DIAGNOSTIC UPDATE 



□ 



Well, we certainly lucked out 

 this autumn in regards to 

 warm temperatures and Indian 

 summer. It was nice not to go 

 from 70 degrees to snow in one 

 week (although anything is pos- 

 sible in New England, so perhaps 

 I should keep my fingers crossed). 



Things have been relatively 

 quiet during the last two months 

 and there have been only a few 

 problems worthy of note from 

 samples submitted to the Plant 

 Diagnostic Lab. Phyllosticta needle 

 BLIGHT was diagnosed on concolor 

 fir. The current year's needles 

 were yellowing. The infected 

 needles will turn brown and cast 

 by the time new growth begins in 

 the spring. The extended cool, 

 wet weather this past spring fa- 

 vored the development of this 

 disease. A New Guinea impatiens 

 sample tested positive for impa- 

 tiens NECROTIC SPOT VIRUS (INSV). 

 Although black ringspots and 

 wave-like patterns were visible on 

 the leaves, the most notable 

 symptom was the black, zonate 

 discolorations on the stem. Spring 

 infections by rhizosphaera are 

 still causing needles to discolor 

 on spruces. The affected trees 

 should be marked for fungicide 

 applications in the spring. Several 

 arborvitae samples were received 

 with browned needles at the tips 

 of the branches caused by arbor- 

 vitae needle miner. These plants 

 should be targeted for insecticide 

 applications next spring. 



The dormant season is the time 

 to check woody ornamentals for 

 evidence of tip blights and can- 

 kers. Check junipers for tip 

 blights (the base of the discol- 

 ored twig should have a slightly 

 sunken, gray canker) and prune 

 out the infected twigs below the 

 canker. Heavily infected plants 

 may require a fungicide applica- 

 tion next spring to protect the 



The dormant season 



is the time 



to checi< 

 woody ornamentals 



for evidence of 



TIP BLIGHTS and CANKERS. 



new growth. Prune dead branches 

 and twigs on other trees and 

 shrubs to remove potential sources 

 of infection for next spring. Wind 

 breaks should also be erected dur- 

 ing the next month to protect ever- 

 greens from WINTER desiccation. 



For turfgrasses, SNOW MOLD fun- 

 gicides should have already been 

 applied to those infection-prone 

 areas. It is still possible to get an 

 application on before the ground 

 freezes and/or the first snowfall. 



There are a few potential prob- 

 lems on greenhouse crops that we 

 should watch for during the next 

 several months. Root rots are a 

 common problem occurring on a 

 wide range of plant material that 

 includes poinsettias, geraniums, 

 and bedding plants. Plants showing 

 symptoms of nutrient deficiency, 

 marginal browning of leaves, stunt- 

 ing, or wilt should be considered 

 suspect. Remove the plants from 

 the containers and check the roots 

 for brown or black lesions or water- 

 soaked, mushy roots. Severely in- 

 fected plants should be discarded. 

 The remaining plants should be 

 treated with a fungicide drench. 

 BoTRYTis blight is another disease 

 that is prevalent on greenhouse 

 crops during the winter months. 

 High relative humidity favors the 

 disease, thus techniques aimed at 

 lowering humidity levels (e.g., vent- 

 ing) and improving air circulation 

 (e.g., plant spacing) are usually ef- 

 fective in reducing the damage 



caused by botrytis. Strict sanitation, 

 particularly removing senescent 

 plant tissues can also help to re- 

 duce botrytis blight. 



I wish all of you have a happy 

 and plant-healthy holiday season! 



If you wish to submit plant material to 

 the UNH-PDL for diagnosis, send 

 samples {with a check for $12.00) to-. 

 The UNH Plant Diagnostic Lab, C/O 

 Dr. Cheryl Smith, Plant Biology De- 

 partment, 241 Spaulding Ha//— UNH, 

 Durham, NH 03824. Samples should 

 be accompanied by an identification 

 form (available from your county Coop- 

 erative Extension office). Cheryl Smith 

 is the UNH Cooperative Extension Spe- 

 cialist in Plant Health, and can be 

 reached at 603-862-3841. 



HOW ABOUT HERBS 



continued from page 32 



These problems, he states, rarely 

 occur with normal dosages and one 

 would simply stop taking it if symp- 

 toms appeared. There seem to be 

 no other dangers associated with 

 St. John's wort and, as always, care 

 and moderation of use are good 

 ideas. Herbal medications can be 

 just as potent as any other. 



It is possible to transplant this 

 herb to one's perennial garden, al- 

 though other hypericums are more 

 suited to such a location. It can be 

 started from seed, cuttings, or divi- 

 sion done in the fall. It spreads by 

 runners, but is seldom invasive on 

 a large scale and can be controlled 

 by pulling. The flat panicles of 

 bright yellow blossoms are attrac- 

 tive throughout midsummer and the 

 dark reddish brown seed heads 

 provide winter interest — especially 

 if you're growing a medicinal gar- 

 den. 



Tanya ]ackson, a well-known area herb- 

 alist, can be reached at 603-431-801 1. 



DECEMBER 1997 & JANUARY 1998 



