Bacterial wilt-resistant tomato rootstock suppresses migration of <Emphasis Type="Italic">ralstonia solanacearum</Emphasis> into soil

Ralstonia solanacearum, the causal agent of bacterial wilt of tomato, grows in infected plants and migrates from the roots into the soil. We investigated the effectiveness of bacterial wilt-resistant tomato rootstock in reducing the migration of R. solanacearum from susceptible scions into the soil. Rootstock stems were either 3–5 cm tall (low-grafted, LG) or ≥?10 cm tall (high-grafted, HG). After inoculation of scions of the susceptible cultivar (SC) with R. solanacearum below the first flower, there was no difference in disease progression among LG, HG, and ungrafted SC plants, and plants had wilted by 2 weeks. However, the rate of detection of R. solanacearum in the soil of wilted plants was reduced by grafting. The size of the R. solanacearum population in the soil of fully wilted plants increased in the order of HG?<?LG?<?SC. These results show that grafting onto resistant rootstock strongly suppressed the migration of R. solanacearum into the soil by the time of full wilting, and the effect was stronger with a longer rootstock. Migration of R. solanacearum into soil increased with increasing disease severity in SC, LG and HG. These facts suggest that early uprooting of slightly infected plants could control the spread of the bacteria into the soil.     

Proteomic analysis of mycelial proteins from <Emphasis Type="Italic">Rosellinia necatrix</Emphasis>

The soilborne pathogen Rosellinia necatrix causes white root rot, a serious disease of various trees, and is extremely difficult to control. In this study, using one-dimensional electrophoresis coupled with nanoliquid chromatography-electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF-MS/MS), we identified 696 proteins from R. necatrix mycelium (KACC 40445) grown in liquid culture. In addition, 573 proteins were assigned to at least one gene ontology term including 26 functional groups. Most were related to catalytic activity in the molecular function category. This proteomic data set advances understanding of R. necatrix biology and will inform further investigations to manage white root rot using novel strategies.     

The application of lettuce in the qualitative and quantitative detection of <Emphasis Type="Italic">Rhizoctonia Solani</Emphasis> AG- 1 IA toxins

The toxins produced by Rhizoctonia solani are important causal agents of rice sheath blight. Effective detection of such toxins could improve the determination of the virulence of this agronomically important fungal pathogen. As such, the objective of the current study was to investigate the use of a variety of plant species [annual sowthistle (Sonchus oleraceus L.), Chinese cabbage (Brassica chinensis), spinach (Spinacia oleracea L.), lettuce (Lactuca sativa L. var. sativa), long leaf lettuce (Lactuca sativa var. ramosa Hort) and tobacco (Nicotiana tabacum)] for qualitative detection of R. solani crude toxins (RHCT) to replace the current rice leaf sheath based assay. This is constrained as rice plant takes long time to grow before the leaf sheath can be harvested From the initial screen, it was found that detached lettuce leaves provided the best alternative to rice material. Quantitative determination of RHCT activity by the phosphorus extravasation method was then performed on both rice (Oryza sativa L.) and lettuce. The results demonstrated that the detached lettuce leaves had the advantages of fast onset of symptoms, high sensitivity and non-perishability after inoculation. The quantity of phosphorus exosmosis observed in both lettuce leaves and rice leaf sheaths were significantly positively correlated. These data indicate that lettuce leaves can be used as a substitute material for rice leaf sheaths, with which to study the RHCT both qualitatively and quantitatively. The current study provides a new way to qualitatively and quantitatively detect RHCT.     

Increased susceptibility of potato to <Emphasis Type="Italic">Rhizoctonia</Emphasis> diseases in <Emphasis Type="Italic">Potato leafroll virus</Emphasis>-infected plants

In Hokkaido potato fields, tubers produced from the plants with leaf curl symptoms caused by potato leaf roll virus (PLRV) were noted to be more densely covered with Rhizoctonia sclerotia. This observation led us to hypothesize that potato infected with PLRV would have an increased susceptibility to Rhizoctonia solani. To test this hypothesis, in a pot experiment, we inoculated PLRV-infected mother tubers with Rhizoctonia. As a result, PLRV-infected plants produced significantly fewer and smaller tubers than virus-free plants did, suggesting that PLRV-infected plants are more susceptible than virus-free plants to R. solani. Virus-free seed tubers should thus be used to reduce Rhizoctonia diseases.     

<Emphasis Type="Italic">Alternaria alternata</Emphasis>: A new seed-transmitted disease of coriander in South Africa

This is the first report of Alternaria leaf spot disease on coriander (Coriandrum sativum L.) in South Africa. Using the agar plate method, Alternaria alternata was isolated from coriander seed lots together with four other fungal genera, which included Aspergillus, Fusarium, Penicillium and Rhizopus. Standard seed germination tests of coriander seed lots infected with seed-borne mycoflora showed a positive correlation with the number of diseased seedlings (r?=?0.239, p?<?0.01). Pathogenicity tests demonstrated that this seed-borne A. alternata was pathogenic on coriander and symptoms on leaves first appeared as small, dark brown to black, circular lesions (<5 mm diam.) that enlarged and coalesced to form dark brown blotches as time progressed. Leaf spot disease was most severe (64%) on wounded leaves inoculated with A. alternata. Re-isolation of A. alternata from diseased coriander plants satisfied the Koch’s postulates, thus confirming it as the causal agent of Alternaria leaf spot disease. Parsimony analysis based on rpb2 (GenBank Accession No. KT895947), gapdh (KT895949) and tef-1α (KT895945) sequences confirmed identity of the Alternaria isolate, which grouped within the A. alternata clade. Alternaria alternata was shown to be transmitted from infected coriander seed to the developing plants.     

Protective role of <Emphasis Type="Italic">S</Emphasis>-methylmethionine-salicylate in maize plants infected with <Emphasis Type="Italic">Maize dwarf mosaic virus</Emphasis>

This study aimed to detect the harmful effects of Maize dwarf mosaic virus (MDMV) infection, and to demonstrate the potential benefits of S-methylmethionine-salicylate (MMS) pretreatment in infected maize (Zea mays L.) plants. The results of chlorophyll a fluorescence measurements showed that in MDMV-infected plants additional quenchers of fluorescence appear, probably as the result of associations between the virus coat protein and thylakoid membranes. It is important to note that when infected plants were pretreated with MMS, such associations were not formed. MDMV infection and MMS pretreatment resulted in a decrease in ascorbate peroxidase (APX) activity in maize leaves, while infection contributed to an increase in activity in the roots. Infection raised the guaiacol peroxidase (GPX) enzyme activity level, which was reduced by MMS pretreatment. MMS contributed to a decrease in both the RNA and coat protein content of MDMV, to an equal extent in maize leaves and roots. The results showed that MMS pretreatment enhanced the stress response reactions against MDMV infection in maize plants and retarded the spreading of infection.     

Fast detection by loop-mediated isothermal amplification (LAMP) of the three begomovirus species infecting tomato in Panama

Potato yellow mosaic Panama virus (PYMPV), Tomato leaf curl Sinaloa virus (ToLCSiV) and Tomato yellow mottle virus (TYMoV) of genus Begomovirus (family Geminiviridae) are the only three begomovirus species detected infecting tomato (Solanum lycopersicum L.) in Panama. PYMPV, ToLCSiV and TYMoV induce symptoms of stunting, yellowing, curling, distortion of leaves and reduction of fruit size and cause important economic loses. A loop-mediated amplification under isothermal conditions (LAMP) assay was developed for the individual detection of these three begomovirus species by using a set of three primer pairs specific per each one of them. Amplification products were visualized by gel electrophoresis or direct Gel-Red staining of DNA into the reaction tube. PYMPV, ToLCSiV and TYMoV were detected in total DNA extracts obtained from different plant tissues such as leaves, stems, flowers, fruits and roots of infected tomato plants collected in different production regions of Panama. LAMP sensitivity was similar to that of conventional PCR but, the first procedure was faster and cheaper than the last one. Moreover, all three viruses were successfully detected by LAMP and not by conventional PCR from sap extracts obtained from leaf tissues of infected tomato plants which were embedded into 3MM Whatman paper and stored several days, facilitating the samples processing as well as the material movement among different laboratories. Therefore, LAMP is a specific, rapid and cheap procedure to detect all three begomoviruses infecting tomato in Panama and it is suitable for field surveys and sanitation programs.     

First report of leaf spot caused by <Emphasis Type="Italic">Alternaria alternata</Emphasis> on <Emphasis Type="Italic">Drimia maritima</Emphasis>

Drimia maritima (squill) is a historically important medicinal plant. During the spring of 2016, small, yellow leaf spots, which became brown and finally necrotic, were observed on squill plants in Kohgiluyeh and Boyer-Ahmad Provinces in Iran. A fungus was consistently isolated from infected leaves and identified as Alternaria alternata based on morphological and phylogenetic analyses. Pathogenicity tests confirmed A. alternata to be the causal agent of the newly observed leaf spot disease. This is the first report of leaf spot on D. maritima caused by A. alternata in the world.     

Overexpression of <Emphasis Type="Italic">SlARG2</Emphasis> or <Emphasis Type="Italic">SlTD2</Emphasis> in Arabidopsis enhances resistance against <Emphasis Type="Italic">Plutella xylostella</Emphasis> L.

Tomato (Solanum lycopersicum L.) ARGINASE2 (ARG2) and THREONINE DEAMINASE2 (TD2) are involved in plant defense. These enzymes act in the midgut of herbivores fed on tomato plants to degrade the essential amino acids Arg and Thr, respectively. Although it has been demonstrated that overexpression of the SlARG2 gene in tomato enhanced its resistance against M. sexta larvae, knock-down the expression of SlTD2 reduced the resistance of tomato to lepidopteran herbivores; it remains unclear whether overexpression of SlTD2 could enhance the resistance of the host plants to herbivores, or whether combined overexpression of SlARG2 and SlTD2 could lead to synergistically enhanced resistance to insects. Here, we generated transgenic Arabidopsis plants overexpressing SlARG2 (SlARG2 OE) and SlTD2 (SlTD2 OE) individually as well as in combination (SlARG2-SlTD2 OE). Overexpression of these genes did not affect Arabidopsis development, seed yield, or Arg and Thr content. Insect-feeding bioassay was performed by feeding diamondback moth (Plutella xylostella L.) larvae on detached leaves of wild-type, SlARG2 OE, SlTD2 OE, and SlARG2-SlTD2 OE plants. Larvae fed on SlARG2 OE leaves showed approximately 31% to 35% reduction in weight and 6% to 10% reduction in survival rate compared to those fed on wild-type leaves. Although larvae fed on SlTD2 OE leaves showed no reduction in survival rate, they gained less weight. Whereas larvae fed on SlARG2-SlTD2 OE leaves showed neither reduction in weight nor reduction in survival rate. We further investigated the arginase enzymatic activity of the SlARG2 OE and SlARG2-SlTD2 OE transgenic plants. The SlARG2 OE line most resistant to diamondback moth larvae displayed the highest arginase activity. Our data indicate that overexpression of SlARG2 or SlTD2 in Arabidopsis can enhance its resistance against diamondback moth, whereas combined overexpression of SlARG2 and SlTD2 did not generate synergistically increased resistance to diamondback moth.     

Foliar diseases of willows (<Emphasis Type="Italic">Salix</Emphasis> spp.) in selected locations of the Karkonosze Mts. (the Giant Mts)

The species of Salix herbacea L. and Salix lapponum L. are the rare relicts within the genus of Salix. With respect to their phylogeography, they are classified into the taxa of the Arctic-Alpine distribution. They can be found in the Arctic zone (Greenland, Scandinavia, Spitsbergen) as well as in such geographically separated areas as the mountains of lower latitudes like the Alps, the Sudetes or the Carpathians. Another species of willow occurring in the mountains of Europe, and more specifically on montane positions of the Balkan-Carpathian distribution is S. silesiaca. The aim of the study was to determine the severity of the diseases of the willows growing in selected locations in the Karkonosze Mountains. The research was conducted in the years 2014 and 2015 in the Kocio? ?omniczki [the ?omniczka Cirque] and the Wielki and Ma?y ?nie?ny Kocio?, [the Great and Small Snowy Cirques] at intervals of 4 weeks, from April to October. Field observations included the species of the genera Salix: S. herbacea, S. silesiaca and S. lapponum. Disease symptoms were identified with the percentage of infected plants at selected locations, as well as the percentage of infected leaves, recorded. In the course of the research, symptoms of rust caused by Melampsora epitea and M. alpina (S. herbacea and S. silesiaca), black spot blight caused by Rhytisma salicinum (S. silesiaca) and leaf spot, probably caused by a complex of fungal taxa (S. herbacea), were detected on the leaves of Salix spp. growing in post glacial cirques. During the study period, there were no disease symptoms on S. lapponum. A total of 13 species of fungi were isolated from the infected leaves of S. herbacea. In the first year, the highest share in the fungal assembly was taken by Penicillium notatum, followed by Alternaria alternata and an unidentified species of the genus Ceuthospora. In the second year of the research, Ceuthospora spp. and A. alternata predominated in the species assembly of fungi in the infected leaves of the herb willow.     

Antagonistic effects of biofilm-forming bacterial strains co-inoculated with blood disease pathogenic strain, <Emphasis Type="Italic">Ralstonia syzygii</Emphasis> subspecies <Emphasis Type="Italic">celebesensis</Emphasis> in banana plants

A blood disease pathogenic strain, Ralstonia syzygii subspecies celebesensis was used to study the possible association of biofilm-forming bacteria with the development and severity of blood disease in banana plants. Therefore, the objective of this study was to determine the effects of mono-culture and co-culture inoculation of isolated biofilm-forming bacteria with the blood disease pathogen in banana pseudostems in glasshouse conditions. Putative biofilm-forming bacteria were isolated from an infected banana plant and were further identified using 16SrRNA sequencing. Four isolates, identified as Enterobacter hormaechei, Enterobacter cloacae, Kosakonia radicincitans and Klebsiella pneumoniae, were inoculated as a mono- and co-culture with R. syzygii subsp. celebesensis into 2 months old banana plants. The observation after the 8 weeks of post inoculation showed that plants which were co-inoculated with the pathogen and K. radicincitans, a biofilm-forming bacterium, were the most susceptible towards the infection. In contrast, plants under two treatments (which were co-inoculated with the pathogen and E. cloacae and the pathogen with E. hormaechei) were less susceptible towards the infection. This study revealed the antagonistic effects of two biofilm-forming strains which reduced the severity of infection caused by the pathogenic agent. Scanning electron micrographs of the cross section of plant rhizomes indicated the dissimilarity of adhesion and host colonization conditions of the pathogen in each infected plant from different treatments.     

Natural infection of <Emphasis Type="Italic">Nicandra physaloides</Emphasis> by <Emphasis Type="Italic">Tomato severe rugose virus</Emphasis> in Brazil

Nicandra physaloides, a common weed in South America, was found to be infected by an isolate of Tomato severe rugose virus (ToSRV), a bipartite begomovirus. The plants developed severe yellow rugose mosaic and were collected in São Paulo State, Brazil. This isolate of ToSRV was transmitted by Bemisia tabaci B biotype from infected plants of N. physaloides to healthy plants of N. physaloides and tomato in a glasshouse. This is the first report of natural infection of N. physaloides by ToSRV in Brazil.     

Weeds as the potential inoculum source of <Emphasis Type="Italic">Colletotrichum fructicola</Emphasis> responsible for strawberry anthracnose in Nara,Japan

Colletotrichum fructicola is a major causal agent among anthracnose pathogens of strawberry in Nara, Japan. We hypothesized that a wide range of weeds growing in and around strawberry fields are inoculum sources of the disease and investigated their potential as hosts of C. fructicola. We also examined the influence of herbicide treatment on C. fructicola sporulation on weeds. The fungus was detected on 31 of 541 (5.7%) leaves sampled from 13 weed species from 2005 to 2008. The fungus was most frequently isolated from leaves of Amaranthus blitum with an isolation frequency of 17.9%; inoculation of A. blitum with the pathogen caused brown leaf spots. Other weeds such as Digitaria ciliaris, Galinsoga ciliata, Solidago altissima, Erigeron annuus, and Sonchus oleraceus were found to harbor the fungus at lower rates (4.3–8.1%) without symptoms. C. fructicola formed acervuli on leaves of A. blitum, D. ciliaris, and S. oleraceus after plants were killed by a herbicide (glyphosate). These results demonstrated that infected weeds associated with strawberry cultivation are potential inoculum sources of C. fructicola, especially after herbicide treatment.     

Races of <Emphasis Type="Italic">Phytophthora infestans</Emphasis> isolated from potato in Hokkaido,Japan

The virulence of 29 isolates of Phytophthora infestans collected in potato fields in Hokkaido, Japan, in 2013 and 2014, was tested for race identification. Thirteen different races were identified, each of which had five to eight virulence factors. All of the isolates caused a virulent reaction against plants with R1 and R7, and most of the isolates caused a virulent reaction against plants with R3, R4, R10, and R11. On the other hand, no isolate was virulent against plants with R9. These results demonstrate that the current Japanese P. infestans population is more complex than the population in the 1990s from the viewpoint of race.     

Description and molecular phylogeny of <Emphasis Type="Italic">Ditylenchus gilanicus</Emphasis> n. sp. (Nematoda: Anguinidae) from northern forests of Iran

Commercial areas containing Eucalyptus plantations have expanded in recent years due to increased demands for pulp, paper and bioenergy. One of the threats that can reduce Eucalyptus production is the eucalyptus rust disease caused by Austropuccinia psidii, a biotrophic fungus that affects a broad range of Myrtaceae. An accurate diagnosis tool for the early detection of rust disease could be useful in breeding programs for selection of resistant plants against rust, in phytosanitary purposes or in rust epidemics studies. The aim of the present work was to develop a SYBR Green-based quantitative real-time PCR (qPCR) assay for the early detection and quantification of A. psidii in Eucalyptus grandis leaves. Three sets of primers based on the A. psidii ribosomal DNA intergenic space region (IGS), beta-tubulin and elongation factor genes were designed and evaluated. The assays using the IGS primer set resulted in the highest detection efficiency, detecting a lower limit of 0.5 pg of A. psidii DNA. Under artificial inoculation in plants, A. psidii was detected immediately after pathogen inoculation until 240 h post-inoculation using qPCR. In field validation of the method, A. psidii was detected using qPCR in naturally infected leaves with or without rust symptoms. This easy and fast method can be used for an efficient detection of A. psidii in E. grandis leaves. The implications of this tool for rust studies are discussed below.     

<Emphasis Type="Italic">Clavibacter michiganensis</Emphasis> subsp. <Emphasis Type="Italic">michiganens</Emphasis>is strains virulence and genetic diversity. a first study in Argentina

Tomato leaves showing severe leaf spot symptoms have been observed and sampled in the central west and southwest Taiwan during 2015 and 2016. The symptoms were similar to those of bacterial leaf spot/late blight diseases, but only Stemphylium-like fungi were consistently isolated from the diseased tomato. Upon spray inoculation of tomato, Stemphylium-like isolates caused leaf spot symptoms identical to those of naturally infected plants, and the pathogenic isolates were successfully re-isolated from inoculated leaves. The tomato-pathogenic isolates were identified as S. lycopersici based on morphological characterization and molecular identification. S. lycopersici has been previously reported to cause gray leaf spot of tomato in the temperate regions, but the majority of S. lycopersici-caused lesions were black/dark brown rather than gray in our surveillance. Accordingly, it is suggested that S. lycopersici-caused disease of tomato is named Stemphylium leaf spot of tomato more appropriately than tomato gray leaf spot. Moreover, S. lycopersici-caused leaf spot disease on tomato has been distributed in major tomato production regions in Taiwan. The information provided by our study will be important for future breeding of tomato cultivars, especially for tomato producers in Taiwan.     

Quantitative detection of <Emphasis Type="Italic">Colletotrichum godetiae</Emphasis> and <Emphasis Type="Italic">C. acutatum sensu stricto</Emphasis> in the phyllosphere and carposphere of olive during four phenological phases

A duplex qPCR detection method was developed to detect and quantify Colletotrichum godetiae and C. acutatum sensu stricto (s.s.) in olive tissues. The method proved highly specific and sensitive with a detection limit of 10 pg for each pathogen. The analysis of green and senescent leaves, fertilized fruitlets with floral residues, green fruit and symptomatic and asymptomatic fruit collected in May, June, October and December revealed a high incidence of both C. godetiae and C. acutatum s.s. in Calabria, southern Italy. In comparison with previous reports, these results highlighted an ongoing population shift from C. godetiae to C. acutatum s.s. Interestingly, C. godetiae was slightly more abundant in terms of number of infected samples, yet the quantity of C. acutatum in infected samples was always higher, suggesting greater aggressiveness and/or sporulation ability of the latter pathogen. The populations of both C. godetiae and C. acutatum s.s. increased sharply in December even though both pathogens were detected widely in asymptomatic samples in May, June and October, confirming an important role of latent infections in the disease cycle. A large quantity of both C. godetiae (1.7 × 10⁸ cells/mg of tissue) and C. acutatum s.s. (7.5 × 10⁸ cells/mg of tissue) was estimated in symptomatic fruit, presenting an enormous inoculum potential for secondary infections. Two other important observations were a high incidence and quantity of both pathogens in senescent leaves and in fertilized fruitlets with floral residues as compared to green leaves.     

Management of laurel wilt of avocado,caused by <Emphasis Type="Italic">Raffaelea lauricola</Emphasis>

Laurel wilt is caused by Raffaelea lauricola, a nutritional symbiont of an Asian ambrosia beetle, Xyleborus glabratus. American members of the Lauraceae plant family are most susceptible and 300 million trees have been killed by the disease in the southeastern USA since 2003. Recently, commercial production of an important crop in the laurel family, avocado (Persea americana), has been affected in southern Florida. We summarize studies in which diverse measures were tested for managing the disease. In all studies, trees were treated with potential laurel wilt control measures and subsequently inoculated with R. lauricola. On potted plants in greenhouse experiments, commercial nutritional products (Greenstim and Keyplex 350) and SAR products (Agri-Fos and Nutri-Phite), when applied as soil drenches or foliar sprays, had either no impact on, or increased laurel wilt symptom development compared to non-treated control treatments. Bark applications of Tilt (a propiconazole fungicide for which emergency registration had been obtained in 2010) in a surfactant (Pentrabark) enabled significant laurel wilt protection in greenhouse studies on small potted plants, but Pentrabark and other surfactants moved little propiconazole into the xylem of fruit-bearing trees in field studies. In efficacy studies in the field, Propiconazole Pro (an injectable formulation of propiconazole), Tilt, and two experimental formulations of another triazole fungicide, tebuconazole, decreased the development of laurel wilt compared to nontreated control trees when applied as undiluted injections into branches and scaffold limbs (microinjection), or injection of dilute fungicide into tree flare roots (macroinfusion). However, symptoms developed in all treated trees by 10–11 months after inoculation with R. lauricola, indicating that trees would need to be re-treated at least on an annual basis. Regardless of how fungicides were applied, insignificant levels of different active ingredients entered fruit. Although fungicide treatment of fruit-bearing avocado trees is not a concern for food safety and several triazole and DMI fungicides can protect avocado trees from laurel wilt, cost-effective measures with which the xylem could be loaded with and protected by these products remains a challenge. Management of laurel wilt in commercial avocado production areas is discussed.     

The Eurotiomycete <Emphasis Type="Italic">Apinisia graminicola</Emphasis> as the causal agent of a leaf spot disease on the energy crop <Emphasis Type="Italic">Miscanthus</Emphasis> x <Emphasis Type="Italic">giganteus</Emphasis> in Northern Germany

Miscanthus x giganteus is a fast growing, perennial energy crop for temperate climates. Because of its high annual biomass production rates and its characteristics as a low-input crop, an expansion of field cultivation can be anticipated to cover increasing demands for sustainable biomass production. However, knowledge about pathogens that could have an impact on biomass production is still limited for M. giganteus. Here, we report about the isolation of the filamentous fungus Apinisia graminicola from necrotic leaf lesions of M. giganteus grown on a field trial plot in Northern Germany. Inoculation assays with the isolated A. graminicola strain confirmed its capacity to cause a leaf spot disease on M. giganteus. Additional inoculation assays revealed that A. graminicola also caused necrotic lesions on leaves of the model grass Brachypodium distachyon. Generally, symptoms of A. graminicola-caused leaf spot disease were stronger on B. distachyon compared to M. giganteus. Incubation temperatures above 22 °C during A. graminicola infection resulted in stronger disease symptoms on both, M. giganteus and B. distachyon leaves. Microscopic analysis of cross sectioned, infected leaf tissue revealed an epiphytic mycelium formation on the surface and an endophytic colonization of the mesophyll leave tissue, especially in M. giganteus. Our results revealed that the isolated A. graminicola strain is a causal agent of a leaf spot disease on grass leaves. Its potential on endophytic growth in M. giganteus might open new possibilities in studying this type of plant-fungal interaction on a cellular and molecular level in an energy crop.     

Airborne basidiospores as an inoculum source of <Emphasis Type="Italic">Typhula variabilis</Emphasis> and the effect of hilling on the incidence of Typhula winter rot of carrots

Typhula winter rot on overwintering carrots caused by Typhula variabilis is a newly confirmed disease, and no practical control measure is yet available. To develop a control method, here we researched the infection period of T. variabilis and the time that winter rot appeared on carrots. Using spore traps, we found that basidiospore rain occurred from September to November before snowfall in Memuro, Hokkaido. In addition, carrot leaves collected in autumn had already been infected by T. variabilis. These epidemiological investigations revealed that the pathogen releases basidiospores to infect carrot leaves before snow cover, resulting in root decay under snow. An effective control method was then developed to avoid direct contact of basidiospores of T. variabilis with plant tops by covering the plants with soil in autumn. Thus, the percentage of rotted roots was reduced to about half.