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'. “Han .u. u’ ‘ 1': 9-31 ' ...-:.:,:wr' ‘ A." :. ’4’— ‘ . , ill/ll ill/illlll/lglil/lllllllll , 9 1385 ‘“ LIBRARY Michigan State University d N “3 IHE515 This is to certify that the thesis entitled NECTRIA CANKER ON BLACK WALNUT IN SOUTHWEST MICHIGAN presented by CARLA SUZ ANNE THOMAS has been accepted towards fulfillment of the requirements for MASTER OF SCIENCE degree in BOTANY AND PLANT PATHOLOGY I V ' fl, Major professor Date DECEMBER 17 , 1981+ 0-7639 MSU is an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES- “ RETURNING MATERIALS: Place in book drop to remove this checkout from your record. ‘FINES will be charged if book is returned after the date stamped below. NECTRIA CANKER 0N BLACK WALNUT IN SOUTHWEST MICHIGAN By Carla Suzanne Thomas A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Botany and Plant Pathology 1984 ABSTRACT NECTRIA CANKER 0N BLACK WALNUT IN SOUTHWEST MICHIGAN BY Carla Suzanne Thomas Nectria canker, caused by Nectria galligena, Bres. is especially severe on black walnut (Juglans nigra LJ in some stands in southwest Michigan. A survey was conducted which indicated several centers of severe disease. 0f the 189 survey observations, nectria canker was more likely to be severe on black walnut associated with wetlands, kettles or depressions than on black walnut growing on uplands. When characterized for 30 survey sites, soil type was not related to disease levels, but surface geology and topography were. A severely infected plantation of 2718 black walnut indicated that number of cankers per tree was not correlated with dbh or canker shape. The number of infections increased from 1961 to 1979 with peak years 1978-1980. Most stem sections were 19 to 27 years old, with peaks at 22 and 24. Growth rates varied between trees and within trees, but were similar for cankered and uncankered trees. ACKNOWLEDGMENTS I wish to express my sincere appreciation to my major professor, Dr. John H. Hart, for his support, insight and encouragement to achieve ambitious goals. I also wish to thank my committee members Dr. R. P. Scheffer and Dr. J. 8. Hart for their insightful input and encouragement. Thanks are expressed to Mr. David Hadley for assistance in locating severely infected stands and to Mr. Greg Kowalewski and Ms. Margaret McLeod for technical assistance. I also wish to thank Ms. Cheryllee Finney for word processing assistance. [ha D. Mokma, Dr..L R. Harman and Dr. H. A. Winters are thanked for their interest and advice. Ms. Penny Houck is thanked for her assistance in locating geological maps. My deepest appreciation is extended to Dr. Bruce A. Stermer for his sincere encouragement and enthusiasm towards this project and my education. ii TABLE OF CONTENTS List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . iv List of Figures ......................... Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Materials and Methods ....... . . . . . . ...... . . . 5 Survey . . . . . ...... . . . . . . . . . . . . . . . . . 5 Soils and Topography . . . . ...... . ....... . . . 6 Effect of Tree Vigor and Competition in a Russ Forest Plantation . . . . .......... . . . . 7 Canker Dissections ................... . . . 8 Results ............................ . . 11 Survey . . . . ...................... . . 11 Soils and Topography ..................... 18 Effect of Tree Vigor and Competition in a Russ Forest Plantation . . . ..... . . . . . . . . . . 3O Canker Dissections ...................... 32 Discussion . . . . . . . . . ....... . . . . . ...... . . 42 Recommendations .......................... 47 Bibliography . . . . . . . . . . . . . . ..... . . . . . . . . . 60 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Appendix C O O O O O O O O O O O O O O O O O O O O O O O O O I O O O 64 Table 10 11 LIST OF TABLES Page Summary of nectria canker data for 40 year old black walnut trees collected from Russ Forest Plantation D46 .. .. 9 Summary of the variables used in the survey of nectria canker on black walnut in southwest Michigan .. .. .. .. . 13 Summary of multiple linear stepwise addition regressions of site factors from a survey of nectria canker on black walnut in southwest Michigan .. . .. . .. . .. . .. . .. 15 Modal description of the sandy soil type ....... . . . . 20 Modal description of the clayey soil type .. ...... .. 21 Modal description of the rocky soil type .. .. .. .. .. 22 Modal description of the loamy soil type . .. .. .. .. .. 23 Relationship of soil and topographic features of 30 black walnut stands in southwest Michigan to nectria canker disease severity .. . .. . .. . .. . .. . .. . .. . . . 25 Summary of the relationship between topography and stand percent infection rating of 189 survey sites for black walnut in southwest Michigan .. . .. . .. .. . .. . .. 29 Summary of multiple linear regressions of row number, diameter breast height, clearing, canker number and canker shape of individual black walnut trees in a plantation in southwest Michigan . .. . .. . .. . .. . .. . .. . .. . 31 Percent growth reduction in top, middle and bottom portions of infected and uninfected black walnut .. ... .. 35 Summary of the relationship betw en glacial deposition and stand percent infection in X contingency tests of 166 nectria canker survey sites for black walnut in southwest Michigan .. . . .. . . .. . . .. . .. . .. . .. . .. . 64 iv Table II III IV VI VII VIII Page Summary of the relationship between soil type and stand percent infection rating in x contingency tests of 30 nectria canker survey sites for black walnut in southwest Michigan ...... . . . . . . . . . . . . . . . . . . . . . 65 Summary of the relationship between C horizon texture and stand percent infection rating in x2 contingency tests of 21 nectria canker survey sites for black walnut in southwest Michigan . . . ...... . . . . . . . . . . . . . 66 Summary'of the relationship b tween microrelief and stand percent infection rating in contingency tests of 30 nectria canker survey sites for black walnut in southwest Michigan . . . . . . . . . . ................. 67 Summary of the relationship between wet and association and stand percent infection rating in contingency tests of 30 nectria survey sites for black walnut in southwest Michigan . . . . . . . . . . ......... . . . . . . . . 68 Summary of the relationship between wet and association and stand percent infection rating in contingency tests of 30 nectria survey sites for black walnut in southwest Michigan . . ....... . . . . . . . . . . . . . . . . . . 69 Summary of the relati nship between aspect and percent infection rating in contingency tests of 23 nectria canker survey sites for black walnut in southwest Michigan .. 70 Summary of the relationship between mode of glacial2 deposition and stand percent infection rating for X contingency tests of 30 nectria canker survey sites for black walnut in southwest Michigan .. .. . .. . .. . .. . 71 Figure 10 11 12 13 LIST OF FIGURES Page Open cankers on black walnut in southwest Michigan cause diSfiguration O O O O O I I 0 O O O O O O O O O I O O O O O O 4 Locations of survey sites for nectria canker on black walnut in southwest Michigan . . . . . . . . . . . ..... 12 Topographic map of Volinia township survey in Cass County . . 17 Relationship of nectria canker on black walnut to surface geology of Kalamazoo, Van Buren, Cass and St. Joseph Counties in southwest Michigan ....... . . . . . . . . 19 Frequency of infection for 200 nectria cankers from 7 black walnut trees collected at Russ Forest Plantation D46 0 ...... O ..... O O O O O O I O O O O O O O O O 33 Relationship between age of black walnut stem tissue and A) frequency of nectria canker infection 8) accumulative percent of total nectria canker infection for 200 trees . . . 34 Cross section of open and closed nectria cankers on one black walnut trunk ....... . . . ..... . . . . . . 37 Closed nectria cankers on a black walnut trunk in southwest Michigan . . . . . . . . . . . . . . . . . . . . . 38 Close up of a cross section of a closed canker on a black walnut trunk in southwest Michigan . . . . . ........ 39 Nectria canker on black walnut that was open, but now is CIOSing I O O O O O O O O O O I O I O O O O O I I O l O 0 O 0 40 Cross section of a similar nectria canker that was open, but now is closing ..... . . . . . . . . . . . . . . . . 41 Relationship between year of nectria canker infection for 200 cankers, total May and August precipitation and average February and October temperature for 1960-1983 . . . 49 Palmer meteorological draught index for the southwest lower climatic division in Michigan (1944-1978). (From Nurnberger, 1980) O O O O O O I O O O O O O O O O O O O O O O 52 vi Figure 14 15 16 17 18 vii Page Annual mean temperature of southern Michigan (OF), 1940- 1969 ............................ 53 Annual mean snowfall of southern Michigan (inches), 1940-1969 ........................ 54 Annual mean precipitation of southern Michigan (inches), 1940-1969 ........................ 55 Summary of calcium levels (lbs/acre) of the C horizon in southwest Michigan ................ . . . 57 Summary of pH levels of the C horizon in southwest Michigan ......................... 58 INTRODUCTION _ Nectria canker of hardwoods was reported in Europe as early as 1865 (Hartig, 1880). The first report of the disease in North America was in 1896 when nectria canker was reported as occurring on "a variety of deciduous hosts" (Galloway and Woods, 1896). Over the next 50 years, this disease was reported on many deciduous trees, including species of oak, birch, maple, beech, hickory, walnut, aspen, cherry and apple. During this time, a controversy about Nectria species taxonomy developed which centered on fungal morphology and host range. Taxonomy and host range have been discussed by others (Ashcroft, 1934; Cayley, 1921; Graves, 1919; Lehman and Watson, 1943; Lortie, 1969; Spaulding, Grant and Ayers, 1936). ‘The causal organism of most perennial, target-type nectria cankers on deciduous trees is referred to as Nectria galligena, Bres. However, there may be strains of the fungus which infect some hosts but not others. Isolates from cankers on apple are pathogenic on pear but not on most forest tree species. For this reason, studies concerning nectria canker of apple will not be discussed in length in this study; they are, however, discussed elsewhere (Dubin and English, 1975 a, b; Ng and Roberts, 1974; Zeller, 1926). Black walnut, Juglans nigra L., is one of our most valuable and beautiful native trees. The heavy, strong, durable heartwood is easily worked and is in great demand. The bark has been used in tanning and a yellow-brown dye can be made from the nut husks. Nuts are eaten by man 1 and many species of wildlife. Nut shells are used by industry in making abrasives. Only one study has been published concerning nectria canker on black walnut (Ashcroft, 1934) even though N; galligena is reported as a serious pathogen of black walnut in many states, including West Virginia, North Carolina, Georgia, Tennessee (Gravatt, 1933), Michigan, Pennsyl- vania (this study), Wisconsin, Ontario and Rhode Island (Ashcroft, 1934). A number of black walnut stands in a four-county area of southwest Michigan have been severely damaged by nectria canker. Although an occasional nectria canker on black walnut is fairly comnunn the situ- ation in southwest Michigan may be unique in several aspects. In some stands almost every tree is affected, usually with more than one canker. Nectria canker significantly restricts the growth rate of infected black walnut trees (Brandt, 1964), destroying the veneer value of infected trees. Decay fungi and boring insects may invade diseased tissues (Gravatt, 1933L Because of the premium prices black walnut wood commands, this disease represents a significant loss to some land- owners in southwest Michigan. The large callus layers produced by the black walnut tree in response to N; galligena create a grotesque distorted appearance which destroys the ornamental value of black walnut (FigUre 1). The mode of infection also may be unique to this region. The Nectria fungus can only attack a tree through a wound, usually wounds associated with a branch crotch or branch stub (Grant and Spaulding, 1939; Keinholz and Bidwell, 1938; Lortie 1969). This may not be true in southwest Michigan, as new cankers are forming on the trunks of mature Figure 1. Open cankers on black walnut trunk in southwest Michigan cause disfiguration. trees where no obvious injury has occurred. Others report that nectria canker occurs on young hardwoods two to 20 years old (Brandt, 1964; Kress and Wood, 1974; Merrill and Finley, 1981). Yet in Michigan, 100- year-old trees have new cankers at various heights along the trunk. Preliminary field observations indicate that the disease has been persistent in this localized area for a period of years and does not seem to be spreading to adjacent areas. Nectria canker of hardwoods is commonly thought to be associated with less vigorous trees growing on shallow, poorly drained, infertile soils (Ashcroft, 1934; Brandt, 1964; Keinholz and Bidwell, 1938). Sites in regions of frequent snow and ice storms or at high elevations also may have severe nectria canker prob- lems (Ashcroft, 1934; Brandt, 1964; Grant and Childs, 1940; Roth and Hepting, 1954). Nectria canker of yellow birch was severe when trees were within five miles of Lake Michigan or Lake Superior in Michigan“s upper peninsula (Anderson and Mosher, 1979). Although Ashcroft did a brief survey by county of nectria canker on black walnut in West Virginia, his work was primarily concerned with fungal taxonomy, host range and histopathology of the disease, not epidemiology and site factors. The purposes of this study were to determine 1) the precise geo- graphic extent of nectria canker severity on black walnut in southwest Michigan and quantify the association of site factors with disease to explain why disease is serious only in a localized area, 2) the wound type, if any, associated with cankers and 3) the ages of trunk sections and chronological years of highest infection levels, 4) the impact of nectria canker on growth of black walnut. MATERIALS AND METHODS 211121 To determine where nectria canker is severe on black walnut, a survey was conducted in five counties in southwest Michigan during 1983 and 1984. Transects were established at three mile intervals from north to south and from east to west for Berrien, Cass, St. Joseph, Kalamazoo and Van Buren Counties. The survey was started at Russ Forest, a known area of severe disease and was continued outward in all directions until a one township wide border consisting of normal levels of disease (<6% stand infection) surrounded the surveyed area. Each stand, 10 or more black walnuts closest to each intersection of north-south and east-west grid lines was identified by county, township, section, quarter section and stand number (in case of more than one observation per quarter section) and the location recorded on township platt maps. The number of acres in the stand, tree stage (pole = <14 inches dbh, mature = >14 inches dbh), site wetness (wet or drained) and origin (roadside, forest or plantation trees) also was recorded. Distribution (local, spotty or general) was recorded for open, closed and combined cankers at each site. Cankers were open if three or more callus layers were seen. Cankers were closed if only one or two callus layers were seen. Then the percent infection per stand and the average percent of a trunk covered by cankers were recorded for open and closed nectria cankers according to the scale 1 = no infection, 2 = 1 to 5 percent, 3 = 6 to 20 percent, 4 = 21 to 50 percent and 5 = greater than 50. Percent infection for open and closed cankers combined (total cankers) was recorded for individual trees and for the stand according to the scale 0 = no infection, 1 =1 to 5 percent, 2 = 6 to 15 percent, 3 = 16 to 25 percent, 4 = 26 to 50 percent, 5 = 51 to 75 percent and 6 = greater than 75 percent. Two scales were used in order to facilitate the coding system of the Michigan State University Cooperative Crop Monitoring Service that was used to code the preceding variables. Basal area (square feet per acre) was recorded for each site. To determine the variability within a more local area, Volinia township in Cass County, was surveyed intensively during 1983. The survey was conducted by driving all roads in the township and recording the information mentioned above for all black walnut stands located. Occasional yard trees or roadside trees were ignored unless there were more than five at a site. All woodlots were surveyed on foot if black walnut was observed growing at the edge of the stand. Elevation above sea level and approximate depth to the water table were recorded from quadrangle topographic maps for each site. Surface geology of each site was determined using quadrangle maps stored at the Michigan Geological Survey, Lansing, from H. Martin's study (1955). An attempt to record soil types from maps was abandoned since Cass County has not been surveyed using currently accepted methods and maps would not have given suitable information. Soils and Topography During July 1984, soil profiles, surface geology, aspect, estimated percent slope, drainage class and parent material were recorded at 30 of the survey sites. Topography was diagrammed. Ten of these sites were locations where disease was severe (stands with greater than 75 percent infectionx These encompassed all of the forest sites where land owners were cooperative agg_disease was severe. Ten sites were randomly selected where normal levels of disease (0-5 percent infection) occurred on flat microrelief. Ten sites were randomly selected where normal levels of disease occurred on rolling microrelief. In no cases did trees on steep microrelief have less than 6 percent infection. Micro- relief was determined from quadrangle topographic maps. Soils were characterized by horizon, depth, structure, consistency, texture and the presence of gravel, boulders, clay skins, mottles and other distinguishing features. Depth to water table was recorded when possible. In each case, the surface soil layers were sampled by digging a pit approximately OJSineters deep. Subsoil and parent material were sampled to a depth of up to 4.5 meters using a three inch bucket agar. In some cases, subsurface horizons could not be penetrated with a bucket agar due to massive structure or a high density of large cobbles and boulders. Several sites south of State College in Huntington County, Pennsyl- vania, where nectria canker is severe on black walnut, were visited to compare disease severity and topography with black walnut in Michigan. Effect 9: Tree Vigor and Competition i_.a Russ Forest Plantation The incidence of nectria canker on black walnut was mapped in a mixed hardwood plantation which was established at Russ Forest in 1945 and 1946. The stand consisted of black walnut planted every fourth row in an east-west direction, with red oak, tulip poplar or ash and black cherry rows planted between the black walnut rows. In every case, black cherry was in the row to the south and red oak or ash was in the row to the north. Clearings were established in spring 1981. These resulted in seven rows of black walnut that had clearings to the north and six rows of black walnut that had clearings to the south. Row number (1- 65), dbh (1-15.5 inches, mean = 6.0 i 2.3) and number of cankers between 1 ft and 12 ft above ground on the trunk (0-51, mean = 1.3 i 3.8) were recorded for all 2,718 black walnuts in the stand. Whether the cankers were open (0 = none or no, 1 = yes), closed (0 = none or no, 1 = yes) or if a tree had an adjacent clearing to the north (0 = none or no, 1 = yes) or to the south (0 = none or no, 1 = yes) also was recorded for each tree. Presence of clearings, canker shape and number, tree dbh and distance to the creek (row number) were used as independent variables in multiple linear stepwise addition regressions with canker number as the dependent variable. The STAT 4 statistical package was used in the analysis. The soil variability of the stand was investigated by charac- terizing the soil in the same manner as for the survey sites. ‘The soil was sampled at 11 pits established between every third and fourth black walnut row in the north two-thirds of the stand. Each pit was dug halfway between two rows of black walnut. The mean number of cankers per tree was calculated for each pit location using the values of the 10 closest trees in each of the two adjacent rows. Canker Dissections Eleven black walnut, 6 inches dbh or larger with 400 ft of each other, from the Russ Forest Plantation were cut in 1984. Seven of the trees were infected with nectria canker. Two of the infected trees were used in the isolation studies. Two hundred cankers were dissected from random logs (Table 1). Cuts were made radially into cross-sections. Table 1 Summary of nectria canker data for 40 year old black walnut trees collected 1984 from Russ Forest Plantation D46. Tree diameters, number of cankers per tree and predominant canker shape are included. Diameter at Tree breast height No. of externally Predominant No. of Cankers 139;? (inches)b apparent cankersb canker shapeb dissectedd 1 7.9 8 closed 13c 2 8. 3 13 open 14C 3 6.0 8 open 24 4 8.8 11 closed 13 5 8.8 21 closed 60 6 8.9 7 open 30C 7 7.2 9 closed 465 mean 8.0 11 - 29 aTrees 1 and 2 also were used for fungal isolation studies. bFrom field observations October, 1983. cNot all cankers from each tree were dissected. dThe number of cankers dissected is greater than the number of externally apparent cankers due to the presence of closing cankers which were not detected from the outside of the tree. 10 To determine the tree growth reduction due to nectria canker, the number of tree rings in the inner 0.4 inch of the cross-section were recorded for the widest and narrowest directions, since infected stems were often asymmetric. Similar measurements were recorded for tree rings in the outer 0.4 inch. The values were used to obtain a mean growth rate before (inner) and after (outer) infection. The four infected trees were used as controls. A mean growth rate for the inner and outer 0.4 inch was obtained from the top (20-25 years old), middle (26-30 years old) and bottom (31-34 years old) of the trunk of each tree. Percent growth reduction was calculated as - _ mean no. rings/0.4 inch inner = m d L1 mean no. rings/0.4inchfouter J x 100 b gr. re ' Percent growth reduction for the top, middle, and bottom sections of non-cankered trees was compared to percent growth reduction for top, middle and bottom sections of cankered trees. To determine the age of the stem section at the time of infection, the number of rings from the pith to the first infected ring was recorded. To determine the year of infection, the number of rings from the bark to the first infected ring was determined. The type of wound and whether the canker was open or closed was recorded as well. No distinction between living branch and branch stub was made. If boring insects were secondary to infection, this was noted. To verify the identity of the causal organism and to determine the location of infected tissues within the tree, two trees were harvested from the Russ Forest plantation. One tree had predominantly closed cankers and one had predominantly open cankers (Table 1). The trunks 11 were cut into five foot lengths, transported to Michigan State University, where the cankers were dissected by cutting radially into 1.5 cm cross sections. These sections were photographed. Isolations were made from discolored and normal sapwood and heartwood of six closed and four open cankers by aseptically removing wood chips and placing them on Difco potato dextrose agar (PDA). Hyphal tips were removed and subcultured on PDA and incubated at 65-720 F under diffuse daylight. Colonies with similar morphology were grouped and identified. After Cylindrocarpon heteronema (Berk. and Br.) Wollenw., the imperfect stage of N; galligena, was identified in pure culture, several media were tested for optimal growth and sporulation. The media used were Difco oatmeal agar, 2 percent water agar, Difco potato dextrose agar, V-8 agar, autoclaved Quaker oats added to sterile water or to 2 percent water agar, Quaker oats autoclaved with water, and autoclaved black walnut twigs placed in sterile, melted 2 percent water agar. Another medium treatment consisted of sterile Quaker oats on top of 2 percent water agar. ‘9; heteronema was inoculated on April 24, 1984 and plates were observed weekly until September for growth and sporulation. RESULTS Email The regional survey contained data for 149 sites. Forty additional sites were located in the Volinia Township survey, resulting in 189 observations in all (Figure 2). Table 2 summarizes the variables used in multiple linear stepwise addition regressions of the factors recorded. The STAT 4 statistical package was used for the analyses. 12 Figure 2. A) Locations of survey sites for nectria canker on black walnut in southwest Michigan. Each dot represents one stand of black walnut. Dots are color-coded for % black walnut trees infected: purple = none, light blue = 1-5, dark blue = 6-15, green = 16-25, yellow = 26- 50, orange = 51-75, red = >75. 13 .umcrmgn mew: mHHom .mmwzcmguo .égw oH “v comum>mHm msmm on» no use muwm mo mcmume com cwgumz .33.. E meow H H33 3 £325 9:32 .33on .8 ocwucmum mm: 985 .3 Ho: on 3 3.8328 mam: 3.8mm 3t oo.¢~ m~.om oeHuoH mHan Loam: 0» suave HHm>mH mom m>oam Hwy mm.~o Hm.Hmw omoHuoHo coHHm>me Hmcum\u$ umv oo.o~ m¢.mm oeH-oH mmc< Human eoH coHpmpcqu Lo HmmLoH u H mm mnwmcmog u o muou chHLo mm Hm; u H HmH umcwmgv u o mmnou mmmcpm: mumm mefi Acne weeds? HHVV apoa u H we Acne mmzucw eHAV mcapme u o muou mmwum ucmum mucmcszuuo Lo comumm>mu came moved so mHanLo> Hucmaomcd ugovcmum mHanLm> mHm>w4 chucmamncH chucmamucH .cmmwcumz Hmm35H=Om cm Hchmz xomHn co mecwu mwcpumc we Hm>cam mgu cw new: mmHanLm> mgu mo Hem553m N mHaw» 14 The results of these regressions are sunnnarized in Table 3. All equations were highly significant (E.< CLOOOS). Stepwise deletions resulted in the same equations. The results of the linear stepwise addition regressions indicated that nectria canker was more likely to be severe at sites that were at higher elevations, on wet sites or in mature stands (Table 3). The percent of a tree with closed cankers was larger with larger basal diameter (basal area). This is not surprising since older trees have larger basal areas. In no case did depth to water table or the origin of trees correlate significantly with disease. The same factors are significant in percent infection resulting in closed cankers, open cankers or total cankers on a per stand or a per tree basis except for basal area code which was only important on a per , tree basis for closed cankers. Site wetness, elevation and stage code were important for total cankering per tree and per stand. For this reason and because of a more sensitive scale used for recording percent total cankers, the percent infection of total cankers per stand values were used for succeeding mapping studies. The independent variables listed in Table 3 explain only about 30 percent of the variability in percent infection of nectria canker. Other, unknown factors may influence disease severity, or perhaps elevation, site wetness and stage are not causative factors, but are associated with some factor that has a more direct influence on disease. While recording elevation values from topographic maps, it was noticed that some of the most severely diseased sites were in very hilly areas (Figure 3). The topography of this area is due to glaciation ....J + fixmm.H + MXNH.H mxHo. Hxam. mxHo. mek. MXNH. meo. mxmc. HxHo. NxHo. mm.m- Nme. om.H- Nxmo. NM.N- ax8. NxHo. mHav. Nxmu. mN.m- > ocopumswm commmmsmmm mm.o mm.o om.o mm.o mm .02 mHanLm> muou macaw coHHm>mHu muou mmmcumz muwm cowum>mHm mcou mmmcumz muwm muou mmmum comumzmHm muou mmmcumz muHm muou mmoum mmc< Hammm mmou mmmcumz muwm coHHm>mHm mcou mmmHm muou mumum mvou mmmcumz mHHm coHpm>mHm numuu< mmHansm> HcmucmqmucH ccmum Lma mcmxcmu Hone» mmLH emu acmum Lma mcmxcmo cmao mmcucma ccmum emu mcmxcmu ammoHu choHHum$cH acmocmmv mmHamHLm> acmucmamo .cmmmguwz Hmmzzuzom cm Hachz xomHa co mecmo mwcuum: Lo xm>czm a some weapumw muwm mo mcopmmmcomc coHHchm mmwzamum cmmcpH mHaHHHse mo accessm m mHan 16 .Hmooo.o v My Hcmuwmwcmwm chmH; mew meowumaum commmmcmmc HH HcmncmamucHn .me u 0 Hz; 3.3 u m 8. N. a ..N H: u m .33 ... N ...H u H 2.2 " o mHm om mcu co ummmn cmcammme mm: mcmxcmu Hope» mo cowuummcm Hemogma .omx u m new .OmuHNu e .ON 0 u m m H u N .mcoc n H mHmum ms» co vmmmn umgsmwme mm: mcmxcmu :mno new ammoHo we coHHommcw Hcmusmam NH muou mmmcpmz mHHm mxoq. H + NxHo. Nx coHHa>mHN + mem. H mm. m- n > NN.o Hx meou amaHm mmLH Lag Humzcmucouv m mHQMH Figure 3. Topographic map of Volinia township survey in Cass County. Brown lines are 20-ft. contour lines. Each dot represents one stand of black walnut. Dots are color-coded for % black walnut trees with nectria canker: purple = none, light blue = 1-5, dark blue = 6-15, green = 16-25, yellow = 26-50, orange = 51-75, red = >75. 18 during the Wisconsin age of the Pleistocene Epoch. The relationship of disease severity (percent stand infection) to surface geology is shown in Figure 4. Sites with abnormally high levels of disease (greater than 5 percent infection) were more likely to occur on glacial till (till plain or terminal moraine) according to a x2 test (P = 0.05, Appendix Table 1). However, not all sites on till have severe disease. This could mean that some factor(s) is involved which is associated with till but is not exclusive to it. Terminal moraines are generally more hilly than till plains followed by outwash, which are more hilly than lacu- strine landforms. Soils which develop on till are comprised of a vari- ety of poorly sorted components. In comparison, soils which develop on outwash are well sorted and often sandy; Lacustrine soils are usually fine textured and are clayey or silty. Soils and Topography Four types of soils were encountered at the 30 sites investigated. One of the most common is a sandy loam over unaggregated sand. Often there is a hard layer with white flecks in it at the boundary between the sandy loam and sand (Table 4). This soil type often occurred on outwash. Another common soil was a sandy clay loam over sandy clay (Table 5). This soil type often occurred on till plains and moraines. Occasionally a soil was encountered which was clayey and had many large cobbles and boulders, to the extent that it was hard to get the bucket agar through it (Table 6). This soil was probably a subcategory of the clayey type just described, but it was not possible to get the bucket agar deep enough to be certain. The other soil encountered was a sandy loam that extended beyond the depth of the bucket agar (Table 7). This Figure 4. Relationship of nectria canker on black walnut to surface geology of Kalamazoo, Van Buren, Cass and St. Joseph Counties in south- west Michigan. Each dot represents one stand of black walnut. Dots are color-coded for % black walnut trees infected: purple = none, light blue = 1-5, dark blue = 6-15, green = 16-25, yellow = 26-50, orange = 51-75, red = >75. Maps are from field notes of H. Martin's study (1955), Michigan Geological Survey. 8) Legend of surface geology. rn (‘1 AB Bt Bx C1 C2 20 Table 4 Modal description of the sandy soil type. 0-10 cm; very dark grayish brown (10 YR 3/2) sandy loam; weak medium granular structure; loose consistency; common medium roots. 10-35 cm; dark brown (10 YR 4/3) sandy clay; weak fine granular structure; loose consistency; common coarse roots. 35-50 cm; dark yellowish brown (10 YR 4/4) sandy clay; strong coarse angular blocky; hard consistency; 10% gravel. 50-80 cm; dark yellowish brown (10 YR 4/4) sandy clay loam; strong coarse angular blocky structure; extremely hard consis- tency; 10% 2-3 mm white gravelly flecks and gravel. 80-150; dark yellowish brown (10 YR 4/4) sand; structureless single grained; loose consistency; 10% gravel. 150-400; dark yellowish brown (10 YR 4/6) sand; structureless single grained; loose consistency; 10% gravel; 50% large brownish yellow (10 YR 6/8) mottles; moist. Btl Bt2 Bt3 C9 21 Table 5 Modal description of the clayey soil type. 0-5 cm; black (10 YR 2/1) sandy clay loam; weak coarse granular structure; soft consistency; many fine roots. 5-50 cm; dark grayish brown (10 YR 4/2) sandy loam; moderate coarse subangular blocky structure; soft consistency; common fine to coarse roots; 3% gravel. 50-60 cm; brown (10 YR 5/3) sandy clay loam; moderate coarse subangular blocky structure; soft consistency; 20% gravel. 60-230 cm; dark yellowish brown (10 YR 4/4) sandy clay loam; moderate medium subangular blocky structure; soft consistency; 30% gravel and cobbles. 230-280 cm; yellowish brown (10 YR 5/4) sandy clay loam; moderate medium subangular blocky structure; soft consistency; 30% gravel and cobbles; 30% yellowish brown (10 YR 5/8) medium mottles; moist. 280-300 cm; yellowish brown (10 YR 5/4) sandy clay; moderate, massive structure; hard consistency; 30% gravel; 30% yellowish brown (10 YR 5/8) medium mottles; moist. +300; grayish brown (10 YR 5/2) sandy clay; weak massive structure; soft consistency; 30% cobbles and gravel; saturated. AC C1 C2 C3 22 Table 6 Modal description of the rocky soil type. 0-13 cm; very dark gray (10 YR 3/1) sandy clay loam; weak medium granular structure; soft consistency; common coarse roots. 9-13 cm; very dark gray (10 YR 3/1) sandy clay; weak medium granular structure; soft consistency; 50% gravel and boulders. 9-23; dark grayish brown (10 YR 4/2) sandy clay; moderate medium subangular blocky structure; extremely hard consistency; 50% gravel and boulders. 23-63 cm; dark brown (10 YR 4/3) sandy clay; moderate medium subangular blocky structure; hard consistency; 50% gravel. +63 cm; dark brown (10 YR 4/3) sandy clay; strong massive structure; extremely hard consistency; 50% gravel and cobbles. A1 A2 Bt CB 23 Table 7 Modal description of the loamy soil type. 0-8 cm; black (10 YR 2/1) sandy loam; weak medium subangular blocky structure; soft consistency; common fine to coarse roots. 8-30 cm; very dark grayish brown (10 YR 3/2) sandy loam; moderate medium subangular blocky'consistency: hard structure; common coarse roots. 30-75 cm; brown (10 YR 5/3) sandy loam; structureless fine single grained; loose consistency. 75-90 cm; dark brown (10 YR 4/3) clay; strong medium subangular blocky structure; hard consistency. 90-135 cm; yellowish brown (10 YR 5/4) loamy sand, medium single grained structure; loose consistency; 30% coarse yellowish brown (10 YR 5/6) mottles. 135-150 cm; dark yellowish brown (10 YR 4/4) sand; medium single grained structure; loose consistency; moist. +150 cm; grayish brown (10 YR 5/2) sandy loam; medium single grained structure; loose consistency; saturated. 24 soil often occurred on outwash or in low areas of accumulation within a moraine system.' The sandy soil was usually but not always an Oshtemo series. The clayey soil was usually a Riddles series. The rocky and loamy soils were more variable. However, since soil chemistry was not investigated, these classifications are only tentative. Soil properties and topographic features were compared for the 30 sites. Qualitative variables were analyzed with a x2 contingency test. Quantitative variables were analyzed with linear regression. Drainage class, soil type (sandy, clayey, rocky or loamy, see Appendix Table II), soil series (taxonomy), depth of rooting, and depth to gleying, to saturation, to the least permeable layer, and to mottles had no apparent relationship with disease rating. The textures of the least permeable layer, A horizon and B horizon showed no apparent relationship to stand percent infection rating. If the C horizon was gravelly, the site was more likely to have severe disease than if it was sandy (P = 0.02, Appendix Table III). Topographic features were related to disease (Table 8). Sites that were more hilly, as measured by steeper microrelief, greater macrorelief index, higher elevation and greater percent slopes, had black walnut with greater nectria canker incidence (Appendix Tables IV - VIII). Also, if sites were in a low flat area, kettle bottom, or adjacent to wetlands, they were more likely to have black walnut with greater disease levels. Sites were considered to be adjacent to wetlands if they were within 200 m, and at similar elevations (:10 ft), of at least 1 acre of standing or slowly moving water. Generally, disease was not severe unless at least two of these factors were present. 0f the stands 25 h<4m mu emm a2 mzho O NH + o.m o a ma omm qz mzpo 0 m4 + HmH mmm DHcomfimommu maon Homaw< mcoHuHmoa umucmemz umeHmc axmocm mmcHHmc .o: u we m>onm mo muoe m oHsamcmoQOH mo locum: mmHHmc mmmmmwo ucoum mcauxmh comum>mHm HumomHu mucmmmca locum: mHHmocuHx .HHHLm>mm mmmmmwu mecoo eHLHum: o» cmchqu Hmmzzusom :H mucmum Hachz HomHa om mo mmcaummw uwgamcmoaou ecu HHom Ho awzmcoHHmHmm m mHnmh 26 .HmHm 3oH u u; .muon cmon uva .muon mHucHE u m: .muon Lmuuu u m: .HmHm uoH u upm .Lmumz was» up dam oHHV mcoHHm>mHm LmHHeHm um ecu cmumz mcw>os HHonm Lo muwucmum mo meow mco HmmmH Hm Ho .5 OON cmsqu mum: 5mg» CH Hcmmmcu mace—Hm: m>ms o» nmgmnmmcou mum: mcowumuouv .mHm>mH mmmmmwu saw; squ oH new mmmmmwv 30H :HHz mcwHHoL HHHcmLmuum oH .mmmmmwu on csz HmHm HHucmcmuum oH Co mwmmn mg» no :mmozu mum: mmuwmo .Hmmz new 520m .53 .578: m5 3 33m m5. so: 5.6.6 mmc: v.73 ..Hs N.H 9.on omcmuczoucm mmcz Lsoucou Hm ON Ho Lmae:c ms» mcwucsou an umcwmuno mmuHm> e No mmmgm>m ms» mm umHmquHmu mm: xmucw mmHHmma .umux n m ecu xmnuHm u m .uomumN u v .meumH u M £33 u N .umnH u H .28: u o "ucmum me» up Hucpmz xumHn co cmxcuo mHLHum: Ho coHHummcw Hcmuumu co ummmo mm: mcwumg mmmmmwom No.0 um umo uHm mw omu mH.o co.o owm ova omoH com com Cum 0mm ohm 4x 4x 4x Ax Ax uz No.0 mzko mzho zipm mZHm Hugh «th mzbo mzho F4ONC>GJ Hcmucmumc mgu mm: mcHHmL mmummwo .cowmmmummc cmmcHH Ha umNHHmcm mum: mmHamHLm> m>HHmHHHcm=o Hum—am» aucmmcmucou Low xwucmuu< mmmv mummH Hocmmcwucoo Nx Ha cmNHHmcm mum; mmHancm> m>HHoHHHm=os .quo u u .HHHm>mLm u w .Hxvccmm n mm .mme u xx .mHHme u Hx .xmmcu mo xcmu uou u H .cmHHHu Ho: u uz .omHuHu u u .mcmmuoz HmcHELmH mwmcuum u «25 6.33 I: u ._u.: .HmCmHmE umvocm mo :oHfimoumu umummuommm mcwmsos .... sumo .53sz6 u mafia.H HumscHHcoou N mHuaH 28 that had disease ratings of 6 (>75 percent infection), none were on south slopes or on high flat positions. 0f the 30 sites studied intensively, all of the stands which were in kettles or on moraine material had severe disease levels (>75 percent infection). North slopes, depressions and wetlands are places where cool air accumulates(cold pockets). To verify these trends, field notes and topographic quadrangle maps were used to determine if the site was located in uplands, wetlands, kettles or depressions for 189 survey sites in the five county area (Table 9). A site was considered to be an upland site if it was not a kettle, a depression or adjacent to a wetland. A stand was much more likely to have abnormally high disease levels (>5 percent infection) if it was adjacent to a wetland, in a kettle or a depression (£_<:CL0005), according to a x2 contingency test. However, not all wetlands, kettles and depressions had abnormally high levels of disease. Not all uplands had low levels of disease. There- fore, other unknown factors in conjunction with cold pockets may result in high levels of nectria canker on black walnut. Black walnut growing in central Pennsylvania was observed in the valley south of Tussey Mountain. This area included portions of Rothrock State Forest and Pennsylvania State University Experimental Forest near Masseyburg. The valley sloped downhill to the southwest between two large ridges. There are several smaller ridges in the center of the valley; Black walnut was abundant in the valley but not on the ridge tops. More than half of the trees observed had nectria cankers. In some places, every black walnut tree had multiple stem and branch cankers. Both open and closed cankers were observed. Perithecia 29 Table 9 Summary of the relationship between topography and stand percent infection rating of 189 nectria canker survey sites for black walnut in southwest Michigan. ‘Topography is significantly related to percent infection according to a X2 contingency test (_P < 0.0005). Stand percent Uplands Wetlands Kettles Depressions infection Number sites observed 0 86 4 O 4 1-5 21 7 1 8 6-15 2 4 1 6 16-25 0 4 1 5 26-50 1 5 0 6 51-75 0 5 0 5 >75 __1 .9 2 _1_ Subtotal 111 35 8 35 TOTAL = 189 30 were present on the callus layers of some open cankers. The soils appeared to be very clayey with many coarse, shaley fragments present. Elevations ranged from 1,000 to 2,000 feet above sea level for valley bottoms and ridge tops, respectively. At another site 40 miles to the northeast, several black walnut trees were observed in a valley named Porter Run. These trees also had multiple nectria cankers and were in a valley. Effect 9: Tree Vigor and Competition 1 a RUSS Forest Plantation The results of the individual tree measurements are summarized in Table 10. When all 2,718 tree observations were used, diameter and presence of open and closed cankers were positively correlated with disease (32 = CL40). However, this is an artifact of the dumby variable system used, since 0 cankers results in a rating of 0 for open and for closed cankers. To eliminate this complication, a second regression was done using only infected trees. This also eliminates any genetically resistant or escape trees. As Table 10 illustrates, dbh and canker shape (open and closed) were positively correlated to canker number and significant (P < 0.0005), but explained a small portion of variability when only infected trees were used (32 = 0.06). Whether or not the trees had adjacent clearings to the north or south and the trees'idistance to the creek as measured by row number were not significant in any of the regressions on canker number. Since most of the clearings were initiated recently (1981), perhaps the duration of the clearing treatment had not been long enough. The soil was characterized for 11 locations within the stand in the same manner as for the survey sites. No apparent differences were 31 .3890 v a 28:29... 3:35 memz mcewmmmemme HE .5533 msem mfi E emfiemme 5.5.63 use 5.52% mmwzumume .HoHAVHu.mV HceuHeHemHm He: memz Hes“ .emumHH He: mee memeceu emmeHe ee memxceo :mue .zeeem meg e» meweemHe .eueee ecu e» mcHeemHu .Hemesee 3eev xmmee ea meeeHmHe mmHeeHe: Hemecmumecw me» ems: .ceHHHeee ee emcee m5 5 emum: mee mmHeeHe: HemecmumecHe HHHee Nx memxeee emmeHu mmmeu emeemeemv Non.H - Heme.e + Hm.N " e No.0 Hx Imu mmee emu meexcae mx :mu Heed: meH.o + Nx memxeee emuo meeHHe>emmee HHev Nxe¢.e + erN.m + ee.e- u e oe.o Hx meexcae emmoHe weep emu memxcae ecewueaem ceHmmmemmu Na .ez mHeeHee> eAmqueeHee> mHeeHee> Hemeemuuo HemecmumecH .cemweeHz “megsueem :H eewueueeHu e eH mmmep HecHez xeeHe Heeew>mecw we mueem emeeee nee emesuc emecee .meweemHe .Hsmwm; Hmemee emHmEeHe .emeE:e 3ee ee meeHmmmemme eemcmH mHuHHHeE we Hee553m oH mHoeH 32 found in depth of rooting, depth to water table, depth to mottles and soil classification in relation to mean number of cankers per tree. Canker Dissections There is a two- to four-fold difference in actual canker number compared to apparent canker number (Table 1). This is partly due to poor visibility of higher portions of the tree, but mainly due to difficult-to-see closed cankers which were present on infected trees. All cankers were initiated after 1960, with peak years of infection 1978 to 1980 (Figure 5% As summarized in Figure 6, there was a higher frequency of infection for black walnut stem sections 19 to 27 years old, with peaks at 22 and 24 years old. Thirty-one percent of the cankers were associated with branch stubs and 0.5 percent with a wound from a boring insect. There was no apparent wound associated with infection for 68.5 percent of the cankers. Secondary flat-headed borers and ants were apparent in 3.5 and 1.0 percent of the cankers, respec- tively. They were usually associated with open cankers. Such insects could be responsible for creating wounds which would not be readily apparent. Trees infected with nectria grew more slowly after infection than before infection (Table 11). However, uninfected trees also exhibited a reduction in growth. The growth reduction for the bottom and top portions was greater in infected black walnut than in uninfected black walnut. Yet growth reduction in the middle portion was similar for infected and noninfected trees. Ranges in growth reduction for healthy and diseased trees overlap, indicating that nectria canker may not significantly reduce growth rates of black walnut. However, there are 33 24F- 'i‘H liOL "HFEKTTKNMS ~50 ‘65 ~7o * ~75 ~eo YEAR mesa-lees) Figure 5. Frequency of infection for 200 nectria cankers from 7 black walnut trees collected at Russ Forest Plantation 046. No cankers were initiated before 1961. 34 1111119511 or cnwxcns R; l 1 1 1 1 1 5 IO IS 20 25 30 35 40 AGE OF STEM SECTION (YEARS) 100 1- B 90- IO- 0F 70- 3: TOTA L CANKERS 60- 501- 40- 30F- 20- ACCUHULATIVE l0- 1 1 1 1 1 1 1 510152025303540 AGE OF STEMSECTION (YEARS, Figure 6. Relationship between age of black walnut stem tissue and A) frequency of nectria canker infection B) accumulative percent of total nectria canker infection for 200 trees. cewue>emmee mce Hemmmeume mmmeH emuemeewc: eee mmeHe> .mmeu we ceHueeu page :H memxeee empemmmweueee ee mememeeee ee xeeH eH mee mHeeHHe>e He: euee u e NN.oH mm.u +1 +1 mm.m¢ mH.mN Nn.wv H~.mN NN.mm Om.e¢ oe.om mu.om Ho.Nc NN.wm Hm.om NH.mm om.0m cemz mme» Nn.mH oe.mN ee.e em.em em.eN Heuee.em Heueu.H¢ HNHueH.ee Heuee.ee HNVNN.Ne Hmuee.em a- E’- ‘t -< E I 4- 9.‘ [III 8 F - E 3 ° ‘3 4 ( ,— )- 540- D “320»- ‘tg _ ‘2‘ a: 3360 0 1-4 0 o l ~00 0‘65 *~70 W75 ’ * ~00 YEAR (1960' l983) Figure 12. Relationship between year of nectria canker infection for 200 cankers, total May and August precipitation and average February and October temperature for 1960-1983 (32 = 0.67, g = <0.0005). N0 cankers were initiated before 1961. Precipitation and temperature were measured at Dowagiac, Michigan, 9 miles west of the cankered site, and compiled by the Michigan Weather Service in cooperation with the ESSA-Weather Bureau, LLS. Department of Commerce. 50 = 0.15). The number of days in the year during which maximum tempera- tures were less than 0° F did not explain the variability in number of infections (32 = 0.17, _P_ = 0.07). The same was true for the number of days in the year during which maximum temperatures were less than 32° F (32 = 0.08, P = 0.22) or were greater than 90° F (32 = 0.16, P = 0.08). Day degrees base 40, 45, 50 and 55° F were not significantly correlated with annual number of infections (3 = 0.10), nor were heating day degrees or cooling day degrees base 65° F (E = 0.10). When annual or February and October mean temperatures were cooler, disease was more severe. Cooler February and October temperatures could prolong the period of fungal activity and shorten the growing season of the tree. Cold temperatures in February could cause injury to the tree, providing more wounds for successful infection. However, the latter is unlikely since most cold injuries occur in late spring when the tree is active and can restrict growth of N; galligena. Cold pockets may have cooler mean February and October temperatures than do uplands. When May and August precipitation was greater, nectria canker infection was also greater. Ascospore release was greater when perithecia were wetted, especially when wetted and then dried (Lortie and Kuntz, 1963; Spaulding et al, 1936). Conidia were released during warm rains (Lortie and Kuntz, 1963). May and August are at the begin- ning and end of the black walnut growing season, respectivelyu A wetter May and August may result in increased spore release and infection frequency during a time when black walnut is not able to limit fungal colonization. Cold pockets may have wetter May and August conditions than uplands because of fog. Fog (100% relative humidity) would provide 51 wet conditions during the evening until early morning, with drying during the middle of the day. According to the Palmer Index, 1945 to 1964 were generally draughty years, with the exception of 1950-52 (Figure 13). The riSe in precipi- tation levels in 1964-1978 corresponded with occurrence of nectria canker since none of the 200 cankers were observed to occur before 1961. Perhaps moisture was not available for spore dispersal in adequate quan- tities for successful infection during susceptible periods before 1960. The climate of southwest Michigan is influenced by Lake Michigan. Annual temperatures are warmer than other parts of Michigan (Figure 14). Thus, winter and fall temperatures are more moderate since lake effects are greatest in fall and winter. These moderate temperatures could result in an increased period of pathogen activity caused by a shorter time period during which temperatures are too low for fungal activity. fiL_galligena spores can be released, germinate and grow at temperatures as low as 0° C (Ashcroft, 1934; Lortie, 1964; Lortie and Kuntz, 1963). However, it is not certain if these temperature differences are enough to be significant. The diseased area also lies within a zone known as the "Snow BeltJ' This region is characterized by increased annual precipitation and _ cloudiness, especially in the fall and winter (Figures 15 and 16). This results in an increased frequency of snow and ice storms in this region. The "Snow Belt" occurs parallel to Lake Michigan and somewhat inland from the lake. Black walnut trees were often severely cankered on sites where frequent snow and ice storms occurred (Brandt, 1964; Grant and Childs, 1940; Roth and Hepting, 1954). Wounds at branch crotches, made Figure 13. 52 l WET WET WET INDEX NORMAL DRAUGHT DRAUGHT DRAUGHT PALMER 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 YEAR (19444973) Palmer meteorological draught index for the southwest lower climatic division in Michigan (1944-1978). (From Nurnberger, 1980.) 53 50 lflL Figure 14. Annual mean temperature of southern Michigan (°F), 1940- 1969, published by the Office of Climatology, Michigan Department of Agriculture, East Lansing. 54 50 rni. Figure 15. Annual mean snowfall of southern Michigan (inches), 1940- 1969, published by the Michigan Weather Service, East Lansing. 55 e_______; 50 NH. 34 32 Figure 16. Annual mean precipitation of southern Michigan (inches), 1940-1969, published by Office of Climatology, Michigan Department of Agriculture, East Lansing. 56 when heavy loads of ice or snow, bend or break branches, may be infection courts for nectria canker (Grant and Spaulding, 1939; Lortie, 1969). Increased fall precipitation may result in increased spore release and infection while the tree is dormant, as discussed earlier. Several workers report that trees were able to close over cankers when soils were fertile (Gravatt, 1933; Brandt, 1964). In Michigan, un- published data from a study by Robertson et al (1975) indicated that soil fertility may be low, especially for calcium levels, within the region of abnormally high nectria canker incidence (greater than five percent infection of black walnut per stand) as illustrated by Figure 17. The same study indicates that soil pH also may be low for the diseased area (Figure 18). Many nutrients, including calcium are less available to plants in acid soils. Trees growing on poor soils will resume growth later in the spring and become dormant earlier in the fall. This decreased growing season could allow a longer period of activity for N; galligena to infect and colonize its host. The location of the region of high nectria canker incidence could be a result of the intersection of the "Snow Belt" with the occurrence of acid, infertile soils. Similar soil and climatic factors could be involved in Pennsylvania. The valleys are regions of high fog frequency in the fall and high ice storm frequency in the winter. Both the Michigan and Pennsylvania sites overlie early Mississippian shales which are usually low in pH and cal- cium levels (personal communication, Dr. H. A. Winters, Dept. of Geo- graphy, Michigan Sate Universityh Therefore, it appears that conditions which shorten the host growing season and/or lengthen the period when the fungus is active, contribute to nectria canker severity on black walnut. 57 1571 -T__- -_- --’ --' I—-' 1300 | | 1440 309' izno Lam: | nu: I I ' I ""'"' "'"'"l 706 2,52 6 0 °' . I l I 1,129 l Figure 17. Summary of calcium levels (lbs/acre) of the C horizon in southwest Michigan (adapted from Robertson et al, 1975L Regions where more than 5% of black walnut per stand were infected with nectria canker are outlined. 58 Figure 18. Summary of pH levels of the C horizon in southwest Michigan (adapted from Robertson et al, 1975). Regions where more than 5% of black walnut per stand were infected with nectria canker are outlined. 59 Cultural morphology of §£_heteronema indicated no differences between closed and open canker isolates. However, studies were not extensive and further studies should include accurate pathogenicity tests. Differences in tree genetic background were not investigated on an individual tree basis. Such differences could be responsible for the shape of the canker. The Russ Forest Plantation D-46, which has many infected black walnut trees, is probably from seed from the Chicago area; however, records are vague. If the stock is foreign, it is unlikely that diseased regions occur in southwest Michigan because of an especially susceptible native gene pool in that area. However, genetic resistance or immunity should be investigated in future studies. In summary; there was preliminary evidence which indicated that poor soil fertility, cooler temperatures and increased precipitation or relative humidity may result in increased disease severity. It is possible that these factors or other unknown factors, such as differences in fungal virulence or host susceptibility result in pockets of high nectria canker incidence on black walnut. Now that we have some of the baseline data needed, the time is ripe to initiate detailed studies concerning the role of environment in nectria canker of black walnut. BIBLIOGRAPHY BIBLIOGRAPHY Anderson, R. L. and D. G. Mosher. 1979. Lakeshore effect on Nectria canker of yellow birch. J. For. 77:412-413. Ashcroft, J. M. 1934. European canker of black walnut and other trees. W. Vir. Agric. Expt. Sta. Bull. 261. 52 p. Brandt, R. W. 1964. Nectria canker of hardwoods. U.S. For. Serv. Forest Pest Leaflet 84. 7 p. Cayley, D. M. 1921. Some observations on the life-history of Nectria galligena.Bres. [hue Bot.35:79-92. Dubin, H. J. and H. English. 1975a. Epidemiology of European apple canker in California. Phytopathology 65:542-550. Dubin H. J. and H. English. 19750. Effects of temperature, relative humidity and desiccation on germination of Nectria galligena conidia. Mycologia 67:83-88. Galloway, B. T. and A. F. Woods. 1896. Diseases of shade and ornamental trees. U.S. Dep. Agric. Yearbook 237-254. Grant, T. J. and T. W. Childs. 1940. Nectria cankers of northern hardwoods in relation to stand improvement. J. For. 38:797-802. Grant, T. J. and P. Spaulding. 1939. Avenues of entrance for canker- forming Nectrias of New England hardwoods. Phytopathology 29:351- 358. Gravatt, G. F. 1933. Nectria canker in the southern Appalachians. Pl. Dis. Rep. Suppl. 85:62-64. Graves, A. H. 1919. Nectria canker of sweet birch. Mycologia 11:113- 117. Hartig, R. 1880. Der Krebspilz der Laubholzbaume. Nectria ditissima Tul. Untersuch ungen a. d. forst-botanischen Institute Munchen 1:109-128. (From Spaulding et al.) Kienholz, R. and C. B. Bidwell. 1938. A survey of diseases and defects in Connecticut forests. Com. Agric. Expt. Sta. Bull. 412. 493- 559. 60 61 Kress, L. W. and F. A. Wood. 1974. Some observations on the occurrence of Nectria canker on Sassafras albidum. Amer. Phytopath. Soc. Proc. 1:152 (Abst.). Lohman, M. L. and A. J. Watson. 1943. Identity and host relations of Nectria species associated with diseases of hardwoods in the eastern states. Lloydia 6:77-108. Lortie, M. 1964. Pathogenesis in cankers caused by Nectria galligena. Phytopathology 54:261-263. Lortie, M. 1969., Inoculations of Nectria galligena on northern hardwoods. Fonds. Rech. Forest Univ. Laval Contrib. 13:3-31. Lortie, M. and J. E. Kuntz. 1963. Ascospore discharge and conidium release by Nectria alli ena Bres. under field and laboratory conditions. Can J. Bot. 41:1203-1210. Martin, H. M. 1955. Map of the surface formations of the southern penninsula of Michigan. Mich. Geol. Survey Division Publ. 49. Merrill, W. and R. J. Finley. 1981. Relationship of stem tissue age to frequency of Nectria canker. Pl. Dis. 65:66-67. Nelson, R. M. 1940. Vigorous young yellow poplar trees can recover from injury by Nectria cankers. J. For. 38:587-588. Ng, K. T. and E. T. Roberts. 1974. Pathogenicity of Nectria galligena. Plant Pathol. 23:49-50. Nurnbberger, F. V. 1980. Meteorological draught in Michigan: A review of the past 50 years. Conference on Supplemental Irrigation: Advantages and Disadvantages, Michigan State University. 21 p. Robertson, L. S., D. L. Mokma, and D. D. Warncke. 1975. Test levels in soil profiles of Michigan corn fields. Mich. State Univ. Res. Rep. 281. 8 p. Roth, E. R. and G. H. Hepting. 1954. Eradication and thinning tests for Nectria and Strumella canker control in Maryland. J. For. 52:253-256. Spaulding, P., T. J. Grant, and T. T. Ayers. 1936. Investigations of Nectria diseases in hardwoods of New England. J. For. 34:169-179. Welch, D. S. 1934. The range and importance of Nectria canker on hardwoods in the northeast. J. For. 32:997-1002. Zeller, S. M. 1926. European canker of pomaceous fruit trees. Oregon Agric. Expt. Sta. Bull. 222. 52 p. GLOSSARYa Basal area (FL The sum of the areas of cut stump surfapes that would be exposed if all trees were felled, usually in ft lacre. This may also be used to apply towards one tree's cut surface area (Basal diameter) Clay films (S). A layer of clay covering the surface of a "clod" of soil or ped. This layer is deposited as water-carrying clay moves through the soil. Consistency (S). The resistance of soil to disruption. A soil's cohesion or adhesion to itself. Levels range from loose to soft to hard. Dbh or diameter at breast height (F). Diameter of the trunk of a tree at breast height. By convention, this is 4.5 ft. above the soil line. Drainage class (S). The aeration level of the soil based on depth to mottles and subsoil color. Poorly drained = depth 6-20 in., subsoil mottled gray and yellow; moderately well drained = 20-40 in.; well drained = >40 in. Glacial till (G). Unstratified or unsorted rock and soil deposited by the ice of a glacier. May have any proportion of sand, clay, silt and rocks. Gleyed soil (S). Soil that is gray-colored due to long term saturation under anaerobic conditions. The soil minerals are in a reduced state. Mottles may be present. Gleyed soils are often colder because of their greater specific heat. Kame (G). A steep sided knob-like hill of stratified soil or rock layers formed when water runs into a hole in the ice of a glacier. They are associated with interlobate moraines. Lacustrine material (G). Materials (usually fine textured) deposited from standing or ponded water. Associated landforms are flat or gently sloping. Microrelief (G). Small-scale, local differences in topography of the site. 62 Moraine (G). Deposits of glacial till, usually in hills or ridges, are formed at the margin of a moving ice sheet or when the backward melting equals the forward advance of ice. Moraine slopes are generally steeper than till plain or outwash slopes. End moraines or terminal moraines mark the furthest advance of the glacier. Mottles (S). Spots or blotches in soil of one color interspersed in a matrix of another shade or color. Color differences are a result of differences in aeration levels (air bubbles) or wetted soils. Mottles are used to determine the wetness and drainage class of a $01 . Outwash (G). Material carried from the glacier by water and laid down in stratified deposits sorted into similar textures. Outwash plains are gently rolling (non-pitted) to rolling (pitted). Parent material (SL The unconsolidated and chemically weathered material from which a soil forms by pedogenic processes. Structure (5). The grade size and shape of peds or "clods" of a soil. Grade ranges from none to weak to strong. Size ranges from very fine to medium to coarse. Shape ranges from massive to plately to columnar to blocky to granular to single grained. Surface geology (G). Landforms on the earth's surface, such as moraines, till plains, outwash plains, etc. Texture (S). The relative proportions of sand, silt and clay in a soil. The presence of gravel, cobbles or boulders is also incorporated into the textural class. Common textures are sand, sandy loam, sandy clay loam, silty loam, gravelly clay, etc. The textural categories are determined by established standards. Till plain (G). Deposits of glacial till, usually level to rolling, spread out between moraines while the glacier is rapidly retreating or melting. aTerms followed b (S) are soil terms. Those followed by'(F) are forestry terms; (G) are geology terms. The reader is referred to any basic textbook for more information. A few are listed here. Foth, H.IL 1978. Fundamentals 9: soil science. Publ. John Wiley and Sons, Inc., New York, New York. T6th Ed. 436 p. Leet, L. D. and S. Judson. 1971. Physical eolo . Publ. Prentice- Hall, Edgewood Cliffs, New Jersey. 4th Ed. 587 p. Forbes, R. 0. ed. 1961. Forestry handbook. Publ. Roland Press C0., New York, New York. 1143 p. APPENDIX 64 Table I Summary of the relationship between glacial deposition and stand percent infection rating in X2 contingency tests of 166 nectria canker survey sites for black walnut in Cass, St. Joseph, Van Buren and Kalamazoo counties. Stand percent Terminal Till Glacial infection moraine ‘plain Outwash drainage/lacustrine Number of sites observed 0 15 8 44 6 1-5 13 4 14 4 6-15 6 2 6 0 16-25 6 2 2 0 26-50 7 1 0 51-75 7 1 2 0 >75 _e .1. .11 .9. 62 19 75 10 x2 = 28.781 3 = 0.05 65 Table II Summary of the relationship between soil type and stand percent infection rating in x2 contingency tests of 30 nectria canker survey sites for black walnut in southwest Michigan. Stand percent infection Sandy Clayey Rocky Loamy Number of sites observed 0 5 2 0 0 1-5 5 . 4 2 2 >75 _e e _1_ 1 15 9 3 3 x2 = 3.150 g = 0.79 Table III Summary of the relationship between C horizon texture and stand percent infection rating in x2 contingency tests of 21 nectria canker survey sites for black walnut in southwest Michigan. Number of sites observed Stand percent infection Gravelly ISQng 0 1 5 1-5 6 2 >75 _6 ‘1 13 8 x2 = 7.471 g = 0.02 67 Table IV Summary of the relationship between micro- relief and stand percent infection rating in x2 contingency tests of 30 nectria canker survey sites for black walnut in southwest Michigan. Stand percent infection Flat Rolling §£ESE Number of sites observed 0 6 1 0 1-5 4 9 0 >75 _e .0 e 14 10 6 x2 = 24.207 3 = 0.0005 68 Table V Summary of the relationship beween wetland association and stand percent infection rating in x2 contingency tests of 30 nectria canker survey sites for black walnut in southwest Michigan. Stand percent infection (:1 91 Sites observed 0 4 3 1-5 11 2 >75 _4 _g 19 11 x2 = 4.996 g,= 0.08 Table VI 69 Summary of the relationship between slope position and stand percent infection rating in X2 contingency tests of 30 nectria canker survey sites for black walnut in southwest Michigan. Stand percent Upper Upper Middle Lower Lower infection .flat_ .glgpe slope_ slgpe .flgt_ Number of sites observed 0 4 0 1 1 1 1-5 2 5 2 2 2 >75 9 1 .3. .1. 9 6 6 6 4 8 x2 = 15.029 3 = 0.06 70 Table VII Summary of the relationship between aspect and stand percent infection ratinginx2 contingency tests of 23 nectria canker survey sites for black walnut in southwest Michigan. Stand percent infection North East South West Number of sites observed 0 1 2 2 0 1-5 4 2 4 1 >75 3 _1_ 9. 3 SD 01 CS 00 x2 = 6.80 g = 0.34 71 Table VIII Summary of the relationship between mode of glacial deposition and stand percent infection rating for x2 contingency tests of 30 nectria canker survey sites for black walnut in southwest Michigan. Stand percent infection Lacustrine Kame Outwash Moraine Till plain Number of site observed 0 1 0 6 o 0 1-5 1 1 4 o 7 >75 9 9. _9 9 .1. 2 1 16 3 8 x2 = 17.815 3 = 0.02 MICHIGAN STATE UNIV. LIBRARIES lWWIWilli“ImmIllllIlllllIIIWIIIWINIH”HI 31293008091385