Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Show Questions - May 31, 2012
1. This viewer sent a picture of an apricot tree and a wound that is oozing sap. What is this and what can be done?
a. This could be peach tree borer that has gotten in the main stem and the tree is now oozing the sap to it push it out, but that won’t work. It could be a diseaseissue, a fungus or bacteria. Regardless, if it got in there it is probably because of a wound. The only thing to do is to prune it out, but it looks like it's a central leader on the tree. If so, this may be the death of the tree.
2. How can you get rid of horsetail or scouring rush from flower beds?
a. We get a lot of questions about this weed and you see it as an ornamental in an arrangment. This is in the Equisetum family; it reproduces from rhizomes in the soil and spores. The rhizomes are black instead of white, which is more common on perennial plants. Herbicides are not very effective on this plant. Tilling up of the soil, really getting the soil loose to dry out the rhizomes, and doing that repeatedly is about the only hope you have of knocking the plant back. It is sold as an ornamental but is very invasive. So be careful.
3. What to do about cedar apple rust in cedars? They are showing symptoms of rust and maybe spider mite damage. What should they do?
a. It doesn't harm the health of the cedar tree; but you do get these big brown balls that release these orange gelatinous masses in the spring. It kind of looks gross, but kind of cool. Pull them off and get rid of them so they cannot infect nearby apple trees.
4. This viewer has a lemon tree in a container so it can be moved it inside in the winter. It lost most of its foliage. They sprayed it with a general product. Still losing leaves, what do we suggest?
a. This tree might have spider mites. Lemon trees are prone to that. A heavier spider mite infestation would cause it to drop leaves. The trick to controlling spider mites is repeating your apllications and doing it often enough so that you can break the cycle from generation to generation. The spider mites can have a pretty fast cycle--sometimes 10-14 days or even less between generations. You also need to make sure that you're using the right product because not everything works very well at killing spider mites. Carbaryl is a very poor miticide. Washing plants off with water---a good strong spray down with a hose or in the bathtub will wash a lot of them off. You won't get all of them, but this is a good way to cut down on them.
5. An insect (bumblebee) the size of a man’s thumb, is going in and out underneath a patio slab. How should they be managed? They know they are beneficial, but they are on the patio. They have not been aggressive to date.
a. This is characteristic of bumblebees. They take over a hole that was already present. Bumblebees only live one year, so they are not permanent. Best to do nothing, try to keep them if possible. If they become aggressive, you need to take care of them.
6. A viewer brought in a plant and wonders what it is. It has characteristics of things they have seen as ornamental.
a. The plant is leafy spurge, a noxious weed. If you have this on your property, you need to try to control it. Now is not the best time to control it. Fall or early spring applications with a Grazon P + D type of product, something with 2, 4-D and picloram. If you pull these leaves back you see a white milky sap; it is a perennial and spreads by both seed and rhizomes. They have a pretty cool seed dispersal mechanism: as the pods dry, they actually burst open and eject seed and disperse the seed that way---up to 5-10 feet away from the plant.
7. A question about raspberries: They are red with white patches. What is this?
a. There are some fruit rots that can occur. If the white parts are fuzzy, it's a good indication that it is a fungus. If it's just a part of the berry that's turning white, there are some viruses that can cause that. Unfortunately if it is a virus, you need to rogue out the plant.
8. PICTURE: This viewer has a baldcypress that a buck rubbed his antlers on. They are concerned about the trunk as well as the foliage that is yellow-green rather than green. Will it recover? What should they do?
a. The color of the foliage is probably not related to the damage on the trunk. It’s two separate issues. The foliage looks like iron chlorosis. You may have to have the tree injected with an iron solution. The damage on the trunk, there's nothing you can do about it. The tree will fix itself; let the tree seal up that wound.
9. There are little holes in this lawn. They are not seeing creatures. Are they an insect hole of some type?
a. This could be the locust holes, where they have come out of the ground. Inspect any nearby tree or wooden fence to see if you can find the shells. Otherwise, if you are watching it and not seeing anything, it's hard to tell.
10. A Kansas viewer has stopped harvesting the asparagus. The patch is full of weeds. What's the best way to do weed control in an existing asparagus patch?
a. Grasses are easy. If it's grasses, use a product like Grass-B-Gon. And try to control both annual grasses---if you have perennial grasses, it might take a couple applications to knock it back. Broadleaf weeds are tougher because any product that is effective on those weeds will also be picked up and translocated by the asparagus. Probably needs hand removal at this point in time. You can try chopping them back and mulching the bed.
Kim: We are not recommending salting the patch which is an old-time remedy.
11. In Nebraska City, a viewer has “rust” on daylilies, the leaves have dried up. They wonder if they will come back.
a. People are seeing pustules on the dead leaves but that's just a secondary infection. So something happened to the plant that killed those leaves off and that made it susceptible to fungi. Probably not a rust going on.
12. A viewer has grapes, third year, light green foliage rather than dark green. Leaves are a little raggedy. They are not blooming as they should. When they are blooming, the fruit is shriveling. They had good grapes last year.
a. Possible herbicide drift situation because grapes are sensitive to herbicide and there's a lot of spraying going on. That could be the lighter coloration, you can see the veins in the leaves going parallel. The leaves might be cupped. And that can cause the berries to fall off too.
Wayne: Another possibility is hail damage.
There's also some fruit rot that can occur. It would be a good idea to take a sample to your county extension office, or send a sample to BYF. If the grapes look fuzzy, that's a good key that it's a fruit rot.
13. A viewer has bumps in the lawn. They can’t see any hole until clear away the soil bump, then they see a ¼ inch hole.
a. That's a nightcrawler. What you're getting is the castings or feces; they are wonderful for the lawn. They cycle a lot of nutrients through the soil and they areate deeper than any aerator could. If you really can't stand the bumps, you can go through with a roller, but if you do that, then you have to go through with a core aerator becuase you're going to have compaction. And then you have soil cores all over the lawn instead of worm casting bumps.
14. How are invasive species determined? Who decides that?
a. A lot of the noxious weeds in the state of Nebraska were identified many, many, years ago and declared so by the state legislature. If one was going to declare a a new noxious weed they would have to go through the Department of Agriculture. And there would have to be some kind of economic threat posed by the species. If it is native species, it won't go on the list. There are county noxious weed supervisors. Not in every county. If you have problems, those are the first people to contact about control. There's a little identification booklet of the noxious species that also lists insects and other pests..
15. A viewer has 5 Marshall seedless ash trees. One has yellowing and has brownish spots on the foliage. What could this be and is it possible to do something about it?
a. It sounds like ash rust. We are seeing it a lot this spring. There isn't much you can do about it. There's some fungicides available. It won't affect the health of the tree. It doesn't over winter here, but gets blown up from somewhere else--down south--every year. This year, we had such a nice warm winter, we did have some over winter but it is something that usually isn’t a continual problem in Nebraska, so we don’t recommend spray treatment. Since it is one of five, this should be watched carefully.
16. Following up on noxious weeds, I won't say where these viewers are from---they have a purple loosestrife. 20 years old. Is there a sterile variety? It has pretty pink flowers; they drop off and don't produce seeds. How can it be bad when it doesn't produce seeds?
a. It was a big loss for horticulture when purple loosestrife was declared noxious; its’ a beautiful garden perennial. There was one that was called Morden Pink. It was self-sterile, but if it pollinates with a wild cultivar, it will produce fertile seed. If you have driven around the state near any of the wetland areas and you see the purple sand bars covered with loosestrife, you can understand why it's a problem; it degrades wildlife habitat. Get it out of there.
17. Several viewers are seeing rose chafer bugs in the walnuts and roses.
a. You are going to be looking at using carbaryl, which is the standard defoliator insecide. Yes, they are out about three weeks before normal. If you have the time you can pick them off by hand. You may have to check back frequently because you'll have more fly in. On the walnut, let them go, and I would see how long they last. Maybe not long at all. Usually I think they’ll go to something else and won’t do enough defoliation to cause problems.
18. This is a viewer who needs an identification of a weed, or plant, they found out by Twin Lakes near Pleasant Dale.
a. We think this is in the prairie larkspur family. It has a distinctive flower. It's a perennial. If they want to get rid of it, applications of a growth regulator herbicide are needed in the spring or fall. And if they have this plant around livestock, they should get rid of it because it is poisonous. It could make the livestock sick or die if consumed.
19. This is a two-year old quaking aspen near Eagle, NE; three quarter of the leaves are black. It is near new construction with adequate water.
a. Depends on what the leaves look like. If they are turning black, it makes me think they are all turning black. Maybe some kind of canker going on, it's hard to say what is causing the canker. Is it an insect or a fungus? Prune those areas out. There are some fungi that can cause the lesions or dark leaf spots. It could be a foliar fungus. Since three quarters of a tree has black leaves, most likely it’s a canker you need to prune out. Is there an issue with a quaking aspen or new construction? I will say the tree is not that happy in Nebraska. They are more adapted to higher elevations and they struggle with warm winters and hot summers. They tend to be stressed and more susceptible if they’re put in compacted soil. They are not well adapted.
20. This is the Columbus viewer who has 26-year-old ornamental pears. The couple in the back are all right but the one on the north is dropping foliage. She has put bricks around the tree and added soil, 4 to 5 inches, and wonders if that's what is causing the stress?
a. Unfortunately, likely it is. The more soil you put over the root system the less oxygen penetrates; you end up with root die back. It will mean foliage loss and branch die back. Don’t raise the soil level around the existing root system of trees. Don't go over a few inches over the roots. Take the bed out and take the bricks out and relevel the soil. If it is not too far-gone, it can probably recover.
21. We have a viewer who knows they need to use wood mulch around the house and not stone for plant health. They are concerned whether shredded cedar mulch will attract termites into the home.
a. Cedar, in general, is very resistant to insects; you will be safe with it. If you’re worried, you can actually rake through it and disturb it. If you disturb the mulch regularly, termites won’t like it.
22. We have a question from Beatrice that's more turf than insect. Should grub control, pre-emergent, and fertilizer be incorporated and applied together or separately?
a. At this point in time, it is time to apply grub control. We are getting to the point in the turf season at which we don't want to over fertilize the turf before the hot part of summer; this should have been done already. The pre- emergent is okay if it’s the second application. If it’s the first, you’ve missed a lot of weeds. It depends on what you’re going after, two out of three; maybe it’s the right time to do it.
23. Is had a question I promised I would ask Sarah. Is moonflower poisonous?
a. Both datura and ipomoea are poisonous. Be careful with those. That’s the problem with using common plant names.
1. Is it okay to use old railroad ties and/or treated lumber for raised beds?
a. If the ties are not using oozing creosote. And the treated lumber, yes.
2. Can you identify the type of apple by the tree when the fruit is small or do you need the full-grown fruit?
a. You have to have a full-grown fruit because you need to see the mature coloration on the apple.
3. We have a viewer who has strawberries; the fruit begins to ripen then the blossom end becomes really seedy.
a. It is poor pollination on the flower or plant bugs (lygus bugs) feeding on the fruit.
4. How possible is it to transplant Tiger Eye sumac and when would you do it?
a. In the fall and it should transplant easily. Just dig up a nice-sized root ball and keep it watered in the new location.
5. Should suckers be removed on sweet corn to prevent ears from being too little?
a. It doesn't matter, doesn’t affect it at all.
1. We have viewers who have powdery mildew on monarda/beebalm. Can anything be done?
a. Not really. Try an avoid water on the leaves. Irrigate the soil, the roots only, in the morning.
2. Is it possible for flowering tobacco to transfer mosaic virus to tomatoes?
a. Yes, they are spread by hand tools. They don't need an insect to be transmitted; they can do it on tools.
3. Is blossom end rot on tomatoes caused by water or high temperatures?
a. Any time the plant is stressed it is more susceptible to things like blossom end rot.
4. Have you heard of hosta virus X?
a. We had samples in the lab. There are wilted smaller leaves and different variagations. There's nothing you can do it about it. Rogue out the plant.
1. Does adding nitrogen control the spread of sweet clover in high traffic areas of the yard?
a. You are trying to make the turf more competitive with the clover. It is not the answer by itself; it can help.
2. Can you control Russian olive that’s spreading in the landscape? (Central-western Nebraska)
a. It’s a tree, woody species. You will probably need a cut stump treatment for a fairly large plant.
3. How can you control wild lettuce?
a. Prickly lettuce, I think. It is a winter annual. The seeds get blown around. Pull them out by hand or hoe them out.
4. Do herbicides move more quickly in sandy soils?
a. It depends on the herbicide you use. Some can move quickly in sand. For Roundup or 2,4-D, it doesn't make a lot of difference.
1. Is there an effective chigger control in the landscape?
a. Not much you can do.
2. Is this the year of the locust or this the 17 year emergence?
a. No. There was a 13-year last year in part of southern Iowa. They may see some stragglers this year but not here.
3. Is it time for grub control in lawns?
a. Yeah. It is time.
4. A lot of viewers have questions about holes in their hosta leaves. It’s not hail.
a. It’s probably slugs. Crushed seashells do a great job. It rips their little guts out.
5. Billlbugs in bluegrass. Is there a preventive or should you wait till you see damage and then treat?
a. In bluegrass you can do a preventative. Typically, it’s like you’re treating white grubs. You’ll want to do a sample. If turf pulls up easily from the stalks, not from the roots, look very closely for white grubs inside the stalk. Treat with imidacloprid.