EASTERN WHITE PINE PLANTATION ASSESSMENT FOREST MANAGEMENT DISTRICTS 1, 2, 5, 7, 8, & 14 by Jeff Motty, Forester II

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1 No. 71, March, 2004 FOREST RENEWAL FOREST IMPROVEMENT NURSERIES TREE IMPROVEMENT MISC. EASTERN WHITE PINE PLANTATION ASSESSMENT FOREST MANAGEMENT DISTRICTS 1, 2, 5, 7, 8, & 14 by Jeff Motty, Forester II ABSTRACT In the summer of 2003, a survey was conducted of white pine plantations established across Newfoundland between 1993 and Of 2476 trees surveyed 71.4% were deemed healthy, 18.1% were lethally infected, and 10.4% were dead. White pine blister rust infected 35.9% of living trees, and was responsible for 88.3% of the mortality captured in this survey. Each tree was assessed by its lowest infection on the stem, branch or both. Of the assessed trees, 90.6% of the lowest stem infections were less than 25 cm from the forest floor, and 88.0% of the lowest branch infections were less than 25 cm from the forest floor. INTRODUCTION White pine blister rust (WPBR), an introduced fungus from Europe, is a serious tree disease affecting eastern white pine throughout its entire range. The disease intensity varies throughout the entire range but is most severe where late summers (July- September) are cool (below 19.4 O C) and damp, conditions necessary for blister rust infection. The main hosts of this fungus include five- needle pines such as white pine and various Ribes species including currants and gooseberries. In order for this fungus to complete its life cycle it requires both hosts and cannot spread from pine to pine. In an effort to increase the status/abundance of eastern white pine in the province of Newfoundland and Labrador the Newfoundland Forest Service (NFS) has been mixture planting low percentages of white pine with other species in their plantations. WPBR Distribution Since the introduction of white pine blister rust in Newfoundland and Labrador it has infected white pine trees throughout is entire range. NEWFOUNDLAND FOREST SERVICE

2 WPBR Identification On Ribes Symptoms of white pine blister rust on Ribes in the spring appear as tiny yellowish spots visible on the upper surface of the leaves, or as orangeyellowish blister-like fruiting bodies that appear on the underside of the leaves. By late summer, yellow to brownish threadlike growths develop on or near these infection spots on the leaf. Infected Ribes bushes are susceptible to premature defoliation. On White Pine Symptoms of infection in white pine trees include: springtime cankers that are surrounded by orange colored spore masses; chlorotic foliage; branch or stem girdling by lesions that exude resin; diamond-shaped cankers with a dead center surrounded by yellowish green infected bark; dead branches (red flagging) (Figure 1). WPBR Life Cycle Through the duration of the rust s life cycle the fungus will produce five different types of spores. Two of these occur on pine and the other three on Ribes. Infection of white pine occurs when the rust spores germinate and penetrate the needles of the pine. The infection moves from the needle into the bark, then into the branch or twig and finally into the main stem. Once infection occurs on a white pine tree a one to three year incubation period will follow. Over this time period a rough bark canker will develop. Clear fluid containing pycniospores is produced on the margins of such cankers. Pycniospores have only a sexual function and are unable to create new infections on either host. In early spring, after a short incubation period, orange yellow blisters develop which house millions of aeciospores, which are unable to infect pine. These spores are carried by wind to infect Ribes species. These spores are long lived and can travel up to 160 kilometers (Atlantic Forestry Center, 2003). Once Ribes have been infected by aeciospores, yellowish blisters develop on the undersurface of the leaves containing urediniospores which spread the disease on Ribes. Several generations of urediniospores may be produced during one growing season spreading the disease throughout the Ribes population. Figure 1. Red flagging in a young white pine. In late summer to early fall teliospores, small hairlike columns of spores, develop on the undersurface of Ribes leaves. Germination of teliospores produces basidiospores which have the ability to infect pine, thus completing the life cycle. The effective range of basidiospores is 300 meters (Atlantic Forestry Center, 2003). WPBR Damage White pine blister rust is damaging to pine trees of 2 NEWFOUNDLAND FOREST SERVICE

3 all ages. Cankers will girdle a tree at the point of infection and ultimately kill the tree beyond this point. Stem cankers that produce large dead tops will eventually weaken the stem enough so the top breaks off at the girdling point. In older trees the infection is frequently isolated to upper portions of the crown. This results in only the upper portion of the tree dying. Unfortunately, younger trees are subject to infection below 2.5 meters (Figure 2), and infections of young pine at low heights are detrimental and often lead to the death of the tree. Thus, white pine blister rust severely affects regeneration of young white pine. During the field season of 2003, field crews visited plantations in six Districts across the island. Circular 100 m 2 sample plots were established in each of the plantations of interest. Plot interval was a function of plantation size, and commonly ranged between 25 and 50 meters. Each plot was surveyed for the following: Slope position - Top, upper, mid, lower, bottom, no slope; Topography - Flat, undulating, rolling, hilly, mountainous; Aspect - North, northeast, northwest, east, west, south, southeast, and southwest; Ribes - Presence or absence; and Indicator species - Ground vegetation. Planted white pine trees that fell into the plot were assessed for the following: Figure 2. A White Pine Blister Rust canker that has girdled the tree and is slowly killing all the foliage above the infection point. METHODOLOGY Prior to the 2003 field season, Wooddale Provincial Tree Nursery shipping reports between 1993 and 1999 were queried to determine what projects in this time frame had received white pine seedlings from the nursery. This list formed the basis of the 2003 white pine plantation survey. In instances where species-specific mapping was not available in the silviculture registry, District staff was contacted for certain mapping requirements. Status - Alive (healthy or non-life threatening infection), lethally infected, dead; Cause of death - Microsite, frost, white pine blister rust, inconclusive; Damage - None, snow, insect, animal browsing, wind drying, microsite, frost, chlorotic needles, other; White pine blister rust - Yes or No; Infection point on the stem - Lowest infection point on the main stem (0-25, 26-50, 51-75, , 100+ centimeter classes above ground level); Infection point on branches - Lowest infection point on any branches (0-25, 26-50, 51-75, , 100+ centimeter classes above ground level) ; Presence of recovery shoots below the lowest infection point of origin - Yes or No; Tree form - Well formed, forked, multiple stems, lateral takeover; and Tree height of uninfected trees - Tree heights were recorded in centimeters for the 2002 and 2001 growing seasons. Trees that fell into the category of severely deformed were not recorded. 3 NEWFOUNDLAND FOREST SERVICE

4 In instances where white pine tree density was not high enough, an alternative sampling method was employed. Trees were sampled along a 5 meter wide transect (2.5 meters either side of the line). Site information was generalized for the entire transect and individual tree information collected remained the same as described above. Planted white pine encountered in the survey was classified as either living or dead. Those classified as dead were excluded from all other analysis except for cause of death. The trees classified as living were further classified as either (1) healthy or (2) lethally infected. The healthy designation captured not only those trees that were blister rust-free but also infected trees that appeared likely to recover. Typically, these trees had one or more live, healthy limbs below the stem infection point from which a new stem could develop. Lethally infected trees had stem cankers below which there were no recovery limbs. Such trees are unlikely to survive. Each tree was assessed to determine the lowest infection on the stem, branch, or both. Infection height (cm) was analyzed by height classes above the forest floor and by infection location (stem or branch). The height classes are identified above. methodology section. Of the surveyed trees, 71.5% were deemed to be healthy. The results indicate that 18.1% of the seedlings surveyed are dead, while another 10.4 % are lethally infected for a total of 28.5 % that are dead or dying due to infection. Figure 3. Tree health status. Healthy also includes trees with non-lethal infections. The result s presented in Figure 4 illustrate that white pine blister rust is accountable for 88.3 % of white pine seedling mortality in plantations surveyed. The other causes of mortality combined account for 11.7 %. RESULTS / DISCUSSION It is important to note two points of interest prior to presenting the results. First, in some instances white pine seedlings were not evenly mixed throughout the plantations but rather were planted in groups or rows. Second, since there was no prior information on planting density or distribution it was impossible to determine the actual mortality of white pine seedlings within the plantations. The results of the province wide assessment of white pine blister rust has been summarized in a series of charts and graphs. Figure 3 indicates the breakdown of tree health status according to the three categories previously described in the Figure 4. Cause of death. Figure 5 depicts the incidence of infection in surviving trees, healthy and lethally infected. The 4 NEWFOUNDLAND FOREST SERVICE

5 provincial average of living trees surveyed with white pine blister rust infection is 35.9 %, while 64.1% are free of blister rust. on average, 49.8% of infected white pine had infections on both the main stem and branch followed by stem only (36.2%), and branch only (14.0%). Figure 5. White Pine Blister Rust incidence. Living trees, healthy and lethally infected, only. Figure 7. The location of the lowest infection site by stem or branch. Figure 6 illustrates the location of the lowest white pine blister rust infection by height class and site (main stem and branches). The lowest infection was surveyed because it is believed that lower infection height increases the severity of infection and often results in higher mortality. Of the stem infections surveyed 90.4 % were less than 25 cm from the forest floor, and 88.0 % of branch infections were less than 25 cm from the forest floor. All of the lowest infections recorded were within 1 meter of the forest floor. The proportion of stem infected white pine that has the potential to recover (i.e., a recovery shoot below the infection) from the current infection is 37.7% (Figure 8). Consequently, 62.3% will not recover from their current stem infection. Figure 6. The incidence of stem and branch infections by height class Figure 7 indicates the incidence of infection by stem, branch or both. It is interesting to note that, Figure 8. Stem infected white pine with and without recovery shoots (i.e., live, healthy, uninfected limbs below the lowest infection). Figure 9 illustrates the distribution of tree form encountered over the course of this survey. Well- 5 NEWFOUNDLAND FOREST SERVICE

6 formed trees accounted for 54.9% of trees surveyed followed by severely deformed trees (15.4%), trees with lateral takeovers (13.1%), trees with multiple leaders (9.2%), and forked trees (7.2%). Figure 9. Tree form of living trees (i.e., healthy and lethally infected). Tree damaging agents other than blister rust accounted for 23.9%(Figure 10). The three major tree damaging agents includes: animal browsing (9.6%), snow damage (4.3%) and mechanical damage of undetermined origin (4.3%). Figure 10. Tree damaging agents by category for all living trees (i.e., healthy and lethally infected). CONCLUSIONS / RECOMMENDATIONS According to the results, 64.1% of the 2219 living white pine seedlings encountered in the survey were not infected with white pine blister rust. Of the remaining 35.9%, 10.2 % are dead or lethally infected, and 25.7% are healthy. With all of the lowest infections within one meter from the forest floor it indicates that white pine blister rust will greatly affect future growth of plantations. It is believed that the small needle to the main stem ratio (the distance that the white pine blister rust infection has to travel in order to infect the main stem) in seedlings increases the severity of infection. The implications of this are twofold: infected white pine will have little chance to recover from infection resulting in heavy mortality; and early infections arising from on the needles directly on the main stem or young branches will have little chance of being managed through pruning. Since pruning of very young seedlings is not productive, it would be beneficial to examine alternative white pine regeneration efforts. Some simple but effective management strategies should be employed in the establishment of future white pine plantations. Considering the eradication of Ribes species on a landscape level is unattainable, the following recommendations should be applied to plantation establishment: Where practical, apply herbicide to planted areas and areas near white pine plantations in an effort to to reduce the local Ribes population. White pine seedlings should be treated with a registered fungicide prior to leaving the tree nursery. Plant white pine in low hazard locations such as dry nutrient poor sites where Ribes are less likely to occur; Reduce potential losses by not planting white pine in small openings or low-lying areas, particularly where cool, moist air may settle. Generally these areas are favorable to disease development; and Decrease losses by mixture planting white 6 NEWFOUNDLAND FOREST SERVICE

7 pine with other species that are not suscepible to white pine blister rust. The additional species will act as barriers to spore dispersal and also ensure that all is not lost if white pine blister rust mortality is high. In addition to the plantation establishment strategies, it is equally important to tend to future growth and health of these stands. The following stand tending recommendations are made. Prune off infected branches 30 cm below the infection point if possible. Stands may have to be pruned as soon as the first m of branches could be removed while retaining the top two or three whorls (Hunt, 1998). It is important to leave material on site to decrease spore circulation in plantations; Studies on thinning treatments demonstrate that thinning alone increases susceptibility to white pine blister rust, but pruning and thinning combined is effective in reducing white pine blister rust (Hynes, 2003). If a plantation is scheduled to be thinned or spaced, pruning should be completed at the same time; and Monitor young white pine plantations for white pine blister rust incidence, and encourage research into new silvicultural treatments. ACKNOWLEDGEMENTS The author wishes to extend thanks to several individuals who assisted with this province wide assessment of white pine plantations. Basil English and Wayne Kelly, with the Newfoundland Forest Service, for technical assistance and editing of this report. collection. The assistance of Frank Skeard, Bert Frampton and District staff from across the province who aided in species-specific mapping and locating White Pine plantations to assess. REFERENCE MATERIAL Atlantic Forestry Center White Pine Blister Rust. index-e/what-e/science-e/forestconditions-e/fore stpestinfo-e/whitepineblisterrust-e.html Hynes, P Impact of PCT and pruning on the growth and blister rust susceptibility of juvenile, naturally regenerated white pine. Silviculture Notebook. Silviculture and Research Section, Corner Brook, NL, A2H 6J8. No. 67 Hunt, R. S Pruning western white pine in British Columbia to reduce white pinr blister rust losses: 10 - year results. West. J. Appl. For. 13(2): Hunt, R.S Can solid deer protectors prevent blister rust from attacking white pines? Can. J. Plant Pathol. 24: Van Ardsel, E.P., Riker, A.J., and Patton, R. F The effect of temperature and moisture on the spread of white pine blister rust. Phytopathology. 46: Wagner, R.J., Colombo, S.J Regenerating the Canadian Forest. Principals and Practice for Ontario. Fitzhenry & Whiteside Limited. Markham, ON, Canada. 472 pp. Ray Warren, Paul Hynes, Randy Hackett, Dion Rideout, David Balsom, and Jim Vokey, with the Silviculture and Research Section, for data 7 NEWFOUNDLAND FOREST SERVICE

8 This report has been prepared by Silviculture and Research Section, Forest Ecosystem Management Division, Newfoundland and Labrador Department of Natural Resources, P.O. Box 2006, Corner Brook, NL A2H 6J8 Supervisor:... Wayne Kelly Foresters:... Eric Earle, Jeff Motty Special Projects Officer:... Ray Warren Conservation Officer III:... Randy Hackett, Paul Hynes Conservation Officer II:... Dion Rideout, David Balsom, Jim Vokey Secretary:... Catherine Head For further information regarding information contained in this report please contact Jeff Motty, Forester II, at the above address, by phone at (709) , by facsimile at (709) , or by at 8 NEWFOUNDLAND FOREST SERVICE