I have lost four 12-15 foot tall white pine trees over the last year. All had the same symptoms, browning needles at the bottom that continued up to the top. Can you tell me what pest is killing the white pines? I am also losing an Austrian pine now. It is experiencing the same symptoms.
White pines in this area are very rarely troubled by disease. They are, unfortunately, highly susceptible to high pH problems, or soil alkalinity, and are utterly intolerant of salt, according to Rich Eyre of Foxwillow Pines, Woodstock. The browning needles could also indicate the plant is getting too much water or has poor drainage.If environmental problems are not the issue for your white pines, consult an expert. Betty Lockwood, Plant Information Specialist at the Chicago Botanic Garden, suggested you bring them a sample branch to check on disease and bring in an arborist for an on site visit to check your growing conditions. Or take a 12-inch sample of an affected tree to your local extension office.Austrian pine is very tolerant of environmental conditions but is prone to certain diseases—diplodia tip blight and dothistroma needle blight, both caused by a fungus. Only an arborist or a laboratory can provide an accurate diagnosis. If you bring in a 12-inch sample for diagnosis, be sure to sterilize your pruning shears with denatured alcohol after cutting the diseased wood.
I have a large variegated sedum with pink flowers that I have had for years. I noticed that it has started to send up some all-green shoots. Why is it doing this and how can I keep my plant variegated?
All variegated plants contain a combination of green cells with chlorophyll and white tissue with no chlorophyll, which produces the green and white effect. Variegated plants are genetically unstable, so sometimes the tissues revert to all-green cells and send up solid green shoots from the base of the plant. Because these shoots contain more chlorophyll than the variegated tissue, they are more vigorous. Thus they can quickly overrun a plant, according to Hortech, a developer and grower of sedums.
Cut the green shoots off at the base of the plant as soon as you see them. It is possible you have induced vigorous growth by giving the plant too much high-nitrogen fertilizer, so it would be wise not to fertilize. It sometimes helps to divide your plant and then choose the most variegated stems for a new plant. Since your sedum, a cultivar of Sedum spectabile, is such a rapid grower, it will quickly become a new clump after division. Newer named cultivars are more genetically stable and do not have this problem.
Is there a best time to plant tulips? I see them at the garden centers in late summer but I am afraid that it is too early to plant them. If I wait too long, I might forget all about them.
Fall bulb planting should wait until soil temperatures drop to 55 degrees or cooler. This usually occurs when nighttime temperatures drop to 50 degrees or lower for two weeks or more. While waiting to plant, store the tulips in a cool, dark place away from direct sunlight—but don’t forget them. After planting, water the bulbs well, advises the Netherlands Flower Bulb Information Center.
If you plant grape hyacinth bulbs amidst your tulips, they will come up early in the fall and serve to mark the position of your tulips.
We are first-time gardeners and have planted Brussels sprouts and green and red cabbage that we are trying to grow organically. There are black egg sacs and small green worms eating the leaves. Is there an organic product we can use on the cabbage?
Egg sacs can be washed off with a hose.
There are several organic methods you can use to deter cabbage worms. Lightweight polypropylene row covers, placed over a row of plants and supported by hoops, will block wind and insects while permitting light, air and rain to reach the plants. Hold down the row covers with soil, stones or bricks.
Another organic method uses pots of mint growing between cabbage plants. The mint odor is said to deter cabbage moths. Don’t let the mint take root, however; it will take over your garden. Rotenone dust is considered organic, as it leaves no poisonous residue on plants. The use of hot pepper spray is an irritant to insects and worms, but also to your skin and eyes. Bacillus thuringiensis (Bt) is a specific biological control that is fatal to cabbage worms if ingested. Note that it can be harmful to certain butterfly larvae.
What is the green worm that eats my roses and columbine every year?
It is hard to diagnose your problem without seeing the caterpillar. There are several green worms that bother roses, and one can be controlled with Bt (Bacillus thuringiensis) but rose slug, for example, cannot. Proper identification is necessary before applying any control method. Do not use an insecticide for anything that"s not on on the product label. Do not use any insecticide as a preventive measure. It doesn"t work and ends up being harmful to the environment and a waste of your money.
Green worm on your columbine could be an inch worm or canker worm. If the caterpillar loops up in the center or arches as it moves along, it could be a looper or cabbage worm. Leaf miners, which are usually white or pink, tunnel in the leaves. “To eliminate insects, use insecticidal soap,” said Nancy Clifton, Chicago Botanic Garden Plant Information Specialist.
For an exact diagnosis, consult your local University of Illinois Extension service or collect a specimen and bring it to the Plant Information Service at the Chicago Botanic Garden or the Morton Arboretum.
What is the best way to dig up, clean and store gladiolus and dahlias? What are the little white sacs on glad bulbs?
Gladiolus corms and dahlia tubers are generally dug up after the first frost or before Halloween. Cut off all the stems and foliage, let the plants dry, and shake off all the soil. Make sure each corm and tuber is firm and not rotted. Place them in a box or tray and cover with peat moss. If you know the cultivar name, tag the plant.
Store them in a dark, cool place, checking them over winter. If the dahlia tubers are shriveled, sprinkle a little water on them. Dahlias can be potted up in spring for an early start in the garden.
“The white sacs you see attached to the gladiolus corms are little bulblets. You can remove them or not. If left on the corm, they will grow larger, and may enhance the number of stems on the plant. If you remove them and plant them, it will take at least three years before they flower,” explains Joni Cotton, perennial manager, Hawthorn Gardens, Hawthorn Woods.
I start ‘Dragon Wing’ begonia from seed under grow lights. What other begonias can I use to cross-pollinate with the ‘Dragon Wing’ so I can collect my own seeds?
‘Dragon Wing’ is a unique hybrid type of begonia named to reflect the shape of its leaves. It is created by interspecific crosses of two different begonia species and can lead to interesting new plants, but they are sterile.
It is impossible to say exactly which species will cross and which will not cross. You can try crossing angel wing begonia, a common houseplant, with another species. There is a good chance viable seed will be produced, according to Brian E. Corr, new crops development manager at Ball Horticultural Company, West Chicago.
The American Begonia Society (begonias.org) is a resource for information on hybridizing. The archives of the bi-monthly journal The Begonian would also be helpful.
I dislike staking perennials. Is there anything I can do to avoid it?
There are several techniques you can use to limit time spent on this chore, but it is difficult to totally
avoid staking some plants.
First and foremost, the old adage “right plant, right place” means full sun perennials need to be grown in full sun for tight upright growth. If they are too shaded, the plant will stretch or bend toward the sun and grow in a loose habit. Growing plants a little closer together also helps because it enables plants to support each other.
The best remedy to avoid staking is to cut some tall plants down by one-half in June. That will delay flowering in helenium, monarda, platycodon, chrysanthemum and aster, but the plants will remain upright. If you really want to eliminate cutting back, grow dwarf versions of these plants.”
Short, thin branches from forsythia or dogwood (known as “pea staking” in England) can be placed around the perimeter of newly emerging plants to help keep the stems upright. Some garden centers have begun selling bundles of branches for this purpose. In a short time, the shrub cuttings are covered by emerging shoots. This technique works well with fine foliage such as baby’s breath or flax.
There are numerous staking supports from bamboo to iron rebar rods. Wire staking supports are available in full, half and even quarter circles to support single stems. Peony hoops can be left in place over winter and will support not only peonies but boltonia, baptisia, and even errant tomatoes.
Some plants always need to be staked. Giant dahlia tubers need a heavy stake dug into the hole at planting time. That prized, single-stemmed iris, lily, or delphinium can get blasted in a storm, and then it’s too late to save it.
Remember: the time to stake plants is during the cooler days of spring when plants are growing rapidly and not on humid July days. Staking should be done unobtrusively and subtly for plants to retain their natural grace.
I plan on saving my amaryllis bulbs that I kept outside over summer, but I noticed red streaks on the inner side of the leaves. What caused that? Will I be able to save my bulbs?
There are several possible causes of red streaks in amaryllis hybrids (Hippeastrum), explains Bill Welter, owner of Victor Hlavacek Florist, Winnetk. If the streaks occur on the foliage only, excess moisture and not enough air around the bulb could have caused the streaks. Amaryllis is also susceptible to leaf scorch, which can cause red streaks on the foliage and on the bulb. This was common on older varieties.
You can save the bulb for next season by letting the leaves die down, then trimming off the foliage, and dipping the bulb in a fungicide solution. Another possible reason for leaf scorch is tobacco mosaic disease, transmitted by insects.
I have a nicely sheltered, rounded 7-foot tall Japanese red maple on the southeast corner of my backyard. Half of the tree has lost its leaves, the formerly red bark is turning gray, and a good-sized square of bark has been stripped off on the side that faces the yard. I sprayed the exposed bark with black pruning spray to close any entry for insects. I have not cut off any of the branches.
Does the winter have any effect on the tree? Should I look for some insect infestation? What should I do now?
“It appears that the tree suffered some kind of injury. Over winter, watch for sun scald on the southern exposure. Use paper tree wrap on the trunk,” advises Mike Geimer, owner of Geimer Greenhouse, Long Grove. If you are fearful of insects, you can use an organic pyrethrum spray. Black pruning spray is not necessary.
Is it possible to plant and grow Italian cypress in the Chicago area? Are our winters too severe for it? If they are, is there an alternative conifer that will provide a similar look?
Do the ants on my peony flowers help buds to open, or is this an old wives’ tale? What are the extremely tiny, microscopic yellow wormy looking bugs crawling on my pink peony flowers? My peonies are beautiful, but I don’t want all these bugs.
After a summer outside, my clivia has returned indoors. Last year it had only one puny flower. What treatment should I give it over winter to bring it into bloom?