The intensification of the st. john’s wort ( Hypericum perforatum ) production in Switzerland at the end of the 1990s was accompanied by the appearance of anthracnose caused by Colletotrichum gloeosporioides (teleomorph Glomerella cingulata
Vincent V. Michel, Nicole Debrunner, and Xavier Simonnet
Jayasankar Subramanian, Richard E Litz, and Raymond J. Schnell
Anthracnose, caused by Colletotrichum gloeosporioides, is the most serious production and postharvest problem of mango. Most mango cultivars are highly susceptible to this disease. Embryogenic nucellar cultures of two cultivars, `Hindi' and `Carabao', were recurrently selected with either the purified phytotoxin or the crude culture filtrate produced by the fungus. Mycelium growth was suppressed in dual cultures involving the recurrently selected lines. Enhanced extracellular production of proteins was observed in the embryogenic cultures and in regenerants, including a newly expressed acidic chitinase isozyme (`Hindi') and greater expression of two other chitinase isozymes (`Hindi' and `Carabao'). Activity of α-1,3-glucanase was also substantially increased in the recurrently selected lines. Resistant lines were characterized using RAPDs on the basis of polymorphisms generated by eight different primers. In most cases, the differences involved the absence of RAPD markers in resistant lines.
Stephanie S. Ningen, Janet C. Cole, and Kenneth E. Conway
Effect of night temperatures on the severity of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. on Euonymus fortunei (Turcz.) Hand.-Mazz. rooted cuttings of `Emerald Gaiety', `Canadale Gold', and `Emerald 'n Gold' was investigated. Uniform cuttings were exposed to day temperatures of 35.3 °C and night temperatures of 19.3 °C or 28.6 °C in growth chambers. Plants exposed to a 28.6 °C night temperature had higher disease ratings than those exposed to a 19.3 °C night temperature. `Emerald Gaiety' was damaged least by C. gloeosporioides compared to `Canadale Gold' and `Emerald 'n Gold'. Disease ratings on all cultivars increased linearly over the 6-week experimental period.
Stephanie S. Ningen, Janet C. Cole, Michael W. Smith, Diane E. Dunn, and Kenneth E. Conway
The effectiveness of shade intensity and time of day in which irrigation was applied were tested for control of anthracnose symptoms caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. on container-grown Euonymus fortunei (Turcz.) Hand.-Mazz. `Canadale Gold', `Emerald 'n Gold', and `Emerald Gaiety' during the 2002 and 2003 growing seasons. Rooted cuttings in 3.8 L containers were placed in 0% (full sun), 63%, 73%, or 80% shade at Park Hill, Okla., in 2002 and 2003 and at Stillwater, Okla., in 2002. Overhead irrigation was used to irrigate one-half of the plants in each cultivar and shade treatment in the morning and the other one-half during the afternoon. At both sites, disease damage ratings were inversely related to shade intensity throughout each growing season. Disease incidence was usually lower on afternoon irrigated plants than on morning irrigated plants. `Canadale Gold' typically had the most anthracnose symptoms followed by `Emerald 'n Gold'. `Emerald Gaiety' had the least symptoms regardless of shade intensity or irrigation time.
Stephanie L. Schupbach-Ningen, Janet C. Cole, James T. Cole, and Kenneth E. Conway
The effectiveness of chlorothalonil, mancozeb, and trifloxystrobin applied alone or in rotations of two or three fungicides to control anthracnose symptoms caused by Colletotrichum gloeosporioides was evaluated on three cultivars of field- and container-grown wintercreeper euonymus (Euonymus fortunei) during the 2001 growing season. Studies were conducted at Stillwater, Okla.; Fayetteville, Ark.; and Park Hill, Okla. Rooted cuttings of wintercreeper euonymus `Emerald Gaiety', `Emerald 'n Gold', and `Emerald Surprise' were transplanted from 1-gal plastic containers into field soil at the Oklahoma State University Nursery Research Station and at the University of Arkansas Horticulture Farm on 10 May 2001. In a parallel study, recently transplanted rooted cuttings of the same cultivars in 1-gal pots containing substrate consisting of pine bark and sand were placed in a shadehouse under 30% shade at Stillwater and Fayetteville and 73% shade at Park Hill on 11 May 2001. `Emerald Gaiety' had fewer disease symptoms than `Emerald 'n Gold' or `Emerald Surprise' in the field and in containers at Stillwater and Fayetteville. At Fayetteville, mancozeb applied alone or in rotation with chlorothalonil or trifloxystrobin provided better anthracnose control than treatments without mancozeb, but no fungicide eliminated anthracnose symptoms. Application of fungicides in rotations that include mancozeb and use of resistant cultivars can help decrease anthracnose symptoms.
Mark A. Ritenour, Robert R. Pelosi, Michael S. Burton, Eddie W. Stover, Huating Dou, and T. Gregory McCollum
Studies were conducted between November 1999 and April 2003 to evaluate the effectiveness of compounds applied preharvest for reducing postharvest decay on many types of fresh citrus (Citrus spp.) fruit. Commercially mature fruit were harvested two different times after the compounds were applied, degreened when necessary, washed, waxed (without fungicide), and then stored at 50 °F (10.0 °C) with 90% relative humidity. Compared to control (unsprayed) fruit, preharvest application of benomyl or thiophanate-methyl resulted in significantly (P < 0.05) less decay of citrus fruit after storage in nine out of ten experiments, often reducing decay by about half. In one experiment, pyraclostrobin and phosphorous acid also significantly decreased total decay by 29% and 36%, respectively, after storage compared to the control. Only benomyl and thiophanate-methyl significantly reduced stem-end rot (SER; primarily Diplodia natalensis or Phomopsis citri) after storage, with an average of 65% less decay compared to the control. Though benomyl significantly reduced anthracnose (Colletotrichum gloeosporioides) in two of four tests with substantial (>20%) infection and phosphorous acid significantly reduced it once, thiophanate-methyl did not significantly reduce the incidence of anthracnose postharvest. The data suggests that preharvest application of thiophanate-methyl may reduce postharvest SER and total decay similar to preharvest benomyl treatments.
Cheryl R. Boyer, Janet C. Cole, and Mark E. Payton
). Wintercreeper euonymus is an integral part of the nursery inventory because of the cultivars available and popularity with consumers. Wintercreeper euonymus is susceptible to Colletotrichum gloeosporioides during production and in the landscape, resulting in
Barbara J. Smith
present in the United States for some time under the name of Gloeosporium spp. ( Maas, 1984 ). Colletotrichum gloeosporioides causes anthracnose crown rot, petiole lesions, and leaf spots indistinguishable from those caused by C. fragariae . In a
Douglas A. Phillips, Philip F. Harmon, James W. Olmstead, Natalia A. Peres, and Patricio R. Munoz
. Weir, B.S. 2012 Colletotrichum —Current status and future directions Stud. Mycol. 73 181 213 Dodd, J.C. Estrada, A.B. Matcham, J. Jeffries, P. Jeger, M.J. 1991 The effect of climatic factors on Colletotrichum gloeosporioides , causal agent of mango
Mark K. Ehlenfeldt, James J. Polashock, Allan W. Stretch, and Matthew Kramer
Response to foliar infection by Colletotrichum acutatum Simmonds ex Simmonds was assayed in a diverse group of 149 blueberry cultivars and selections using a detached leaf-disk assay. Disks were inoculated and incubated for one week, then were digitally imaged, and images analyzed for percent leaf decay. Infection percentages across cultivars averaged 32%, and ranged from 8% to 79%. The lowest levels of foliar infection were seen in the cultivars, Burlington, Sharpblue, and Berkeley. Foliar responses were compared to anthracnose fruit rot susceptibility data from a previous study. Several clones were observed to have low levels of both foliar and fruit infection. Cultivars with particularly good resistance to both phases included `Sharpblue', `Sunshine Blue', `Legacy', `Little Giant', `Flordablue', `Elliott', `Blue Ridge', `Blue Rose', and `November Glow'. Little correlation was observed between foliar response and fruit response to anthracnose infection (r = 0.15). Since C. acutatum overwinters primarily in vegetative tissue, breeding new cultivars with foliar resistance may assist in reducing inoculum levels of this disease under field conditions.