scholarly journals Behavior of Italian Lemon Rootstocks towards Mal Secco Leaf Infection with Tunisian Fungus Phoma tracheiphila in Controlled Environment

2012 ◽  
Vol 03 (07) ◽  
Author(s):  
Sana Ziadi
Keyword(s):  
Controlled Environment ◽  
Leaf Infection ◽  
Phoma Tracheiphila ◽  
Mal Secco

Impairment of leaf hydraulics in young plants of Citrus aurantium (sour orange) infected by Phoma tracheiphila

2007 ◽  
Vol 34 (8) ◽  
pp. 720 ◽  
Author(s):  
Fabio Raimondo ◽  
Francesco Raudino ◽  
Santa Olga Cacciola ◽  
Sebastiano Salleo ◽  
Maria Assunta Lo Gullo
Keyword(s):  
Conidial Suspension ◽  
Sour Orange ◽  
Citrus Aurantium ◽  
Citrus Species ◽  
Leaf Hydraulics ◽  
Primary Mechanism ◽  
Major Vein ◽  
Leaf Infection ◽  
Phoma Tracheiphila ◽  
The Impact

Phoma trachephila (Petri) Kantschaveli et Gikachvili causes dieback of several Citrus species. The impact of this fungus on leaf hydraulics was studied in Citrus aurantium L. (sour orange) with the aim of identifying the primary mechanism of damage to leaves. Leaves inoculated with a conidial suspension were measured for conductance to water vapor (gL) and specific hydraulic conductance (Kleaf) every 3 days after inoculation. The earliest symptom of infection consisted of vein chlorosis. Functional vein density (FVD) was monitored and microscopic observations were made of major vein conduits. Impairment of vein hydraulics started 25 days after inoculation with a losses of Kleaf of 40% and gL of ~60%. Most minor veins within chlorotic areas were no longer functioning and some conduits of the major veins showed digested interconduit pits leading to vein cavitation. The close Kleaf–FVD relationship revealed that vein impairment caused drop of Kleaf and, consequently, of gL at chlorotic areas. Leaf infection was focused to veins that were first forced to embolise and then invaded by fungal hyphae. The vein embolism due to the Phoma amplifies the native dominant hydraulic resistance of leaf veins, and leads ultimately to early shedding of infected leaves.

scholarly journals Mal Secco Disease Caused by Phoma tracheiphila: A Potential Threat to Lemon Production Worldwide

Plant Disease ◽  
2009 ◽  
Vol 93 (9) ◽  
pp. 852-867 ◽  
Author(s):  
Quirico Migheli ◽  
Santa Olga Cacciola ◽  
Virgilio Balmas ◽  
Antonella Pane ◽  
David Ezra ◽  
...  
Keyword(s):  
Potential Threat ◽  
Phoma Tracheiphila ◽  
Mal Secco

An aggressive vascular-inhabiting Phoma (Phoma tracheiphila f. sp. chrysanthemi nov. f. sp.) weakly pathogenic to chrysanthemum

1985 ◽  
Vol 63 (10) ◽  
pp. 1730-1735 ◽  
Author(s):  
Kenneth F. Baker ◽  
Lily H. Davis ◽  
Stephen Wilhelm ◽  
William C. Snyder
Keyword(s):  
Verticillium Wilt ◽  
Home Gardens ◽  
Infested Soil ◽  
Sour Orange ◽  
Rough Lemon ◽  
Decline Disease ◽  
Phoma Tracheiphila ◽  
Intact Roots ◽  
Mal Secco ◽  
Mycelial Development

A form of Phoma tracheiphila (Petri) Kant. & Gik., newly designated as f. sp. chrysanthemi Baker et al., massively invades the phloem and xylem and to a lesser extent the cortex and pith of chrysanthemum plants but causes only slight injury in the first season. However, infected plants either produce weak shoots the following year or commonly fail to resume growth. Injury appears to result from depletion of photosynthates and nutrients rather than from vascular plugging or toxins. Infection occurs through intact roots or through wounds of roots or stems, and the pathogen spreads to the top of 120-cm stems in 3 months. Infection occurs readily from 10–29.4 but most abundantly at 10–21° C. Mycelial development in the stems is retarded at 10 and is optimal at 21° C. This Phoma decline disease was prevalent in commercial and home chrysanthemum plantings in California in 1948–1956, but it has since been controlled by the annual planting of healthy cuttings in fumigated soil, as practiced for control of verticillium wilt. In home gardens the disease may cause severe losses if plants are grown as perennials, but if healthy cuttings are planted annually, the disease will be minimal even in plants grown in infested soil. The pathogen is indistinguishable morphologically from Phoma tracheiphila f. sp. tracheiphila Baker et al., cause of "mal secco" of citrus, but will not infect sour orange or rough lemon plants.

Phoma tracheiphila (Mal secco).

2021 ◽  
Author(s):  
Keyword(s):  
Plant Protection ◽  
The Black Sea ◽  
Citrus Limon ◽  
Black Sea Region ◽  
Mediterranean Countries ◽  
The World ◽  
Phoma Tracheiphila ◽  
Means Of Transmission ◽  
International Plant ◽  
Mal Secco

Abstract P. tracheiphila is a conidial fungus causing serious damage and death to the host, particularly lemon [Citrus limon], in Citrus and related genera, in Mediterranean countries and the Black Sea region. So far, however, it is unknown in Spain, Portugal and Morocco, as well as other major citrus-growing regions of the world. This fungus is of concern to many international plant protection organizations and must be prevented from being spread in infected propagative material. It was once reported as seedborne in lemon, but there is no further evidence of this means of transmission. Once in the orchard, the fungus can be carried as spores from pycnidia and from hyphae on the plant and on fallen debris by rain, wind and irrigation water, and perhaps by birds and insects.

Susceptibility of subterranean clover varieties to powdery mildew under controlled environment and field conditions

1991 ◽  
Vol 31 (1) ◽  
pp. 81 ◽  
Author(s):  
MJ Barbetti ◽  
PGH Nichols
Keyword(s):  
Powdery Mildew ◽  
Subterranean Clover ◽  
Field Conditions ◽  
Controlled Environment ◽  
Excellent Correlation ◽  
Good Resistance ◽  
Breeding Programs ◽  
Leaf Infection ◽  
High Degree ◽  
Field Plots

Thirty-three subterranean clover varieties, comprising 16 commercial cultivars and 17 promising midseason breeding and introduced lines, were screened for resistance to powdery mildew (caused by Erysiphe polygonii) under controlled environment conditions, and where possible, comparisons were made with their performance in field plots. There were large differences between varieties in the incidence and severity of powdery mildew on plants. Under controlled environment conditions, Tallarook, CPI 47308C, CPI 89860D, 75S13-12, CPI 6.53284 CPI 89820D and Clare had the lowest levels of leaf infection, the lowest mildew sporulation scores and the least amount of leaf scorching from mildew infection. Karridale had the highest level of leaf infection, followed by 69837-1, 76841-1, Junee, Bacchus Marsh and 69S37-3. Under field conditions, Tallarook, CPI 47308C, CPI 65328A and CPI 65328F were mildew-free, while CPI 89777C, CPI 89860D, CPI 89830F, CPI 89841E, Clare and Rosedale had good resistance. Junee was clearly the most susceptible under field conditions, followed by 76S41-1, 69837-3, Karridale, Bacchus Marsh and 69S37-1. There was generally excellent correlation between the different powdery mildew disease parameters, namely leaf infection, mildew sporulation and leaf scorch, measured under controlled environment conditions, and there was also good overall correlation between controlled environment and field data. Bacchus Marsh, Junee, 69337-1, 69837-3 and 76341-1 were highly susceptible under both controlled environment and field conditions, indicating that either environment could be used to identify highly susceptible varieties. Under controlled environment conditions, a high degree of resistance was observed in Clare, CPI 47308C, CPI 65328A, CPI 89820D, CPI 89860D and 75S13-12, while field plots of the varieties Tallarook, CPI 47308C and CPI 65328A showed a complete absence of powdery mildew. These varieties may have value as parents in breeding programs for powdery mildew resistance.

Susceptibility of subterranean clover varieties to rust under controlled environment and field conditions

1991 ◽  
Vol 31 (1) ◽  
pp. 77 ◽  
Author(s):  
MJ Barbetti ◽  
PGH Nichols
Keyword(s):  
Rust Resistance ◽  
Subterranean Clover ◽  
Field Conditions ◽  
Controlled Environment ◽  
Good Resistance ◽  
Breeding Programs ◽  
Commercial Cultivars ◽  
Leaf Infection ◽  
High Degree ◽  
Field Plots

Thirty-two subterranean clover varieties, comprising 17 commercial cultivars, 1 named variety and 14 promising midseason breeding and introduced lines, were screened for resistance to rust (caused by Uromyces trifolii-repentis) under controlled environment conditions, and where possible, comparisons were made with their performance in field plots. There were large differences between varieties in the incidence and severity of rust on plants. Under controlled environment conditions, cvv. Gingin, Meteora and Enfield, and to a lesser extent Larisa and Trikkala, had the lowest levels of rust leaf infection, the lowest rust pustule densities and the smallest rust pustules. Seaton Park had a relatively low pustule density and CPI 89830F had relatively small pustules. Gingin and Enfield had the least leaf collapse. Green Range was the most susceptible under controlled environment conditions, followed by Bacchus Marsh, Karridale, CPI 47308C and CPI 89841E. Under field conditions, Enfield, Meteora, Trikkala and CPI 89822H were rust free, while Larisa, CPI 47308C, CPI 65328F, 75S13-12, 76841-1, CPI 89830F and CPI 89880J had good resistance. Green Range was clearly the most susceptible under field conditions, followed by Seaton Park, Karridale, Bacchus Marsh, CPI 89774F and CPI 89841E. While there was often good correlation between the field and controlled environment data for the different parameters, the resistance rankings of some varieties varied widely, depending upon whether screened under controlled environment or field conditions. Green Range, Karridale, Seaton Park and CPI 89841E were highly susceptible to rust under both controlled and field conditions, indicating that either environment could be successfully used to identify highly susceptible varieties. The high degree of resistance observed in Enfield, Gingin and Meteora, and to a lesser extent in Larisa and Trikkala, suggests their value as parents in breeding programs for rust resistance.

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