NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
October 5, 2000
Ron Smith, Extension Horticulturist
North Dakota State University
Q: I am having some problems with my petunias. I asked a local florist if it was aster yellows, but he had never heard of it. The leaves have become pale and you can see the veins clearly. Have I given the correct diagnosis, and if so, what needs to be done? (E-mail reference, Jamestown, N.D.)
A: Vein clearing, followed by general yellowing, twisted, epinastic growth, and deformed flower parts are the general symptoms of aster yellows. It sounds more like a problem with a delayed root rot that is not allowing your plants to grow properly. Ours are doing very poorly this year as well, most likely from the heavy rains in June. If the plants are not contributing to what you intended, remove them. Aster yellows is spread by leafhoppers, generally picking up the pathogen from surrounding weeds and transmitting them to healthy ornamental plants. So to control AY, spray to control the leafhoppers, and keep the weed population under control.
Q: I have scab on both my beets and spuds. Is there anything that can be done other than planting in a new spot? (E-mail reference, LaMoure, N.D.)
A: Nope . That is the best alternative, and to plant resistant cultivars.
Q: When we moved into a 30-year-old house in 1998, we were very pleasantly surprised to see the sickly tree in the backyard bear beautiful, delicious Italian plums. Last summer the tree did not bear fruit (probably due to a killing frost) but this year is another bountiful one. An entire half of the plum tree broke off earlier this year, possibly due to rot. The other half is bearing fruit on schedule but the weight of the plums is so great that the fruit-laden branches have bent to the ground. Some branches have cracked but seem to have enough moisture and sap to still nourish the fruit. Clearly, this poor little tree has been badly hurt. We are utterly ignorant city folk who can't keep houseplants alive. Can this plum tree be saved? What should we do? (E-mail reference, Longmont, Colo.)
A: The plum tree can be saved -- for a short time, likely. First thing I suggest is to brace the branches that are under load stress with either clothes poles or cotton clothes line. Next spring, I suggest contacting a local nursery or greenhouse and see if they would be willing to root some cuttings for you, to replace this tree when it finally caves in. Then prune the tree while still dormant to help support the weight load better. Generally, when fruit trees bear heavier than normal it is a sign of impending death, or a struggle against it. As you harvest this summer, selectively save some of the seed and plant them in an appropriate location before the soil freezes. With luck, you may get something coming up next spring.
Q: Our blue spruce has these sac-like needles that hang off the branches, and they have a worm in them. We've been picking them off. Do you know what they are and how to keep the tree free of them? (E-mail reference)
A: Yes, they are known quite descriptively as bagworms. Picking off is the best way to control them if your tree isn't too big and you don't have too many. Generally, natural control from parasites keeps their numbers in check, so sprays are not recommended. Getting as many of the bags as possible collected and destroyed at this time will prevent emergence of the male moth in September, which will mate with the wingless female and perpetuate the problem.
Q: Can you tell me what kind of tree the enclosed sample comes from? Also, are little leaf linden trees fast growing and what size is a good one to plant? (Larger the better, right?) We also have to reseed our front yard and I am wondering what kind of grass to plant? (Walhalla, N.D.)
A: The partial leaf sample looks like a green ash. If they are oppositely arranged on the stem, thatís what it is. If not, itís something else. Lindens take two to three years establishing their root system with very little aerial growth being evident. Then they take off, being moderately fast growers. No, the smaller the better, as less of the root system is disturbed or lost. Iíd suggest a 5- to 15- gallon container- grown tree for best results. For the lawn Iíd suggest Fairway Crested Wheatgrass without knowing another thing. Now is the time to get it established. Sow at 4 to 5 pounds. per 100 square feet.
Q: Can you identify the enclosed weed and tell me how to get rid of it? It is invading the yard and the garden. It lays very flat to the ground and quickly takes over the area. (Cogswell, N.D.)
A: You have sent me one of the most beautiful samples of large crabgrass - Digitaria sanguinalis - I have ever seen! So good in fact, that Iím having it mounted to show to my future turfgrass management classes. It is best controlled with a pre-emergent herbicide in the spring about the time lilacs are in bloom. There are several products labeled for grassy annual weed control. Make sure the one you pick contains pendimethalin. Do not use a weed and feed product. The concentration is not strong enough to be very effective.
Q: I am sending you some leaves off of our maple tree. Can you tell me what is wrong with them and what I should do? (Oberon, N.D.)
A: Your maple has been attacked by a gall-forming mite, known as Eriophyes aceris, forming what we call erineum galls. Nothing to worry about and nothing to do. They cause no serious harm to the tree. Enjoy the color changes.
Q: Can you tell me what the enclosed sample is? It is a perennial flower that someone gave me, but Iím not sure what it is called. (Carrington, N.D.)
A: The plant sample you sent was Anaphalis triplinervis, better known as Pearly Everlasting. They typically get 12 to 18 inches tall, although Iíve seen them taller. ĎSummer Snowí is a compact cultivar, getting to no more than 10 inches tall. This one makes a neat compact border of silver gray foliage. A closely related species, A. margaritacea, gets to 2 feet tall and tends to be more invasive but it appears to survive drought periods better.
Q: I have a potentilla bush which is looking pretty stressed. Can I prune it back to about 6 inches or would it be better to wait til spring ? (E-mail reference, Jamestown, N.D.)
A: Better to wait until spring. You'll get a good flush of growth then.
Q: I have a hydrangea bush that means the world to me because it belonged to my grandmother, who passed away a few months back. The place is going up for sale and I just gotta figure out if there's a way I can take a piece of it and start a new plant. It seems like I remember her taking a cut off the bush and just putting it in water and the roots took off. I'm trying that now. Do you think it'll work or is there a different method? (E-mail reference)
A: That should work. You can also root them in moist sand or a 50/50 sand/peat mix.
Q: We have what we think is a large leafed linden in our front yard. Every couple years or so, the tree produces billions (upon billions!) of quarter- inch round green pods or fruit which turn brownish grey, dry up and drop to the ground. When this happens, it seems that the lawn beneath suffocates; the grass gets sparse, and is not as green. Trying to rake up these round pods is totally futile. My questions are, first, is this a linden, and second (actually a lawn question) is there anything I can put on the lawn to sort of break down the pods faster? (E-mail reference, Chicago, Ill.)
A: I cannot tell for certain of course, that what your are describing is a linden, but it certainly sounds like it. If it is, this is the first time I have heard of the linden fruit causing anything other than a temporary mess on the lawn. While I know of nothing that you can apply that will break these "pods" down, I suggest vacuuming them up with a rotary mower with a bagger attached, whether or not the lawn needs mowing. If that doesn't work, try renting a "Billy Goat," which is a lawn vacuum that sucks up everything but the rooted grass (hopefully)! Lindens and lawns are completely compatible; that is why they are so frequently used in landscape situations.
Q: I would like to know how webworms get into the trees. Are they laid in egg form by butterflies, or moths, or do they travel from the ground up the tree trunks? I have tried to keep them out of my trees, but my black walnut has gotten so tall that I can no longer reach them to cut out the infested branches (which I have burned immediately in previous attempts). I would like to know if there is some way to spray the tree to discourage future infestations. The neighborsí cottonwoods also have the same problem. (E-mail reference, Oakes, N.D.)
A: The fall webworm adult is a moth that emerges from pupation during late spring and lays hundreds of eggs on the underside of the leaves. Following a spring spray schedule -- roughly in May and again in June-- should keep them in check. Typically predators keep them in check, with two being especially important - the ichneumon wasp and the braconid wasp. Important also is the leaf litter clean up in the fall, as that is where the overwintering pupation takes place.
Q: I have a flowering crab apple tree that is 12 to 15 years old. Over the years itís had the typical problems, such as gypsy moth, tent caterpillar and leaf fall off through the summer. I've sprayed it with Sevin, which seemed to work at the time. This year I've noticed a green scale or flaky material on the trunk and lower branches and the bark is now peeling off. What's the problem and how can I deal with it? (E-mail reference, Lewistown, P.A.)
A: It sounds like your current concern is nothing to worry about. That is either moss, lichen, or algae forming on the lower, east, or north sides of the tree. Bark exfoliation is also somewhat normal at that age, with the older parts of the tree. It often occurs after a period of rainy weather that was preceded by an extensive dry period. I'd suggest spraying the tree next spring with a dormant spray lime-sulfur next spring before the leaves emerge, then spray with Bordeaux after the blossoms have fallen, and again about 10-14 days later. That should keep your tree somewhat healthier than it sounds like it has been.
Q: What causes dry rot on a tomato? Is there anything that can be done to prevent the dry rot? Thanks for your help. (E-mail reference, Bowman, N.D.)
A: Dry rot, better known as blossom end rot, is caused by insufficient calcium being unable to reach the developing fruit at that end. Generally there is enough calcium in the soil, but sometimes over-zealous weed cultivating damages the roots and the plant is unable to take up enough calcium to transmit it to the blossom end of the tomato fruit. It also occurs after a period of no rain or irrigation, followed by rain and/or heavy irrigation -- a sudden surge of new growth in tissue. It is often confined to the first tomatoes to ripen; some cultivars are more prone to this problem. A solution is to mulch the plants to maintain even moisture levels and to keep from cultivating too close.
Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at firstname.lastname@example.org.
Source: Ron Smith, (701) 231-8161, email@example.com
Editor: Gary Moran, (701) 231-7865