Foliar Fungi Research Articles

Diseases in Intercropping Systems

Intercropping, the simultaneous cultivation of multiple crop species, has been used throughout history and remains common among farmers of small landholdings in the tropics. One benefit of this practice may be disease control. In phenomenological research comparing disease in monocrops and intercrops, primarily due to foliar fungi, intercropping reduced disease in 73% of more than 200 studies. Nematodes are the primary pathogen for which disease increases are reported, but variability in disease impacts among studies can be high for all types of diseases. The mechanisms by which intercrops affect disease dynamics include alteration of wind, rain, and vector dispersal; modification of microclimate, especially temperature and moisture; changes in host morphology and physiology; and direct pathogen inhibition. The effect of intercropping on host density is a factor underlying many of these mechanisms. By synthesizing our growing understanding of mechanisms and their interactions with phenomenological studies, we may develop a theoretical grounding that allows us to improve the application of intercropping for tropical smallholders and industrial farmers alike.

Evaluation of secondary metabolites from mangrove associated fungi Meyerozyma guilliermondii

BackgroundMangrove associated fungi are the second most diverse organisms that remain less explored. Cytotoxic and antibacterial activities of foliar fungus Meyerozyma guilliermondii were investigated. MethodsFoliar fungus was isolated from the leaves of Rhizophora mucronata collected from Pichavaram mangrove forest, Tamilnadu. Extracts from liquid state culture were tested for cytotoxicity against two cancer cell lines using the MTT assay. Antibacterial activity was determined using the well diffusion method. The DNA was isolated from the fungi, and the ITS region of 5.8s RNA was sequenced. The spectral properties (GC/MS) of the purified compounds were determined. ResultsThe ethyl acetate extracts showed potent cytotoxicity against Hep2 and human breast adenocarcinoma (MCF-7) cell lines with IC50 values of 1.25 and 0.625 μg/ml, respectively. Antibacterial activity of the fungal extract was demonstrated against five test organisms. The fungus was found to be a new strain based on ITS sequence and database in NCBI Blast tool. ConclusionResults indicate the potential for production of bioactive agents from mangrove foliar fungi.

Host Genotype Shapes the Foliar Fungal Microbiome of Balsam Poplar (Populus balsamifera)

Foliar fungal communities of plants are diverse and ubiquitous. In grasses endophytes may increase host fitness; in trees, their ecological roles are poorly understood. We investigated whether the genotype of the host tree influences community structure of foliar fungi. We sampled leaves from genotyped balsam poplars from across the species' range, and applied 454 amplicon sequencing to characterize foliar fungal communities. At the time of the sampling the poplars had been growing in a common garden for two years. We found diverse fungal communities associated with the poplar leaves. Linear discriminant analysis and generalized linear models showed that host genotypes had a structuring effect on the composition of foliar fungal communities. The observed patterns may be explained by a filtering mechanism which allows the trees to selectively recruit fungal strains from the environment. Alternatively, host genotype-specific fungal communities may be present in the tree systemically, and persist in the host even after two clonal reproductions. Both scenarios are consistent with host tree adaptation to specific foliar fungal communities and suggest that there is a functional basis for the strong biotic interaction.

An ethnobotanical study of medicinal plants in Sonebhadra District of Uttar, Pradesh, India with reference to their infection by foliar fungi

Sonebhadra district is one of the less studied regions of India for its ethnobotanical values. The present paper synthesizes the first report related to the documentation of ethnomedicinal plants of Sonebhadra district and their infection by foliar fungi. Ethnobotanical data were collected using semi-structured interviews and field observations. Correct identity of the plants was done with the help of relevant flora. Fungal organisms were identified on morphotaxonomic bases. The use of 143 medicinal plants belonging to 56 angiospermic families, by the tribal communities of Sonebhadra district has been documented. Out of 143 medicinal plants, 31 were found infected by different species of foliar fungi viz. Pseudocercopsora, Alternaria, Cercospora, Passalora, Corynespora, Mycovellosiella, Veronia and Dreschslera. Documentation of indigenous knowledge used for cure of different diseases by the tribes of the area can be used as basis for developing management plans for conservation and sustainable use of ethnomedicinal plants of the area. The report on foliar fungi infecting medicinal plants may draw attention of pharmaceutical firms and responsible sectors for proper care of the traditionally used medicinal wealth of the area. Key words: Ethnobotanical, medicinal plants, indigenous knowledge, foliar fungi, Sonebhadra district.

Anticancer and antimicrobial activity of mangrove derived fungi Hypocrea lixii VB1

Aim Mangrove is one of the oldest living tree species and its leaves are among the most extensively studied botanicals in use today. Scientific research throughout the world has found evidence to support the fact that its foliar extracts have great potential against human microbial pathogens. This study highlights the isolation of foliar fungi from Rhizophora mucronata, Avicenna officialis and Avicenna marina. Method It was isolated in Sabouroud's Dextrose Agar and mass cultivation was done in Sabouroud's Dextrose broth. Results The ethyl acetate extract showed maximum antibacterial activity which inturn checked for different concentration against bacterial pathogens and anticancer activity for Hep2 and MCF7 cell line in vitro. The DNA was isolated from the fungi and the ITS region of 5.8 s RNA was sequenced and assigned to new species as they are separated from the type strains phylogenetic neighbors by sequence similarities. Conclusion This preliminary screening of fungal endophytes revealed their potential to yield potent bioactive compounds for drug discovery programmes.

Can dispersal mode predict corridor effects on plant parasites?

Habitat corridors, a common management strategy for increasing connectivity in fragmented landscapes, have experimentally validated positive influences on species movement and diversity. However, long-standing concerns that corridors could negatively impact native species by spreading antagonists, such as disease, remain largely untested. Using a large-scale, replicated experiment, we evaluated whether corridors increase the incidence of plant parasites. We found that corridor impacts varied with parasite dispersal mode. Connectivity provided by corridors increased incidence of biotically dispersed parasites (galls on Solidago odora) but not of abiotically dispersed parasites (foliar fungi on S. odora and three Lespedeza spp.). Both biotically and abiotically dispersed parasites responded to edge effects, but the direction of responses varied across species. Although our results require additional tests for generality to other species and landscapes, they suggest that, when establishing conservation corridors, managers should focus on mitigating two potential negative effects: the indirect effects of narrow corridors in creating edges and direct effects of corridors in enhancing connectivity of biotically dispersed parasites.

Increased Severity of Foliar Diseases of Sweet Corn Infected with Maize Dwarf Mosaic and Sugarcane Mosaic Viruses.

Maize dwarf mosaic (MDM), caused by Maize dwarf mosaic virus (MDMV) and Sugarcane mosaic virus (SCMV), is an economically important viral disease of sweet corn (Zea mays). MDM is known to increase the severity of fungal root rots and southern corn leaf blight (SCLB). The effect of infection with MDMV-A and SCMV on eight foliar diseases was evaluated on 32 sweet corn hybrids (27 MDM-susceptible hybrids and five MDM-resistant hybrids) in 2007, 2008, and 2009. Virus infection substantially increased the severity of five diseases, including: SCLB, northern corn leaf spot (NCLS), gray leaf spot (GLS), Diplodia leaf streak (DLS), and eyespot. Among MDM-susceptible hybrids, mean severity of SCLB, NCLS, GLS, DLS, and eyespot on virus-infected plants was typically double that of plants that were asymptomatic of viral infection. Three diseases were not substantially increased by MDM, including: common rust, northern corn leaf blight (NCLB), and Stewart's wilt. Virus infection appeared to affect the severity of diseases caused by necrotrophic foliar fungi that colonize mesophyll tissue. MDM did not appear to substantially affect the severity of diseases caused by pathogens that form haustoria or invade the vascular system. The extent to which SCLB severity is increased by MDM in terms of changes in level of host resistance also was determined. For MDM-susceptible hybrids, reactions to SCLB ranged from resistant to moderately susceptible in MDM-free treatments, but each of these hybrids was classified as moderately susceptible to susceptible when infected with MDMV-A and/or SCMV. The results of this experiment demonstrate the importance of breeding for MDM resistance, not only to control this important viral disease of sweet corn, but also to lower the potential for detrimental effects from several other foliar diseases that often are of minor importance on sweet corn in the absence of MDM.

A Test of Taxonomic Predictivity: Resistance to Early Blight in Wild Relatives of Cultivated Potato

Host plant resistance offers an attractive method of control for early blight (caused by the foliar fungus Alternaria solani), a widespread disease that appears annually in potato crops worldwide. We tested the assumed ability of taxonomy to predict the presence of early blight resistance genes in wild Solanum species for which resistance was observed in related species. We also tested associations to ploidy, crossing group, breeding system, and geography. As in a prior study of Sclerotinia sclerotiorum (white mold) resistance, tremendous variation for resistance to early blight was found to occur within and among species. There was no discernable relationship between the distribution of resistant phenotypes and taxonomic series (based on an intuitive interpretation of morphological data), clade (based on a cladistic analysis of plastid DNA data), ploidy, breeding system, geographic distance, or climate parameters. Species and individual accessions with high proportions of early blight resistant plants were identified, but high levels of inter- and intra-accession variability were observed. Consequently, the designation of species or accessions as resistant or susceptible must take this variation into account. This study calls into question the assumption that taxonomic or geographic data can be used to predict sources of early blight resistance in wild Solanum species.

Impact of foliar fungi on dogroses

Wild roses of the section Caninae, commonly known as dogroses, have been described as more disease tolerant than ornamental roses and could therefore become valuable for breeding improved rose cultivars. Two fields with dogroses, one with plants obtained by open pollination in wild populations, and one with plants obtained from intra- and interspecific crosses, were evaluated for blackspot, powdery mildew, rust and leafspots in the autumn of 2005. Symptoms of the different fungi on different dogrose species were carefully evaluated in a microscope and documented by photography. Interestingly, almost no symptoms of powdery mildew were found in either field, although the fungus infected wild roses of a different section in a field closeby. Surprisingly few symptoms were found also of blackspot, and they differed considerably from those found on ornamental cultivars, indicating a lower susceptibility in dogroses. The most important fungal disease in 2005 was rust, followed by leafspot symptoms. The latter were apparently caused by Sphaceloma rosarum and Septoria rosae which can be properly discriminated only in a microscope. The investigated dogrose species and their progeny groups varied significantly in disease susceptibility and in the appearance of encountered symptoms but there was no evidence of major resistance genes, except possibly in Rosa rubiginosa which did not show any symptoms of Septoria. In 2006, a subset of the plant material in Field 1 was evaluated to check for consistency between the years. Leafspots had overtaken rust as the most important disease but results were otherwise very similar to those of 2005.

New species of Mycosphaerella from Myrtaceae in plantations and native forests in eastern Australia

The majority of Mycosphaerella species from eucalypts (Eucalyptus, Corymbia and Angophora) in Australia have been recorded only from trees growing in plantations. This illustrates a bias in research in the past two decades toward commercial enterprise, and it emphasises a lack of understanding of the occurrence of these important fungi under natural conditions. Surveys of foliar fungi in native forests in eastern Australia, as well as adjacent plantations, thus have been initiated in recent years. In this study we describe four new species of Mycosphaerella from Eucalyptus spp. as well as other Myrtaceae. Mycosphaerella tumulosa sp. nov. (anamorph: Pseudocercospora sp.) was found on more than seven species of Eucalyptus and Corymbia in native forests and plantations in northeastern New South Wales and southeastern Queensland and appears to be relatively common, although not damaging to these trees. Mycosphaerella multiseptata sp. nov. was recorded from several locations on species of Angophora in native forests and amenity plantings. Mycosphaerella pseudovespa sp. nov. was found in one location in native forest on E. biturbinata. The first species of Mycosphaerella to be described from Syncarpia, M. syncarpiae sp. nov., was found in native forests in numerous locations from Sydney through to northeastern New South Wales and appears to be relatively common.

New species of Mycosphaerella from Myrtaceae in plantations and native forests in eastern Australia

The majority of Mycosphaerella species from eucalypts (Eucalyptus, Corymbia and Angophora) in Australia have been recorded only from trees growing in plantations. This illustrates a bias in research in the past two decades toward commercial enterprise, and it emphasises a lack of understanding of the occurrence of these important fungi under natural conditions. Surveys of foliar fungi in native forests in eastern Australia, as well as adjacent plantations, thus have been initiated in recent years. In this study we describe four new species of Mycosphaerella from Eucalyptus spp. as well as other Myrtaceae. Mycosphaerella tumulosa sp. nov. (anamorph: Pseudocercospora sp.) was found on more than seven species of Eucalyptus and Corymbia in native forests and plantations in northeastern New South Wales and southeastern Queensland and appears to be relatively common, although not damaging to these trees. Mycosphaerella multiseptata sp. nov. was recorded from several locations on species of Angophora in native forests and amenity plantings. Mycosphaerella pseudovespa sp. nov. was found in one location in native forest on E. biturbinata. The first species of Mycosphaerella to be described from Syncarpia, M. syncarpiae sp. nov., was found in native forests in numerous locations from Sydney through to northeastern New South Wales and appears to be relatively common.

Foliar blight spectrum and genetic variability of Pyrenophora tritici-repentis

A survey was conducted for the assessment of foliar blight of wheat in main rice-wheat cropping areas of Punjab province. Foliar samples were collected at the maturity stage of wheat crop from 20 key locations of four districts: Gujranwala, Sheikhupura, Sialkot and Narowal. The foliar fungi were isolated using the blotter method. Prevalence of foliar blight was 100% in the four surveyed districts. From leaf samples, Pyrenophora tritici-repenti isolates were isolated using the standard blotter method. From the survey, it was concluded that foliar blight (tan spot) was a more prevalent fungal disease. It could not be differentiated in the field and it was confirmed in laboratory after the isolation of fungi (P. tritici-repentis). After isolation and identification, the Random Amplified Polymorphic DNA (RAPDs) technique was used for identification and differentiation of P. tritic-repentis isolates. For plant pathogenic fungi, RAPDs analysis has been used to analyse genetic variations or distinguished the P. tritici-repentis isolates. Fifteen strains were studied using a RAPDs analysis with different decamer primers. The molecular fingerprint patterns revealed differences in all the strains of identified P. tritici-repentis and showed genetic variability. In some of the isolates, the amplification profiles of P. tritici-repentis were highly polymorphic among each other, presenting differences. On the other hand, some of the isolates presented amplification profiles quite monomorphic among each other. It indicates RAPDs is a good molecular tool that could be used to characterize the P. tritici-repentis isolates for their genetic characters. From this survey it was concluded that foliar blight was a more prevalent fungal disease and it cannot be distinguished in the field and it was confirmed in the laboratory after the isolation of fungal pathogens. The blotter method is one of the best methods for the isolation of foliar fungal pathogens. After isolation, RAPDs is very quick method for the study of genetic variability.

Forest health condition in New South Wales, Australia, 1996–2005. I. Fungi recorded from eucalypt plantations during forest health surveys

Forests New SouthWales manages over 26 000 ha of young eucalypt (Eucalyptus and Corymbia) plantations, established since 1994. Forest health surveillance of these plantations was initiated in late 1995 to help protect this valuable and expanding resource. Fungi recorded during surveys from 1996 to 2005 are reported here. Over 50 species of fungi were identified, the majority being leaf spot fungi. The most commonly recorded were Quambalaria pitereka from leaves and shoots, Aulographina eucalypti, Kirramyces (=Phaeophleospora) epicoccoides and Mycosphaerella cryptica, all foliar fungi, and Botryosphaeria eucalypticola from both leaves and stems. Several species of fungi were recorded from many hosts, including A. eucalypti (18 hosts), M. cryptica (20 hosts), K. epicoccoides (14 hosts) and Botryosphaeria spp. (11 hosts). Others were restricted in their host range, such as Q. pitereka, Stigmina eucalypti, Kirramyces corymbiae prov. nom. and Lembosina corymbiae prov. nom., which were only found on species of Corymbia during these surveys. The published host range for several foliar fungi has been expanded from observations from these surveys, including for A. eucalypti, K. epicoccoides, M. cryptica, Mycosphaerella marksii, Mycosphaerella suberosa, Kirramyces eucalypti, Phaeothyriolum microthyrioides and S. eucalypti. Six new species of foliar fungi were identified during these surveys: Mycosphaerella tumulosa prov. nom., Mycosphaerella associata prov. nom., Mycosphaerella exentricum prov. nom., K. corymbiae, L. corymbiae and Lembosina eucalypticola prov. nom. Some foliar fungi were observed for the first time from New South Wales during these surveys, including M. marksii, M. suberosa, M. parva, Cryptosporiopsis eucalypti and Trimmatostroma excentricum. Tubercularia lateritia and Caliciopsis sp. spleomorpha, both stem fungi, are reported from eucalypts in New South Wales for the first time.

Aggressiveness analysis of foliar fungi to leaves of wheat and rice crops

The investigations were based on two surveys of wheat and one survey of rice. Alternaria alternata, Curvularia lunata, Helminthosporium tetramera and Bipolaris sorokiniana were isolated and identified from foliage and soil of both wheat and rice crops and their aggressiveness was studied by aggressiveness analysis screened out into different aggressiveness classes. The aggressiveness of isolated fungi was studied on wheat varieties (Inqalab-91 and Chakwal-86) and rice varieties (Basmati-385 and IRRI-6) under controlled conditions. In the foliar aggressiveness test of A. alternata, the overall number of aggressive isolates was higher on wheat varieties than rice. Bipolaris sorokiniana isolates showed foliar blight symptoms on wheat but not on rice varieties. In C. lunata, the overall number of aggressive isolates was higher on wheat. In the foliar aggressiveness test of H. tetramera, the number of non-aggressive isolates was almost the same on wheat and rice varieties. In the present study it became clear that A. alternate, B. sorokiniana, C. lunata and H. tetramera are common foliar pathogens in rice and wheat crops and can cause soil-borne and foliar diseases.

Olive mill residues affect saprophytic growth and disease incidence of foliar and soilborne plant fungal pathogens

Abstract Olive oil mill residues constitute a major environmental problem. Although these wastes have a high fertilizer value when applied to the soil, there is concern about their use because of their antimicrobial and phytotoxic properties. Furthermore, their effect on saprophytic growth and pathogenicity of soilborne and foliar fungi is poorly known. In this study we investigated the effects of olive mill dry residue (DOR) on: (a) growth of the four crop species Lepidium sativum , Lycopersicon esculentum , Lactuca sativa and Triticum aestivum ; (b) saprophytic growth of the four phytopathogenic fungi Fusarium oxysporum f.sp. lycopersici (FOL), Fusarium culmorum (FC), Sclerotinia minor (SM) and Botrytis cinerea (BC); (c) influence of soil amendment with DOR on the three plant–soilborne pathogen systems, L. esculentum –FOL, T. aestivum –FC, L. sativa –SM, and the two plant–foliar pathogen systems, L. esculentum –BC and L. sativa –BC. Residues resulted phytotoxic, both in laboratory and greenhouse bioassays, for all plant species in relation to their concentrations. L. sativum and L. sativa were the most sensitive species to the residues, followed by L. esculentum and T. aestivum . In contrast with the results observed with plant species, the performances (radial growth and hyphae density) of the tested phytopathogenic fungi were positively affected by DOR. In greenhouse bioassays, L. sativa mortality imputable to SM increased on soil amended with DOR. BC foliar disease dramatically increased on L. sativa and L. esculentum plants grown on soil amended with DOR at all used concentrations. Differently, soil amendment with DOR did not significantly affect the disease incidence of FC on T. aestivum and FOL on L. esculentum . Our study demonstrates that, in controlled conditions, undecomposed DOR affects the growth of crop species (phytotoxic effect) and phytopathogenic fungi (substrate effect), and that the interaction between these factors, in some cases, drives to an increase of fungal disease incidence.

Endophytic foliar fungi in Betula spp. and their F1 hybrids

SummaryWe examined foliar endophyte frequencies in two native (Betula pendula and Betula pubescens) and three exotic (Betula ermanii, Betula platyphylla and Betula resinifera) birch species and their hybrids in Punkaharju, Finland. The most frequently isolated endophytic fungi in the experimental trees were Fusicladium betulae and Gnomonia setacea making up 80–90% of all endophyte infections. Total endophyte infection levels varied from 0.5 colony forming units (CFU)/cm2 in B. platyphylla to 8.6 CFU/cm2 in B. pubescens that had highest total infection levels of both examined endophyte species. The resistance of hybrids was generally very close to the more resistant parent (the only exception being Fusicladium in B. platyphylla × B. pendula hybrid) supporting the hypothesis that the resistance of birch hybrids to these fungi is genetically based and caused by dominant inheritance of resistance traits.

Biotic injuries on conifer seedlings planted in forest understory environments

We investigated how partial overstory retention, understory vegetationmanagement, and protective Vexar® tubing affected the frequency andseverityof biotic injuries in a two-storied stand underplanted with western redcedar(Thuja plicata Donn ex D. Don), Douglas-fir(Pseudotsuga menziesii (Mirb.) Franco, grand fir(Abies grandis (Dougl.) Lindl), and western hemlock(Tsuga heterophylla (Raf.) Sarg.). The most prevalentsource of damage was browsing by black-tailed deer (Odocoileushemionis columbiana); deer browsed over 74% of Douglas-fir and over36% of western redcedar seedlings one or more times over the four years of thisstudy. Neither the spatial pattern of thinning (even or uneven) nor the densityof residual overstory affected browsing frequency. Spraying subplots may haveslightly increased browsing frequency, but the resulting reduction of theadjacent understory vegetation increased the volume of all seedlings by 13%,whether or not they were browsed. Vexar® tubing did not substantiallyaffectseedling survival, browsing damage frequency, or fourth-year volume. Greaterlevels of overstory retention reduced frequency of second flushing. Chafing bydeer and girdling by rodents and other small mammals began once seedlingssurpassed 1 m in height. Essentially all grand fir seedlingsexhibited a foliar fungus infection.

Quantification of Phaeocryptopus gaeumannii colonization in Douglas‐fir needles by ergosterol analysis

Current assessments of infection levels of Phaeocryptopus gaeumannii, the incitant pathogen of Swiss needle cast disease on Pseudotsuga menziesii, typically rely on surveys of abundance of fruit bodies on diseased needles. The relationship between this measure and internal fungal colonization is unknown. In this article, a series of experiments to determine whether ergosterol can be used to quantify P. gaeumannii internal colonization within Douglas‐fir needles is reported. It was found that ergosterol content in seven commonly occurring Douglas‐fir foliar fungi is proportionally related to biomass, and in P. gaeumannii this relationship is not affected by age of the culture. Furthermore, at four sites tested, P. gaeumannii was the most common fungus species isolated from Douglas‐fir needles, accounting for approximately 50% of the isolations. Ergosterol content in these needles was best related to P. gaeumannii despite the presence of other fungi. The strong relationship between ergosterol and P. gaeumannii is attributed to its greater contribution to total fungal biomass compared with all other fungi present within Douglas‐fir needles.

Technique for large scale isolation of Discula umbrinella and other foliar endophytic fungi from Quercus species

This paper describes a useful large scale technique suitable for isolation of Discula umbrinella and other foliar endophytic fungi. This technique provides an efficient means to collect large numbers of fungal isolates necessary for fungal ecology and genetic variation studies. Also, this method is easily modified for isolation of other fungi residing within a leaf. An oversized vacuum filtration unit was built to accomodate large numbers of leaf discs and all sterilization procedures were carried out on this unit. Leaf discs were incubated on white oak leaf agar in 24-well tissue culture plates for a 12-hr light period at 24 C for Discula umbrinella conidiomata production. Conidia were streaked onto white oak leaf agar. Isolates were transferred to Difco potato dextrose agar and stored in sterile water at 24 C for future fungal population studies. Discula umbrinella infection levels on Quercus alba and Q. rubra were monitored monthly using this technique. Conidiomata infection levels within leaves of Q. alba were higher than Q. rubra in the months of May, Jun, and Jul. Leaves of Q. rubra showed higher infection levels in the months of Aug and Sept. The feasibility of isolating other endophytic fungi with the large scale technique was also tested. Using the large scale method, 18 different fungal isolates were collected from fallen leaves of Quercus alba. Tubakia dryina (Sacc.) Sutton was the most frequently isolated endophyte from fallen leaves regardless of the media used.

The effect of nitrogen fertilization and rust fungus infection, singly and combined, on the leaf chemical composition of Rumex obtusifolius

1. The chrysomelid beetle Gastrophysa viridula occurs on Rumex obtusifolius growing in a range of nutrient conditions and also on plants infected with the foliar fungus Uromyces rumicis. In a controlled environment, we investigated the effect of fertilizing plants with eight nitrate and four ammonium concentrations, with or without infection, on leaf nutritional quality. 2. Increasing nitrate fertilization increased leaf oxalate, total nitrogen and nitrate concentrations and water content, and decreased total non‐structural carbohydrate (NSC) concentrations. Increasing ammonium fertilization increased leaf nitrogen concentration and water content, decreased nitrate and NSC concentrations, and had no effect on oxalate concentrations. 3. Infection produced a mainly additive effect to fertilization, increasing NSC and oxalate, and decreasing nitrate and nitrogen concentration in whole plants fed nitrate, and increasing nitrate and NSC in whole plants fed ammonium. 4. Young leaves on infected plants remained uninfected and had greater nitrogen and NSC concentrations, and lower oxalate and nitrate concentrations, than infected leaves on the same plant. 5. These results are discussed in relation to changes in C:N and NSC:organic nitrogen ratios, the effect of nitrate and oxalate, and the known feeding and oviposition preferences of the beetle. The results suggest that there is an optimum nitrogen fertilization level for G. viridula development.