April 17, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I am having reoccurring problems with quackgrass in my garden. Can you tell me how to get rid of it? It starts out as a fine grass and then, as it grows, gets a hard stem to it. I have tried Roundup but it didn’t work. (Jamestown, N.D.)

A: Try Roundup again. Buy the already-prepared formulation that is available at retail outlets, as it has a sticker added which should make it more effective.

Q: We have an evergreen which we are quite certain has needle cast disease. Can this tree be saved and with what type of treatment? (Minot, N.D.)

A: It can be saved but I would suggest that you contact Mike Rose, the Ward County extension agent. He is a sharp horticulturist and can confirm whether or not it is needle cast that is devastating your tree. If it is in the early stages, corrective action can be taken; if it is in the later stages, it may be too late.

Q: I recently repotted my jade plant but now have found very little worm-like things in the soil. I repotted another jade at the same time with the same soil and it does not have them. What can I do? (E-mail reference)

A: The worm-like animal most likely came from the old soil still clinging to the roots of one plant and not the other. They could just be feeders of the organic matter in your soil or the larval stage of a root maggot. You can try controlling them with insecticidal soap. Water the plant which usually drives these creatures to the surface and, when they appear, spray them with the soap solution. It kills the soft-bodied insects via desiccation and is not harmful to either you or the plant. You will have to do this several times to get them all. The soap is sold by Safer, a company that specializes in organically approved pest controls, and is available at local garden stores.

Q: My landscaped beds are overridden with thistle and dandelions. There are certain areas of the beds that are infested with thistle and other areas with clumps of dandelions. What is the best way to get rid of these weeds? (E-mail reference)

A: That is a perpetual challenge! Since it is early in the growing season, I suggest the physical removal of them at this time. In other words, create a cleanly cultivated bed with nothing remaining but the ornamental plants that you want. There is a product known as Bio-Barrier that creates both a physical and chemical barrier between the soil surface and the germinating weeds. Place this in your landscape beds after the weeds are removed and cover with an organic mulch like bark or wood chips. You should be virtually weed-free for the next 10 years if everything is done correctly.

Q: I have a client that has two apricot trees, a sungold and a moongold, that have great fruit sets but later in the summer drop all fruit when it is about a half inch in diameter. There are no visual symptoms. Is there any inherent problem in these varieties or would you suspect another cause? (Devils Lake, N.D.)

A: A number of things can cause premature fruit drop of apricots. The most common one is overbearing. When the fruit is pea to pigeon egg size, begin thinning to prevent fruit drop. Pollination and fertilization are carried on at too great a level for the tree to sustain all of the set fruit and consequently simply drop the whole load. This will reduce the energy expenditure of the tree and it can then put more of it into upsizing the remaining fruit. You can also thin the blossoms rather than the fruit. Considerably less damage is done to the tree with selective blossom removal and the procedure goes much faster. The problem could be pollination but no fertilization or fruit maggots inside the fruit. I doubt that either of these is the cause since it wasn’t a selective drop and you saw no visual symptoms.

Q: Can a crepe Myrtle be moved and transplanted? If so, when do you do it? (E-mail reference)

A: It can be transplanted as a balled and burlapped plant when dormant. The best time is either early spring or fall.

Q: I have a Christmas cactus that is more than 60 years old and is very large. I can no longer move it or repot it. This year it's not looking very well. I think it's just too big. Can I cut it way back without killing it? (E-mail reference)

A: I cannot answer that question. I would suggest that as you make your cuttings, try and root some of them. Many if not all, should develop a root system for you. Just stick some in a 50/50 sand/peat mixture, and keep moderately moist.

Q: I would like to try to grow Niger thistle for bird feed in a corner of my home garden and at my son's home in Alberta. What are your recommendations in this regard? ( Victoria, B.C., Canada)

A: I'd say go for it and not pay out valuable Canadian dollars to the imported material that I'm sure is saturating your market as it is ours. There is a short-season cultivar known as early bird that we have successfully grown in the Northern Plains - specifically in the Carrington, Langdon, and Minot Research and Extension Centers. The crop was productive at all sites even when a delayed planting (June 13) took place at Carrington. The seeding rates were experimented with and it was found that the 9-pounds per acre rate consistently outproduced the 3- and 6-pound per acre rates. The yields ranged from as low as 300 pounds per acre to as high as 700 pounds. So, if you get something successfully going there, you might have yourself a small economic nest-egg!

Q: I have a stand of golden willows that are defoliated every season by a crawling caterpillar. They start at the bottom and work their way up. I am looking for an aerosol tanglefoot. Would this work and where could I find it? (E-mail reference)

A: As far as I know, there is no such thing. I have seen it only in a toothpaste-type tube. Even if it did exist, I would hesitate to recommend it. I would suggest you spray immediately with a dormant oil spray, assuming that your tree is still dormant. This will take care of any overwintering eggs or pupae. If the tree has already begun leafing out, I would suggest hitting it with Orthene, which is a systemic spray and should give you some control. Tanglefoot can be applied to the trunk in bands about 4 inches wide, following directions. It does a good job, in most instances, of catching the majority of cankerworms.

Q: I'm sure you have heard the theory that if you want to grow large pumpkins, feed them milk. Is this true? My mission this year is to grow a large pumpkin. I have three different varieties of large pumpkin seeds and I will be planting them in different locations around the farm. I've read a lot of articles on selecting the female plant and choosing one flower to produce the pumpkin but I was going to try some of these legendary growing tips to see if they work. Do you have any advice? (Fargo, N.D.)

A: Talk about an old farmer's tales! This one takes the cake. It is purported that some farmers would custom-grow their pumpkins to the size desired by the customer via milk injection into the vine. A rubber tube was connected to the needle, the other end inserted into a quart of milk, and the pumpkin supposedly pulled the milk. More credible stories have involved pumpkins grown under a cloth with gallon milk cartons under and next to the developing plant. One of them would have some pinholes in it, the other would have hot water. They would be placed by the developing plant at nightfall with the one with holes supplying water slowly and the other keeping the air and soil around the plant warm to encourage growth. I have heard that some people keep their pumpkins shaded under the cloth to keep the plants from reaching the heat stress compensation point. That is where the plant carries on respiration faster than it does photosynthesis. Others have a family concoction of black tea sweetened with honey and milk that they feed to the plant every other week. Perhaps the easiest trial to follow is to simply select the first female blossom, hand fertilize it, keep all other blossoms picked off, and try to maintain a balanced water and nutrient regime. Quite frankly, largeness in pumpkin has never attracted me as I have always preferred the more manageable sizes that make good jack-o-lanterns or delicious pies! Good luck and let me know what works for you.

Q: There was a flowering shrub in Hoven, S.D. last year that throngs of people in the area were stopping by to see. It was an evening primrose. What was so fascinating was that its profusion of yellow flowers opened a few at a time every evening at sundown right before our eyes! Then all of a day's blooms would fall off before morning and the next day the whole cycle would repeat again. Where can we get seeds or a young plant? Is it a perennial hardy for north-central South Dakota? (E-mail reference, S.D.)

A: The plant is a hardy perennial in our upper great plains. Seed should be available just about anywhere perennial seeds are sold. Most nurseries would also have the young plants available. It is native to the prairie.

Q: We have several maples in our yard that are about 10 to 15 years old. We need to do some major pruning of the lower branches. When is the best time to do this so the tree won't die? (E-mail reference)

A: Maples are known as "bleeders" when pruned early in the season and still dormant. This fact usually upsets most homeowners when they see the excessive sap flow pouring out of pruning wounds. It is messy and attracts some insects, but doesn't kill the tree. Assuming the tree is otherwise healthy, I suggest pruning the plant after full leaf-out and expansion of the foliage. Minimal to no bleeding will take place and it will still be early enough in the growing season for the wounds to begin complete compartmentalization and healing.

Q: My yard is very damp with clay soil and lots of direct sunlight. The soil is soft for the first 12 inches then turns into hard clay. Would a weeping willow grow well under these conditions? (E-mail reference)

A: Yes it will. There are only two places that I know of where a weeping willow won’t grow, in a blacktop parking lot and a desert environment.

Q: We are planning to move some evergreens in our yard this year. They are Colorado blue spruce and balsams. When is the best time to do it? The trees are at least 10 years old. (Jamestown, N.D.)

A: The best time is as early as possible for digging a rootball. If you are planning to do this yourself, you have a monumental job on your hands. I suggest recruiting some professional help.

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 ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu