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Rose Rosette Disease (RRD)

What is rose rosette disease? I lost two antique roses and removed a hedge of multiflora roses that were supposed to be undesirable. How bad is it?

Rose rosette disease is a plant killer of unknown origin and no known cure. It is known to plant pathologists, but unknown to most rose gardeners in this area.

The disease is believed to be caused by a virus or virus-like pathogen that has been spreading through much of the wild rose population in the Midwest, probably transmitted by a mite introduced to the U. S. to eradicate multiflora roses. It is lethal to the wild multiflora rose and potentially lethal to many rose species and cultivars.

Symptoms of rose rosette disease are highly variable, depending on the species or cultivar. Some of the more recognizable symptoms include rapid elongation of new shoots forming witches brooms, or clustering of small branches with distorted leaves of conspicuous red pigmentation and distorted flowers.

David Robson, Springfield, extension educator, horticulture with the University of Illinois, reports that it is all over our area. Mike Geimer, owner of Geimer Greenhouse, Long Grove, reports coming across RRD in a Long Grove garden. One plant in a bed of Flower Carpet roses caught his eye because of its uncharacteristic red clumping stems. He looked up the symptoms on the internet, identified it as RRD and advised immediate removal of the plant. Also important, warns Geimer: “Always sterilize pruning shears.”

Kathy Hallgren, Sycamore, is worried about the future of old roses. Two summers ago she noticed some peculiarly rampant irregular, hyper-thorny pink growth with irregular leaves on an antique Alba rose.

After researching the symptoms, Hallgren determined the irregularities were from RRD. “I dug out the plant and burned it. Once I learned that multiflora roses could be the culprit, I removed them even though they were healthy. This summer I saw it on one of my ‘William Baffin’ roses so cut it down and burned it. This disease means business,” says Hallgren.

No effective control is available for existing rose rosette disease. All cultivated roses are potentially susceptible. Be on the lookout for it. Early detection is the key to effective cultural control. If the disease is recognized early and the rose is removed, it is possible to save other roses in the garden and hopefully curb the spread of RRD.


Good Annuals for Shade

Now that bedding impatiens (I. walleriana) are not recommended because of impatiens downy mildew, what are three good annuals for shade?

Chris Williams, production manager, K&W Greenery, Janesville, Wisc.

I like New Guinea Impatiens. They make nice bushy plants that are full of large colorful flowers and are easy to grow. You also get a large color selection with New Guineas. The SunPatiens and Bounce impatiens are fairly new plants, and they are recommended for sun as well as shade. Then there’s coleus. Who doesn’t like its colorful foliage? Many varieties grow upright, but others also spread. Torenia, also known as wishbone flower, has trumpet-like flowers of white, yellow, rose and purple that cover nicely mounded, low-growing plants.


Karen Wedel, manager of the outdoor floral department, Wedel’s Nursery, Garden Center, Kalamazoo, Mich.

One of my favorites is begonia. Tuberous varieties have large colorful blooms; wax begonias are good for mass planting. I’m also a fan of the big leaf, 16-20 inch tall Whopper series with large waxy leaves and summer-long flowers.
Another idea is coleus and caladiums. They come in different foliage colors, work great in gardens and containers. They are both also easy-care.
Finally, torenia or wishbone flower, named for the small “wishbone” inside the mouth of the pink, yellow or blue-purple flowers. Blooms all summer. Some varieties will trail.

Kevin DeBoer, manager, Big John’s Farm Market and Greenhouse, Chicago Heights

My favorite is Dragon Wing begonias. They’re usually sold in 4½ inch pots or hanging baskets. At my house I removed them from the baskets, then planted them in the ground in full shade. They turned out awesome! Plain wax leaf begonias are also good.
In addition, I like coleus. They don’t produce flowers, but they have many different vibrant leaf colors. In full shade New Guinea Impatiens will flower sparingly, but if you put them in some sun, they will flower more.


Planting Tulips

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.


Purple Coneflower

I have read that purple coneflowers (Echinacea) are a good source of food for birds in the winter. Will they be okay if not trimmed back until spring? If so, how early should they be trimmed?

If your coneflowers remain standing over winter, the seed heads will be available as bird food and will also be an attractive presence in the winter garden. They should be cut back in early spring before April. If you prefer, you can cut the plant back after frost and throw the seed heads on the ground.


Gardening Trends

What are some trends in gardening you see becoming more prevalent in the next few years?

Nick Urhausen
Current gardening trends continue to explore a variety of annual shade alternatives. Consider begonias of all types, such as fibrous, hiemalis, nonstop, rex, tuberous and the trademarked Big series and Dragon Wing. For a tropical feel, caladiums, elephant ears, and banana plants are not only exotic but add an element of height. Lastly, the hundreds of coleus varieties, along with black and chartreuse sweet potato vines, are colorful, reliable, and rich in texture.

Diana Stoll
I believe choosing plants for butterflies, bees and other pollinators will be an important trend in 2015 as folks realize the important role they play in our environment. Growing fruits and vegetables will also remain an important focus of gardeners, especially those that can be grown in containers and small spaces. Low-maintenance plants, preferred by both aging and beginning gardeners, will be another trend to watch in 2015.

Anna Keesling
People are looking for “bee-safe” plants that are free of neonicotinoids and other harsh pesticides. Also, they want to do vegetable gardening with non-GMO varieties. Succulents are very hot. The indoor use of succulents in dish gardens is a no-brainer; they look cool, they’re so easy to care for and make great unique gifts. Ornamental kale and cabbage have become very popular for fall decorating.

Rich Hornbaker
The popularity of hostas has made gardeners realize how much fun it is to use foliage for color, so they are looking beyond flowers to the reds and purples of coral bells (Heuchera); the yellow fall bottlebrushes of Amsonia hubrichtii; and the great fall colors of shrubs such as Viburnum, oakleaf hydrangeas (H. quercifolia), witch hazel (Hamamelis) and trees such as seven son flower, (Hepticodium), Ginkgo and scarlet oak (Quercus coccinea).


What suggestions can you offer for more exotic herbs that I could add to my garden to spice things up?

We all seem to plant the basic herbs like basil, rosemary and parsley. What suggestions can you offer for more exotic herbs that I could add to my garden to spice things up both for cooking and adding interest/beauty to my landscape?

Ron Peterson, head grower, Milaegers Garden Center, Racine, Wisc.

I think lemon grass (Cymbopogon citratus) would be a good candidate for landscape interest and culinary use; it is even reported to have more mosquito control attributes than citronella. It is a warm season annual grass that grows quickly and is used in teas and Thai cooking to add a lemony flavor without the acidity of lemon juice. Stevia is a natural sweetener option for those trying to avoid added sugar. There is also a mint called Berries and Cream which merges peppermint with berry flavors for a unique twist on the traditional mint options.

Lisa Hilgenberg, horticulturist, Chicago Botanic Garden, Glencoe

Golden lemon thyme (Thymus x citriodorus) adds good citrus flavor to dishes and tea. The 8-inch tall cultivar ‘Aureus’ makes a good edging paired with Salvia officinalis ‘Icterina’. The chartreuse ‘Lime’ shines in dark garden corners.

Red shiso (Perilla frutescens) has frilly garnet red leaves, edible flowers and a spicy cinnamon/clover flavor. Papalo (Porophyllum ruderale) has a taste between arugula and cilantro. Plant once cilantro bolts to seed. Steely blue foliage up to 5 feet tall.

Joe Heidgen, co-owner, Shady Hill Gardens, Elburn

A plant that is often included with the popular herbs that gardeners know at Shady Hill is the scented geranium. It doesn’t look anything like a garden geranium, but it has a wide range of fragrances, as well as varying leaf shapes and colors. The fragrances may be lemon, rose, pine, ginger, lime, balsam or apple. It can be used in cooking and also in potpourri and sachets. Some scented geraniums are upright, some cascading, but all are unique and quite easy to grow. They are ideal for planters.

Kevin DeBoer, manager, Big John’s Farm Market, Chicago Heights

Onion or garlic chives can be grown and cut for use in potatoes and eggs. We also have five different types of mint that can be grown and used for mojito, flavoring water and teas. Some varieties such as pineapple mint are attractive and add beauty to the garden. Thymes such as English and lemon can be used in pasta and in marinades for grilling. A good marinade for meat can be made from thyme, rosemary, sage, Italian olive oil and pepper.


Cycas

I have a cycas palm and am not sure how much direct sunlight or water it needs. It has light brown marks developing on the leaves. What is causing this, and how do I care for my plant?

Cycas palms or sago palms (Cycas revoluta) are tough house or patio plants. They are neither palms nor ferns but primitive cone-bearing relatives of conifers. A rosette of green feather-like leaves, 2 to 3 feet in height, grows from a central point at the top of a single trunk.

Cycas need bright light and should be kept relatively moist with weekly watering. However, prolonged rainy spells can cause fungal leaf spot disease.

“The shiny brown spots are probably caused by scale,” says Jeff Frohn, sales associate at Geimer Greenhouses, Long Grove. “It can be treated with fish oil, vegetable oil or an all-in-one insecticide spray,” adds Mike Geimer, owner, Geimer Greenhouses.


African Violets

I have twelve beautiful blooming violet plants on my office desk, placed 12 inches from a light source that’s kept burning day and night. I water them from the bottom and let the water remain in the saucer.

No matter what I spray, I continue to have gnats and other insects in my soil. I also occasionally start to get yellow spots on the tips of the leaves and then the spots start going down the leaves. What’s going on here?

A number of factors could be causing your problems.

“Yellow tips indicate your plant is showing stress either from lack of humidity or watering too much; it’s hard to pinpoint,” says Sandy Fuller, Palatine, past president of Barrington Bloomers, who grows 100 African violets under lights in her basement.

Peat-based soil needs to dry out for fungus gnats to disappear. Use a magnifying glass and try to identify them. Gnats eat only decaying plant material and do not damage the plants. If you have mealy bugs, their cottony waxy sac is easy to identify.

Office tap water may be too cold. Let it sit for half a day before using it. If the water is too cold, the plant could rot. Some violets are more sensitive than others to temperature changes.

Repot your plants in African violet soil and use a 20-20-20 fertilizer.


Variegated Sedum

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.


Voles

How can I get rid of voles? I think they are doing a lot of damage to my bulbs.

Voles are mice-like rodents that gnaw on roots and bulbs. They are hard to control.

There are repellents on the market that you can try—Deer Off, Moletox, and a new product named Shot Gun Repel. The latter repellent was designed specifically to protect bulbs from chipmunks, moles, voles and mice. Treat the bulbs before storing or planting. Remove old skin and soil, and then spray thoroughly until wet. Allow the bulbs to dry before storing or planting.


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questions

What is rose rosette disease? I lost two antique roses and removed a hedge of multiflora roses that were supposed to be undesirable. How bad is it?

I’d like to start composting. Do you have any advice on what kind of bin to purchase/build so that it is successful in the Chicago climate?

We all seem to plant the basic herbs like basil, rosemary and parsley. What suggestions can you offer for more exotic herbs that I could add to my garden to spice things up both for cooking and adding interest/beauty to my landscape?

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