Symbiotic Systems NZ Ltd

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1 Symbiotic Systems NZ Ltd Removing a significant constraint limiting the diversity of the forestry estate SFF Grant 05/142 Ian R. Hall and Chris Perley Background information on the project and some results to date - 30 June 2006

2 Symbiotic Systems NZ Ltd 2006 P.O. Box 7116, Dunedin, New Zealand telephone mobile: Fax: chris@perleyandassoc.co.nz web 2 Front cover: Mycorrhizas on Nothofagus

3 Contents 1 Summary 4 2 Introduction The New Zealand forestry estate Mycorrhizas More on mycorrhizas Types of mycorrhizas 7 3 Initial findings 10 4 Nothofagus raised in soilless media 11 5 Douglas fir bare root nursery trial The situation in Finland 15 6 Endomycorrhizal inocula 15 7 References 16 Appendix 1. Some arbuscular mycorrhizal species. 17 Appendix 2. Some ectomycorrhizal species. 19 Appendix 3. Effects of fungicides on containerised plants in Finland. 20 3

4 1 Summary Background information on deficiencies in New Zealand s forestry estate is outlined. The association most plants have with mycorrhizal fungi is also described and the possibility poor growth of speciality timber species in the past may not have been as good as it might have been in New Zealand because of a lack of effective mycorrhizal fungi. We also outline the first 8 months of work on SFF Grant 05/142 Removing a significant constraint limiting the diversity of the forestry estate. The high rate of application of nutrients and fungicides in some nurseries, at least in part, accounts for the poor development of mycorrhizas on nursery stock. These rates are driven partly by economic necessity but also to achieve healthy looking plants that meet industry standards irrespective of whether plants are well infected with mycorrhizas or not. In a greenhouse trial at Oregon Nursery, Oamaru, good mycorrhizal infections have been established on Nothofagus menziesii using techniques that could be employed commercially. Douglas fir seedlings in a bare root nursery with a range of rates of applied nutrients were inoculated with the mycorrhizal fungus Rhizopogon parksii. Three months after inoculation no infections were detected. This may have been due to routine preventative applications of fungicides once every 10 days, a problem that has also been identified in Finland. Arbuscular mycorrhizal inocula have been prepared for experiments on redwoods, cypresses and other specialty timber species.

5 2 Introduction 2.1 The New Zealand forestry estate Over the past 50 years the New Zealand forestry industry has become increasingly dependent on structural and industrial timber (lumber and pulp furnish) in general and radiata pine timber in particular, at a time when our competitive advantage in forest growing is reducing. This lack of estate diversity: decreases our competitive and comparative advantage, increases the biological and market risk profile of the total forest estate, reduces future market and economic flexibility especially related to high value products that are more economically transportable as energy costs rise, reduces regional development and sustainable land management options, and increases social risks associated with the public perception of forests as largely unattractive producers of industrial products with no other values. While the plantings of Douglas-fir and Eucalyptus experienced an encouraging increase through the 1990s, the structure of the estate still lacks diversity. This is especially the case when considering higher value finishing timber, a position made worse by the rapid decline in the availability of native timber over the last two decades. This lack of diversity has been met by the importation of timbers sourced from often unsustainable forest management practices in Southeast Asia. 2.2 Mycorrhizas Mycorrhizas are an intimate association between plant roots and specially adapted mycorrhizal fungi. All trees are completely dependent on mycorrhizal fungi for their mineral nutrition, and in particular phosphorus. Mycorrhizas also help prevent root diseases. It is, therefore, essential to ensure that plantation forest trees become infected with effective mycorrhizal fungi either in the nursery or just after outplanting. Some plants also require the right mycorrhizal fungi to grow, i.e. there is specificity of plant for fungus and fungus for plant. For example, a radiata pine mycorrhizal fungus may not infect a speciality timber species, and even if it did the mycorrhiza may fail to produce an adequate growth response. A significant reason for the dominance by radiata pine in New Zealand is the poorer establishment success of other species. In the late 1950s Gilmore (1958) recognised that the poor growth of Douglas fir was due to a lack of mycorrhizal fungi. Many other speciality timber species, such as the stringybark eucalypts, also struggle in New Zealand when compared to their successful performance overseas and it is quite possible that this too is due to a lack of correct mycorrhizal fungi. As a consequence, eucalypts generally are being planted on more fertile soils normally reserved for farming, whereas they ought to be able to perform on soils more akin to those in their home environment. Spontaneous mycorrhizal infections that are formed by mycorrhizal fungi resident in a bare root nursery or spores that might blow into a greenhouse through vents and doors cannot be relied upon to ensure the correct and adequate mycorrhizal formation. This is particularly important with plants raised in containers where the soilless potting mixes used are invariably devoid of mycorrhizal fungi. A recent quote from a New Zealand nurseryman illustrates this false, yet commonly held assumption:

6 ..currently our nurseries have good mycorrhizal populations, including our containers, which we feel is a result of the proximity of the outside conditioning area to open ground beds, allowing for mycorrhizal infection. Such a lack of understanding and a failure to ensure adequate mycorrhizal formation of Douglas fir in a bare rooted nursery (coupled with poor planting practices) recently resulted in the failure of a 60,000 tree plantation in Southland. Litigation was only avoided when the nurseryman agreed to pay all the costs of replanting plus reparations. In our experience this is not an isolated occurrence with species other than radiata pine. Some nurserymen compensate for a lack of mycorrhizal fungi on their plants, make them look healthy and ensure that they meet the industry standard simply by applying large amounts of nutrients and fungicides but eventually the lack of mycorrhizas may surface after outplanting. Figure 1. A non-mycorrhizal stunted and chlorotic Douglas fir in front of a mycorrhizal one of the same age. Figure 2. The effects of soil fumigation on mycorrhizas of onions. The fumigated non-mycorrhizal onions are on the right.

7 We believe that the opportunities for improving New Zealand s competitive advantage provided by diversifying the forest estate could be unlocked by the careful management of mycorrhizas in nurseries. As a result we anticipate reduced biological and market risks, improved regional and industry development options, increased value-added opportunities in primary and secondary processing industries, improved growth rates, cheaper establishment costs, greater returns on investment and a reduction in root diseases. 2.3 More on mycorrhizas 1 Mycorrhizas were first described by Gibelli in 1883 when he was working on chestnut ink disease but it was Frank s discovery that the Périgord black truffle was one of the fungal partners (Frank 1877, 1888; Trappe 1985) which was later to provide the hint as to how truffles might be cultivated. We now know that, with a few notable exceptions like the brassicas (Brassicaceae), nettles (Urticaceae), the convolvulus family (Convolvulaceae) and the knotweed family (Polygonaceae), most higher plants form mycorrhizas. While mycorrhizal fungi actually infect the roots of their host plants the relationship is generally beneficial because the cost of the carbohydrate they receive is more than made up for by the additional phosphorus the plant gains. The fungus does this by sending out a network of fine threads called hyphae that penetrate areas of soil that the plant is not able to exploit (Front cover; Figures 3 and 4). Mycorrhizal fungi have been around since the Ordovician, about 460 million years (Redecker et al a, b), so it is hardly surprising that most are now so specialised that they cannot survive unless in contact with their host plants. Many plants have also become equally dependent on mycorrhizal fungi and without them become stunted and yellow often due to a lack of phosphorus. It is because of this close relationship that plants raised by your local nurseryman in a mycorrhiza free, high fertility soilless potting mix may fail to survive after transplanting to relatively infertile situations such as your garden. 2.4 Types of mycorrhizas There are a number of types of mycorrhizas and, unfortunately, all have rather cumbersome names such as ectomycorrhiza (often shortened to EM), vesicular-arbuscular mycorrhiza (arbuscular mycorrhiza, AM or VAM) and ericaceous mycorrhiza (Smith & Read 1997). In an ectomycorrhiza the fungus wraps itself all around the outside of the host plant s fine roots just like the fingers of a glove (hence the name ecto- (outside) mycor- (fungus) rhiza (root); Front cover; Figures 3 and 4). It has been estimated that there are somewhere between 5000 and 6000 species of ectomycorrhizal fungi. Many of these produce mushrooms or truffles of which about 1000 species are edible or medicinal (Hall et al. 2003). The ectomycorrhizal association has probably been around for a mere 100 million years or so and so are considerably younger than the arbuscular type (Le Page et al. 1996; Trappe 1987). Ectomycorrhizas have a layer of fungal tissue on the surface of the fine roots called the mantle (Figures 3 and 4). From this tongues of tissue run in between the outer layers of the root to produce a three dimensional structure called the Hartig net. This can be visualised by imagining that the outer layers of cells of the root are like the bricks in a brick chimney and the fungus is the mortar between them. On the outside of the mantle hyphae run out into the soil (Figure 4 and cover). Saffron milk cap mycorrhizas (Lactarius deliciosus, Figure 3) are bright orange in colour and turn green with age which makes them fairly easy to identify. However, such examples are rare and the identification of most requires considerable experience and the aid of a powerful microscope. 1 This section of text has been adapted from the forthcoming book Truffles by Ian Hall, Gordon Brown and Alessandra Zambonelli.

8 Figure 3. Young bright orange ectomycorrhizas of Douglas fir on an older root covered by the characteristic older green hyphae of the fungus (photo Y. Wang). Figure 4. A greatly magnified truffle mycorrhiza showing the surface of the mantle surrounding the infected root tip and fine fungal hyphae radiating out into the soil (photo A. Zambonelli).

9 In arbuscular and ericaceous mycorrhizas the fungus actually gets right inside the cells of the outer layers of the roots producing structures called vesicles (Figure 5) and arbuscules (Figure 6). Despite the enormous ecological and economic importance of these fungi they go unnoticed because their fruiting bodies are usually microscopic and only provide lunch for very small animals like beetles, fly larvae and nematodes (Bratek et al 2001; Hall 1984; 1987; Smith & Read 1997). Fungi that form one kind of mycorrhiza are very different from those that form another and so generally ectomycorrhizal fungi cannot produce an arbuscular type of mycorrhiza and vice versa. Figures 5 and 6 showing an arbuscular mycorrhizal infections inside a fine root. The round vesicles (red arrow) and tiny tree-like arbuscules (below) are small enough to fit inside a cell in the outer layer of the root. The fungal hyphae are about 1 Fm wide ( 1 / 1000 mm). (Figure 6 courtesy of Jim Gerdemann)

10 Generally plants within a plant family tend to form the same kind of mycorrhizas (see Appendices 1 and 2). Most of the trees that dominate the forests of the Northern Hemisphere including birches (Betulaceae), oaks and beeches (Fagaceae), many softwoods (Pinaceae), European limes (Tiliaceae) and the tropical dipterocarps (Dipterocarpaceae) as well as the Australian eucalypts (Myrtaceae) form ectomycorrhizas. In contrast, the vast majority of cultivated crops, flowering plants, almost all New Zealand natives, ferns, cycads, and some gymnosperms such as North American redwood and cypresses (Taxodiaceae) form arbuscular mycorrhizas. There are a few exceptions such as the Myrtaceae and Rosaceae that contain both ecto- and arbuscular mycorrhizal species. A few tree species like the poplars and willows (Salicaceae), some eucalypts and Leptospermum (Myrtaceae) have the best of both worlds as they are able to form both ecto- and arbuscular mycorrhizas (Smith & Read 1997). 3 Initial findings High rates of applied nutrients and fungicides are generally applied in the nurseries we visited. These rates are driven partly by economic necessity but also to achieve healthy looking plants that meet industry standards. Plants for challenging sites are being supplied by nurseries without mycorrhizal infections. We believe that the high rates of applied nutrients and fungicides, at least in part, accounts for the poor development of ectomycorrhizas on nursery stock we inspected. The ubiquitous lack of inoculation with arbuscular mycorrhizal fungi to AM plants grown in soilless media certainly accounts for the complete absence of mycorrhizas on the roots. The subsequent application of very high rates of nutrients ensures that even rare spontaneous infections from wind blown spores have no chance of survival. While nursery personnel appreciate the importance of mycorrhizas and may inoculate ectomycorrhizal species there is a general lack of background information in the industry. For example, people are not aware that Rhizopogon parksii inoculum works well with Douglas fir but is useless on radiata.

11 4 Nothofagus raised in soilless media The first genus we decided to work on was Nothofagus because there was considerable anecdotal information that it was difficult to infect and often failed when transplanted into pastures a situation where it would have been unlikely for ectomycorrhizal fungi to be present. In this first experiment there were 12 treatments: 4 rates of applied nutrients 3 inocula one of which was an uninoculated control The experimental unit was the Lannen 64 tray (Figures 7 and 8). The treatments were applied to all the cells but only the centre 16 plants were considered part of the main body of the experiment with the rest as guard rows and plants available for sampling as the experiment progressed. A randomised block design was used with 4 replicates. The basal treatments were herbicides and pesticides (but not fungicides) as recommended by nursery personnel. Figure 7. The Lannen 64 tray used in the Nothofagus experiment. Figure 8. Layout of the cells in a Lannen tray with the outer guard row, innermost experimental plants with the plants that can be used to check for progress during the experiment in between.

12 Figure 9. Part of the Nothofagus trial at Oregon Nurseries 3 months after establishment. Within 3 months of inoculation most of the inoculated plants were showing early signs of mycorrhizal formation. Six months after inoculation mycorrhizas were found on all of the inoculated plants (Figure 10) with some being particularly heavy. With one or two exceptions the uninoculated plants remained non-mycorrhizal. Figure 10. Mycorrhizal root tips (three are arrowed) on Nothofagus 6 months after inoculation

13 Six months after the start of the trial there were extensive mycorrhizas on the inoculated Nothofagus menziesii but not on the uninoculated plants. The common greenhouse contaminant Thelephora appeared on the plants 2 months later. A field trial using the inoculated and uninoculated Thelephora contaminated plants is planned for later this year. 5 Douglas fir bare root nursery trial In the mid 1990s Ian Hall was able to demonstrate that containerised Douglas fir grown in a soilless medium in a greenhouse could be infected with the mycorrhizal fungus Rhizopogon parksii. However, this did not provide any assistance to those raising Douglas fir in bare root nurseries some of whom as recently as 2004 were having problems producing plants with adequate mycorrhizal infections. In 2005 an experiment was therefore laid down at Leithfield Nurseries near Wyndham, Southland, to investigate the effect of nutrients, fungicides and R. parksii inoculum on mycorrhizal formation by Douglas fir. This was in an area of the nursery that had been left fallowed for a few years (Figure 11) and where there was experience that mycorrhizal infection was likely to be poor in the first year (Figure 12). Figure 11. The area set aside for the Douglas fir field trial at Leithfield Nursery is immediately to the right of the fence line. Figure 12. Leithfield Nursery where Douglas fir germination, growth and mycorrhizal formation is generally poor in the first year after fallow.

14 Figure 13. Location of the experiment (in turquoise) spread over a single planting row two rows in from the fence line. Inset: an experimental plot 0.9 m long separated from adjacent plots by 0.6 m guard strips. There are 4 rates of applied fertiliser, with and without fungicide, with and without Rhizopogon parksii inoculum and 4 replicates giving a total of 64 experimental plots. Each plot is the width of a row and 0.9 m along the row and there is a 0.6 m guard strip between the plots (Figure 13). As expected by the nurseryman only 50% of the seed germinated, a feature that he considers may be due to a lack of mycorrhizal fungi in the fallowed soil. The inoculum was applied in January when sufficient second order lateral roots had developed (Figure 14). Figure 14. Poor germination, January 2006.

15 By January 2006 there was no effect from fertiliser that was applied at the start of the experiment. This strongly suggests that the more than half a tonne of fertiliser recommended by a consultant for the nursery was highly questionable. In mid April a small sample of seedlings was collected. At this time we learnt that the whole experiment had been sprayed with fungicide every 10 days as a preventative measure. No mycorrhizas could be detected on the sample of plants that was taken even though we would have expected them by this stage. 5.1 The situation in Finland In Finland, like other parts of the world, containerised plants have largely replaced bare rooted seedlings. During their production fungicides are applied routinely to control various fungal pests (Appendix 3). These fungicides have been shown to have a detrimental effect on mycorrhizal formation. It will be interesting to follow mycorrhizal formation in our trial as the year progresses. 6 Endomycorrhizal inocula Traditional, non-high tech techniques (Brundrett et al. 1996) were used to establish endomycorrhizas on white clover in a greenhouse from four different sources of inocula: vigorous stands of S. sempervirens, S. giganteum and C. lawsoniana. Within 3 months mycorrhizas from all four inocula had become well established on all of the clovers. The clover inoculum will be used in inoculation studies with S. sempervirens, S. giganteum, C. lawsoniana and possibly other speciality timber species.

16 7 References Bratek, Z.; Papp, L.; Merkl, O Beetles and flies living on truffles. In: Proceedings fifth international congress on the science and cultivation of truffles. Aix-en-Provence, France, 3-6 March FFT, Paris. Pp Brundrett, M Introduction to mycorrhizas. CSIRO Forestry and Forest Products. Frank, A.B Über die biologischen Verhältnisse des Thallus einiger Krustenflechten. Beiträge zur Biologie der Pflanzen 2: Frank, A.B Ueber die physiologische Bedeutung der Mycorhiza. Berichte der Deutschen Botanischen Gesellschaft 6: Gibelli, G Nuovi studi sulla malattia del Castagno detta dell'inchiostro. Memorie dell' Accademia delle Scienze dell'istituto di Bologna 4, Gilmore, J.W Chlorosis of Douglas-fir. New Zealand journal of forestry 7: Hall, I.R Truffles & Mushrooms web site. Hall, I.R Taxonomy of vesicular arbuscular mycorrhizal fungi. In: Vesicular arbuscular, eds C.L. Powell; D.J. Bagyaraj, CRC Press, Boca Raton, U.S.A. Pp Hall, I.R. 1987: Taxonomy and identification of vesicular arbuscular mycorrhizal fungi. Zeitschrift fur angewante botanik 61: Hall, I.R.; Stephenson, S.L.; Buchanan, P.K.; Wang Y.; Cole, A.L.J Edible and poisonous mushrooms of the world. Timber Press, Portland. LePage, B. A., R. S. Currah, et al. (1997). "Fossil ectomycorrhizae from the middle Eocene." American Journal of Botany 84(3): Redecker, D.; Kodner, R.; Graham, L.E. 2000a. Glomalean fungi from the Ordovician. Science 289: Redecker, D.; Morton, J.B.; Bruns, T.D. 2000b. Ancestral Lineages of Arbuscular Mycorrhizal Fungi (Glomales). Molecular phylogenetics and evolution 14: plantbio.berkeley.edu/~bruns/ftp/redecker2000a.pdf Smith, S.E.; Read, D.J Mycorrhizal symbiosis. Academic Press, London. Trappe, J.M Translation of B. Frank On the root symbiosis-depending nutrition through hypogeous fungi of certain trees. In: Proceedings of the 6th North American conference on mycorrhizae. Molina R. (ed.) June, Bend, Oregon, USA Trappe JM Phylogenetic and ecologic aspects of mycotrophy in the angiosperms from an evolutionary standpoint. In: Safir GR (ed) Ecophysiology of VA Mycorrhizal Plants. CRC Press, Boca Raton, Florida. pp T Trevor, E.; Yu, J.-C.; Egger, K.N.; Peterson, R.L Ectendomycorrhizal associations characteristics and functions. Mycorrhiza 11:

17 Appendix 1. Some arbuscular mycorrhizal species. Common name Botanical name Plant family Akeake Dodonaea viscosa Sapindaceae, Akiraho Olearia paniculata Asteraceae Almond Prunus dulcis Rosaceae Apple Malus Rosaceae Apricot Prunus armeniaca Rosaceae Angelica tree Aralia Araliaceae Ash Fraxinus Oleaceae Avocado Persea americana Lauraceae Bamboo Bambusa Pooideae Banana Musa Musaceae Barberry Berberis Berberidaceae Bayberry Myrica Myricaceae Black locust Robinia Fabaceae Blackberry Rubus eubatus Rosaceae Box elder Acer negundo Aceraceae Broadleaf Griselinia Griseliniaceae Boxwood Buxus Buxaceae Buckeye Aesculus Hippocastanaceae Burning bush Euonymus Celastraceae Cacao Theobroma cacao Sterculiaceae Camellia Camellia Theaceae Catalpa Catalpa Bignoniaceae Cherry Prunus avium Rosaceae Chinaberry Melia azedarach Meliaceae Coral tree Erythrina indica Fabaceae Crabapple Malus Rosaceae Cryptomeria Cryptomeria japonica Taxodiaceae Cucumber tree Magnolia acuminata Magnoliaceae Dogwood Cornus Cornaceae Fig Ficus carica Moraceae Flax, New Zealand Phormium tenax Agavaceae Fuschia Fuchsia Onagraceae Gingko Ginkgo biloba Ginkgoaceae Gorse Ulex europaeus Fabaceae Grapes Vitis Vitaceae Hackberry Celtis Ulmaceae

18 Hibiscus Hibiscus rosa-sinensis Malvaceae Holly Ilex Aquifoliaceae Horse chestnut Aesculus Hippocastanaceae Juniper Juniperus Cupressaceae Kamahi Weinmannia racemosa Cunoniaceae Karamu Coprosma robusta Rubiaceae Kauri Agathis Araucariaceae Korokia Corokia buddleoides Cornaceae Kowhai Sophora spp. Papilionaceae Lacebark Hoheria populnea Malvaceae Lawson cypress Chamaecyparis lawsoniana Cupressaceae Lemonwood Pittosporum Pittosporaceae Leyland cypress X Cupressocypari s leylandii Cupressaceae Macrocarpa Cupressus macrocarpa Cupressaceae Magnolia Magnolia Magnoliaceae Mahoe Melicytus ramiflorus Violaceae Maples Acer Aceraceae Marbleleaf Carpodetus serratus Carpodetaceae Mulberry Morus Moraceae Olive Olea europaea Oleaceae Palms Cycad Cycadaceae Papaya Carica papaya Cariceae Paulownia Paulownia Paulowniaceae Peach Prunus persica Rosaceae Pear Pyrus communis Rosaceae Persimmon Diospyros Ebenaceae Plum Prunus Rosaceae Podocarp Podocarpus Podocarpaceae Pohutukawa Metrosideros excelsior Myrtaceae Privet Ligustrum Oleaceae Rain tree Koelreuteria elegans Sapindaceae Rata Metrosideros Myrtaceae Redwood, coastal Sequoia sempervirens Taxodiaceae Redwood, giant Sequoiadendron giganteum Taxodiaceae Ribbonwood Plagianthus betulinus Malvaceae Rowan Sorbus Rosaceae Sycamore Acer Aceraceae Tree-of-heaven Alianthus altissima Simaroubaceae Tulip tree Liriodendron Magnoliaceae Viburnum Viburnum Caprifoliaceae Yew Taxus spp Taxaceae

19 Appendix 2. Some ectomycorrhizal species. Common name Botanical name Plant family Alder Alnus Betulaceae Strawberry tree Arbutus Ericaceae Aspen Populus * Salicaceae Beech Fagus Fagaceae Birch Betula Betulaceae Cedars Cedrus Pinaceae Chestnut Castanea Fagaceae Cherry, bird Prunus padus Rosaceae Cherry, dwarf Prunus cerasus Rosaceae Cherry, wild Prunus avium Rosaceae Douglas fir Pseudotsuga menziesii Pinaceae Eucalyptus Eucalyptus * Myrtaceae Fir Abies Pinaceae Hawthorn Crataegus Rosaceae Hazels Corylus Betulaceae Hemlocks Tsuga Pinaceae Hickory Carya Juglandaceae Hornbeam Carpinus Betulaceae lronwood Casuarina Casuarinaceae Kanuka Kunzea ericoides * Myrtaceae Larch Larix Pinaceae Lime Tilia Tiliaceae Manuka Leptospermum scoparium * Myrtaceae Oak Quercus Fagaceae Pine Pinus Pinaceae Poplar Populus * Salicaceae Redbud Cercis canadensis Fagaceae Rock rose Helianthemum Cistaceae She-oak Casuarina * Casuarinaceae Spruce Picea Pinaceae Walnut Juglans Juglandaceae White leaved rock rose Cistus Cistaceae Wild service tree Sorbus torminalis Rosaceae Wild pear Pyrus pyraster Rosaceae Willows Salix * Salicaceae * Can also form arbuscular mycorrhizas.

20 Appendix 3. Effects of fungicides on containerised plants in Finland. Tarja Laatikainen Side effects of nursery fungicides on ectomycorrhiza of Scots pine seedlings. In: EUROSOIL 2004, September 04 to 12, Freiburg, Germany. Abstract (abridged) About 150 million forest tree seedlings are annually produced in Finnish forest nurseries. During last two decades container seedlings have extensively replaced barerooted seedlings. In containers seedlings are growing as dense moist mats, which is favourabl e to pathogenic fungi. Furthermore, in Finland seedlings are usually stored over winter outdoors under the snow cover, which allow some fungi, like scleroderris canker (Gremmeniella abietina Lagerb.), and snow blights, to spread from one container to another. Therefore, routine controls for fungal diseases with fungicides are considered to be a necessary forest nursery practice, and there is practically no seedling production in Finland wi thout fungicide treatments. Fungicides chlorothalonil and propiconazole have become common forest nursery practice for control of scleroderris canker and snow blights of conifers (e.g. Phacidium infestans P. Karst. and Herpotrichia juniperi Duby) during over winter cold storage. The repeated and long-term use of fungicides has raised the concern of the side effects of pesticides on soil microorganisms, especially on ectomycorrhizal infection of seedlings after outplanting. In the preset study the side effects of the fungicides, chlorothalonil and propiconazole, on ectomycorrhizal fungi on Scots pine (Pinus sylvestris L. Karst.) seedlings have been evaluated both in laboratory and field experiments. Toxicity tests were performed with pure culture tests on agar petri dishes, where the fungal growth was measured as colony dia meter, and in liquid pure cultures, where the growth was determined as mycelium biomass and ergosterol concentration. Fungicide effects on nutrient uptake and allocation by mycorrhizal fungi to symbiont seedling were studied both in allocation tests in pure cultures, and in laboratory microcosms with Scots pine seedlings inoculated with Paxillus involutus or Hebeloma cf. longicaudum, as well as, in a field experiment in a forest nursery. Both chlorothal onil and propiconazole had a clear inhibitory effect on the growth of almost all tested mycorrhizal fungi. Allocation tests showed that ectomycorrhizal fungi have differential capability to take up ammonium, and propiconazole might influence on these processes depending on a species of ectomycorrhizal fungus. Propiconazole induced free amino acid arginine synthesis both in pure culture tests with P. involutus mycelium, and in shoot of i noculated Scots pine seedling. Noteworthy was the accumulation of arginine in samples both from non-mycorrhizal and mycorrhizal seedlings. Chlorothalonil caused growth reduction and a retarded frost hardening in forest nursery container seedli ngs. The effect can be seen still two years later as changes in concentrations of total nitrogen and total free amino acids. Results of this study may indicate a stress-related influence of both fungicides in Scot pine s eedlings.