The Boxwood Bulletin A Quarterly Devoted to Man's Oldest Garden Ornamental An entrance to the boxwood display gardens at Kimberly Boxwood Gardens, Wilsonville, Oregon. See article. page 52. (Photo: Mrs. Robert L Frackelton) IN THIS ISSUE Boxwood Leafminer, Monarthropalpus. Gabe d'Eustachio ............................. 43 Four Recently Registered Boxwood Cultivars, Lynn R. Batdorf ..................... 45 ABS Supports Boxwood Genetics Research Project, Henry F. Frierson. M.D . ........................................................................... 47 Reducing Synonyms of Infraspecific Nomenclature, Lynn R. Batdorf ............ 48 Correspondence, Decca Frackelton ................................................................. 52 News of the Society .......................................................................................... 62 Notices .............................................................................................................. 63 January 1999 Volume 38. Number 3 The American Boxwood Society The American Boxwood Society is a not-for-profit organiza­ Available Publications: tion founded in 1961 and devoted to the appreciation, scien­ tific understanding and propagation of the genus Buxus L. Back issues of The Boxwood Bulletin (thru Vol. 37) (ea~h) $ 4 Boxwood Handbook: A Practical Guide (Revised)** $ I7 Officers: Boxwood Buyer's Guide (4th Edition) $ 6 International Registration List of Cultivated Buxus L $ 3 PRESIDENT: Index to The Boxwood Bulletin 1961-1986 $ IO Mr. Thomas Saunders Piney River, Va. Index to The Boxwood Bulletin 1986-1991 $ 4 VICE-PRESIDENTS: Index to The Boxwood Bulletin 1991-1996 $ 3 Mr. Charles Fooks Salisbury, Md. Publications may be ordered from Mrs. K. D. Ward, ABS Mr. Daniel Moses St. Louis, Mo. Treasurer, 134 Methodist Church Lane, West Augusta, VA SECRETARY: 24485-2053. **Price includes tax, postage and handling. Mrs. Sigrid Harriman Fredericksburg, Va. EXECUTIVE TREASURER: Contributions: Mrs. Katherine D. Ward West Augusta, Va. Gifts to the Society are tax-deductible and may be undesig­ REGISlRAR: nated or applied to: Mr. Lynn R. Batdorf Washington, D.C. Boxwood Memorial Garden Fund DlRECfORS: Boxwood Manual Fund Mr. John W. Boyd III (2001) Roanoke Va. Boxwood Research Fund Mr. Scot Butler (2000) Winchester, Va. Mrs. Robert L. FrackeIton (2000) Fredericksburg, Va. Correspondence: Dr. Henry Frierson (2000) Charlottesville, Va. For address changes, memberships, dues, contributions, or to Mr. Richard D. Mahone (2001) Williamsburg, Va. order back issues or publications, write: Mr. Ian Robertson (1999) Charlottesville, Va. Mr. Jiin W. Saunders (1999) Piney River, Va. Treasurer, The American Boxwood Society Mr. Clyde Weber (1999) Bentleyville, Pa. P.O. Box 85, Boyce, Va. 22620-0085 Mr. Steve Zapton (2001) Port Republic, Va. For general information about the Society, advice concerning EX-OFFICIO: boxwood problems or cultivar selection, write to The Ameri­ Dr. Michael Bowers Boyce, Va. can Boxwood Society at the same address. You are also welcome to write directly to the President: BULLETIN EDITOR: John S. McCarthy St. Louis, Mo. Mr. Thomas Saunders 2498 Tye Brook Hwy. Memberships: Piney View, Va. 22964 Memberships forthe year May through April include $16 for four quarterly issues of The Boxwood Bulletin: Call for Papers: Individual $25 Sustaining $75 Technical articles, news, history, lore, notes, and photographs Family $35 Life $500 concerning boxwood specimens, gardens or plantings are· Contributing $50 solicited for possible publication in The. Boxwood Bulletin. Material should be submitted to: Non-member SUbscriptions for groups and institutions, such Chairman, Bulletin Committee as botanic gardens and libraries, are $25 by the calendar 1714 Greenway Drive year as established or current year for new subscriptions. Fredericksburg, Va. 22401-5209 The Boxwood Bulletin (ISSN 0006 8535) is published quarterly for $16.00 per year by The American Boxwood Society, Blandy Experimental Farm, Boyce, Va. 22620. Periodicals postage paid at Boyce, Va. POSTMASTER: Send address changes to The Boxwood Bulletin, P.O. Box 85, Boyce, Va. 22620. The Bulletin is printed by M-J Printers, Fredericksburg, Va. Boxwood Leafminer, Monarthropalpus flavus New Research on Chemical Control Gabe d'Eustachio Over the past few years The Ameri­ molasses/nicotine sulfate were coinciding with emergence of adult can Boxwood Society has been applied at the first sign of adult leafminers seems to be important, supporting the research of Mr. Gabe emergence. Cyanide fumigation was although not essential, for effective d'Eustachio, a graduate student at done in the fall when plant growth control. the University of Maryland who is had slowed to reduce damage to plant To test the effectiveness of doing his masters thesis on the box­ tissue. different pesticides and different wood leafminer. This is the second Modem control is usually at­ times of application, trials were article detailing his work on the use tempted with a contact insecticide for initiated during the summer of 1995. ofpesticides to control boxwood adults and systemic insecticide to leafminer in landscape settings. control larvae (Brewer 1980, Batdorf METHODS 1994). Brewer (1980) tested Soldep, Boxwood plants fonn a key part of pirimiphos-methyl (Actellic), and Two trials were conducted to test numerous landscape settings. Fortu­ omethoate (Folimat). Pirimiphos­ the efficacy of different pesticides nately, it has few arthropod pests. The methyl seemed to provide reasonably applied at different stages of box­ three pests of economic significance good control. Schread (1967) ob­ wood leafminer development. The are the boxwood leafminer (Monar­ tained effective control with late (July first trial tested early application of thropalpus flavus, Schremk), the 22) applications of diazinon Avid (avermectin) and Merit boxwood mite, and the boxwood (Diazinon) and even later (August 4) (imidacloprid). The second trial psyllid. This paper shall deal with applications of dimethoate (Cygon). examined the effect of late applica­ chemical control of the boxwood tion of Avid, Merit, and Orthene leafminer. The most important aspect for (acephate), all of which are systemics. At the present time, control of the implementing chemical control of the For the early trial, five plants boxwood leafminer is unreliable due boxwood leafminer is proper timing (Buxus sempervirens 'Arborescens') to a lack of knowledge regarding the of application. Catching the adults as were sprayed for each chemical choice and optimal timing of pesti­ they oviposit, before the boxwood evaluated at the first sign of adult cide applications. Historically, timely leafminers are hidden in the leaves, is emergence in late April. Both Avid applications of molasses plus nicotine crucial. and Merit were used at concentrations sulfate, fumigation with hydrogen recommended for leafminer control. cyanide gas, or even dipping smaller Carbaryl (Sevin) (also applied July A control group of five plants was plants in boiling water have provided 22) was found to give less control. sprayed with water and spreader/ adequate control of the leafminer Late applications of dimethoate were sticker only. Plants in each group (Hamilton 1925). Sulfur dusts have not very effective when tested in the were sprayed to a point slightly been used against adult leafminers summer of 1994 at Dumbarton Oaks beyond leaf drip using a two-gallon with moderate success, and applica­ (P. Page, personal communication). hand sprayer. Ten leaves were tions of arsenic have been attempted Newer pesticides such as avennectin harvested from each of the plants in with minimal success (Hamilton (Avid) and imidacloprid (Merit) are September, and the number of 1925). The main problem with dusts currently under examination for surviving larvae were compared and molasses-based sprays is they are potential usefulness. Studies indicate among different pesticide treatments. washed off by rain and wind. Since that the timely application of aver­ To detennine if pesticide treatments adults emerge over a two-week mectin or imidacloprid both provide affected oviposition behavior, the period, keeping materials on the plant exceptional control (d'Eustachio, number of ovipositions was measured long enough to kill all of the adults unpublished). A common feature of by counting the number of oviposi­ proves difficult. DDT was recom­ all these methods is a limited time tion scars still plainly visible on the mended for control of adults as they period for effective control (Hamilton underside of the leaves. Oviposition emerged and walked through the 1925, Brewer 1980, Batdorf 1994, scars remain visible for the entire material (Barnes 1948). DDT and Reif 1994). Application of pesticides lifetime of a leaf and because box- January 1999 43 wood leafminers only oviposit on the RESULTS AND DISCUSSION waxy cuticle, which is thick on current year's growth, only oviposi­ boxwoods, may have developed to tions from the current year were Recalling Hamilton's (1925) the point that water-based materials observed. threshold of six larvae per leaf, both cannot enter. Another possibility A second trial was initiated in Avid and Merit proved quite effective could be that larvae have developed mid-July to test the efficacy of late when applied at the first sign of adult enough by this stage to resist the pesticide application. Plants were emergence and showed significant small amount of pesticide that selected and leaves were harvested levels of control. In practical terms,