Mango anthracnose, caused by Colletotrichum spp., is the most significant disease of mango (Mangifera indica L.) in almost all production areas around the world. In Mexico, mango anthracnose has only been attributed to C. asianum and C. gloeosporioides. The aims of this study were to identify the Colletotrichum species associated with mango anthracnose symptoms in Mexico by phylogenetic inference using the ApMat marker, to determine the distribution of these species, and to test their pathogenicity and virulence on mango fruits. Surveys were carried out from 2010 to 2012 in 59 commercial orchards in the major mango growing states of Mexico, and a total of 118 isolates were obtained from leaves, twigs, and fruits with typical anthracnose symptoms. All isolates were tentatively identified in the C. gloeosporioides species complex based on morphological and cultural characteristics. The Bayesian inference phylogenetic tree generated with Apn2/MAT intergenic spacer sequences of 59 isolates (one per orchard) revealed that C. alienum, C. asianum, C. fructicola, C. siamense, and C. tropicale were associated with symptoms of mango anthracnose. In this study, C. alienum, C. fructicola, C. siamense, and C. tropicale are reported for the first time in association with mango tissues in Mexico. This study represents the first report of C. alienum causing mango anthracnose worldwide. The distribution of Colletotrichum species varied among the mango growing states from Mexico. Chiapas was the only state in which all five species were found. Pathogenicity tests on mango fruit cultivar Manila showed that all Colletotrichum species from this study could induce anthracnose lesions. However, differences in virulence were evident among species. C. siamense and C. asianum were the most virulent, whereas C. alienum and C. fructicola were considered the least virulent species.

Strawberry root and crown rot caused by the fungus Neopestalotiopsis rosae is an emerging disease that has caused yield losses of up to 70% in Mexico and other regions worldwide. This research evaluated the effects of biological and chemical fungicides applied as preventive and curative applications for controlling root and crown rot caused by N. rosae in strawberries under greenhouse conditions. Treatments included these chemical fungicides: prochloraz, prochloraz + thiram, cyprodinil + fludioxonil, difenoconazole + azoxystrobin, iprodione, captan, thiram, pydiflumetofen + fludioxonil, fluxapyroxad + pyraclostrobin, and hymexazol; each was applied at commercial doses. Also tested were biological treatments based on Trichoderma koningiopsis, T. asperellum, Streptomyces sp., and Bacillus amyloliquefaciens strain D747 (B. velezensis). Disease incidence, severity, plant mortality, root length, and dry weight were determined. Results showed that overall, preventive applications of the fungicides pydiflumetofen + fludioxonil, cyprodinil + fludioxonil, and prochloraz resulted in the smallest area under the disease progress curve and the lowest final disease incidence, severity, and plant mortality. An intermediate group of effective treatments entailed hymexazol, iprodione, T. asperellum, and T. koningiopsis (50 to 75% efficacy). Treatments with greater efficacy (99 to 100%), pydiflumetofen + fludioxonil, cyprodinil + fludioxonil, and prochloraz, also had maximal total plant biomass vis-à-vis the untreated control. By contrast, each treatment’s efficacy was significantly reduced when applied curatively (0 to 37% treatment efficacy). These results suggest that certain treatments are useful for controlling strawberry root and crown rot caused by N. rosae when applied preventively (as root dipping). These results will contribute to designing more effective management programs for root and crown rot caused by N. rosae on strawberry.

Gray mold (Botrytis cinerea), late blight (Phytophthora infestans), powdery mildew (Leveillula taurica), pith necrosis (Pseudomonas corrugata), and bacterial canker (Clavibacter michiganensis) are major diseases that affect tomato (Solanum lycopersicum L.) in greenhouse production in Mexico. Management of these diseases depends heavily on chemical control, with up to 24 fungicide applications required in a single season to control fungal diseases, thus ensuring a harvestable crop. While disease chemical control is a mainstay practice in the region, its frequent use increases the production costs, likelihood of pathogen-resistance development, and negative environmental impact. Due to this, there is a need for alternative practices that minimize such effects and increase profits for tomato growers. The aim of this study is to evaluate the effect of biorational products in the control of these diseases in greenhouse production. Four different treatments, including soil application of Bacillus spp. or B. subtilis and foliar application of Reynoutria sachalinensis, Melaleuca alternifolia, harpin αβ proteins, or bee honey were evaluated and compared to a conventional foliar management program (control) in a commercial production greenhouse in Central Mexico in 2016 and 2017. Disease incidence was measured at periodic intervals for six months and used to calculate the area under the disease progress curve (AUDPC). Overall, the analysis of the AUDPC showed that all treatments were more effective than the conventional program in controlling most of the examined diseases. The tested products were effective in reducing the intensity of powdery mildew and gray mold, but not that of bacterial canker, late blight, and pith necrosis. Application of these products constitutes a disease management alternative that represents cost-saving to tomato growers of about 2500 U.S. dollars per production cycle ha⁻¹, in addition to having less negative impact on the environment. The products tested in this study have the potential to be incorporated in an integrated program for management of the examined diseases in tomato in this region.

Fusarium head blight (FHB) is one of the most important diseases affecting wheat production worldwide. In Mexico, Fusarium boothii and F. avenaceum are the dominant species causing FHB of wheat (Ce...

Taro (Colocasia esculenta var. antiquorum), family Araceae, is an important tropical crop cultivated throughout the world for its edible corms. During the summer of 2017, irregular brown lesions, typical of anthracnose were observed on approx. 40% of taro plants in a commercial orchard located in San Juan Bautista Tuxtepec, Oaxaca, Mexico. Small pieces of the lesions of five symptomatic leaves were surface disinfected with 1% NaOCl for 2 min followed by rinsing with sterile distilled water and plated on potato dextrose agar plates which were then incubated at 25°C for 5 days in darkness. Colletotrichum-like colonies were consistently isolated and 10 monoconidial isolates were obtained. Two isolates were selected as representatives for morphological characterization, multilocus phylogenetic analysis, and pathogenicity tests. The isolates were designated as UACH289 and UACH290 and were deposited in the Culture Collection of Phytopathogenic Fungi at the Chapingo Autonomous University. Conidia (n = 100) of is...

Dieback of sapote mamey [Pouteria sapota (Jacq.) H. E. Moore and Stearn] grafts caused by Lasiodiplodia theobromae significantly reduces the success of grafting in Mexican nurseries. Semi-commercial tests were conducted in a sapote mamey nursery during two grafting seasons to evaluate the effectiveness of a physical treatment (washing) and three chemical treatments (fungicide dip) on scions. Washing reduced disease incidence up to 31 %, whereas chemical treatment reduced it up to 62 %. The combination of washing and thiabendazole dip resulted in an incidence decrease of 81 %. Twelve other fungicides were screened in vitro to evaluate mycelial growth inhibition of L. theobromae. The pre-formulated mix of cyprodinil + fludioxinil was the most effective fungicide with EC50 value of 0.0043 μg mL-1, followed by pyraclostrobin + boscalid, prochloraz and tebuconazole with EC50 values < 0.1 μg mL-1, and iprodione and thiabendazole with EC50 values < 1.0 μg mL-1. This study provides novel information about strategies for controlling L. theobromae infection during the grafting process of sapote mamey and it also showed the effectiveness of several fungicides under in vitro conditions for controlling this plant pathogenic fungus.