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Tuesday, March 8, 2011

Peony Care Starts in Early Spring

Herbaceous peonies are rugged heirloom perennial plants valued for their drought tolerance and deer resistance.  Breeders continue to introduce exciting hybrids to the marketplace featuring new color breaks, patterns and flower forms though carefully selected, nature will find any defect.

Hybrid herbaceous peonies flourish in mild springs.  Flower durability and longevity translates into a long bloom season.  Wet springs punctuated by persistent rainfall are a perfect environment for disease outbreaks. A chemical program begun in early spring as new shoots emerge mitigates future fungal problems. 

Powdery Mildew
Botrytis blight (Botrytis paeoniae), measles (Cladosporium paeoniae), and powdery mildew (Erisyphe polygoni) fungal spores can easily jump from plant to plant.  Heavy winds or rains are great transportation modes for these nasty pathogens.  Infection from neighborhood plantings or new garden center purchases is entirely possible.  Rather than lamenting over misfortune or exacting blame, know the facts and respond with proper identification and treatment. 

Botrytis is the most common peony disease.  Symptoms appear in late spring on young leaf shoots about one foot in height.  Susceptible center stems wilt and die.  A brown or blackish rot appears at the base of leaves and stems.  Affected areas of the stalk above ground will be covered by a gray mold filled with large spore populations.  Immediate removal and treatment is essential to combat infection.

Peony Measles or “Red Spot” resemble small circular discolored lesions on leaves.  Spots can combine to make foliate look irregularly blotched.  The under surface of these areas becomes light brown.  Different powdery mildew disease species can attack plants in the home and commercial landscape.  Native dogwoods and hybrid lilac, honeysuckle, bee balm and zinnias are common hosts for these fungi.  Herbaceous peonies have their own powdery mildew specialists that develop as a white film on leaves and stems.  Infestation effects are seen in late summer.  Protection applied during wet springs mitigates the disease’s devastating visual appearance.

Immunox® (Myclobutanil) is a reliable systemic fungicide labeled for botrytis and peony measles control.  Spectracide® packages formulations in one quart containers for tank mixing.  The Pest Management Guide from Virginia Cooperative Extension also suggests Ortho® Rosepride® (triforine) for powdery mildew control.  Protective sprays should be made during favorable disease conditions as new foliage emerges and matures through spring.  A spray for Measles is a good tool immediately following bloom season. 

Remove Old Blooms
 Good garden sanitation is a must.  Spent flowers should be immediately removed during bloom season.  Remove declining foliage each October.  Collected debris should be tossed in the garbage or burned.  NO COMPOSTING.  Additional advice and information can be obtained from your local Cooperative Extension Office.  Please follow product label for mixing and applying registered pesticides.  Use a spreader sticker (surfactant) in your spray solution for best results. 


Friday, February 25, 2011

Rebloom Searches for Silver Lining (Published in American Iris Society Region 4 Newscast , March 2011)

Rebloom was put to the test this past summer in Region 4. Record heat and dryness wilted many gardeners and their cherished plantings. Prospects for summer and fall flower were dim. Against all odds, consistent rebloom did materialize. Survival had some unexpected pleasant blessings.

The Richmond area saw its hottest summer on record. The National Weather Service considers summer to be June, July and August. The average daily temperature for the three month period was 81.3° F, which eclipsed the previous record of 79.6° F posted in 1900!! 

Meager summer rainfall added to the misery. Only 5.93 inches were recorded during the span. Summers with drier readings were 4.46 inches in 1921 and 5.24 inches in 1912. Lack of rainfall was one factor contributing to abnormal summer warmth according to a meteorologist interviewed by Rex Springsten for the Richmond Times Dispatch.

The bleak growing conditions however did not discourage rebloom in my garden. My daily diary indicates summer flower began appearing during the second week of June. SDBs Double Overtime (Tasco, 2004) and Sailboat Bay (Zurbrigg, 2001) kicked off the early parade TBs Summer Radiance (Wilkerson, 1996), Anxious (Hager, 1992), Durham Dream (Zurbrigg, 2000) and Northward Ho (Zurbrigg, 1991) flowered on multiple bloomstalks until crushing heat arrived in early July.

July heat was oppressive. Daytime temperatures frequently hovered between 90° F and 100° F. As August approached, rebloom suddenly reappeared on both named varieties and seedlings. ‘Northward Ho’ without any prodding resumed summer flowering.  The strawberry pink plicata has now turned in solid summer rebloom in consecutive years.  A combination of ‘Northward Ho’ and Double Vision (Ghio, 1999) has produced children with summer and early September flowering. They had performed well during the same time frame in 2009. It was encouraging to see similar
results under more challenging conditions during the past year.

The big surprise in August was finding bloomstalks on offspring featuring Gate of Heaven (Zurbrigg, 2004) mated with Zurbrigg Seedling Nos.# TT109 and 20360A-L. The extreme growing conditions clearly affected stalk height, branching and flower quality. An important Zurbrigg breeding goal was to develop reliable late summer and early September remontants. The performance of both ‘Northward Ho” and ‘Gate of Heaven’ seedlings in my garden indicates future rebloomers can acquire this valuable genetic trait.

Lois Rose from Partlow, VA has dedicated a large portion of her bearded iris plantings to remontants. The FAIS member has worked with me over the years to use her garden results as an important check against mine in Powhatan, VA. We strive to test new selections and chart rebloom consistency on well known varieties. Micro climate quirks still confound our best intentions. Lois however was able to water, so she did have good fall results despite Dante’s Inferno. Outstanding rebloom was obtained during September on IB Low Ho Silver (Byers, 1989). The white median had a whopping eight plus stalks through October. The late Sterling Innerst’s tall bearded rebloomers turned in solid efforts. Lois recorded four stalks on Again and Again (Innerst, 1999), seven on Lunar Whitewash (Innerst, 2003) and six on Over and Over (Innerst, 2000). Sterling effectively used Hager, Hall, Mahan and Zurbrigg breeding to create a rich rebloom
legacy to benefit both iris gardeners and future breeders.

Solid September-October median performers were SDBs Rosalie Loving (Spoon, 2003) and ‘Sailboat Bay’, IB Tawny (Pray, 1974), BB September Buttercup (G.P.Brown, 1962) and MTB Lady Emma (F.P. Jones, 1986). Maryland Ho (Hornstein, 2003) was an exceptional Region 4 origination. A tall bearded plicata out of ‘Northward Ho’, it produced four stalks during the period. Past Zurbrigg TB favorites also did well. Earl of Essex (Zurbrigg, 1980), I Do (Zurbrigg, 1974), Jennifer Rebecca (Zurbrigg, 1985), Renown Zurbrigg, 1992) and Youth Dew (Zurbrigg, 1980) had an average of three bloomstalks per clump. The late Bernice Miller’s ‘Born Again’ (1977) was a prolific fall bloomer. The dark crimson bitone tall bearded had seven stalks!!

FAIS president Doug Chyz and member Sue Shackleford filed encouraging reports. Doug found median bloom on SDBs Blueberry Tart (Chapman, 2002), Giggler (Spoon, 2001), Pretty Girl (Spoon, 2001), Sky Willow (Spoon, 2004) and Smell the Roses (Byers, 1988). He also reported fall bloom on TBs Queen Dorothy (Hall, 1984) and Witch of Endor (B. Miller, 1978).

The Shackleford garden had rebloom on both older and recent releases. Four recent tall bearded introductions from Kentucky remontant breeder Betty Wilkerson made the grade. Fall flower occurred on Another Bridge (Wilkerson, 2005), Echo Location (Zurbrigg, 2007), Star Gate (Wilkerson, 2005) and Tara’s Choice (Wilkerson, 2004). Zurbrigg releases re-
blooming for Sue were Clarence (Zurbrigg, 1991), ‘Earl of Essex’, English Cottage (Zurbrigg, 1976) and ‘Gate of Heaven’. Innerst TBs mentioned were ‘Again and Again’ & Lunar Whitewash. Older selections in fall flower were TBs Buckwheat (Byers, 1989), Istanbul (Byers, 1990), Rosalie Figge (McKnew, 1991) and ‘Queen Dorothy’. 

CVIS members reported the following fall bloom in their November 2010 Newsletter. June and John Rosini had June rebloom on IB Double Your Fun (Aitken, 2000). Other median rebloom in their garden was Plum Wine (Weiler, 1986) and MTB ‘Lady Emma’. TBs Perfume Counter (Zurbrigg, 1972) and Iceland (Byers, 1991) reached fall flower. A number of additional remontants had developing stalks and buds. Jim Diggs enjoyed rebloom on TB (Daughter of Stars, 2000) and Shirley Shelton had multiple fall bloom on ‘Again and Again’. 

Don Rude from Blacksburg, VA saw rebloom on ‘Gate of Heaven’ for a month. Initial flowering started on September 1st. Don also saw fall bloom on TBs Mango Parfait (Spoon, 2008) and Frost Echo (Aitken, 1995). Linoa Adams from Raleigh, NC had November/December flowering on TB Matrix (Hall by Zurbrigg, 1992). 

Extreme summer heat and drought for the most part delayed bloomstalk formation on most reliable rebloomers until the latter stages of October throughout Region 4 in 2010. Hard frosts started materializing in the beginning of November damaging most developing stalks. This report tried to focus on reports of actual bloom. We still however appreciate any emerging fall bloomstalk reporting. This information is still tabulated and available to any interested member or rebloom breeder. Results indicate many recent introductions seem to be consistent in any weather condition. Lets focus on the positives in an otherwise brutal year.  If some of the current reporting trends continue, rebloom still has a great future ahead of it.