky. It doesn’t happen overnight. It’s over a period of time. It’s one of those things, you turn your back and you turn back around and it's right behind you. That’s the problem with elderberry. It’s alright to have, just know you’re getting something that can be aggressive. As far as the cultivar, is it coming back from the ground?
Kim: Yes, it comes from the base. They are not getting very much top growth ever. It always seems to die at the ground.
Jeff: Elderberry will do that anyway. It will die back. You’ll lose the previous year’s big cane every year. So they can just cut that off.
13. We have a viewer who has tobacco bud worm on their geraniums. The last two years they have been healthy, they bloom until mid-August. But then they can’t get rid of the bud worm and get them to flower again.
a. It's always a real challenge. We didn't used to have tobacco bud worm. It's a relatively new phenomenom in the last ten years or so. The moths fly in and they come in at night (a little brown moth) and lays its eggs on the geranium, on the petunia, and on some other plants. And then those eggs hatch. The caterpillars grow very, very quickly. Over just a period of a week or ten days they can get quite large and they do all that damage. The challenge is how do you control them? One way: you can shake them off by just physically going in and shaking the geranium. They will drop to the ground. Make sure they don't drop back into the pot. That’s one way. You can also control them with something like a BioNeem, which would work. The BT formulations really work quite well. And, then again, you can use one of the standard insecticides like Permethrin or Sevin. But, of course, you don’t want to use the dust because that’s going to destroy the aesthetics of the geranium--it would be all covered with white stuff. So you need to use the liquid formulation. It's a tough one. For every one you kill, 50 come to its funeral. The new moths come in the next day, so you start all over again. Keep on top of them.
14. We have a Kearney viewer who wants to know how to grow clover. She has purchased seed before. All she got was weeds and a plant with yellow flowers which might have been Black Medic.
a. You know clover, it’s just like any other species. If you get some weed contamination in it, it often is going to struggle. A lot of our soils in eastern Nebraska, not quite as far as west, tend to have a whole lot of nitrogen in them. Clovers like to fix their own. And they tend to get a little lazy—the clovers and the medics. So, if there’s a lot of nitrogen in there to begin, they struggle and then the grasses and other weeds dominate in that regard. You don't want to fertilize them. Everyone wants to grab the Miracle Grow or whatever every time they try to grow a plant. And for something that fixes its own nitrogen, you are not really going to see other nutritional deficiencies because they are very efficient nutrient users. It could have been a combination of too much nitrogen. It could have been a bad seed source that had other things in it, like black medic, the yellow-flowered beast. So there's a lot of things that could have gone wrong. Buy quality seed. It’s hard to get certified seed of white Dutch clover, but it is available from better known mail order places. Garden stores don’t usually carry it. Glad to hear some people are willing to give it a try and get it planted. If you’re having trouble, it’s probably too much nitrogen. That’s why we love that plant.
15. We've had a lot of pictures sent in from all over the state and from multiple locations of red maples showing problems. Are we seeing diseases? Environmental?
a. I had a couple of samples that came in. I've run tests A through Z and I haven't found anything pathogenic. People will put these trees in the ground and forget to water them. It could be a drought issue. Or it is possible it could be chemical drift from neighbors that drifted on the tree.
Fred: Leafhoppers on maple: They feed on the leaves and cause small distorted leaves and it looks like herbicide drift, when in fact, it isleaf hoppers. I know on my own little maple, that's what's going on there. I would suspect it might those. I would use a hose sprayer, but make sure it is leafhoppers.
16. This viewer has planted the “three sisters garden” (corn, beans, and squash) and they seem to have difficulty keeping the birds away from the corn. How do you suggest keeping blackbirds away from corn?
a. Well, I guess for me, and sometimes it's not always great, but I have fruit trees incorporated into my garden. That creates sheltered areas. You could get bamboo poles and bird netting and set yourself up a sort of net tent over the corn. We do this with insects and you can do the same thing with birds.
17. This viewer has a question about grapevines that get infested every summer with Japanese beetles.
a. The Japanese beetles are moving further west and we are seeing them in Lincoln now. It's a difficult problem because they fly in. You need to treat them with an insecticide. Sevin works well. The challenge is later in the season: if you get into July and early August, you have to be careful with spraying; check the label to make sure about the pre-harvest interval. You can control them with Permethrin and Sevin. Again, you probably are going to need multiple applications.
18. Here is a nutsedge question: This viewer has nutsedge in shrubs, annuals, and perennials, so has just been pulling it.
a. Once you get it into the garden, you’ll have to spot spray. This year is so messed with what we might predict for the latest spray date. You have a couple weeks to hit it with Roundup, but don't get it on the green plant material. There are some products, one called Weed Beater Ultra. I like the pulling idea if it's not too overwhelming. If you are going to use an herbicide, I'd wipe it down or paint brush it on--or spray it on and be careful.
19. Here is a boxwood question: This viewer has a 10-year old boxwood that has a brown stripe through one side and it is brown on the other side. They pruned out those areas so now they have holes and they are still seeing the problem occurring. Are there particular diseases?
a. There is one particular root rot that will cause patchiness. You can cut it out, but it will come back again. Those organisms live in the plant. There are also stem borers and if they are feeding in the stem, the stem will die and cause the same condition. Again, when do you look for borers? They are not common. You have to look for sawdust right at the base and that would help differentiate. Boxwood borers are not that common.
20. The viewer who sent the next picture wants to know what this weed is. They spotted it along 48th and Highway 370
a. This is Japanese knotweed. It's one that has really gotten press lately on the list of noxious weeds. It's a tough one. I have been treating since I was 12. They are very hard to get rid of. You could try an herbicide to get rid of it. Burning also works well. It gets rid of enough of it that the growth is retarded. There are propane weed burners available. You have to make sure the conditions are okay for burning.
21. This question is from a viewer with a cucumber beetle problem. How can they control them?
a. They not only cause damage to the leaves and plant, but also transmit bacterial wilt disease which is often more of a problem than the beetles themselves. You could use a row cover up until they start to flower, but you’d have to take it off because they are insect pollinated. Generally for beetles, you need to rely on permethrin or Sevin; any of the standard products will do a nice job. They will generally last 3-5 days so it may take multiple applications. They seem to come in waves and they dissipate and go away for a few weeks and then reappear. They are actually different generations of beetles.
22. We have a question about a yellow flowering weed.
a. There are two that have yellow, one is black medic. It makes its own nitrogen. It is a seed producer and will spread seeds everywhere. The birds will move it. It doesn't have aggressive taproot. If you want, you can pull it if it is in the lawn. It's an annual. The other one is birdsfoot trefoil. It is robust and has a clover-like look to it. Some people say it is clover, but it's not. It has a leaf that looks like it. It has a bunch growth habit. It doesn't spread as badly. It can get up to 18-26 inches tall. They feed cattle with it in Europe and in portions of Asia. The flower is much more showy and it has a better look to it. If you mow it, it would continue to flower. It is not fixing nitrogen and it can get away from you.
1. When is the time to prune an overgrown walnut tree?
a. Earlier in the spring before it leafs out. But if you have issues such as it growing into the house or other things, you can do it now.
2. Do you have any idea why somebody with a smoketree cannot get it to bloom? They have not cut the flowers off.
a. Maturity may be an be an issue. It blooms better with age. It could also be hardiness. I would look at the tips of the plant dying back or losing the branches.
3. Are you familiar with Jan and Joy cherries or is good old Nanking cherry the one you would suggest for a bush variety?
a. Nanking does well here. It's a plant that they put in tree rows and windbreaks. I would say it would be a good one.
1. We are getting millions of questions about yellowing daylilies.
a. It's environmental, either heat or drought stress. A lot of them are showing it.
2. Are there any viruses of clematis with yellowing and spotting from the base up?
a. Spotting from the base up is usually a sign of a bacterial infection, nothing viral.
3. Can corn gluten meal be used as a fungicide?
a. I would like to phone a friend on that one.
4. We have red raspberries that are crumbly but the black ones aren't.
a. It could be that the crumbliness is caused by a fungus that the black one is resistant to.
1. In older neighborhoods with 50 percent sun and north facing, what can be done to get the turf to grow?
a. A turf-type actual fescue may do fine. But they might want to run a soil test to see if they have a nutritional imbalance.
2. How much water does bluegrass need?
a. If you want to keep it alive, irrigate once every 21-28 days. If you want to keep it green, irrigate an inch and a half a week, unless you get rain during the week.
3. It is possible to spray bindweed in a spruce windbreak?
a. You can use the glove-in-glove method: plastic glove with a cotton glove on top, wipe with Roundup.
1. This viewer had a cat playing with a junebug toy. Is it time to put down grub control?
a. For annual white grubs, now would be a good time to get started.
2. And the product is . . .
a. Merit is a good product and Grub X. And there's others.
3. A viewer in Fall City has an ash that has round holes.
a. It sounds like a borer problem. If it was large, it wouldn't be emerald ash borer.