source of pathogens or insects) Any changes in the sur- 

 rounding environment should also be noted. Have heat- 

 ing or cooling systems recently been activated? Do the 

 vents from those systems blow on the planting? Is an 

 outdoor planting located in a windy or frost-prone site? 

 Has any construction or painting taken place nearby? 

 Have there been extremes of moisture (drought/flood) 

 or changes in light intensity? Questions such as these 

 will help determine if the problem is environmentally- 

 caused. 



Diagnostic testing 



Once a problem has been recognized and potential 

 causes identified, it may still be necessary to submit 

 plants to a diagnostic laboratory for confirmation or fur- 

 ther identification. When plants are submitted for diag- 

 nostic testing, there are a few steps to follow to ensure 

 an accurate and timely diagnosis. Include as much infor- 

 mation as possible about the history of the problem 

 (when symptoms were first noted, rate of progression, 

 any visible pattern to the symptoms, percentage of 

 crop or plants affected). It is also important to provide 

 information on pesticide and fertilizer applications, and 

 any changes in the growing environment. And, last but 

 certainly not least, be sure to include the name and va- 

 riety of the plant. Be sure to include a healthy sample 

 for comparison purposes. If samples are submitted by 

 mail, package the sample well to avoid shifting during 

 shipment and mail the package early in the week or by 

 overnight delivery. 



There are several diagnostic kits available for in- 

 house or on-site testing. For bedding plants and other 

 greenhouse crops, Agdia Inc. (Elkhart, IN: www.agdi.com) 

 produces the QTA-Tospo test kit for viruses. This kit 

 tests for both impatiens necrotic spot (INSV) and to- 

 mato spotted wilt (TSWV), but does not distinguish be- 

 tween the two viruses. NEOGEN Corp. (Lansing, MI) 

 produces the Reveal test kits for turfgrass diseases. The 

 brown patch and pythium test kits are particularly use- 

 ful since both diseases occur in hot, humid weather and 

 produce symptoms that are easily confused. It is impor- 

 tant to keep in mind that the results obtained from the 

 test kits depends upon the sample tested. Be sure to 

 sample symptomatic areas of the plant. Otherwise, the 

 pathogen may not be present in detectable levels, re- 

 sulting in a false negative. 



Solutions to the problems 



The best approach is to prevent problems in the first 

 place. This may seem to be a rather obvious statement, 

 but in reality, many simple practices that can prevent 

 plant health problems are overlooked. 



Sanitation techniques are the best prevention and 

 control measures for problems caused by pathogenic 

 microorganisms and many insects. Inspect all plant ma- 

 terial when it is received. Don't hesitate to refuse any 

 plants that exhibit symptoms of any kind. Start clean! 

 Use clean, sanitized pots and sterile potting mix. Sani- 

 tize potting benches before each use. Sanitize cutting, 

 planting and pruning tools before each use. Any tissues 



V ^si^ 



The Griffin Guru 



Winter's here and It's time to crank up the 

 heat. If you haven't done so already, It's 

 time to make those routine checks necessary to 

 ensure that your heating equipment will function 

 well when you need It most. 



Here's a check list that will make the task 

 easier. 



1. Check equipment for any physical damage 

 that may have occurred over the summer. 

 This should include damage to sheet metal, 

 fans and air movers, wiring, gas piping, and 

 vent systems. 



2. Check for cleanliness of heat exchanger and 



burners. 



3. Check to make sure vent system is clear. 



4. Check to make sure no obstructions block 



the air Inlet or air discharge of equipment. 



5. Ensure unit supports are secure and unit 



hangs level. 

 All this should ensure a warm, problem-free winter. 



infected with pathogenic microorganisms can serve as a 

 source of infection for nearby plants. Infected leaves or 

 stems should be removed and destroyed. If a large por- 

 tion of the plant is infected, it may be better to re- 

 move the entire plant. When pruning infected trees and 

 shrubs, sanitize the cutting tools between each cut and 

 destroy the prunings. When watering, avoid wetting the 

 foliage as this splashes and spreads fungal spores and 

 bacteria to adjacent plants. 



Proper horticultural practices can help reduce plant 

 stress. Match the plant to the site: shade-loving plants 

 in shady areas, winter-hardy plants in exposed areas, 

 etc Remember, plants under stress are usually more 

 susceptible to attack by both pathogens and insects. 



The diagnosis of plant problems can be both frustrating 

 and rewarding. It is helpful and at times necessary to have 

 a collection of reference sources including plant, disease, 

 and insect identification guides to aid in the diagnosis. As 

 with any other skill, the more you practice, the more re- 

 fined your skills will become Remember, you can always 

 send samples to a diagnostic lab for confirmation prior to 

 selecting a management practice, so don't be afraid to 

 hone your own diagnostic skills. 



Cfteryl Smith can be reaacked at 603-862-3841. 



THE PLANTSMAN 



