Preview Software Manual - BioQUEST Curriculum Consortium
Contents
1. the temperature effect is determined by the appropriate polynomial function in Table 1 LesionExp is 1 5 1 4 and 1 4 for the susceptible moderately resistant and resistant cultivars respectively IncrFact is a factor that decreases linearly from 1 0 to 0 0 over the five days following the latent period and FungicideFact is a factor between zero and one calculated fromthe dose response of the fungicide See Fungicide effects below The total lesion area assumes circular lesions LesionArea age LesionN umber age LesionDiam age 2 p In the original model the numbers of lesions of each age were passed daily into the next age class LesionN umber age LesionN umber age 1 I nthe current version of the model this has been modified to pass a proportion of the lesions in each class on to the next age class each day LesionN umber age LesionN umber age LesionN umber age 1 TRANSFER LesionN umber age 1 LesionN umber age 1 LesionN umber age 1 TRANSFER where TRANSFER 0 38 essentially a tuning parameter adjusted so that the model s output gave a good fit to disease progress observed in the field trials in 1977 and 1978 near Freeville NY S porulation Sporulation occurs on lesions from the end of the latent period until they are 14 days old AttachedS porangia SPRMAX SporulationFct TempEffSporu HumidityFct SysFungicideF ct TotalLesionArea 1 0 Blight Proportion where SPRMA2. 26 0 2482 TempHumid90 0 03817 TempH umid902 0 00252 TempHumid903 5 32 1075 TempHumid904 Parameters of the polynomial equations were estimated by multiple regression using the data of Crosier 1934 S porangial Germination Sporangia germinate by two pathways direct and indirect depending on the ambient temperature during the period of leaf wetness See Table 1 GermS porangia LandedS porangia DI RMAX TempEff Direct Zoospores LandedS porangia INDMAX ZSPR TempEffI ndir where DIRMAX 0 29 sporangia day INDMAX 0 81 sporangia day and ZSPR 6 567 zoopores sporangium Marks 1965 Ullrich and Schober 1972 Warren and Calhoun 1975 The temperature effect is determined by the appropriate polynomial function in Table 1 The zoospores germinate only while the leaves are wet and in response to the mean temperature during the period of leaf wetness GermZoospores Zoospores ZOOMAX TempEffZoosp where ZOOMAX 0 96 zoospores day 29 Infection Infection efficiency is afunction of leaf wetness mean temperature during the period of leaf wetness the susceptibility of the potato cultivar the type of fungicide and its residue level and the amount of uninfected tissue remaining Latent nfections I NFMAX_SP GermS porangia 1 NFMAX_ZSP GermZoospores TempEfflnfec LeafWetEff Susceptibility FungicideEf fect 1 0 BlightProportion where INFMAX_ SP 0 1linfections germinated
3. McCulloch and W E Fry 1988 Distribution and temporal dynamics of metalaxyl in potato foliage Phytopathology 78 555 559 Milgroom M G and W E Fry 1988 A model for the effects of metalaxyl on potato late blight epidemics Phytopathology 78 559 565 Ullrich J and B Schoger 1972 Zoosporenzahl und Sporangiengrube bei Phytophthora infestans Mont DeBary Phytopath Z 74 268 271 Waggoner P E and G Horsfall 1969 EPI DEM a simulator of plant disease written for a computer Bull Conn Agr Exp Sta New Haven No 698 80 pp 39 Wallin J R and W G Hoyman 1958 Influence of post inoculum air temperature maxima on survival of Phytophthora infestans on potato leaves Amer Potato J our 35 769 773 Warren R C and J Calhoun 1975 Viability of sporangia of Phytophthora infestans in relation to drying Trans Brit Mycol Soc 64 73 78 36
4. OK Price Enter the market price per cwt or per kg for the current season s potato crop and click on OK Show Hide Report The economic report is available at the end of the season when the simulation has terminated It is invoked fromthe Economics menu Exit the economic report by double clicking the close box inthe upper left corner of the window or by selecting Hide Report from the menu 16 View Menu Check I tems The View menu allows you to select which of the simulation variables will be displayed on the graph as the season progresses A checked variable will be represented by a line of the same color as the check mark In this way the View menu doubles as a legend for the graph In addition the View menu also shows the current scaling factors for all variables American Metric Measure The American Measure and Metric Measure check items in the View Menu allow you to choose which system of units will be used throughout the program The American system expresses distances in feet and inches areas in acres weights in pounds lbs or hundredweight cwt 100 lbs and temperatures in degrees Fahrenheit The metric system expresses distances in meters areas in hectares weights in kilograms and temperatures in degrees Centigrade Whichever system of measurement you choose will be used consistently in all dialog boxes and other program displays Set Colors The Set Colors command allows you to change the colors that
5. all our sprays it will be handy to save the simulation at this point for starting all the subsequent simulations Select Save As fromthe File menu and name the file SPRSTART LBT Select Spray Protectant fromthe Management menu and apply the fungicide at the def ault dose of 1 25 kg ha Advance the simulation 5 days and repeat the protectant spray Spray the protectant every 5 days for atotal of 14 sprays and determine the final percent blight at the end of the season Open SPRSTART LBT again to start a new season and spray the protectant every 7 days for a total of 10 sprays Repeat using 7 protectant sprays at 10 day intervals and again with 5 protectant sprays at 14 day intervals Systemic Fungicide Sprays Restart the simulation by opening the SPRSTART LBT file that you created for the protectant fungicide sprays Select Spray Systemic and apply the fungicide at the default dose of 0 22 kg ha Apply atotal of 3 sprays at 3 week intervals and determine the final percent blight Fungicide Weather Interactions I n addition to providing longer periods of leaf wetness for the development of the fungus rain reduces the effectiveness of the fungicide by removing the protective residues on the foliage Restart the program with STARTUP LBT and use the MODWET LWX weather data file Spray the protectant beginning on J uly 20 and continuing at 7 day intervals for a total of 10 sprays Compare the final percent blight with that of th
6. box in the upper right or by dragging the lower right corner of the window Lateblight CROP1 LBT File Potato Environment Inoculum Management Economics View Fl Help 100 View F1 Help Leaves L A x10 By choosing View you can see what the different Y Bight Temperature F color lines onthe graphs represent Rainfall 10ths in Hrs RH gt 90 New Infections 1 0000s Sporangia 100000000s AUDPC Residues American Measure Metric Measure Set Colors Arange You can add more variables in View See Temperature red added below Lateblight CROP1 LBT File Potato Environment Inoculum Management Economics View F1 Help v Leaves LAI x10 Y Blight Y Temperature F v Rainfall 1Oths in Hrs RH gt 90 New Infections 100005 Sporangia 100000000s AUDPC Residues American Measure Metric Measure Set Colors Arrange Po A im AN EEE qe AA MA 14 28 5 12 19 26 2 9 16 23 30 6 13 20 27 July Aug ul Today is Sept 29 Choose Economics from the menu and highlight Crop Report This shows you the profit or the loss for the growing season Note loss in the bottom line below Economic Report CROP1 LBT xi Season ended on Sept 28 with 106 807 blighted foliage Your crop is 241 11 cut acre At the current market price of 5 66 this would bring 1205 57 acre 38 9 of your tubers are blighted YIELD REPORT Revenue Total Total Potential Yield 1566 66 Yield Los
7. if found You can also load it from the File menu by selecting Open In addition to providing a convenient means of restoring the def ault values without having to restart the program this mechanism allows you to change default values The options and values that are in effect when STARTUP LBT is saved will become the new defaults Effects of Weather Select Run from the File menu A dialog box will appear prompting you to open a weather data file Open the file COOLWET LWX Once the weather data are loaded a pair of axes will appear with calendar days along the x axis and a scale ranging from 0 to 100 as the y axis Advance the simulation to the end of the season by pressing the lt End gt key on the keyboard The three curves that appear represent the leaf area index the percent blighted foliage and the area under the disease progress curve AUDPC Note the date on which the percent blight reaches 50 by placing the tip of the arrow cursor approximately at the 50 point on the curve and pressing the left mouse button Hold the button down and move the arrow along the curve until Y 50 Similarly move the arrow to the end of the AUDPC curve and note the final AUDPC 22 To save this graph actually the complete state of the program at this point in a disk file select Save As fromthe File menu and enter COOLWET LBT as the file name Save the text output in a disk file by selecting Log to disk fromthe File menu and entering the nam
8. necrotic lesions during periods of high relative humidity These sporangia are dispersed to initiate new infections thus completing the infection cycle During periods of favorable weather many such cycles occur resulting in an explosive epidemic Late season leaf damage Arneson 2000 Management of potato late blight begins by 1 Keeping the numbers of infected seed tubers to very low levels by planting only certified seed potatoes 2 Crop rotation to reduce the numbers of volunteer plants which may be infected 3 Burying or composting cull piles or at least keeping them a great distance from the potato fields Control of late blight by means of potato varieties with a high degree of resistance to P infestans has generally proven impractical because of the rapid selection of virulent races of the pathogen Varieties with moderate levels of resistance however have been very useful when combined with other management tactics particularly the use of fungicides n most potato growing areas regular fungicide applications are an essential component of late blight management Because of environmental concerns the problem of fungicide resistance and the high cost of fungicides and their application potato growers have been forced to reduce their overall use of fungicides and to improve the efficiency of the fungicides they apply One approach has been to improve the timing and adjust the dose of fungicide applications acc
9. the following potato cultivar spray schedule combinations 1 Low resistance Protectant 7 day intervals 2 Moderate resistance Protectant 14 day intervals and 3 Low resistance Systemic 21 day intervals Side by side Comparison of Epidemics Open the MODMOD LBT file that you saved earlier Temporarily reduce this copy of Lateblight to an icon To do this click on the small downward pointing triangle in the upper right corner of the window Notice that the icon displays the name of the file you opened Start another copy of Lateblight and open COOLWET LBT which you saved earlier Double click on the icon displaying MODMOD LBT to restore it to anormal sized window Now with both instances of Lateblight running simultaneously select Arrange fromthe Viewmenu of either instance This will rearrange both instances so that each occupies half of the screen Notice that there is a scroll bar for each window as well as a now nonfunctional scrollbar for each graph Click inthe pageup area the grey part of each window scrollbar to move to the end of each graph Side by side comparison of the graphic output is now possible 25 Printing or Editing Text Output The output saved with Log to Disk is a plain text file which can be edited and or printed with any word processing program including Windows Notepad and Windows Write The text is formatted for afixed pitch font such as Courier and uses the ANSI character set You can ed
10. the fungicide on the date given at the top of the dialog box or on Cancel to exit the dialog box without applying the spray A warning is given if it is currently raining A spray applied in the rain will not leave the full residue of fungicide on the foliage 15 Kill Vines The order to kill vines immediately defoliates the crop Tuber development will continue for seven days after defoliation Blitecast The Blitecast f orecasting system Krause et al 1975 sums the rain f avorable days and blight severity values for the past week and makes a spray recommendation for the current day The decision whether or not to use the Blitecast system is indicated by checking the appropriate item at the bottom of the Management menu prior to the beginning of the season bef ore selecting Run If you decide to use Blitecast you will be charged for the service at the end of the season even if you never request a Blitecast report A report is requested during the season by selecting the Blitecast menu item This item will be present only if Blitecast is being used Economics Menu The costs and revenues of the potato field being managed can be established before the start of the season bef ore Run is selected by selecting Costs or Price At the end of the season a full accounting can be displayed with Show Report Costs For each of the items enter the cost per acre or per hectare When all of the items show the desired values click
11. tubers Arneson 2000 The fungus survives between seasons in lesions on the tubers New infection may come from new seed tubers that are infected from volunteer tubers that were left inthe field from the previous year s harvest and from piles of culled or discarded potatoes during the grading and packing of the crop Early signs of late blight in the field Arneson 2000 The first infections barely visible except to well trained eyes usually are on the sprouts emerging from infected tubers Sporangia of the Late Blight fungus Phytophthora infestans Arneson 2000 Sporangia form by the thousands on these lesions and are disseminated by wind and splashing rain to the developing leaf and stem tissues Germination of these spores occurs while the leaves are wet either directly by the formation of a germ tube or indirectly through the release of zoospores which swim through the water film encyst on the leaf surface and then germinate zoospore production direct germination 9 sporangia Asexual Life Cycle of the Late Blight Fungus Phytophthora infestans Infection takes place under cool moist conditions by direct penetration of the cuticle nf ection efficiency is a function of the environmental conditions and the potato cultivar Microscopic lesions gradually enlarge into necrotic lesions which continue to expand until they coalesce blighting entire leaves Sporangia are produced around the margins of the
12. Dn gt operate the vertical scroll bar while Ctrl gt PgUp gt and lt CtrlI gt PgDn gt operate the horizontal scrollbar Note the distinction between the horizontal window scroll which appears at the very bottom of the window when it is displaying a graph that is wider than the window and the simulation scrollbar which appears below the x axis when a season is in progress and is used to advance the date The simulation scrollbar uses the lt gt key to advance one day or Ctrl gt t gt to advance one week lt End gt is equivalent to dragging the thumb all the way to the right and advances the simulation to the end of the season Dialog Boxes lt Enter gt and sc gt operate the OK and Cancel buttons respectively The lt d ab gt key shifts the input focus from one control to the next The control with the input focus is the one that will respond to keyboard actions other than Enter gt or lt Esc gt The input focus is indicated by highlighting of the text in an edit control or adotted rectangle around a radio button Whena radio button has the input focus the spacebar toggles its status If the button is one of a mutually exclusive group when it is deselected the next button in the group will automatically be selected 19 The Colors Dialog The Colors dialog box allows you to reassign the colors that are used to represent the various simulation variables on the graph It is a little different from most of the other dialog bo
13. Program Manager or File Manager window To learn more about the help system press 1 gt while the Help window is active or select Using Help from the Help window s Help menu 21 TUTORIAL This tutorial assumes that you are already acquainted with Microsoft Windows Therefore our instructions will focus on the simulation and the features unique to Lateblight f you need help with the Windows environment itself go to the Help menu of either the Program Manager or the File Manager The information presented there explains the standard features of the environment The exercises suggested here represent only a small fraction of the versatility of Lateblight and the ways in which it can be used to explore epidemiological concepts In addition to the structured exercises such as these we encourage you to ask your own questions and run the simulations necessary to answer them Saving a Startup File When you start Lateblight for the first time all program options and parameters will be set to the default values that are written into the program After running a season with different values for some options or parameters you will want to restore the original values To make this easier you will now save the def ault values in a disk file Select Save As fromthe File menu When the dialog box appears prompting you for afile name enter STARTUP LBT and click OK When Lateblight is started it will look for this file and load it automatically
14. TION cccccccssssssssssccscccsssssssscscssccsssssssssceccccssssssssssccsseee TEMPERATURE EFFECTS cccccccccssssssceccccceccsscesescceccescsseusscscsccsseesueusccececesessssuueusessessssssuueusgeseesess 28 SPORANGIAL GERMINATION ccccccsssesseccccccccssessesccscceseucuscsesecescsssuuuuseecececessuuuussesesesssssuuausaeecesess 29 INFECTIONS ride 30 LESION DEVELOPMENT iviecfe2ssadccescedecdee deal iedscnsnsleaseadbcegcodnacde Sua atve 30 SPORULATION ui dci 31 LESION INACTIVATION ahi deta 32 DISPERSAL OF SPORANGIA cccccccessssscscccccsccssscssescccecsccssccseseseesseesseusssescesecssseuueusesssescsssuuuunsessesess 32 HOST GRO W UE sich 255 55555 a 32 FUNGICIDE EFFECTS scccssecccttiscenesdoteacestetestoadovsacedbidessesdusencsstbucetesduveceacbidessendidvccesteue eedGeseesbbidessenced 33 WEATHER a 34 E Destroyed potatoes Arneson 2000 W hat is Late Blight Late blight is a disease of potatoes caused by the fungus Phytophthora infestans Under favorable environmental conditions and in the absence of any control measures this disease can destroy virtually 100 of the above ground parts of susceptible crops Spores produced on infected foliage can be disseminated to the tubers where infections can also occur Losses include e reduction of photosynthetic area resulting in reduced bulking of tubers yield loss e blighted tubers quality loss e decay of tubers in storage postharvest loss Spoiled
15. X 763 2 Lapwood 1961 31 SporulationFct is 0 55 0 45 and 0 45 for the susceptible moderately resistant and resistant cultivars respectively and the temperature effect is determined by the appropriate polynomial function in Table 1 Sporulation occurs only if the relative humidity is above 90 DeW eille 1963 The effect of the systemic fungicide on sporulation is determined by the dose response discussed below Lesion inactivation On the fifteenth day following its initiation a lesion ceases sporulation and its area is added to the inactive lesion area which is added to the total blighted area when calculating the blight proportion All lesions become inactive if the daily mean temperature exceeds 41 C for three consecutive days Wallin and Hoyman 1958 Dispersal of sporangia No attempt has been made in Lateblight to simulate the biophysical mechanisms of dispersal of sporangia All of the spores that are produced are dispersed but the proportion of sporangia surviving are first adjusted for temperature dependent mortality if DailyMeanT emp gt 21 0 Spores ur vival a 6 0 0 0256 DailyMeanT emp 0 537 else SporeSurvival 1 0 The number of sporangia landing on susceptible sites and thus available for infection depends on the amount of foliage present LandedS porangia AttachedS porangia SporeSurvival 0 025 min LeafAreal ndex 3 5 1 0 Host growth The increase in leaf area index is linea
16. and Fry 1982 There is no longer an effect of canopy level only an average response simulated with a linear probit log dose function ProbitResponse 5 0 ProbitS lope logy AverageResidue LDs9 33 The proportional effect is simulated with a logistic function that approximates the probit function and is exactly equal at 0 01 0 50 and 0 99 The details of the simulation of the systemic fungicide effects are described by Milgroom et al 1988 The only effect of the protectant fungicide is the inhibition of infection Bruhn and Fry 1981 whereas the systemic fungicide not only inhibits infection but also reduces the rate of lesion expansion and inhibits sporulation Milgroom and Fry 1988 Weather The following environmental variables are read from an external weather data file Rainf all Daily rainfall in inches DailyMeanTemp Daily mean temperature _C Humid90Hours Hours per day of relative humidity above 90 TempHumid90 Mean temperature _C during the above humid period In addition two environmental variables are approximated with the following calculations Leaf W etHours Humid90 Hours 3 0 TempLeaf W et DailyMeanTemp TempHumid90 2 0 34 REFERENCES Bruhn J A R I Bruck W E Fry P A Arneson and E V Keokosky 1980 Lateblight A Disease Management Game Computer program and manual Department of Plant Pathology Cornell University I thaca NY Bruhn J A and W E Fry 1981 Analysis o
17. are used to represent the various simulation variables on the Lateblight graph In this way you can be sure the different lines on the graph are readily distinguishable regardless of what combination of variables you choose to display The Color Choices dialog box shows all of the variables that can be displayed on the graph along with their currently assigned colors When the radio button next toa variable is checked the color for that variable can be changed by clicking on the new color inthe palette at the bottom of the dialog The line next to the variable name will change color immediately to reflect your choice When a variable is checked inthe View menu indicating that it is to be drawn on the graph the check mark will be the same color as that variable s line on the graph Arrange One of the benefits of the Microsoft Windows environment for a program such as Lateblight is that it allows multiple copies or instances of a program to be run 17 Simultaneously n this way it is possible to do side by side comparisons with each instance of Lateblight simulating a different situation The arrange command is intended to be used when more than one instance of Lateblight is running Selecting this command from the View menu will cause all non iconic Lateblight windows to be arranged side by side to use the full screen without overlapping This command will arrange any number of Lateblight windows but is really only practical with thre
18. be different developmental processes Indirect germination Direct germination Infection Lesion expansion Sporulation Lesion inactivation cessation of expansion Necrosis cessation of sporulation Dispersal of sporangia Catch of sporangia The model operates on a daily time step 21 Temperature Effects The effect of temperature on disease development is simulated independently for each of six different developmental processes using polynomial equations Table 1 Table 1 Rates of Pathogen Development as a Function of Temperature _C Temperature Range Effect Equation Min Max Direct Germination TempEffDirect 2 1 14 29 0 48 TempLeaf W et 0 031TempLeaf W et 0 00045 TempLeafW et 3 4 5 106 TempLeaf W et4 Indirect Germination TempEffI ndir 0 0134 0 24 0 0698 TempLeaf W et 0 0185 TempLeaf W et 0 00223 TempLeafW et3 7 48 1075 TempLeaf W et4 7 68 1077 TempLeaf W et Zoospore Germination TempEffZoosp 0 00494 0 28 0 364 TempLeaf W et 0 05813 TempLeaf W et 2 0 00452 TempLeaf W et3 1 617 10 4 TempLeaf Wet4 2 068 10 6 TempLeafW et Infection TempEffInfec 0 4846 15 30 0 3735 TempHumid90 0 03556 TempHumid902 0 001509 TempH umid903 2 405 1075 TempHumid904 Lesion Expansion TempEffLesEx sqrt 8 4 10 4 0 33 0 1261 DailyM eanT emp 0 03079 DailyM eanTemp 0 00308 DailyM eanTemp3 1 152 10 4 DailyM eanTemp4 1 414 1076 DailyM eanT emp 28 Sporulation TempEffSporu 0 3882 0
19. crop inthe absence of disease One of three resistance levels low moderate or high and one of three times of tuber initiation early mid or late can be selected Enter the maximum yield To facilitate repeated simulations using the same values for the potato cultivar the setup conditions can be saved in a disk file using the Save As command prior to starting the simulation with Run Environment Menu Length of Season This variable is the number of days from median emergence of the potato vines to harvest Emergence Date This is the calendar date on which median emergence of the vines occurs It is used as the basis for the labeling of the x axis 13 Weather Report A weather report may be requested fromthe Environment menufor any day of the season The report includes actual temperature and rainfall data from the previous day as well as a forecast of temperature and chance of rainfall for the current day and the next two days Asinthe real world there is a degree of randomness inthe forecasts They are based on the weather data that will actually be used in coming days with a random component to reflect the inherent difficulty of predicting the weather I noculum Menu In Lateblight there are two independent sources of inoculum sporangia and infections Sporangia can be released all at once as initial inoculum or each day during the course of the epidemic while infections occur on the potato plants at the time of emerg
20. e Claudia Neuhauser University of Minnesota Angelo Collins Knowles Science Teaching Foundation Patti Soderberg Conserve School Terry L Derting Murray State University Roscoe Giles Boston University Louis Gross University of Tennessee Knoxville Yaffa Grossman Beloit College Raquel Holmes Boston University Stacey Kiser Lane Community College Daniel Udovic University of Oregon Rama Viswanathan Beloit College Linda Weinland Edison College Anton Weisstein Truman University Richard Wilson Emeritus Rockhurst College William Wimsatt University of Chicago Copyright 1993 2006 by Phil A Arneson and Barr E Ticknor All rights reserved Copyright Trademark and License Acknowledgments Portions of the BioOQUEST Library are copyrighted by Annenberg CPB Apple Computer Inc Beloit College Claris Corporation Microsoft Corporation and the authors of individually titled modules All rights reserved System 6 System 7 System 8 Mac OS 8 Finder and Simple Text are trademarks of Apple Computer Incorporated HyperCard and HyperTalk MultiFinder QuickTime Apple Mac Macintosh Power Macintosh LaserWriter Image Writer and the Apple logo are registered trademarks of Apple Computer Incorporated Claris and HyperCard Player 2 1 are registered trademarks of Claris Corporation Extend is a trademark of Imagine That Incorporated Adobe Acrobat and PageMaker are trademarks of Adobe Systems Incorporated Microsoft Windows MS DOS and Wi
21. e COOLWET TXT The log file will remain open to record more than one run of the simulation You must close it by selecting Close Log File fromthe File menu Select File New and Run and repeat the above sequence with the weather data sets MODMOD LWX moderate temperatures and moderate rainf all and then HOTDRY LWX Note the date on which 50 blight occurs and the final AUDPC as before Disease Resistance Partial or rate reducing resistance to Phytophthora infestans plays an important role in late blight management despite the fact that it does not complet ely prevent infection To observe the effect of this resistance alone on a late blight epidemic check Resistance Level Low in the Potato menu and run the simulation usingthe MODMOD LWX weather data set Consider this the susceptible check against which you will compare Resistance Level Moderate and Resistance Level High As before save your graphic output with Save As using the file names RESISLOW LBT RESISMOD LBT and RESISHI LBT and or save text output with Log to disk using the same file names with the extension TXT Do not forget to close the log file When you are finished with this exercise restore the default values by opening STARTUP LBT Sources of noculum As with real epidemics the initial inoculum in Lateblight can be introduced as sporangia or lesions or both The source of sporangia can be piles of cull potatoes fromthe packinghouse or a nearby uns
22. e or fewer If there are more than three Lateblight windows to be arranged each gets only a very narrow Slice of the display making viewing very difficult Note that instances of Lateblight which have been minimized and are represented only by icons will not be arranged 18 Keyboard Actions Like most Microsoft Windows applications Lateblight is designed to use a mouse Although a mouse is strongly recommended it is not essential A keyboard interface has been provided for all of the essential features of the program Even when a mouse is present there may be times when the keyboard interface is more convenient for certain actions Wherever possible we have used the keystrokes that are standard among Windows applications The following is a brief summar y of the keyboard interface of Lateblight The Main Window The menu system uses the standard Windows keystrokes underlined letters in menu items represent hot keys The Alt gt key followed by the appropriate hot key provides access to a popdown menu For example Alt gt F causes the File menu to pop down The arrow keys move the highlight to different items within the menu Pressing lt Enter gt with a menu item highlighted is the same as selecting that menu item with the mouse Pressing the hot key for a menu item has the same effect W hile the File menu is pulled down pressing O invokes the Open dialog box The window scroll bars also use the standard keystrokes PgUp gt and lt Pg
23. e same spray schedule using the MODMOD LW X weather dataset Nowrestart the simulation using the MODDRY LW X weather data set 24 Compare the results of the 7 day and 10 day spray intervals with those of the corresponding spray schedules using the MODMOD LWX weather Partial Resistance Fungicide nteractions W hile a moderate level of resistance alone may not provide adequate control of late blight it will markedly reduce the number of fungicide sprays required to control the disease Review the results for the unsprayed epidemics on the potato cultivars with a low level of resistance and a moderate level of resistance This can be done by opening previously saved LBT files or by using a text editor to review the TXT files previously logged to disk Compare the results of epidemics where the protectant fungicide was applied at 5 and at 7 day intervals on the low resistance potato cultivar with those where the protectant was applied at 10 and 14 day intervals on the moderately resistant cultivar Economics In Lateblight it is possible to compare the costs and benefits of various spray options by entering the appropriate values under the Costs and Price items in the Economics menu These menu items are available only at the start of the simulation and the Show Report menu item is available only at the end of the season Either using your own values or the default values for the costs and price compare the costs and revenue of
24. ees 1 INSTALLATION AND QUICK INSTRUCTIONS 0 ccssssssccsssssrcccssssrcssssssccccsssscccssssssees 5 GETTING STARTED WITH LATEBLIGHT cccccssessececcccccccssssssceccccseceusecsceccesseseuseusscecsessseeuuauseesecess 6 MINI CASE INVESTIGATIONS WITH LATEBLIGHT scsssssscccccccsscessssscscccecseeesssccescceseeseuseseceseeseeenes 9 PROGRAM FEATURES acictcicecsscessasseccsecassectencsstescessecostsosevescossecessdeesccssoseecassenesscestesesecssssneoosess 11 FILE MENU ida 12 nn A A teen ses 12 Noia iaa 12 A E nn E E E TE E EA 12 DAVE A Sora a O a a a E RAN 12 Pi A a E E E EE 13 Ei ea a es 13 POTATO MENU coacciones EAA EAN 13 ENVIRONMENT MENU sets 13 Pa a a ae E ea a E a one 13 Emer pence Late A a a 13 A ca a cna aerecieeets aa teans es arcaaceoad tact ieees nem adcees 14 INOCULUM MENU Srnice rronin arat A OE tbccdaaged cas d s 14 Number OT PSOE ANN tdci oido 14 SOULCESOL UAB O vasatonseaasnbuciaenbvenba 14 Number of Infectio0nS coccccncnnnonncnnnnnnnnnnnnnancnonononnnnnananonoconnnnonennnnrnoronnnnonnnnnnrncrcrnnnonenaninicoss 15 Sources OL INPECHONS as 15 MANAGEMENT MENU nt doseceetttaccesstuncecsateudesea dossceettducceesSuadecsetiudedes deuecesabtacsaeaduaseesedeadebeatee 15 Spray DY SUC MC cess ccsiza vacuz dunia sicazave th avis aA EE EEEE AE EA EE E ER EAE EA AEE EEE OREA 15 Spray EO crestor cpa sorses ironinen gentei anes Aseara aS Eora EADE iR SETE Ean NSE EAEE 15 KAN is 16 A ta eeen aee a e E a caeeamens S
25. ence Both Sporangia and I nfections can be initialized either by designating the Number or by selecting the Source of inoculum Only the values in the checked item are used and the values in the unchecked item are ignored Number of Sporangia This is one of two alternative means of setting the number of initial sporangia Enter the number of sporangia released per unit area The number of sporangia indicated will be released all at once on the day of plant emergence or each day of the season depending on the alternative selected Typical values are 2 5 107 sporangia ha as initial inoculum or 2 5 10 sporangia ha each day Sources of Sporangia As an alternative to setting the Number of Sporangia you can set the quantities of sporangia contributed by two possible sources a cull pile potatoes discarded from a packing line and a neighboring unsprayed field To account for dispersal losses the distance between the field being managed and each of these inoculum sources can be set Enter the maximum sporangia per day released at the source Inthe case of the cull pile the number of sporangia released each day will decrease exponentially from this maximum as the season progresses A typical value for this maximum is 1000 sporangia day 10 meters fromthe field Inthe case of the unsprayed field the number of sporangia released per day will increase logistically from 0 001 to 1 0 times this maximum as the season progresses A 14 ty
26. et eedecdeaateeiane ea E EE 16 ECONOMICS MENU ic ss 16 COSS e E E E EE E E E Ea 16 Pacers 16 Ao A 16 VIEW MENU ui 17 AA scene E E E E dunt ovasaestecsscceustasazeacerscesesesedessens 17 American Metric Measure cccccccccccccsssscsceccccccesscsesccsscesseusessssecsscsssusucssesessscsesuaeessescesess 17 SECO cold 17 DI a sMaboneed 17 KEYBOARD ACTIONS ARO OONU U NOOUONN5 O 0AZ eEe CP 2 A 19 The Man Win Wii as 19 Dialoz HO a 19 The Colors Dial da ei 20 GETTING HELP sra diia 21 NONI AAA NO 22 SAVINGA STARTUP FILE as 22 EFFECTS OF WEATHER ic 22 DISEASE RESISTANCE ua a eA AOE O AT OEC TEAR 23 SOURCES OF INOCULUM tidad t 23 ti PROTECTANT FUNGICIDE PRAYS cccccccccsececcccssceccccsscccecssecccccsseccccsssceceacseseceusesccecesececeueesceeaes 24 SYSTEMIC FUNGICIDE SPRAYS ccccscscsccccceccesscsscscccccessssusseseescsesssuueseecesesessucuusscecesssssuuaeusgessesess 24 FUNGICIDE WEATHER INTERACTIONS cssssssseccccceccscesssseccccsscesseuscccceccsesssuuususescsssssseuuensgeesesess 24 PARTIAL RESISTANCE FUNGICIDE INTERACTIONS cscsescecscccccessssscccsccsccesseueecsesccesesssucenseeseesess 25 ECONOMICS isidro 25 SIDE BY SIDE COMPARISON OF EPIDEMICS ccccccccccccccscsssscsccccccssseeussescescssssucuussececsssssuueuseeesecess 25 PRINTING OR EDITING TEXT OUTPUT ccccssssssceccccceccsseesscececcescssseuseececcsssesuuueusesceesssseuueusgeesesess 26 MODEL TECHNICAL DESCRIP
27. f potato late blight epidemiology by simulation modeling Phytopathology 71 612 616 Bruhn J A and W E Fry 1982 A mathematical model of the spatial and temporal dynamics of chlorothalonil residues on potato foliage Phytopathology 72 1306 1312 Crosier W 1934 Studies inthe biology of Phytophthora infestans M ont DeBary Memoir 155 Cornell University Agricultural Experiment Station March 1934 37 pp DeW eille G A 1963 Laboratory results regarding potato late blight and their significance in the epidemiology of blight Eur Potato J our 6 121 130 Glendinning D R A MacDonald and J Grainger 1963 Factors affecting the germination of sporangia of Phytophthora infestans Trans Brit Mycol Soc 45 595 603 Guzman N 1964 Nature of partial resistance of certain clones of three Solanum species to Phytophthora infestans Phytopathology 54 1398 1404 Lapwood D H 1961 Potato haulm resistance to Phytophthora infestans Lesion production and sporulation Ann Appl Biol 49 316 330 Lapwood D H and R K McKee 1966 Dose response relationships for infection of potato leaves by zoospores of Phytophthora infestans Trans Brit Mycol Soc 49 679 686 Marks G E 1965 The cytology of Phytophthora infestans Chromosoma 16 681 692 Melhus I E 1915 Germination and infection with the fungus of the late blight of potato Phytophthora infestans Wisc Agr Exp Sta REs Bull 37 1 64 Milgroom M G C E
28. is is an arbitrary scale of 0 to 100 used to display the various inputs and results of the simulation The View menu allows you to choose which variables will be drawn on the graph and shows the units and color for each variable The scrollbar just below the x axis is used to advance time Management actions are selected from the menu system while the season is in progress For more detailed information about running Lateblight please consult the Lateblight Tutorial and Program Features sections of this manual Lateblight features a help system which is accessed by pressing the 1 gt key or using the Help menu Use the help system and this manual to learn more about the programas you go along Example scenarios for Lateblight investigations are provided in the Getting Started with Lateblight and the Mini Case nvestigations with Lateblight sections of this manual There is also a Tutorial section later in this document These sections are also provided separately inthe Tutorial and Activities document Getting Started with Lateblight First time users of Lateblight may become familiar with this program by looking at two different seasons for growing potatoes and comparing management strategies and the resulting losses or profits To do this double click the Begin Lateblight potato icon Go to File in the menu and choose Open Highlight crop1 Ibt and a finished season will appear Resize the window by clicking in the middle
29. it the saved text without exiting from Lateblight just be sure the log file is closed from Lateblight s File menu before editing it with another program 26 MODEL Technical DESCRIPTION This version of Lateblight was adapted from the simulation originally written by J A Bruhn et al 1980 and modified in various ways over the years by different people working inthe research program of W E Fry Department of Plant Pathology Cornell University We have attempted to retain as much as possible the original structure of the model but some small modifications have been necessary to enhance its pedagogical value While the simulation is sufficiently realistic for teaching purposes this version should not be trusted as aresearch tool or a management decision making aid I n order to make Lateblight respond as realistically as possible to environmental and management variables the development of the fungus is simulated mechanistically closely following the P infestans life cycle The model s state variables represent the major morphological stages in the f ungus development S porangia landed on susceptible sites Zoospores following indirect germination Germinated sporangia Germinated zoospores Latent lesions Sporulating expanding lesions Sporulating inactive lesions not expanding I nactive lesions nonsporulating necrotic tissue Sporangia available for dispersal Dispersed sporangia The model s transfer functions descri
30. j Bio UES 3 Lo F Tran vH LATEBLIGHT A Plant Disease Management Simulation Version 3 1 User s Manual Phil A Arneson Cornell University Barr E Ticknor Cornell University A BioQUEST Library VII Online module published by the BIOQUEST Curriculum Consortium The BioQUEST Curriculum Consortium 1986 actively supports educators interested in the reform of undergraduate biology and engages in the collaborative development of curricula We encourage the use of simulations databases and tools to construct learning environments where students are able to engage in activities like those of practicing scientists Email bioquestObeloit edu Website http bioquest org Editorial Staff Editor John R Jungck Managing Editor Ethel D Stanley Associate Editors Sam Donovan Stephen Everse Marion Fass Beloit College Beloit College BIOQUEST Curriculum Consortium University of Pittsburgh University of Vermont Beloit College Margaret Waterman Southeast Missouri State University Ethel D Stanley Online Editor Amanda Everse Editorial Assistant Sue Risseeuw Beloit College BioQUEST Curriculum Consortium Beloit College BIOQUEST Curriculum Consortium Beloit College BioQUEST Curriculum Consortium Editorial Board Ken Brown University of Technology Sydney AU Peter Lockhart Massey University NZ Joyce Cadwallader St Mary of the Woods College Ed Louis The University of Nottingham UK Eloise Carter Oxford Colleg
31. med STARTUP LBT Lateblight will load it automatically when you start the program In this way you can override the default values provided for the various parameters and options A document saved before selecting Run will contain only the program options and initial parameter values and will take considerably less space on disk A document saved while a season is in progress will contain all information for that season up to the time when it was saved 12 Log to Disk A plain text record of all parameter values and day by day simulation results can be saved to disk using the Log to Disk selection in the File menu This is especially useful for preparing printed reports Whether you choose Log to Disk before a season is started in the middle of a season or at the end of a season the log file will include all initial values and results fromthe beginning of the season onward If the log is closed before the end of the season only the data up to the day when the log was closed will be saved A single log file can be used to record the results of several successive seasons Exit This selection terminates Lateblight The same thing may be accomplished by double clicking the close box inthe upper left corner of the Lateblight window Potato Menu Different potato cultivars can be simulated in Lateblight by altering the level of resistance to Phytophthora infestans the time of initiation of tuber production and the yield potential of the
32. ndows NT are either registered trademarks or trademarks of Microsoft Corporation Helvetica Times and Palatino are registered trademarks of Linotype Hell The BioQUEST Library and BioQUEST Curriculum Consortium are trademarks of Beloit College Each Bio0QUEST module is a trademark of its respective institutions authors All other company and product names are trademarks or registered trademarks of their respective owners Portions of some modules software were created using Extender GrafPak by Invention Software Corporation Some modules software use the BioQUEST Toolkit licensed from Project BioQUEST Lateblight is based on the work of J A Bruhn et al 1987 The simulation has been refined and adapted to the Microsoft Windows environment ver 3 0 or higher by Barr Ticknor and Phil Arneson Department of Plant Pathology Cornell University The following files should be kept together in the same folder Begin Lateblight exe the main program LATEBLIT DOC the manual KEYHOOK DLL the keyhook library which supports the context sensitive help system LATEBLIT HLP the help file The sample weather files COOLWET LWX HOTDRY LW X MODDRY LW X MODMOD LW X MODWET LWX Sample scenario files CROP1 LBT CROP2 LBT PAST1 LBT PAST2 LBT PAST3 LBT POTATO1LBT POTATO2 LBT POTATO3 LBT Table of Contents WHATIS LATE BLIGHT ovcsccdeccswes cesessecsescsevecdsesssscssessescecesesussensseccecosesessusssecccsessceesessssccscoesss
33. ording to environmental conditions Various kinds of forecasting systems have been employed to help growers decide when and how much to Spray By using potato varieties that are partially resistant to P infestans it is possible to markedly reduce the doses and or frequencies of fungicide sprays INSTALLATION AND QUICK INSTRUCTIONS Lateblight will run on any system which supports Microsoft Windows nstallation To install insert the BioQ UEST Library CD that is compatible with the Windows operating system into the appropriate drive of your computer Open the Online Guide Using the instructions on the first page of the Online Guide navigate to the Lateblight section of the Guide Clicking on the I nstall button on the bottom of the page will start the installation process Follow the instructions on the screen Note To use the Online Guide the Acrobat Reader must be installed on your computer For best results we suggest that you install Acrobat Reader version 4 0 or later An installer for Reader version 4 0 is included on the BioQ UEST Library CD Quick Start Select the Begin Lateblight exe file potato icon or use File Run to begin your first simulated season A dialog box will appear asking you to choose a weather data file Sample weather files with the LW X extension are distributed with Lateblight Once you open a weather file a pair of axes will be drawn The x axis represents time and is labelled with dates The y ax
34. pical value for this maximum is 1 107 sporangia ha at 10 meters fromthe field Number of Infections This is one of two alternative means of setting the number of initial infections Enter the number of infections per hectare or per acre present at plant emergence A typical value is 100 infections ha Sources of Infections There are two possible sources of initial infections inf ected seed tubers and volunteer potatoes in the field being managed Enter the numbers of infections per unit area present at plant emergence A typical value is 100 inf ections ha Management Menu After the potato plants have emerged that is after the simulation has been started with the Run command the only disease management options available are to spray a fungicide or to terminate the season early by killing the vines There are two general types of fungicide available Spray Systemic applies a fungicide that is absorbed by the plant tissues and is therefore not subject to weathering by subsequent rains The systemic fungicide also acts to suppress inf ections that are already established Spray Protectant applies a fungicide that interacts with the fungus only on the plant surface To be effective it must be applied prior to infection and its residues must be maintained on plant surfaces by frequent applications Spray Systemic Spray Protectant Enter the dose of the active ingredient in kg hectare or lb acre Click on OK to apply
35. prayed field of potatoes The source of sporulating lesions can be infected seed tubers which give rise to infected plants or volunteer potatoes fromthe previous year s crop a portion of which also gives rise to infected plants Select Sporangia Sources fromthe noculum menu and set the maximum number of sporangia per day coming froma cull pile 10 meters fromthe field to 5000 The number of sporangia coming from an adjacent unsprayed field should be zero Run the simulation using the MODMOD LW X weather file and note the date of 50 blight and the final AUDPC Select New fromthe File menu and this time run the simulation with the cull pile 20 meters from the field recording the date of 50 blight and the final AUDPC as before 23 Repeat the simulation using 40 and 80 meters as the distance from the cull pile to the field Protectant Fungicide Sprays The weather data files included with Lateblight have been modified to facilitate studies of regular spray schedules No rain will occur on intervals of 5 or 7 days starting on either day 15 or day 50 after emergence J une 15 or J uly 20 if emergence is set at J une 1 Reset the starting conditions by opening STARTUP LBT Usethe MODMOD LWX weather data file and advance the season to uly 20 by dragging the thumb on the scroll bar or by clicking on a combination of pageup advance one week at a time or the right arrow advance one day at a time Since this will be the starting date for
36. r two hundred years with good success Inthe 1840 s potato farming became far more problematic Let s look at the results of three different seasons in 1830 with no late blight 1843 when the first late blight occurred in your county and 1844 a Open the file past1 Ibt and look at the results of the 1830 season How many potatoes can you expect to harvest b Open the file past2 lbt and look at the results of the 1843 season You should note that signs of late blight infection are observed near the end of the summer How many potatoes can you expect to harvest c Open the file past3 Ibt and look at the results of the 1844 season The agricultural methods of the day contribute to your problems Volunteer potatoes tubers left in the ground over winter were common Also cull piles damaged or tubers that aren t used are found near the growing sites Since no one suspected how this inf ection spread How many potatoes can you expect to harvest in the third season 2 You are farming in upper state New York during the 1990 s and have been having trouble with late blight during the cool wet weather the county has been having for the past three years Encouraged by a neighbor s success with a new hybrid potato that has high resistance to late blight you are thinking of trying these potatoes yourself The new seed certified potatoes will cost you about 100 more per acre than your standard low resistance potatoes a Openthe file po
37. r up to the day determined by the characteristics of the cultivar early mid or late season and reaches a maximum also characteristic of the cultivar 32 Early Mid Late Day foliage growth stops 44 52 59 Maximum leaf area index 25 35 4 5 Tuber production is a function of temperature cultivar and time Tuber initiation can occur above 0_C and below 30_C A temperature factor for tuber initiation is generated by the quadratic Tuber nitFact 0 00911 0 1038 Temp 0 00296 Temp2 Physiological time is then accumulated at arate that depends on the cultivar Tuberl nitTime Tuberl nitTime CvTuberFact Tuber nitFact where CvTuberFact is 1 600 1 404 and 1 333 for the early mid and late season cultivars respectively Tuber production is initiated when 45 physiological time units have accumulated The rate of tuber production is also a quadratic function of temperature TuberProdFact 0 3837 0 1261 Temp 0 00298 Temp Again physiological time is accumulated for the production of tubers TuberProdTime TuberProdTime CvTuberFact TuberProdF act The production of tubers in tons hectare is then Tubers 0 56 TuberProdTime Fungicide effects The protectant fungicide effect was modified from that of earlier versions of the model where the average effect was calculated from the individual effects of the fungicide residues distributed among four levels in the canopy according toa gamma distribution Bruhn
38. ses due to Plant Blight 294 43 Yield Losses due to Tuber Blight 469 39 Total Losses due to All Blight 763 82 Net Yield 736 18 SPRAY REPORT Fungicide Sprays Protectant 15 Systemic 15 COST REPORT Fixed Costs 1106 00 Spray Costs 6 66 Application Costs 6 60 Blitecast Costs 25 00 Net Loss 388 82 Go to File in the menu and choose Open Highlight crop2 lbt Lateblight CROP2 LBT File Potato Environment Inoculum Management Economics View F1 Help 100 Leaves A DS BD 3333 3333333333038 EOE s Today is Sept 29 If you open your Economic Report you can see that spraying with a systemic has resulted in a net profit under otherwise identical conditions Economic Report CROP2 LBT ES Season ended on Sept 28 with 6 81 blighted foliage Your crop is 298 11 cwt acre At the current market price of 5 66 this would bring 149M 54 acre 6 6 of your tubers are blighted YIELD REPORT Price Yield Revenue cut cut Total Total Potential Yield 5 BB 300 0 1566 06 Yield Losses due to Plant Blight 5 66 1 9 9 46 Yield Losses due to Tuber Blight 5 66 6 6 Total Losses due to All Blight 5 66 1 9 Net Yield 5 00 298 1 SPRAY REPORT Fungicide Sprays Protectant 2 Systemic 2 COST REPORT Fixed Costs 1100 00 Spray Costs 8 86 Application Costs 16 66 Blitecast Costs 25 98 Net Profit 346 68 Mini Case I nvestigations with Lateblight 1 The Irish grew potatoes in reland for ove
39. sporangium day and INFMAX_ZSP 0 01 inf ections germinated zoospore day Lapwood and McKee 1966 The temperature effect is determined by the appropriate polynomial function in Table 1 Maximum inf ection efficiency occurs at 21 C with 24 hours of leaf wetness but the effects of temperature on inf ection efficiency are small between 10_ and 22_C No infections occur below 1 5_C or above 30_C Crosier 1934 Infection occurs only if the leaves are wet The susceptibility factors for the susceptible moderately resistant and resistant cultivars are 1 0 0 9 and 0 8 respectively The protectant and systemic fungicides have different dose responses the systemic requiring a lower residue to achieve the same effect See Fungicide effects below Lesion development Lesions are divided into four types Latent lesions Sporulating expanding lesions Sporulating inactive lesions not expanding nactive lesions nonsporulating necrotic tissue All successful infections produce latent lesions The latent periods for the susceptible moderately resistant and resistant cultivars are 6 6 and 7 days respectively At the end of the latent period the lesion diameter is set at 2 mm f ollowing which the sporulating lesions expand for four days LesionDiam age LesionDiam age 1 MAXLES TempEffLesEx LesionExp I ncrFact FungicideF act 1 0 BlightProportion 30 where MAXLES 4 35 mm day Guzman N 1964 Lapwood 1961
40. t to simulate a low moderate or high level of resistance to P infestans tuber initiation occurring early mid or late season and the maximum yield potential Next you set the amount of initial inoculum either sporangia or infections or both Finally you can enter the production costs and the market price for the harvested potatoes You can save all of these start up values in a disk file to facilitate repeated simulations using the same initial values for most of the parameters The simulation is then started and you can progress one day at a time one week at a time or you can advance the season to any desired day During the season you can consult the weather forecast and the Blitecast spray advisory prior to applying aspray of either a protectant or asystemic fungicide You can select which of the output variables you would like to see graphed on the screen the fungicide residues rainfall daily mean temperature hours of relative humidity above 90 leaf area index latent lesions sporangia production percent foliage blight and area under the disease progress curve At the end of the season you can look at an economic summary of the season and if you wish you can save a text summary of the season s simulation The following describes each of the commands in each of the menus 11 File Menu Run Once you have decided on the appropriate options and parameters select Run from the File Menuto begin the simulated season Yo
41. tatol lbt which was created by selecting Potato and changing resistance level from low to high and then selecting Economics and increasing costs from 1100 to 1200 per acre Did you make a profit b Unexpectedly your region experiences a moderately dry growing season Cc Open the file potato2 Ibt which was created by running the file using moddry lwx and no other changes Review the results Did you make a profit The uncertaintity of the weather raises new issues for you You decide to try a more vigorous spray program instead of planting the high resistance potato Open the file potato3 lbt which was created by selecting Potato and changing resistance level from high to low and then selecting Economics and decreasing costs from 1200 to 1100 per acre You are spraying a systemic every two weeks in late J une until harvest Note When it rains these sprays are delayed Did you make a profit How does it compare to the use of high resistance potatoes W hat are the costs 10 PROGRAM FEATURES Lateblight is designed to allow you to manipulate the variables that affect the development of the disease and to adjust the economic parameters that determine the cost effectiveness of the disease management procedures You must first select a weather data file that determines the environmental conditions under which the simulation will execute You can then set the characteristics of the potato cultivar that you wan
42. u will then be prompted to select a weather data file that will provide the season s weather To advance the progress of the simulation during the season use the scroll bar beneath the graph New New allows you to begin a new simulation You may repeat the same problem or change parameters and or options before running the new season Any parameters or options not changed will be the same as inthe last season You may want to use the Save As command before selecting New so that you can recall the current season at a later time Open O pen allows you to open a saved Lateblight document in which is stored the state of the program at the moment you executed the Save As command in a previous run This includes all program options and parameter values If the season was in progress when the document was saved opening it will return you to the day on which it was saved This is a good way to explore and compare different management strategies Save As Save Ascreates a Lateblight document on disk using the name and extension you provide Use of the LBT extension is strongly recommended to distinguish Lateblight documents from other types of files If you add a line for the LBT extension to the extensions section of your WIN INI file you will be able to start Lateblight simply by double clicking a document A Lateblight document contains the complete state of the program at the time the document was saved If you save a document na
43. xes lt Tab gt cycles among the currently selected radio button the color palette the OK button and the Cancel button When the input focus is ona radio button the spacebar or the arrow keys can be used to select a different button When the input focus is in the color palette it is represented by an inverted rectangle on the current color button The focus is moved from one color button to the next by using the arrow keys Pressing the spacebar while the input focus is on a color button has the same effect as clicking that color with the mouse that color is assigned to the variable whose radio button is selected 20 Getting Help Lateblight features a context sensitive help system which provides inf ormation about all aspects of the program To access the help system press 1 gt This will take you directly to the help item most appropriate for your current situation If no specific help item exists you will be presented with the help index Selecting Index from the Help Menu will take you directly to the help index To get help on a menu command pull down the menu and highlight the command using either the mouse or the arrow keys While the command is still highlighted don t let up on the mouse button press 1 gt The Help window will appear with the appropriate information To get help while in a dialog box press lt F1 gt If you need more general help with the Microsoft Windows environment use the Help Menu in either the
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