Fall Pansy
Robert Berghage, Jay Holcomb and Alan Michael

The pansy, Viola x Wittrockiana, has traditionally been grown as an annual (spring planting) in the north or biennial (fall planting) in warmer climates. In recent years breeders have selected for increased winter hardiness, developing cultivars that can be successfully planted in the fall in most of the US. Planting pansy in the fall provides a number of advantages for both commercial producers and consumers alike. Fall pansy production provides commercial producers with an option for extending the profitable bedding plant season. For the consumer, fall planting extends the gardening season, and if suitable cultivars are selected leads to a greatly improved spring display (Figure 1).

Pennsylvania has lagged in the adoption of fall pansy production and use, perhaps because of our conservative and traditional nature. As a result we are missing out on some very good economic opportunities. In areas where this market is better developed, extensive use of fall pansies by landscapers in commercial plantings provides spectacular displays early in the spring leading to increased interest from home gardeners. Pennsylvania flower growers should make an effort to create "showcase" fall pansy plantings in their area to help develop this market. When creating "showcase" plantings, remember that these plants should be replaced with summer annuals in late May to June depending on your local climate. Even though the plants may look "great" at that time, they will soon decline in the summer heat. Delaying replacement will delay the establishment of the summer planting and reduce the overall impact of the demonstration bed.

>Fall pansy plantings were made at both the University Park and Landisville trial garden sites in 1997. Pansies were planted in beds and mulched with bark for weed control and to help protect overwintering plants. Twenty plants of each cultivar were planted at University Park and 10 in Landisville. The spring evaluations are summarized in Tables 1 and 2. University Park evaluations were conducted on 5/1, and Landisville evaluations on 4/14 reflecting the climatic differences of these two test sites. Cultivars in the tables are sorted based on the combined average of the two sites. An early evaluation of flowering was also conducted at University Park on 3/31. Most cultivars were evaluated at both sites and results can be found on both tables. Results for several cultivars are presented only for University Park. Height and width are given in cm. Ratings were 5 = Excellent, 4 = Good, 3 = Fair, 2 = Poor and 1 = Unacceptable. The full data set including photos of each cultivar will be available on the Trial Garden Web Site early this summer at http://garden.cas.psu.edu.

Nursery and Landscape Weed Control
Part II: Established Plantings
Jim Sellmer

It's June and the phone calls coming into the office are predominantly asking the same question. "How do I get rid of the weeds in my rows and among my landscape plants?" Oddly enough this is the third phase of a good weed control program. Eliminating weeds as they appear. If you overlooked the first two phases of the weed control program, you may be spending extra time and money eliminating the weeds as they appear. After spending the year fighting fires and reviewing where your employees spent their time, you may reconsider implementing the first two steps of the weed control program. Remember, the most effective weed control program has three parts:

1. Eliminate the weeds in and around the growing area before planting.
2. Prevent weed growth in and around the growing area.
3. Eliminate weeds as they appear. Since few preventative methods provide
   total control, hand weeding, cultivation, or careful spot treating with a
   postemergence herbicide are usually necessary.

In light of the questions that have been filtering past my desk. We are going to review weed control options for established plantings.

Preemergence Herbicides
Year-round weed control requires that herbicides are applied in the spring, summer, and fall as needed. Spring applications of preemergence herbicides should be made before weed seed germination. Soil that was treated with a preemergence herbicide last fall may have delayed weed seed germination for up to 8 weeks after ground thaw. In contrast, weeds start germinating in untreated soils soon after the thaw.

Fall herbicide applications are useful from a timing standpoint. First of all, there is more labor available for spraying in the late fall than in the spring. Secondly, fall treatments prevent winter annuals and perennials from infesting the fields during the peak spring digging season at a time when your employees cannot be spared for spring cleanup. Although spring applications could prevent most of the weed problems, most growers cannot get the job done due to the spring rush or the spring inclement weather. Fall or winter applied herbicides include: atrazine, dichlobenil (Casoron, Barrier, Dyclomec, Norosac), Devrinol, Factor, Gallery, Kerb, Princep, Pendulum and Surflan.

We are at the stage now, where the fall or winter applied herbicides are no longer effective in suppressing weed growth. At this stage, clean cultivation in combination with a spring or summer preemergence herbicide is one approach to maintain control. For broadspectrum weed control, apply one best for broadleaved weeds with one best on grasses or apply one of the premixed combinations. The combinations remain effective longer and provide a wider spectrum of weed control than a single chemical. More than one application will likely be needed to control weed growth throughout the summer. Do not use the same preemergence herbicides for both applications in one year. Alternate products to avoid resistant weed populations. Always read the label to assure that the species you are treating is on the label. One of the following herbicides or combinations would be effective.

For broadleaf weed control:

• Gallery
• Princep
• Ronstar

Preemergence herbicides for grass control include:

• Devrinol
• Barricade, Factor, Endurance
• Pendulum
• Surflan
• XL 2G

Combination products include:

• Ornamental Herbicide II, OH2 (a premixed granular formulation of Goal and Pendulum)
• Regal O-O (a premixed granular formulation of Goal and Ronstar)
• RegalStar II (a premixed form of Ronstar and Factor)
• Rout (a premixed form of Goal and Surflan)
• Snapshot TG (a premixed granular of Gallery and Treflan)

Care must be taken to read all label instructions. Each of the listed products has label restrictions on use in specific species and under specific nursery and landscape situations, application limitations, incorporation requirements, and recommended application rates.

Postemergence Herbicides
An effective preemergence herbicide program should minimize the need for postemergence control for annual weeds. There are only a few exceptions where preemergence herbicides are effective in controlling weeds that have started to grow. Atrazine, Casoron, Kerb, and Princep will kill weed seedlings in the early stages of growth. Atrazine is currently labeled for use in conifer plantings only. Goal will kill weeds up to 4 inches tall. In all other cases, preemergence herbicides will not kill weeds that have started to grow.

At this stage of the season, most growers and landscapers are finding unwanted annuals and perennial weeds growing up among their trees and shrubs. For these growing weed problems, the preemergence herbicides are ineffective.

This is the time of year where we wish for a quick and easy over the top postemergence herbicide that will kill all of the perennials and annuals without damaging our plants. We do not have a selective postemergence herbicide to fit that need. For annual weed control, cultivation and mowing can be affective in preventing these weeds from maturing and setting seed. Another option for control of both annual and perennial weeds within a planting is the use of a nonselective postemergence herbicide. This type of application entails the risk of injuring nontarget crop plants.

Postemergence herbicides that can be employed in established plantings include:

• Finale
• Envoy
• Fusilade II
• Garlon (labeled for conifer plantings and noncrop areas)
• Manage
• Reward
• Roundup Pro
• Vantage

Care must be taken with these herbicides. They can be applied as directed sprays, spot treatments, or with a wick applicator. A directed spray involves applying the herbicide so that it hits the weeds without contacting the foliage of the ornamentals. This type of application is most commonly used in plantings of large shrubs or trees. Spot treatments are used to eliminate pockets of weeds scattered throughout a planting. Wick applicators give the most control and allow exact placement of the herbicide on the weeds. There is no chance of drift. This type of applicator is especially useful in situations where weeds are growing above low-growing ornamentals such as ground covers.

Once an area has been cleared of weeds, measures should be taken to prevent immediate regrowth. Apply a mulch or a preemergence herbicide. Otherwise the area will have to be treated again with a postemergence herbicide two or three times during the growing season. To kill existing weeds and preventing emergence of others consider applying a preemergence and postemergence herbicide in combination.

These are just a few tips to answer questions that are showing up now at nursery and landscape sites. Remember, you can control your weed problems most effectively by establishing a complete weed control program rather than constantly fighting fires.

The information provided above is excerpted from the PSU extension publication Controlling Weeds in Nursery and Landscape Plantings by Larry Kuhns, Tracey Harpster, Mary Ann Rose and Scott Guiser. This publication is available from your county extension office or the Publications Distribution Center, 112 Agricultural Administration Building, University Park, PA 16802. For ordering information call (814) 865-6713.

CALENDAR OF PROGRAMS

JUNE 18 from 1:00 - 5:00 p.m.
Tree Appraisal Workshop
York County Cooperative Extension
112 County Annex Building
Pleasant Acres Road
Contact Bill Elmendorf at (814) 863-7941 or Tom Becker at (717) 840-7408 for further details

JUNE 23
Christmas Tree Growers Summer Meeting
Whispering Pines Tree Farm, Breinigsville
Contact George Perry at (717) 622-4225 for further details

JUNE 24 from 9 a.m. - noon
Understanding Athletic Field Amendments
Montgomery County 4-H Center
for further details contact: Nancy Bosold at (610) 489-4315

JUNE 25 from 10 a.m. - 3 p.m.
Ornamental Horticulture Extension Publications Planning Committee Meeting
ASI Building, University Park
Contact Scott Guiser at (215) 345-3283 for further details

JUNE 30
Greenhouse Twilight Meeting
Segan's Bloomin' Haus, Allentown
Contact Emelie Swackhamer at (610) 391-9840 for further details

JUNE 30
Garden Center Educational Tour
Bus Tour of Four Central PA Garden Centers
Contact Jim Sargent at (215) 345-3283 for further details

If you have an upcoming educational program that you would like to announce, drop us a note and
include the program date, title, time, location and contact person and we'll print it in the next newsletter.

Information provided by Rob Berghage and Jim Sellmer Penn State Department of Horticulture, Ornamental Horticulture Extension Specialist, 103 Tyson Building, University Park, PA 16802, (814) 863-2571

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