The arrival of Teratosphaeria nubilosa drastically impacted the production of Eucalyptus globulus Labill in Uruguay. However, information regarding growth losses is scarce. The objective of this work was to quantify the effect of the disease on the productivity of E. globulus plantations through modeling and simulation of growth with different levels of disease. For this, diameter at breast height (DBH) and total height were measured in 7 year-old plantations and individual volume was calculated. This information was used to adjust linear and non-linear mixed models that would allow estimating DBH average, total height average of the stand and volume per hectare, relating growth parameters with the Crown Damage Index (CDI) at 6, 12 and 24 months old. The results indicated a significant negative relationship of CDI12 (P < 0.05) with DBH and volume (predictor variables). The estimated growth at 7 years by modeling with CDI = 0 (without crown damage) was higher than the observed growth (14.5 vs. 13.1 cm for DBH and 116.5 vs. 93.7 m³/ha for volume, respectively). The intensity of Teratosphaeria Leaf Disease (TLD) and the relative wood volume loss caused by the disease damage did not vary with site quality. This reinforces previous results showing that site selection does not significantly contribute as alternative management to mitigate the impact of the disease. This work allowed an estimation of the negative effect of TLD on E. globulus in Uruguay.

The international spread of the myrtle rust pathogen, Austropuccinia psidii, can be largely attributed to the “pandemic” biotype that has more than 450 host species. However, within South America, the putative native range of A. psidii, multiple biotypes have been characterised, each with a restricted known number of hosts. These biotypes may pose a significant biosecurity threat to countries already affected by the pandemic biotype. Here, we report the susceptibility of four species of Myrtaceae from New Zealand, pōhutukawa (Metrosideros excelsa), mānuka (Leptospermum scoparium), kānuka (Kunzea ericoides), and rawiri mānuka (Kunzea ericoides ‘gumland ecotype’), to a strain of the Eucalyptus biotype of A. psidii. Symptoms and signs developed on inoculated plants of all species. Qualitative resistance phenotypes, with no disease development, were observed for all four species. However, no hypersensitive responses were observed. As seen for other biotypes, pōhutukawa had the greatest susceptibility, while kānuka had the lowest. These findings are consistent with prior work, showing that the Eucalyptus biotype can infect a broader range of species than its field host association implies. As well as uredinia (asexual spores), telia (sexual spores) developed on several plants, indicating that these species could provide a universal host for sexual reproduction and outcrossing between biotypes. Knowledge that the Eucalyptus biotype of A. psidii is virulent on several indigenous New Zealand Myrtaceae will inform future biosecurity risk assessments. These findings highlight the need to develop diagnostics tools to differentiate between biotypes and allow rapid responses to potential future incursions.

The emerald ash borer (EAB) is an invasive beetle that has killed hundreds of millions of ash trees throughout North America since its arrival. The use of entomopathogenic fungi as part of integrated pest management approaches is considered effective against a wide range of insect pests. The aim of this study was to screen and select locally adapted EAB-associated entomopathogenic fungi with ovicidal effect on EAB eggs under laboratory conditions. The pathogenicity of nine fungal strains, previously isolated from EAB galleries, and the commercial Beauveria bassiana strain GHA was tested. Three of these, Akanthomyces muscarius 48-27, Lecanicillium longisporum 66-14 Lecanicillium psalliotae 59-2, and GHA B. bassiana strain consistently showed significant ovicidal effects and a high percentage of inoculum recovery both from eggs and neonate larvae. The high levels of inoculum recovery from neonate larvae demonstrate that, even after emergence, larvae were infected. The possibility of disrupting EAB’s life cycle at the egg stage through microbial control represents a potential management opportunity that should be explored in future field studies. Future work should also study the effect of EPF on neonate larvae survival and performance. To our knowledge, this is the first study to evaluate the effect of entomopathogenic fungi against the egg stage of EAB.

The emerald ash borer is causing dramatic losses following its introduction into North America, with hundreds of millions of ash trees killed. Attacked trees lose wood integrity rapidly after infestation and are prone to failure. The aim of this study was to investigate the wood degrading potential of Basidiomycota fungi previously found associated with EAB galleries. Laboratory soil and agar microcosm experiments showed that many of the white-rot fungi isolated were aggressive wood degraders. Trametes versicolor, Phlebia radiata and Phlebia acerina were among the top decomposers from the 13 tested fungi, resulting in as much as 70%, 72% and 64% weight loss, respectively, after 6 months of incubation. Micromorphological observations documented the significant wood cell wall degradation that had taken place. The decay capacity of these fungi confirms their contributing role to the loss of wood integrity in ash trees after EAB attack.

The emerald ash borer (EAB) is an exotic forest pest that has killed millions of ash trees in the United States and Canada, resulting in an ecological disaster and billions of dollars in economic losses of urban landscape and forest trees. The beetle was first detected in Michigan in 2002 and has spread through much of the Eastern and Midwestern U.S., reaching Minnesota in 2009. Since then, it has spread across the state and poses a great risk to the more than 1 billion ash trees in Minnesota. The larval stage of EAB creates wounds on trees as they feed on the inner bark, causing disruption of water and sap flow that results in tree death. The fungal community associated with EAB larval galleries is poorly understood and the role these fungi may play in tree death is not known. This study describes fungi isolated from EAB larval galleries sampled throughout the main geographic areas of Minnesota where ash is affected by EAB. Fungal cultures were identified by extracting genomic DNA and sequencing the ITS region of the rDNA. Results from 1126 isolates reveal a diverse assemblage of fungi and three functional guilds comprised of canker pathogens, wood decay, and entomopathogenic fungi. The most common canker-associated genera were Cytospora followed by Phaeoacremonium, Paraconiothyrium, Coniothyrium, Nectria, Diplodia, and Botryosphaeria. Fungi in the Basidiomycota were nearly all wood decay causing fungi and many were species of pioneer colonizing genera including Sistotrema, Irpex, Peniophora, Phlebia and Ganoderma. Some of these fungi seriously affect urban trees, having the potential to cause rapid wood decay resulting in hazardous tree situations. Several entomopathogenic genera with the potential for biological control of EAB were also isolated from galleries. Purpureocillium was the most commonly isolated genus, followed by Beauveria, Clonostachys, Lecanicillium, Akanthomyces, Cordyceps, Microcera, Tolypocladium, and Pochonia. The results identify important fungal functional guilds that are occupying a new niche in ash trees resulting from EAB and include fungi that may accelerate decline in tree health, increase hazard tree situations, or may provide options for biological control of this destructive invasive insect.

The bronze bug Thaumastocoris peregrinus is an invasive pest, affecting Eucalyptus plantations worldwide. Although its natural enemy Cleruchoides noackae has been tested for the biological control of this pest, other strategies like the use of native entomopathogenic fungi are needed. For this, native virulent fungal isolates should be selected, massively multiplied in an efficient way, and prepared to obtain a stable product. Isolates of native Beauveria bassiana obtained from T. peregrinus and from different collections were screened for their virulence towards this insect and for their amenability to be massively produced in a low-input liquid submerged fermentation and prepared as a dry powder. Three out of six virulent strains were suitable for their massive production in a 2% corn flour suspension, achieving 10(9) submerged propagules/g of dehydrated preparation. The LC50 achieved by the dry submerged propagules did not differ from the LC50 of fresh aerial conidia. The proposed dual selection of strain and a complex substrate, and the procedures leading to the production of a dry preparation, allowed for high viability and virulence of the fungal spores of three strains.

Thaumastocoris peregrinus Carpintero & Dellape (Heteroptera: Thaumastocoridae) is a sap-sucking insect that feeds on leaves of Eucalyptus. In Uruguay, it was detected in 2008 causing significant economic losses in Eucalyptus plantations. At present, there is no efficient control for this pest; thus, the use of biological control agents seems to be an environmentally friendly alternative to reduce the damage caused by this insect. The aims of this study were to isolate and identify the species of entomopathogenic fungi that naturally infect T. peregrinus in Uruguay and to characterize and select the most virulent isolates towards this pest. Individuals of T. peregrinus were collected in eight Eucalyptus plantations infested by the pest. The entomopathogenic fungi were isolated and identified by observation of their micromorphological characteristics, and their identity was confirmed by molecular methods. The pathogenicity and virulence against T. peregrinus of the isolated entomopathogenic fungi were evaluated. Isolates causing the highest insect mortality were selected to evaluate the effect of temperature and water activity on conidial viability. Entomopathogenic fungi were found in very low number with the prevalence of less than 3%. Isolates corresponded to Beauveria, Fusarium, Isaria, Lecanicillium, Paecilomyces, Pochonia, Purpureocillium and Simplicillium genera. Two species, B. pseudobassiana and L. muscarium, were first recorded in Uruguay. Among all the tested species, an isolate of B. bassiana (FI 2403) showed the highest virulence followed by an isolate of B. pseudobassiana. The isolate of B. bassiana presented the highest percentage of spore germination at the three temperatures and the highest viability at low water activities. Isolate FI 2403 was selected as a promissory candidate for the development of a commercial formulation against T. peregrinus.

Teratosphaeria nubilosa severely affects young plantations of Eucalyptus globulus and Eucalyptus maidenii in Uruguay. This work analyzes the effect of the damage caused by T. nubilosa on tree growth and survival of E. globulus and E. maidenii, based on data from a trial naturally infected by this pathogen. The effect of defoliation and proportion of adult foliage on tree growth and mortality was evaluated at 50 months of age. Defoliation in E. globulus was higher than in E. maidenii, reaching average values of 52.5 and 28.8 %, respectively, at 21 months of age. By contrast, E. globulus showed higher precocity of vegetative phase change than E. maidenii. Although the damage threshold for diameter growth was 40 % on E. globulus and 20 % on E. maidenii, the detrimental effect on growth was similar in both species, where the most defoliated trees suffered a reduction in diameter of 49.4 and 47.5 %, respectively, at 50 months of age. Mortality increased significantly when defoliation exceeded 30 % in E. globulus and 40 % in E. maidenii. The results showed that E. maidenii has lower defoliation, higher growth and lower mortality than E. globulus after epidemics of T. nubilosa. However, the lower defoliation and higher proportion of juvenile foliage showed by E. maidenii represent a greater source of inoculum, suggesting that a large-scale replacement of E. globulus by E. maidenii in areas where T. nubilosa is a problem could be risky from an epidemiological point of view.

GENOTYPES THAT CAUSE RUST DISEASE ON DIVERSE MYRTACEOUS TREES AND SHRUBS Amy L Ross-Davis' , Rodrigo N Grar;a, Acelino C Alfenas, Tobin L Peever, John W Hanna, Janice Y Uchida, Rob D HaufF, Chris Y Kadooka, Mee-Sook Kim, Phil G Cannon, Shigetou Namba, Nami Minato, Sofia Simeto, Carlos A Perez, Min B Rayamajhi, Mauricio Moran, D Jean Lodge, Marcela Arguedas, Rosario Medei-Ortiz, M Armando L6pez-Ramirez, Paula Tennanr , Morag Glen, and Ned B Klopfenstein

Over the last 5 years foliar diseases had caused devastating damages in young plantations of Eucalyptus globulus in Uruguay. The sustainability of this species, the most important in the country with more than 270,000 ha of commercial plantations, depends on the rapid development of resistant genetic stock. The genetic variation in resistance of juvenile foliage to diseases and in the onset to adult foliage were examined in a field trial of E. globulus naturally infected by Mycosphaerella leaf disease (Mycosphaerella spp. and Teratosphaeria spp.) and Eucalyptus rust (Puccinia psidii). The genetic material included 226 open pollinated seed lots from 16 provenances of Australia, Chile and Uruguay. Disease severity (% of leaf spots and % defoliation) was assessed 8 months after planting and precocity of phase change (% of adult foliage) at 20 months. Tree growth and survival were evaluated every 2 years up to the ninth year. Differences in disease severity and in precocity of phase change were significant among countries of origin and provenances. Within provenances, the narrow-sense individual tree heritabilities for leaf spot severity (0.37), defoliation (0.41) and proportion of adult foliage (0.40) were higher than those obtained for tree growth (0.19 to 0.33) and similar to those obtained for survival (0.33 to 0.45). Genetic correlations between disease severity and growth traits were negative (−0.20 to −0.44) and were also negative between disease severity and survival (−0.28 to −0.51). There were positive genetic correlations between precocity of phase change and growth traits (0.34 to 0.41) and between precocity of phase change and survival (0.29 to 0.37). Our results demonstrate that selection for low disease severity in the first year and for high proportion of adult foliage in the second year are feasible in order to obtain genetic material for sites at risk of infection of both Mycosphaerella leaf disease and Eucalyptus rust.

Since the first report of Teratosphaeria nubilosa (Cooke) Crous & U.Braun in Uruguay in 2007, young plantations of Eucalyptus globulus Labill. and E. maidenii F.Muell. have been severely damaged by Mycosphaerella leaf disease. The genetic variation in disease resistance and in the timing of heteroblastic phase change was examined in 194 open-pollinated families of E. globulus and 86 families of E. maidenii growing in a field trial in south-eastern Uruguay, naturally infected by T. nubilosa. Disease severity, precocity of vegetative phase change and tree growth were assessed at 14 months. E. globulus was significantly more susceptible to T. nubilosa than was E. maidenii, presenting higher severity of leaf spots (10.6% and 5.6%, respectively), higher defoliation (31.9% and 22.9%, respectively) and higher crown-damage index (39.1% and 27.4%, respectively). However, the heteroblastic transition began significantly earlier in E. globulus than in E. maidenii, with 34.1% and 2.8% of the trees having some proportion of their crown with adult foliage at 14 months, respectively. Significant individual narrow-sense heritabilities were found in E. globulus for severity of leaf spots (0.40), defoliation (0.24), crown-damage index (0.30) and proportion of adult foliage (0.64). Additive genetic variation in E. maidenii was significant only for defoliation and crown-damage index, with a moderate heritability (0.21 and 0.20, respectively). Although E. maidenii was more resistant to T. nubilosa than was E. globulus, the degree of resistance was not enough to consider this species as an alternative to E. globulus for high-risk disease sites. In addition, the small genetic variability for resistance on the juvenile foliage and the late transition to adult foliage suggested that the chances for early selection in E. maidenii are quite limited. By contrast, the genetic variation in E. globulus clearly indicated that through selection for resistance of the juvenile foliage, and especially by selecting for early phase change, it is possible to obtain genetic stock suitable for sites with high risk of T. nubilosa infection.

Eucalyptus globulus is the most important forest species in Uruguay, with more than 250,000 ha of commercial plantations. Despite its high susceptibility to diseases, production losses caused by foliar diseases have not been properly quantified in this country. This study analyzes the effects of foliar damage on growth and survival using data from a progeny test of E. globulus naturally infected by Teratosphaeria leaf disease and eucalypt rust (Puccinia psidii). The severity of leaf spots and defoliation were quantified 8 months after planting and tree growth and mortality were evaluated 2, 4 and 6 years later. The trial had a high incidence of foliar damage, with a mean leaf spot severity of 28.7% and a mean defoliation of 37%. The greatest impact of foliar damage, both on growth rate and mortality, occurred in the first 2 years after damage was assessed. During this period, leaf spot severity less than 40% and defoliation below 50% did not affect growth, while survival was affected when leaf damage was 70% or greater. By the sixth year both stem growth and survival were affected by severe foliar damage (spotting or defoliation of 80% or more), with a loss of up to 25% in diameter and an accumulated mortality over 70%. It has been established for the first time that under the intensive Uruguayan productive conditions, E. globulus trees can tolerate a relatively high degree of leaf spotting or defoliation but severe foliar damage in the first months can cause considerable production losses, putting at risk the economical viability of this species.

El Eucalyptus globulus es la especie forestal más plantada en el Uruguay, existiendo más de 270.000 hectáreas de plantaciones comerciales. Sin embargo actualmente está siendo sustituido por otras especies, como E. grandis y E. dunnii, debido a los severos daños foliares provocados por Teratosphaeria nubilosa en las plantaciones jóvenes. La continuidad en la plantación de esta especie depende del rápido desarrollo de material genético resistente a la enfermedad. La variación genética de la resistencia del follaje juvenil y la velocidad del cambio de follaje de juvenil a adulto fueron evaluadas en una prueba de progenies de E. globulus naturalmente infectada por T. nubilosa. El material genético incluyó 194 familias de polinización abierta provenientes de dos huertos semilleros pertenecientes al Instituto Nacional de Investigación Agropecuaria (INIA)

Eucalyptus or guava rust caused by Puccinia psidii is a serious disease of Eucalyptus and other Myrtaceae. In Uruguay, it has been previously found on Eucalyptus globulus and Psidium brasiliensis. Almost nothing is known regarding the occurrence of this pathogen on other Eucalyptus species or native Myrtaceae in that country. In this study, we determined the presence of P. psidii on Eucalyptus species and native Myrtaceae trees in Uruguay and evaluated the pathogenicity of specimens from native myrtaceous hosts on E. globulus and E. grandis. Phylogenetic analyses based on the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA operon were used to confirm pathogen identity. Comparisons of ITS sequences confirmed the identity of P. psidii on Eucalyptus globulus , E. grandis , Myrcianthes pungens , and Myrrhinium atropurpureum var. octandrum. This is the first report of P. psidii on M. atropurpureum var. octandrum . Pathogenicity tests showed that isolates from native Myrtaceae could infect both Eucalyptus species tested, indicating a strong biological relationship between both introduced and native Myrtaceae. This study supplies relevant field data, morphological information, molecular phylogenetic analyses and infection studies that contribute to a better understanding of an important and little studied pathogen.

Varias species residentes en la familia Botryosphaeriaceae son importantes patogenos causantes de cancros y «dieback» en numerosas plantas lenosas. En Uruguay, cancros del fuste observados en plantaciones de Eucalyptus globulus han estado asociados a Neofusicoccum eucalyptorum (=Botryosphaeria eucalyptorum), N. ribis (=B. ribis) y B. dothidea. Estos hongos tambien habitan como endofitos en hojas, ramas y fustes asintomaticos de Eucalyptus volviendose patogenos luego de la ocurrencia de algun estres. Existen evidencias que sugieren que otras especies de Botryosphaeriaceae, ademas de las antes mencionadas podrian causar cancros en Eucalyptus spp. y mirtaceas nativas en Uruguay. En este estudio, identificamos las especies Botryosphaeriaceae presentes en Eucalyptus spp. y en mirtaceas nativas, y analizamos la diversidad genetica entre los aislamientos aislados de ambos grupos de hospederos. Muestras de material vegetal de Eucalyptus spp. y mirtaceas nativas con y sin sintomas fueron colectadas desde diversos puntos del pais. Los cultivos fungicos monosporicos obtenidos de dichas muestras, fueron identificados en base a la morfologia de conidios y a tecnicas moleculares mediante comparacion de secuencias de ADN correspondientes a la region ITS del ADN ribosomal. Los resultados muestran que aislamientos identificados dentro del complejo N. parvum-N. ribis, y otros identificados como B. dothidea fueron aislados de ambos hospederos, Eucalyptus spp. y mirtaceas nativas. Por el contrario, N. eucalyptorum fue aislado unicamente de Eucalyptus spp., mientras que aislamientos de una especie relacionada a Diplodia seriata (=B. obtusa) fueron obtenidos unicamente de arboles nativos. Este estudio permite expandir los conocimientos acerca de las especies Botryosphaeriaceae presentes en mirtaceas nativas e introducidas en Uruguay.