Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Show Questions - May 24, 2012
1. Jim, the first question goes to you. We typically try to give people a non-chemical approach to doing anything, if we possibly can. We have a question about whether killing a spider with a burning a rag is a good idea. Is that the kind of thing that will get rid of that spider quickly?
a. Possibly, but I wonder what kinds of collateral damage it will cause, too. I think most of us are pretty reactive or impulsive when we kill spiders. We think they'll bite or be poisonous, but the best way to deal with a spider when you see it is stay calm and get something like a paper towel or Kleenex or something like that and just very carefully move your hand close to it and then, you know, whomp, smash it and wipe it with the Kleenex. If you don't have something to use, just use the flat portion of your hand. They're not going to be able to bite into something flat. Just kind of a stiff whomp and you have him. Some people try to follow them around with a jar, which I think is very noble, and they put the lid back on top when they catch it, and put it back outside. If you manage to do that, they are beneficial. As opposed to the fire. The fiery approach sounds like it could be contagious and spread.
2. Zac, how do you kill Allium or wild garlic, if you choose?
a. Allium or wild garlic have waxy leaves, so they don’t absorb herbicides very well. The best way is to mow it and immediately spray with 2,4-D.
3. Amy, a Lincoln viewer has peonies, only half the buds opened on the shoots, half of them stay closed, and they're brown around the edges.
a. You’re dealing with a classic case of botrytis blight. We’ve had wet weather and this causes fungus. It's affecting the buds, and it will kill that bud, and it kill the bud and it will never open up. You've got to dead head, remove those buds so the rest of them can open, and use preventative fungicides. Start making those applications as the buds are setting and you have to continue on if you want to have nice, full peonies. How often do you treat? You have to read the label. It could be 7, 14, or 21 days to do it again. Read the directions.
4. Sara, someone has three Endless Summer-type hydrangeas that are 6-7 years old. Any conjecture on why two of the three are not blooming well?
a. That can be really frustrating, because it seems like they sometimes do it out of spite and won't set flower buds. There are a few different things that could be playing into this. The Endless Summer-type hydrangeas are supposed to bloom on both old wood and new wood. So typically pruning is not the big issue, unless you're looking for early-season flowers, and then if you're pruning off the old wood, you may have flowers that come on later in the season. Sometimes with some of these plants, it can be a maturity issue, so you just have to have the plant develop a certain maturity level before it will develop flowers. So it can be real frustrating, and it's hard to give good advice as far as how to get it to bloom. I would just be a little more patient and see if it will start to bloom for you in the next couple of years, and try not to prune it late in the season so you're not pruning off any old wood or flower bud that may have developed.
5. Jim, our first picture tonight is from Benkelman, so we appreciate that for our western viewers. Lots of roses, different roses in the beds. This one they're saying they did buy in a plastic bag, but they've had it for about four years, it seems to be the one that does this, and we're looking at this in terms of some damage. They're doing some disease and insecticide control. They're wondering if they should replace it. It's a totally different variety than the rest.
a. That could be thrip damage. I'm not sure whether the buds themselves are not as sound or whatever early in the season, but thrips like to get beneath the buds of the roses before they start to bloom. They penetrate deeply when the flower is growing and, as the flower expands, they can be right down at the bases of the petals, feeding. So you get that response along the edges, where you get some desiccation that's starting to occur.If you want to know if you have hrips, you pull the petals apart and look down into the base of the blossom. Thrips are elongated, small, and wiggle around. When they feed, it causes a lot of little black speckling not only from their feces but also from the scars they leave. One thing that can suppress them on roses is imidacloprid or Merit. That might extend the appreciation of that rose variety for at least a while in the future. Sarah: Flowers with fewer petals have a more open flower, might be a little less susceptible. But I think if they prune off the ones that they're having damage that might help lessen the thrip population for additional damage later in the season.
6. This is viewer in Omaha: they have a lawn under four mature Black Walnut trees. It is quite shady. They seeded the lawn eight years ago and it is still struggling. What can they do? There is foot traffic involved with this; dogs and children.
a. You have the trifecta -- Black Walnuts, shade, and dogs and children. The quadfecta, I guess. Turf and trees don't get along very well, and Black Walnut is going to have an allelopathic effect on the grass underneath. If you even get it established, the dogs and the children are going to whomp on it. So something has to start going away. Probably you've got to get rid of the trees. You have the children and the dogs, so they need something to play on, and so you've got to get rid of the shade as best you can.
Kim: Or let your children play under the trees.
Zach: And then what are they going to play on, mulch?
Kim: Dirt! Dirt is good!
Amy: Wild violets!
Zach: I think they mentioned in the two years in particular they had grass dying. You might get lucky and get grass established under a tree for X number of years; five, six, eight, ten, whatever. And then we get a couple of summers that provide a totally different stress than that grass is used to. It kills off that grass, and you have to start all over, and it takes a long time for us to find a cultivar or species of grass that will fit in there.
7. Every year an apple tree gets spots on the leaves and brown spots on the outside of the apples themselves. They've been using a combination spray. The apple tree looks like it's going to get it again. They want to know what it is. They think it's cedar-apple rust. The real question is can they still eat the apples?
a. Yes, it sounds like cedar-apple rust and, yes, you can eat the apples. There’s nothing wrong with the apples. If you don't like the look of the skin, peel it off. Use a fungicide application; it's key. The trick with tree fruit sprays is, are you applying a fungicide or an insecticide? There are a lot of fruit tree sprays where we're looking at a combination of products. They say spray the fungicide now and come back with an insecticide spray, and then the fungicide again and the insecticide . . . If you grab the wrong bottle off the shelf, you've missed your target. With cedar-apple rust, you have to start early and you have to follow the directions. Make sure the label is for fungicide, not insecticide.
8. A fun question about a journey into composting. It's three questions, actually. Can they use coffee grounds in the compost pile? What about the color of the coffee filter? Does brown break down quicker than white? And, can the filters themselves actually be put in the compost pile.
a. Okay. Good questions! Yes, both coffee grounds and coffee filters can be used in compost. I don't know that there is any difference between white or brown filters; I think you can use either one. Even though they're brown colored, they're considered as a "green" material or a material that's high in nitrogen. So you're going to need to balance those with something that has a higher level of carbon.
9. We have a couple of ash tree questions. This is from Otoe County: A 30-year-old ash tree where one inch-pieces of the bark pop off and there are holes in the trunk where the bark has come off.
a. It sounds like Ash Bark Beetle, and if you see tunnels and galleries, it means something has occurred negatively. It could have had borers that strangulated some of the branches early on. Needless to say, the tree expresses that and you've got real serious problems. The survival of the tree is pretty doubtful. How large?
Kim: 30 years old, 30 feet.
I say new tree.
10. This is a viewer, we asked for a picture of the weed, fairly aggressive.
a. I'm pretty sure it's pale dock with that taproot. In terms of control, 2,4-D will control something like that relatively easily. But with that taproot, it's best to do it--- like all broadleaf herbicides--- in the fall. That will give you the best chance for that herbicide to get down to the taproot.
11. Amy, this is a Brainard viewer with daylilies with the leaves turning yellow. Any diseases of daylilies or is it potentially environmental?
a. It could be environmental. The rain has been spotty the last couple of weeks. How wet is it around that daylilly? They're prone to a few crown rots. Pull back that mulch and see how wet it is. And, if that's really wet, that might be your issue. Sometimes cooler weather can give you some yellowing. Different situations like that. So check the soil condition first.
12. We have about three or four fruit tree questions. I'm going to lump them together.
* A Dunbar viewer has a North Star cherry about two years old on the west side of the house with yellowing leaves; they are not watering very often. But, the leaves are yellowing.
a. The cherry tree with yellow leaves might be environmental. When the trees leaf out in the spring and we get hot, dry weather, sometimes they abort a few leaves. That would be my first guess. It could be borers if there is sappy discharge at the base of the branch.
* A viewer in Leigh has a North Star cherry planted several years ago, rabbits ate it off, grew back up, gets cherries, and they fall off.
a. The cherries dropping the fruits, that could be a pollination issue. We saw some of the earlier flowers that set fruits. Some of those didn't pollinate properly, so you had that little cherry on there, and it fell off. There is nothing you can do about it at this point.
* And then a peach question. Is it too late to do any thinning or can they possibly do that now.
a. The peaches. No, it's not too late to thin. You want to thin to about one peach per shoot or one every six inches of branch.
13. We have a Sandhills viewer who wants to know if there is something that would prevent grasshoppers around raised beds before they get too big.
a. I don't think there is.
14. We have a Lincoln viewer who has a mostly black bumblebee that is boring into the pergola roof supports.
a. That's not a bumble bee. It's an eastern carpenter bee and a close relative of the bumblebee. It will continue to do damage to that structure. What I would suggest you do is, if there are any holes or open holes now, take something like Bifenthrin and give it a good soaking. Protect yourself. Don't get any splash back on you. Soak those holes and tunnels, because that's where their brood are developing, and soak the portions of the wood there. That hopefully will act as a preventive. They can be a real detriment to the structure in some cases.
15. Zac, we had a viewer send us a sample of grass from Norfolk. She wondered what it was. She has been mowing for almost 50 years, and this is a new one. What is this grass and how can it be killed?
a. Unfortunately the quality of the sample was pretty rough by the time we got it through the mail, so it's difficult. The seed head looked like a ryegrass or tall fesscue. Controlling a perennial grass in another perennial grass fescue is always difficult. Control is to spot spray with a Glyphosate product.
16. This is a Bellevue viewer who has Vinca minor, usually very healthy. The new tips started to show some browning.
a. There is a fungal disease that will infect along the stem itself. It starts girdling the stem and the tip can't get water and nutrients. There isn't a lot you can do about it. Creighton campus had a major problem with it years ago. Prune out the affected tips and reduce water to that area. You need to reduce watering and it should come back. Vinca minor is excellent at coming back and taking over once again.
17. Okay, Sara, are you familiar with how to grow fava beans in our climate and make them set bean pods?
a. No. I'm not sure if they're going to be tremendously different from other beans. I don't know. Probably have to look up a little information on that one. Maybe we'll try it next year in our Backyard Farmer Garden and provide information.
18. Blue spruce and saw flies. Is this a pest of blue spruce?
a. Blue spruce with flies; I'm not that familiar with it but I'll take the word of the person. Could be saw fly caterpillars, I suppose. Control will have to be done every year that you observe them. If you can knock them off, that helps reduce the population or a good dose of carbaryl spray, that will kill them.
19. A viewer has wild strawberries in their yard. They have tried to control them. They would like an organic treatment to control the wild strawberries in their yard.
a. The organic treatment for that one is to pull it and they have runners so you'll pull it and pull it and pull it. If all else fails, your typical herbicide in the fall, obviously that's not organic, but pulling would be the best one for that.
20. Amy, a Hastings viewer has a bluegrass lawn with moldy sort of white on the leaf blades that does not wipe off. It's killing the turf, with random circular patterns throughout shady areas of lawn.
a. If it's in the shady areas, it has to be powdery mildew. We're having lots of issues with that, not enough air circulation. There isn't a lot you can do for powdery mildew. Try resistent varieties. A lot of times you can mow it off. I haven't ever seen it kill turf, though. So if your turf is actually growing, powdery mildew shouldn't do too much injury to it. If the turf is dying, there is something else going on.
21. This is from the Omaha area. They sent in pictures of serviceberry, five years old. After the second winter, they thought it rabbit damage at the base, so they wrapped it with kraft paper, then they saw a neighborhood cat or porcupine damage on the trunk, and then they noticed some dead tips in the crown of the tree. They wonder, is it hopeless, or could they do something like mulch to help this tree to recover?
a. I don't think it's hopeless, although the tree appears to have fairly significant bark damage, but the kraft paper won't help that, because anything that wants to damage the trunk can get right through the paper. You might want to put up chicken wire to prevent cats or rabbits from doing additional damage, but mulch around the base of the tree would be helpful to eliminate competition with the grass, and make sure the tree stays well watered this summer as we go through the hot, dry periods. If we're not getting an inch a week, make sure the tree is getting a good soaking at least twice a month. Hopefully the tree will regain a little bit of vigor, and you'll stop seeing that branch die-back at the tips.
22. A Lincoln viewer has a 3-year-old oak showing a little bit of dead, some curling leaves, but mostly dark-brown marble-sized clusters and peeling bark.
a. Especially on younger trees, you can get fairly heavy infestations of oak bullet gall. Hang with it, because as the oak ages the incidence is less. Its too late to do anything about it. We don't really understand the life history. It's just one of those phenomenoms that is associated with the oak tree. It will tolerate the galls pretty well.
25. Zac, we have a Wilbur viewer who has brome; they want to kill it but its always too windy to spray. He wants to know if they can cut it really close and then transplant into that area. He has plants waiting.
a. It depends; there are two types of brome. The downey brome is a winter annual, so when it dies out in the summer, you can transplant into it, and then put a preemergent down, but if it's the perennial brome, just cutting it back and thinking it's going to go away, that won't work. You'll have to spray it out, using glyphosate, then seed back into it.
26. Amy, this is a viewer from Crofton: 20-year-old Bartlett pear and a Kieffer pear, usually lots and lots of bushels, but noticed ---and this was this past Tuesday--- every pear on all three trees is brown on the blossom half. They wonder is it a late freeze right after flowering and will they be edible?
a. I'm afraid that this is actually an environmental thing, maybe a late freeze that affected these fruits---the fact that all three trees have it at the same time. There isn't a lot of fungal diseases. You might see some fungii on there, but this would be secondary. I haven't seen any fungal disease that starts at the bottom and works its way up and be that exclusive throughout the whole tree, so most likely it's just cold weather. You're most likely going to need to buy pears from somebody else.
27. Sara, we talked last week about landscape fabric, we said we really don't use it. Do you want to comment on that a little bit again?
a. The only time you should really use it is if you're going to do a rock mulch. It prevents the rock from burrowing its way down into the soil, but you would never use that under an organic mulch. You want the organic mulch to break down to improve the soil, plus, if you get wood chips on top of landscape fabric and we have a big rain, it will just float right off. You want the mulch to be in contact with the soil so only use the landscape fabric if you're going to do rock mulch. And, as horticulturists, we don't recommend that as rock mulch because they have real drawbacks in terms of plant health.
28. Jim, we had a viewer send us a picture of an absolutely beautiful moth. Was it a Cecropia moth?
a. Yes, it deserves repetition, because it's such a beautiful moth, large and rusty red color mingled with black, eye spots, there it is, with a 4-1/2 to 6-inch wing span, always active at night. A lot of us miss it.
29. Zac, a Bennington viewer cut down a 40-year-old linden; they removed the stump and filled the area with soil, then planted grass. It came up, but it doesn't grow.
a. Any time you're planting grass in an area that was formerly a tree, it's hard to say what's going on. Needs extra water, needs extra fertility, depending how much of the root you got out of there. Pretty difficult to convert from a stump directly to grass. May take extra tender loving care. Some of us would say stick another tree in that hole. I'm all for that as long as we don't have dogs and children underneath the tree. It all comes around.
30. Amy, we've had a lot of conversation about issues with maples, particularly red maple. This is an Elkhorn viewer that gave us a pretty good description: a Red Sunset Maple. It was planted fairly large, two-inch-caliper, south side of the house. The leaves are turning brownish-yellow, leaf ends are blackish or brownish
a. It's environmental stress. Whenever you're transplanting a large tree, especially in the fall, and we run into a dry winter, they don't have the root system there anymore because they cut it all out. You really have to make sure you're adding supplemental water, even in the winter, and in the summer, and if we get hot and dry and get drought conditions, you've got to make sure that you keep that tree watered. It's just a stress issue.
31. A viewer has a lily pond with slimy moss and algae. How do they get rid of it?
a. First, just do some cleaning of the pond, to try to physically remove the moss, the scum, and scrub it out of there. Try to make sure that in the fall you're not getting a lot of organic material into the pond, like tree leaves and things like that, because they'll break down and contribute to the algae and moss problem. You could also go to a nursery or garden center that has a good pond-care selection, and look for a copper-type product that would be targeted at killing algae in the water. That's what we usually use in larger ponds, is a copper-type product, and I think, you know, you find a nursery that has a good chemical selection for pond maintenance, you'll be able to find something like that, that you can put in the water to help control some of that.
32. Jim, we have one of our biggest fans in the garden state calling us about fungus gnat infestations in the basement. He seems to do everything right, but he's wondering how do they get into his basement?
a. They're so small, they can fly in from outside, like even in the autumn and the spring. They're so prevalent outside whenever there's moisture, they can get inside, or they can come in on soil that hasn't been sanitized or whatever. If you haven't tried something like this formulation for fungus, Bacillus thuringiensis, for fungus nats and other kinds of greenhouse pests that developed in the soil or sand medium, give that a try, it's virtually non-toxic to humans, and it's tailored to kill off the larval form of those gnats. Whatever you're growing in that house -- make sure you have good air flow, and you're not overwatering.
33. Zac, we have an Omaha viewer who wants to know if it's okay to dig up the pinkish red thistles that grow near the road because she wants some.
a. I would be really leery about that because anything with pinkish-red thistles is probably going to spread and I would be really leery about moving in things from a ditch.
34. Amy, Springfield, coneflowers. They have brown spots on the surfaces of the leaves. Wondering is that something she should worry about?
a. It's nothing to really worry about, it is a fungal infection. As we get into dryer weather, it's going to disappear.
1. We have a Waverly viewer who wants to know about the best time to move columbine.
a. Columbine does not transplant well. It's better to re-seed or re-establish. If you're going to try to move them, I would do it in the fall.
2. A viewer has zucchini so thick he can't get through it. Will he kill it if he cuts off some of the foliage?
a. No, you won't kill it; you could pull off a few leaves. You might consider thinning it. Just pull out an entire plant
3. A Dodge, Nebraska viewer has a peach tree that's 16 feet tall. Can it be topped?
a. We don't like to use the word topped. You can prune the height down to make it easier to do the harvesting. It can be done.
4. We have a viewer that keeps losing their peas to something that disappears. Could it be a bird?
a. Could be a bird. My thought is that it's probably cutworms.
5. Is it the right time to pinch mums and those sort of things for fall bloom?
a. Yes, the rule is PINCH UNTIL THE 4th OF JULY , then let them go.
1. Is oak wilt an issue in Nebraska?
a. We have two confirmed cases in Omaha.
2. What are oak wilt symptoms?
a. Redding and browning of the leaves, typically on the margins and the veins and if you strip the bark back around the branches you will see brown streaks in the vascular system itself.
3. Does sunflower rust attack the ornamental sunflowers?
4. And the control would be?
a. Fungicides, but normally I don't recommend anything for sunflowers. It just gives more color to the sunflower.
5. Someone has rot in their Montgomery and yellow Bing cherries.
a. Most likely blossom brown rot. Fungicide application is best.
6. Have you heard of turnip veining virus?
a. I have, but I can't remember what it infects. Viruses infect so many different plants, it might affect turnips, but it might affect pea trees.
1. Are small curling or drying-up of the leaves on redbuds a sign of 2,4-D damage?
a. Could be. Herbicide damage is really hard to identify, to confirm, but it could be.
2. How do you prevent purselane coming up through cracks in the patio?
a. Pull them up. And Roundup works only OK.
3. Is corn meal the same for corn gluten meal for use in turf?
a. Depending on the brand, essentially, it is.
4. How calm does it have to be for a person to safely spray Glyphosate or 2,4-D in their landscape?
a. 5 miles an hour.
5. How much water per week should be applied to buffalograss if you're in the panhandle?
a. As much as it needs, which is not very much. As an established stand, maybe one inch a month, you could get by with.
1. There are little white rounded things attached to branches on trees in Omaha. Is that a scale?
a. Probably some kind of scurfy scale, something like that. You can try something to control them in the month of June.
2. In Mitchell in the panhandle, when is the best time to spray for Zimmerman pine moth?
a. That's a good question. There are lots of different pine moths. Mid to late August into September, that's the first application. And you can also catch it in early April, before things start to get active again.
3. Is there anything that can be applied to prevent grasshoppers from invading raised beds?
a. I don't think there is. They're quite mobile. You can try, maybe neem oil as a repellant for those young little ones.
4. Are cucumbers inedible if they have become infested with cucumber beetles?
a. No. Eat whatever you can.