Q: We have potted petunias that are turning yellow, so we would appreciate your thoughts as to what to do. The plants get full sun on the south side of our house. They are watered daily and fertilized on a routine basis. Any ideas?
A: My first guess is that they are being overwatered. This is easy to do, especially if the containers are not free draining and the soil is heavy. About all you can do is back off on the watering. Water the plants when the soil is dry down to the first knuckle of your index finger.
Q: I have problems with tomato blight, so my tomato crop is a total loss. Now I have brown spots on most of the leaves on my beets. Could this be blight or some type of bug infestation? Will the beets still be good to eat fresh, freeze or use for pickling? Also, is the blight situation this year going to cause a problem for next year's growing season?
A: This could be either a leaf miner infestation or fungal spots showing up. The best thing you can do this year is to remove the affected foliage as the spots appear. For next year, don't manure the soil, practice crop rotation and clean up all the garden litter this fall. Turn the soil over before it freezes this fall.
Q: I am redoing some landscaping and would like to move some bulbs. I have tulips, daffodils, lilies and irises. If I dig these up now, how long will they last before I need to replant them? How should I store them until I am ready?
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A: All the bulbs can be dug up and stored for a few weeks before planting. Don't wash the bulbs! Just knock off most of the soil. Keep the bulbs out of direct sun, cover with mulch or store in a cool basement until ready to plant. Replant only healthy stock.
Q: My established hostas are fine, but the ones I planted this spring have tiny holes on the leaves. What is eating them and what can I do about it?
A: Very likely your problem is slugs. There are several materials on the market that will take care of slugs. It is almost never fatal to these plants because slugs and hostas evolved together. You also can get some beer and pour it into a shallow pie tin. Set the pie tin into the soil to attract the slugs. They will fall in and drown.
Q: I've had my fishhook cactus now for almost 10 years. We brought it outside for the summer sun. All of a sudden, some of the tops of the cactus plant started to turn a brownish-red color and are turning white in some places. Could you possibly help me in finding out what is going on and how I might be able to save my cactus? I would greatly appreciate it.
A: I don't think you have anything to worry about. The cactus is reacting to being put in full sunlight after a winter of darkness. Like humans who react to their first full day in the sun by getting sunburned, the same thing happens to plants. I predict that if you moved it into a semishady spot, such as under a tree, it will recover from this shock with no harm being done to the plant.
Q: I saw a schefflera actinophylla (umbrella tree) at my doctor's office. I'm planning to grow one because I want a large plant in my front window. However, I read this plant can grow to more than 20 feet tall. Can I keep this plant trimmed so it will not grow into the ceiling?
A: You certainly can limit the height of this plant. You can do it by selective and careful pruning or limiting the size of the container.
To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, N.D. 58108-6050 or e-mail ronald.smith@ndsu.edu .
