A G N O S T 



UPDATE 



The month of September held 

 true to my predictions: sam- 

 ples continued to arrive throughout 

 the month, resulting in the greatest 

 number of samples for the month 

 of September in the nine years I've 

 been here Thankfully, the num- 

 bers dropped by half during Octo- 

 ber and I can finally direct some 

 time to computerizing the PDL 

 records 



The majority of the diseases di- 

 agnosed during September and Oc- 

 tober were also problems that were 

 also seen during the month of Au- 

 gust Thanks to the warm weather, 

 brown patch and Pythium contin- 

 ued to plague home lawns and a 

 few golf course putting greens 

 The moisture and somewhat cooler 

 temperatures during early Septem- 

 ber created ideal conditions for 

 mushroom growth As a result, I re- 

 ceived several telephone calls from 

 worried home owners concerned 

 with ridding their lawns of the 

 troublesome fungi I usually sug- 

 gested mowing or having patience 

 and waiting for drier weather Pow- 

 dery mildew was also a common 

 problem on home lawns during 

 September and October A few in- 

 dividual cases of anthracnose on 

 deciduous trees, Botrytis on 

 various flowering plants, and mis- 

 cellaneous fruit rots were also di- 

 agnosed 



There were a few interesting or 

 important diseases that were diag- 

 nosed in the last two months 

 iSept -Oct I Five samples of fir 

 seedlings (balsam and fraserl with 

 basal Phomopsis canker were diag- 

 nosed The disease appears to be 

 more of a problem on plants that 

 have been stressed Drought stress 

 (l<593 and |une 1004), cold injury 

 before a good snow cover was es- 

 tablished, and a late frost in (Vlay 



|004 all contributed to predispos- 

 ing the tissues at the base of the 

 stems to infection by Phomopsis 

 Similar problems on fir seedlings 

 were reported by most of the diag 

 nosticians at a recent Northeast pa 

 thology meeting in Ithaca. NY 

 Phyllosticta needle blight was diag 

 nosed on balsam, fraser. and 

 concolor firs This needle blight 

 has been increasing in frequency 

 over the last few years Very little 

 is known about the life cycle of the 

 fungus, but the general consensus 

 among tree pathologists is that in- 

 fections first occur around the time 

 of bud break and may continue for 

 three weeks or more Three hem- 

 lock samples with Fabrella needle 

 blight were received in September 

 This is a disease that occurs spo- 

 radically, usually after periods of 

 stress caused by drought or winter 

 injury Symptoms of Rhizosphaera 

 needlecast on spruce began to 

 show up in mid-October The 

 symptoms were most likely the re- 

 sult of infections that occurred dur- 

 ing late-August or early-September 

 The most notable problems on 

 greenhouse crops were Fusarium 

 wilt and impatiens necrotic spot vi- 

 rus IINSVI on cyclamen Fusarium 

 wilt seems to be a significant prob- 

 lem in the cyclamen crop this year 

 Symptoms include yellowing and 

 wilting of the older, outer leaves, 

 stunting, and eventual collapse of 

 the entire plant Another diagnos- 

 tic feature of the disease is a black 

 streaking or discoloration of the 

 vascular system that is evident 

 when a cross-sectional cut is made 

 through the corm Infected plants 

 should be destroyed and the re- 

 mainder of the crop should be 

 drenched with an appropriate fun- 

 gicide At the recent Northeast pa- 

 thology meetings, Rob Wick |U 



fVlass I reported the occurrence of 

 another disease called Cryptocline 

 that has symptoms similar to 

 Fusarium wilt. The discoloration is 

 limited primarily to the upper 

 portions of the corm, however, 

 and streaking also occurs in the 

 petioles Pythium root rot has shown 

 up on a few poinsettias, but doesn't 

 seem to be a major problem 



During the next month, be sure 

 to protect shrubs and against snow 

 and ice damage and winter desic- 

 cation If the Old Farmers Almanac 

 is correct, we should have snow 

 cover by the end of November! 

 Poinsettias should continue to be 

 monitored for powdery mildew (to 

 the best of my knowledge, only 

 four cases have been reported na- 

 tionally! If mildew is suspected, 

 please submit samples to the PDL 

 for confirmation As I mentioned in 

 the last issue, geraniums should be 

 carefully inspected and monitored 

 for bacterial blight (see the |une/ 

 luly issue of The Plantsman for a de- 

 scription of symptoms) And re- 

 member, nothing beats good SANI- 

 TATION and careful monitoring for 

 preventing disease problems 



There is one additional note I'd 

 like to mention and that is that a 

 fee system will be instituted for 

 samples submitted to the Plant Di- 

 agnostic Lab by late spring. 1005 

 The exact fee and final details will 

 be reported in one of the upcom- 

 ing issues of The Plantsman 



If uou wish lo suhmil plant material to 

 the PDL for diagnosis, send samples to 

 Dr Cheryl Smith. Plant Diagnosti( Lab. 

 Nesmith Hall. UNH, Durham. NH 

 03824 Samples should he a(companied 

 by an idenlili(ation form {available from 

 ifour county Cooperative Extension office] 

 There is no fee [at this time) Cheryl 

 Smith is the UNH Cooperative Extension 

 Specialist in Plant Health, and can be 

 reached at (003) 862-3841 



The Plantsman 



