GRAPHICAL TRACKING 



A useful tool for New Hampshire growers 



Paul R. Fisher 



^ ^M Mith increasing competition from other 

 % J» ^ Northeastern states and Canada in the pro- 



^m^w duction of flowering potted plants — for ex- 

 ample: poinsettias, chrysanthemums, and lilies — it is 

 especially important that our local growers can consis- 

 tently produce crops of a high quality and value. 



Growers of potted flowering crops know the costs of 

 having a crop finish at an unacceptable height: higher ship- 

 ping charges, downgrading of product, and lost sales. 



Graphical tracking is a grower-management tool that 

 helps you clearly see whether your plants are too tall 

 or short at any time in the season and make timely cor- 

 rections. The technique is to plot plant height onto a 

 graph once or twice each week and make height-control 

 decisions by comparing actual and target heights (Fig- 

 ure I) The small monitoring cost (about 15 minutes in 

 labor per crop each week) for graphically tracking a 

 crop rapidly pays for itself in improved quality. 



This tool has been used successfully for the last ten 

 years by hundreds of growers, regardless of whether 

 their greenhouse business is large or small, located in 

 the North or South, or low-tech or sophisticated. 



Here at UNH, in collaboration with Dr. Royal Heins 

 at Michigan State University (MSU), we are developing 

 new graphical tracking tools to help growers avoid short 

 or tall crops. Previous work by Dr Heins developed 

 graphical tracking target curves for poinsettia, chrysan- 

 themum, and Easter lily. 



New research has developed target curves for Orien- 

 tal and Asiflorum (hybrid) lilies, a simple tool called a 

 Height Meter, and a new computer program called UNH 

 FloraTrack which is now being used by over 40 growers 

 in the U.S. and overseas. UNH FloraTrack is available to 

 NH grower members of the New Hampshire Plant Grow- 

 ers Association at only $30 00, which is 25% of the nor- 

 mal retail price. (You can phone me at 603-862-4525 to 

 obtain a copy ) 



Graphical tracking consists of the 

 following steps: 



1. creating the graph; 



2. monitoring the crop; 



3. plotting heights on the graph; 



4. making height-control decisions. 



Step 1. Creating the graph 



Several pieces of information are necessary to create a 

 graphical tracking graph: 



1 the crop species and cultivar (there are curves for 

 pinched and single-stem poinsettia, chrysanthemum, 

 Easter lily. Oriental lilies, and Asi-florum lilies); 



2. the start date for the graph, which depends on the 

 crop (Table 1); 



3 a middle date for the graph, needed for several 

 crops (Table 1 ); 



4. the finish date when the crop is in flower and ready 



to ship; 

 5 the starting height for the crop; 

 6. the range in target final heights for aesthetic and 



shipping purposes. 



If you have the UNH FloraTrack program, the above 

 six pieces of information are entered into the com- 

 puter, which will automatically make the graph to 

 your specifications (Figure 2). If you would like to 

 provide the above information to me at UNH for one 

 or two crops, I will send you a paper copy of the 

 graph to try out Several educators in UNH Coopera- 

 tive Extension are also starting to work with graphical 

 tracking. 



Figure I shows a graphical tracking chart for 

 pinched poinsettia (solid lines), along with measured 

 heights (rectangles) and growth retardant applications 

 (G symbols). On the time (horizontal) axis in Figure 

 I, the start date for the curve represents the time 

 plants are pinched and the end date represents the 

 flowering time 



On the height (vertical) axis, the start and end 

 heights represent the height at pinch and the final 

 target heights, respectively. The curve follows the 

 pattern of stem elongation of poinsettia; the shape of 

 the target growth curve depends on the crop species. 

 Growth is initially slow as apical dominance is bro- 

 ken. Rate of elongation then increases to a maximum, 

 decreases as the flower develops, and eventually 

 stops when the flower matures 



This s-shaped growth curve is used to generate a 



22 



THE PLANTSMAN 



