Varieties of Impatiens Shown Resistant to Downy Mildew, Once a Huge Headache for Growers
LANDISVILLE, Pa. — It’s the year for geraniums at Penn State’s Southeast Agriculture Research and Extension Center (SEAREC) in Landisville, Pa., near Manheim.
“The geraniums are about as good as I’ve seen them out here,” Penn State horticulturist Robert Berghage said. “The geraniums are perfect right now.”
Those flowers, deadheaded a week earlier, were already in bloom again July 25 at the research farm’s commercial field day. More than 300 people, mostly producers selecting varieties to sell next year, came to inspect the 1,246 cultivars that Penn State is testing this year at the flower trials.
All of the flowers were planted over three days at the end of May with the help of Penn State master gardeners. Three plugs of each variety were put in a four-inch pot, and three pots were made of each.
Alyssa Collins, who oversees both the flower trials and the Landisville farm, said the weather has given the flowers “a real test.” Two weeks of rain brought on fungus problems, she said, but then the weather switched to “blazing hot.”
Planning for the trials was a little different this year, she said, because Rapho Township shifted the farm’s outlet to Auction Road late last year. The realignment displaced some of the trials that had been run near the parking area. The flowers are all in one place near the pole barn this year, she said.
Collins, who trained in field crop diseases, has been in charge of the flower testing for the past two years since the retirement of Penn State floriculture legend Alan Michael. With a new flower-trial director soon to be hired, Collins will then be able to refocus her efforts on the farm’s other research pursuits.
Still, she said working with pretty flowers was a nice change from agronomic studies.
Growing flowers has also been a new experience for Rachael Grube, an environmental studies major from Gettysburg College who is interning at the farm this summer.
“It’s been very interesting,” she said of her work at Landisville.
Her tasks have included hand spraying, potting and hooking up the irrigation system.
The biggest challenge in caring for the plants has not come from rain, fungus or heat, she said. Voracious bunnies earn that distinction.
“Rabbits really like the spaghetti tubing” used in the irrigation system, she said. She repairs several pieces of rabbit-damaged tubing every day.
Grube had not been involved in flower production before taking the internship, and she learned a lot from her experiences, she said. She has been surprised at “how easily some flowers fall to diseases.”
Geraniums, in particular, require a lot of precautions. When she deadheaded the flowers, Grube had to change clothes after she was finished with each plant breeder’s flowers and wash her hands between varieties. The goal was to avoid spreading to other flowers any diseases one company’s seeds might have carried in, she said.
The trials included varieties from the “tried and true to the new and exciting,” Collins, the director, said.
Otomeria, which has smaller flowers in mostly warm colors, has been in the trials “a couple years,” Berghage said. People like the flower because “it’s different” and “it flowers reasonably well,” he said.
Caladiums, a South American native with two-colored leaves, are in their second year at the trials. They come in a wide range of colors, from the watermelon-like red-and-green to an almost-black purple.
The trial highlighted breeders’ work to produce new colors of echinacea. Kieft Seed’s new Cheyenne Spirit variety produces reds, oranges and yellows and won an All-American Selections Flower Award this year.
Several varieties of sweet potato vine were also on display. Breeders have been experimenting with leaf form, texture and color.
“Most are really good performers,” Berghage said.
The flower trials feature many new or recent coreopsis cultivars. The blooms on Danziger’s Highland Blast have a rich red interior and a bright yellow edge. Bees like the flowers, too, which makes Highland Blast a good pollinator, he said.
Euphorbia is “always really good” at the trials and is gaining traction in the region because it resembles baby’s breath but fares better than it in Pennsylvania, Berghage said.
Evolvulus is popular because it is one of the few flowers with “true blue” petals, Berghage said. The flowers are a bit underwhelming in size, he said, but the color makes them attractive.
Across the field of bright, thriving plants, the brown, wilted lobelias stuck out. The plants have become something of a byword among Mid-Atlantic horticulturists because the summer heat kills them.
Angelonia, by contrast, is a strong performer that is easy to grow, Berghage said. It comes in many forms with flower colors from white to blue. Agastache is another generally reliable flower, he said.
Penstemons, with many smaller flowers along their stems, have had an “unusually good” year, Berghage said.
He described the vincas and begonias in the trial simply as “outstanding.”
Mandevilla is a nice vine option, but the tropical plant does not survive the winter, he said.
Berghage characterizes coleus, another import from other continents, as “great plants” that can handle sun or shade. They actually tend to grow bigger in shade, he said.
Rudbeckia — black-eyed Susans — have seen “a lot of breeder action” that has resulted in trial pots bursting with flowers, he said.
Phlox and scaveola have also been improved. Scaveolas used to collapse in the center and end up with all of the flowers on the edge of the plant, but breeders have fixed that issue, he said.
The hanging basket selection at the trials has been changing in recent years, Berghage said. Greenhouses used to create combinations of color and species, but the industry now offers pre-mixed seed combinations for baskets, he said, pointing out petunia baskets with pinks, purples or other colors growing together.
The industry mixes are intended to save greenhouses time and effort in choosing color combinations that work.
“It’s been an interesting container year,” he said. The heavy rainfall this year washed the fertilizer out of the planters, which necessitated repeated fertilizer applications. On the other hand, the baskets dried better than the pots, which probably saved the baskets from some of the diseases that affected the potted samples, he said.
The increased disease pressure has been useful in distinguishing the more resistant varieties of verbena and calibrachoa from the weaker breeds. The wet weather was especially hard on the petunias, he said.
Also on display were varieties of impatiens resistant to downy mildew, once a huge headache for growers of that flower.
“It’s almost hard to find bad New Guinea impatiens” now, Berghage said.
In addition, Sakata’s SunPatiens line is “very, very vigorous,” he said.
The trial staff treats the non-resistant impatiens with fungicides, but none of those fungicides are licensed for home use. Home growers are therefore not likely to get non-resistant impatiens as good as those in the trial, he said.
The testers try to take a little better care of the flowers than home growers might, but Penn State Extension does not give the flowers the amount of attention a greenhouse would, he said.
The trial gardens, at 1446 Auction Road, Manheim, are open to the public Mondays Thursdays. Comprehensive data on cultivars from this year’s and previous years’ trials are available at the garden’s website, trialgardenspsu.com or by calling 717-653-4728.