When is the best time to prune a caragana hedge? (email reference)
The best time is in the early spring before new growth emerges. Generally, when this question is posed about caragana, it really needs pruning. If you want to slow it down, prune it now to remove the leaf cover, which is pumping photosynthates into the system of the plant for storage to use next growing season. The early spring pruning should be done if you want to cut a woody, funky hedge back and to get it to thicken again that year. It will come back vigorously and bring you lush, leafy growth that you can shape. This pruning can be done right down to the crown of the plant using a sharp chain saw.
My raspberries are on the east side of the garage, so they get plenty of sun. Later in the day or evening, some may get shade from the garage. I alternate rows, so one spring we mow a row down and pick from the other row. This year, something is eating the leaves. Because something is eating the leaves, I’m getting a much smaller crop of berries. (email reference)The damage could be something Japanese beetles would do to the rose family, which includes raspberries. The problem is that Japanese beetles have not been documented in North Dakota as of yet. For this time of year, I can't tell you what insect would be doing that much leaf feeding but leaving the veins alone. Can you scout a little and see if you can find the culprits? If they are Japanese beetles, they usually feed at night and then crawl off somewhere cool to sleep. If it is a caterpillar of some kind, such as a fall cankerworm, there should be some evidence of them. You could spray Sevin on the plants. However, if the damage has been done and the insect pest exited, it would be akin to locking the barn door after the animals departed. I really hope this isn’t Japanese beetle damage. If they are established in the state, we will have a major headache on our hands. Almost any other insect is easier to control than this voracious beast!
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We have several arborvitae trees. This summer has been abnormally hot. The trees were doing great but now are showing brown spots. We have been watering them frequently, but nothing has improved. Do you have any suggestions on how to get rid of the brown spots? (Wisconsin)Brown spots don't translate into anything definitive that I can assist you with. It could be from insect or disease activity or something in the environment, such as a dog, causing the discoloration. At the very least, I would need a couple of sharp photos and a little more written description for me to come close to giving you good advice.
I am hoping you can help me save my begonias. I have 13 baskets of tuberous begonias hanging under my scrub oak trees that surround my home. Last year, thinking I was being good to them, when it came time to repot and start warming them up, I used new basket liners and Miracle-Gro potting soil in the baskets. I don't think that could have caused my problem, but I don't know. They started out looking very healthy and growing well but then started developing white patches on the stems. These became larger, turned brown, shriveled and caused the whole stem to break off. The bulbs continue to put out new stems and some of the old stems continue to grow and flower. Is this problem some strain of wilt disease? What do I do about it? After the plants die in the fall, I store them in my garage until spring. (email reference)Something has changed in the ecosystem of the begonias. It could be the basket liners, potting soil, drainage or the water. The change is causing a pythium-type of rot to take place on the stems of the begonias. It could be the media stayed too wet too long. Perhaps your hanging basket liners are not voiding the water quickly enough.
I have a huge grapevine growing on a chain link fence. Last year was wonderful because I got so many grapes. This year, the vine grew what would have been another beautiful crop but the grapes are drying up as they are ripening. What is causing this? (email reference)Look at the year we’ve had. We have had excess rain and high temperatures and humidity. Because of this weather, grapes, especially vigorously growing varieties, become vulnerable to lurking pathogens waiting for the opportunity to infect. For infection or disease to occur, a vulnerable host (grape vine), virulent pathogen (many out there) and the right environment (which we’ve had) are needed. If you want an exact determination of what it is that is destroying your crop, you would need to send a sample showing the symptoms to our plant diagnostic lab at NDSU. For information on how to contact the lab, go to http://www.ag.ndsu.edu/pdl. If it is any comfort, there are many old standby crops, such as rhubarb, sweet corn, carrots and even zucchini squash, that have been wiped out this year because of the weather conditions.
Our lawn was flooded in June and July. Since the water receded, no new growth, including weeds, has appeared. I tilled the lawn last weekend and plan on seeding this fall. How much fertilizer should I apply before seeding? What analysis would you recommend? At what rate should I apply the seed? I have a large lawn, so watering it daily is not possible. Should I dormant seed the lawn in mid- to late October and have it germinate in the spring or should I plant in mid-September? Someone told me to apply lime to kill bacteria in the soil that the river water may have left. Do you agree? Thanks for your assistance. (Minot)There is a product on the market that is referred to as winterizer turf fertilizer. It has a modest amount of nitrogen in it and ample phosphorus and potassium to help the emerging seedlings tough it through the winter months. I would suggest seeding now and then overseeding in October to act as a dormant covering. This will condition or prime the seed to sprout and grow next spring. It also will fill in the areas that might have suffered winterkill or washout during autumn rains. Seed a mixture of Kentucky bluegrass, creeping red fescue and perennial rye at the rate of 3 to 4 pounds per 1,000 square feet. Be sure the bluegrass is of the common type, such as Park or Kenblue. If the label states common Kentucky bluegrass ecotypes, then you have grass that doesn’t need to be treated like royalty for it to grow and look decent. In other words, it doesn’t need frequent fertilizing and watering. The key to good grass is high purity and germination percentages and no weed seed. Typical purity percentages are 98 percent or more, with a germination rate of 85 percent or more. The higher the percentages, the better. As for the lime treatment, this is a typical snake oil recommendation that is not supported by science or research. The UV rays from the sun do a better job than anything else. Lime is the last thing most soils in North Dakota need.
(Ron Smith is a horticulturist with NDSU Department of Plant Sciences. He answers questions about flowers, trees, gardens and shrubs. He can be contacted at firstname.lastname@example.org.)