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DIAGNOSTIC UPDATE 



The flow of samples Into the 

 Plant Disease Diagnostic Lab 

 was typically slow during January 

 and February. Although most of the 

 samples were from greenhouse op- 

 erations, one apple and a few coni- 

 fer samples were also received. 

 The problems diagnosed on the 

 greenhouse samples were predomi- 

 nantly botrytls and edema, although 

 two samples with pythlum were re- 

 ceived. Needlecasts and insect 

 damage were the problems on the 

 conifers. 



Most of the diseases and disor- 

 ders that occur during the winter 

 months will continue to plague 

 greenhouse operations during April 

 and May. The three major problems 

 to watch for are botrytls, pythlum, 

 and edema. All of these are related 

 to watering practices and humidity 

 levels. As I mentioned in the last 

 Issue, be sure to space plants 

 properly, provide good air circula- 

 tion, don't over-water, and remove 

 senescent plant tissues (such as old 

 flowersK Be sure to inspect all in- 



coming stock for diseases (espe- 

 cially tomato spotted wilt virus) and 

 Insects. Bacterial blight in gerani- 

 ums is always a potential problem, 

 so continue to monitor your crops 

 on a regular basis. If you notice 

 suspicious plants, submit samples 

 to the PDDL for testing. 



During the next month (if we can 

 ever dig out from the snow), in- 

 spect woody ornamentals for winter 

 injury. Prune any branches broken 

 by Ice and snow loads, remove any 

 leaves that are dead or severely 

 winter-burned, and after bud-break, 

 remove any branches that fail to 

 leaf out. April-May is the time to 

 apply controls for many of the fo- 

 liar diseases such as anthracnose, 

 leaf spots, and needlecasts. The 

 fungi that cause these diseases are 

 usually capable of Infecting the 

 leaves/needles during the period 

 between bud-break and leaf/needle 

 expansion. Sanitation measures 

 prior to bud-break can greatly re- 

 duce the levels of Infection; how- 

 ever, fungicides may be required 



for valuable specimens or where 

 disease has been severe the previ- 

 ous year. Control measures for 

 shoot blights, such as phomopsls 

 tip blight on junipers and lilac 

 blight, also need to be applied as 

 growth resumes in the spring. 



Since we have had plenty of 

 snow cover this winter, I would ex- 

 pect snow molds to rear their ugly 

 heads on turf grass again this year. 

 Look for patches of dead turf grass 

 as the snow melts. (You may want 

 to submit a sample to the PDDL to 

 confirm your diagnosis since similar 

 symptoms can be caused by envi- 

 ronmental factors). ^ 



1/ you wish to submit plant material to 

 PDDL for diagnosis, send samples to: 

 Dr. Cheryl Smith, Plant Disease Diagnos- 

 tic Lab. Nesmith Hall, UNH. Durham. 

 NH 03824. Samples should be accompa- 

 nied by an identification form {available 

 from your county cooperative extension 

 office). There is no fee [at this lime). 

 Cheryl Smith is the UNH Cooperative 

 Extension Specialist in Plant Health, 

 and can be reached at (603) 862-3841. 



GROWER'S RIDDLE 



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Watch the June/July issue of The Plantsman 

 for comments from customers on their spring results. 



TAK Equipment, Inc. 



80 River Road, Penacook, NH 03303, (603) 753-8250 



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22 



The Plantsman 



