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-i*. 



DIAGNOSTIC UPDATE 



Well, it finally looks like the 1995 

 growing season has arrived! March 

 was a rather slow month in the PDL, 

 but the sample submissions took off 

 in April It's good to see growers 

 getting a jump on plant disease and 

 health problems (or, maybe it was to 

 get all of your questions answered 

 before the $12.00 fee went into ef- 

 fect on 1 iVlay? ...hmmm). Impatiens 

 necrotic spot virus (INSV) appears 

 to be more of a problem this year 

 than last. During the last two months 

 the virus has been confirmed on 

 New Guinea impatiens and double 

 impatiens. INSV, previously known 

 as tomato spotted wilt virus-! 

 (TSWV-I), causes problems on impa- 

 tiens. New Guinea impatiens, cycla- 

 men, cineraria, and gloxinia (to name 

 a few of the many hosts). TSWV-L 

 (lettuce strain) is often found on 

 dahlias and mums (but also has a 

 wide host range). Vegetable trans- 

 plants, particularly tomatoes and 

 peppers, are also hosts the both vi- 

 ruses Both viruses are transmitted 

 by western flower thrips (WFT). In- 

 spect new stock carefully for thrips 

 and use blue (or yellow) sticky cards 

 to monitor for thrips in the green- 

 house (more than 10 WFT per card 

 per week seems to be a useful 

 threshold). If insecticides are neces- 

 sary for thrips control, be sure to ro- 

 tate between chemical classes every 

 3-4 weeks to reduce the chance of 

 resistance building up in the thrips 



population Plants infected with 

 INSV/TSWV cannot be cured and 

 should be destroyed (if kept, they 

 will serve as a reservoir for the vi- 

 rus). Suspicious plants should be 

 submitted for testing since several 

 other controllable diseases can 

 mimic INSV/TSWV symptoms. 



The majority of the samples re- 

 ceived during March and April were 

 diagnosed with abiotic, or environ- 

 mentally-related, problems Over- 

 watering continued to cause root rot, 

 oedema, and botrytis problems. Nu- 

 trient deficiencies (Mg, N) were diag- 

 nosed in tomatoes and geraniums 

 Improperly applied pesticides 

 caused injury on fuschia and snap- 

 dragon Winter injury/desiccation 

 caused browning and dieback on 

 hemlock, arborvitae, holly, and 

 rhododendron. Fungal diseases in- 

 cluded pythium root rot on several 

 crops, powdery mildew on rosemary, 

 tulip fire (botrytis) on tulip, phyl- 

 losticta needle blight on taxus, and 

 botrytis canker on exacum Both 

 pink and gray snow mold have 

 shown up on a couple of home 

 lawns Damage from arborvitae leaf 

 miners is becoming evident and the 

 larvae have begun to emerge prior 

 to pupation. 



Diseases and problems to watch 

 for during the early summer months 

 are brown patch, pythium blight, 

 and leaf spot on turf-grasses Shoot 

 blight (monllinia) has been a severe 



problem on Prunus sp. during |une for 

 the last two years. Fungicides such 

 as Captan or Daconil provide good 

 control for the disease. Primary 

 apple scab lesions should be evi- 

 dent on Malus sp. by early |une. Sec- 

 ondary scab infections should be 

 controlled with fungicides to reduce 

 the likelihood of early defoliation. 

 May through lune is the time to ap- 

 ply fungicides for many of the foliar 

 diseases of trees and shrubs such as 

 conifer needlecasts, anthracnose, 

 and the various leaf spots Fungi- 

 cides are most effective when ap- 

 plied between bud-break and full 

 leaf/needle expansion Leaf spots on 

 perennials (i.e., tulip fire, didymella 

 on iris) should be controlled with a 

 combination of sanitation and fungi- 

 cides The damage caused by botry- 

 tis blight to annuals and perennials 

 can be reduced by thinning the 

 plantings to allow for better air cir- 

 culation 



If you wish to submit plant material to the 

 PDL for diagnosis, send samples [with a 

 check for $12.00) tO: The UNH Plant 

 Diagnostic Lab, C/O Dr. Cheryl Smith, 

 Plant Biology Department, Nesmith hiall, 

 UNH, Durham, NH 03824. Samples 

 should be accompanied by an 

 identification form [available from 

 your county Cooperative Exten- 

 sion) Cheryl Smith is the UNH , 

 Cooperative Extension Specifll- Q^ 

 ist in Plant Health, and can ^ x 

 be reached at (603) 862- ■^ 

 3841. 



STEENBURG & CALLIORAS 



THE AUCTION 

 PROFESSIONALS, INC. 



AUCTIONEERS: 



Archie Steenburgh 



603/989-5690 



Route 10, Haverhill, NH 03765 



Peter Callioras, C.A.I. 

 603/8681070 



Calef Highway (Lee), Dover, NH 03820 



^Bemcrs ^arbcn (Center 2\nc, 



656 South Mammoth Road (Rte. 28A) 



Manchester, NH 03109-5049 

 (603) 625-8298 • Fax (603) 622-4073 



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 Craft & Christinas Shop 



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