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THE YEAR OF THE ZINNIA

written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

It’s the “Year of the Rabbit” for the Chinese, but it’s also the “Year of the Zinnia” for U.S. gardeners. Each year the National Garden Bureau, representing the professional horticulture industry, selects one flower to be showcased. Plants selected for this honor are chosen because they’re popular, easy-to-grow for gardeners, widely adaptable, and versatile.

The zinnia, this year’s honoree, is an old garden favorite. The ancestor of the modern zinnia is Zinnia elegans, native to Mexico. As a native species, Zinnia elegans didn’t look attractive to the Spanish colonials who “discovered” this small plant with purple-red daisy-like flowers. Ugly or not, zinnias were taken to Europe where they received their scientific name in the 1700

s from Dr. Johann Gottfried Zinn, the first botanist to write about them.

Probably because native zinnias were not particularly attractive plants, breeders didn’t pay much attention to them for about 100 years. The result of their initial efforts was a double-flowered plant that was still not pretty enough to create excitement in the gardening world. In 1920, additional efforts by breeders yielded two fairly attractive varieties with dahlia-like flowers, ‘Giant Dahlia’ and ‘California Giant.’

Over the years, continued breeding efforts have yielded common zinnias in different sizes, from eight inches to over three feet in height, and in a variety of brightly colored flower forms. Zinnia flower colors include yellow, gold, pink, rose, red, orange, salmon, purple, ivory and white. The cheery flowers of the common zinnia (Zinnia elegans) will keep coming through the summer only if their faded flowers are removed regularly. This practice is called deadheading.

While the common zinnia proved a dependable garden flower in our grandmothers’ gardens, today’s gardeners often find the required deadheading and tendency to develop mildew too much trouble. For more modern zinnias, plant breeders have looked to another native Mexican zinnia, Zinnia angustifolia, for help. Breeding efforts have combined the best traits of these two species and have yielded more compact zinnias that don’t require deadheading to keep them flowering. These new hybrids are also resistant to powdery mildew and are more tolerant of heat and humidity.

My current zinnia favorites are in the Profusion series of zinnias. Introduced in 1994, ‘Profusion Orange’ was the first in the series with orange flowers. White, cherry, apricot, gold, and scarlet-orange flowered members of the series followed. Profusion zinnias have two-inch single and double flowers. Their compact branched plants grow from 12 to 18 inches tall and 24 inches wide. They keep flowering through fall and don’t require deadheading.

I hope to try some of the Zahara series of zinnias this year. Zahara zinnias are also hybrids of the Z. elegans and Z. angustifolia. This newest series touts flowers that are 20 per cent larger than the Profusion series. Zahara flower colors include coral rose, orange-red, scarlet, white, yellow, double cherry, double orange-red and a delightful white and pink bi-color called Starlight Rose.

Zahara zinnias are heat loving plants that thrive under hot, sunny conditions. Once established, they’re drought tolerant. Their bushy plants produce flowers all season long and grow to a height and width of 12 to 18 inches with double-flowered varieties growing 16 to 20 inches in size. Both the Zahara and Profusion zinnias are great in containers and flower beds.

The WSU Extension Master Gardeners will be planting some of the Zahara zinnias in the Formal Garden in The Master Gardener Demonstration Garden this year. Drop by during the summer to see these tough but pretty new zinnias.

Published: 3/5/2011 2:51 PM

STRANGE THINGS IN THE GARDEN

written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Apparently, humans like to be scared out of their wits. Just look at all those creepy new television shows and the horror movies that are produced every year. Our imaginations are fertile fields for the strange, scary, and seemingly unexplainable. So it’s no wonder that when bizarre things show up in the garden , we can come up with some pretty creative explanations. Really odd things do pop up in the garden now and again, but they can be explained. Let’s talk about a two”weird” manifestations that showed up in local gardens this year and discuss the science behind them.

The most recent problem that presented itself was a plant disease in zinnias. The symptoms noticed by gardeners were weirdly deformed flowers with leaves and other flower parts popping out of the flowers. Those not familiar with the disease might think the cause was exposure to chemicals or genetic tinkering. They do look quite odd, but the real cause is a bacteria-like disease called aster yellows.

Aster yellows is a phytoplasma disease. It’s spread from plant to plant via leafhoppers. Once a “clean” leafhopper feeds on an infected plant it picks up the disease in its salivary glands and then transmits it to the other plants that it feeds on after that. That leafhopper carries the disease for the rest of its life. Generally, the disease shows up more in years where the summer weather is cool and wet, because these conditions are favorable to leafhopper populations. Hot, dry weather is not favorable to leafhoppers or the development of aster yellows disease.

This year the aster yellows has appeared in zinnias from at least two local gardens, but I have also seen it on coneflower in other years. Aster yellows can infect over 300 species of plants. Of most interest to gardeners are asters, coneflowers, coreopsis, chrysanthemum, nasturtium, zinnia, marigold, chrysanthemum, petunia, snapdragon, lettuce, carrot, beets, tomato, potato, pumpkin and onion. This disease generally causes malformed growth and color changes in plant parts. Usually the leaves will turn yellowish with the veins remaining green… the reason for the “yellow” part of the diseases’s name. Infected plants grow more slowly and leaves may become stunted, narrower, or curled. On some plants like zinnia and coneflower, the flowers may be greenish and the flower centers may become enlarged with breakouts of tufts of deformed growth. On carrots, the roots become bitter and “hairy” or covered with little roots.

There is no cure for disease. Once infected, plants should be removed. That’s not too upsetting when annual flowers, like zinnia or petunias, are infected, but it’s much more heartbreaking for gardeners when a large perennial, like coneflower, falls victim.

There is also no simple control for aster yellows. It’s brought to the plants by infected leafhoppers which migrate to this area each year from their winter homes along the Gulf of Mexico. To prevent the leafhoppers from infecting plants in the vegetable garden, row cover fabric can be utilized early in the season. Some commercial vegetable growers also use shiny silvery mulches to deter leafhopper feeding. It’s also important to remove weeds from around vegetable and flower gardens. That’s because susceptible weedy hosts, like dandelion and plantain, can act as reservoirs for the disease and increase the spread of aster yellows in your garden.

Not that long ago, aster yellows and other phytoplasma diseases were thought to be caused by viruses. In 1967, new technology via the electron microscope allowed scientists to determine that the organism was not a virus, but resembled mycoplasmas found in animals and humans. They were then called “mycoplasma-like” diseases. More study revealed that they were unique organisms that more closely resembled bacteria. In 1994, they were given the new name of “phytoplasma”. There are over 300 distinctly different phytoplasma diseases. These include aster yellows, peach X-disease, ash yellows, elm yellows, and a long list of cherry diseases. Fasciation on woody plants that was once thought to be a genetic aberration is now believed to be caused by a phytoplasma. If you’re like me and find all this fascinating, you can find out more information about phytoplasma diseases by going to http://www.agriculture.state.pa.us/plantindustry/lib/plantindustry/pdfdocs/vol25_9.pdf

At this site you can find “Diseases Caused by Phytoplasmas, Ruth Welliver, Plant Pathology Circular No. 82, Department of Pennsylvania Department of Agriculture, Bureau of Plant Industry, Spring 1999.”

Corn smut is another weird looking problem that showed up on corn in a number of vegetable gardens this summer. Instead of developing normally, large gray tumors or galls grew out of the ears. These galls started out small, but grew bigger and bigger. The greenish to silvery-gray outer covering on the galls later dried and split open, releasing a mass of black to olive green powdery spores. If you don ‘t know what it is, the appearance of corn smut can be quite worrisome.

Corn smut is a fungus, Ustilago zeae, that is spread by spores. In some areas of commercial sweet corn production, as much of 20 per cent of the corn crop can be ruined by the disease. It infects sweet, pop, and dent corn, but

Golden Jubilee

and

Super Sweet Jubilee

are particularly susceptible.

Spores are spread by wind and in manure from cattle fed with infected corn stalks. As corn begins to mature and form ears, it’s less susceptible to infection, but injury from hail, detasseling, or corn earworms all provide a way of infection and can increase the chance of the disease. Weather and growing conditions also influence the chance of infection. High temperatures and high soil moisture both contribute to higher levels of infection. Because of these influences, earlier (May) plantings of corn are less likely to be infected than those planted later (June).

Control of corn smut involves several cultural practices. First, if corn smut has been a problem in area gardens, it’s good to plant smut resistant varieties such as

Blitz

,

Commander

,

Goldie

,

Reliance

, ‘Apache’, ‘Aztec’, ‘Comanche’, ‘Sweet Sue’, ‘Bellringer’, ‘Golden Security’, ‘Merit’, ‘Calumet’, ‘Capitan’, ‘Golden Gleam’, ‘Wintergreen’, ‘Midway’, ‘Pacer’, ‘Bravo’, and ‘Gold Cup’.

It’s very important to remove and dispose of corn smut galls before they burst open and release their spores. Removal must be practiced over a wide area for two or more years, since the spores can persist for two to three years. Perseverence will pay off over time, if all gardeners in the area practice gall removal. It’s also a good idea to follow long crop rotations of three years or more. In the fall, you also need to remove and dispose of diseased plants. Don’t put them in the compost.

If all else fails, you can eat the corn smut galls. Corn smut is a delicacy called “cuitlacoche” in Mexico. The galls are harvested and cooked before they’re mature. I’m told they taste like mushrooms. After all, they are a fungus.

Published: 10/21/2005 11:37 AM

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